Jackson Laboratory Research Articles

Synergistic Growth Inhibition of NPM1 Mutant AML PDX By Combined Therapy with BCL-2 Inhibitor Venetoclax (ABT-199) and Menin Inhibitor DS-1594b In Vivo

Introduction: Mixed-lineage-leukemia (MLL) translocations are prevalent in hematologic malignancies, resulting in aggressive leukemias resistant to standard therapies and low 5-year survival rates. These translocations lead to the production of MLL fusion proteins that promote leukemia development by enhancing proliferation, inhibiting hematopoietic differentiation, and driving leukemogenesis. Acute myeloid leukemia (AML), an aggressive blood cancer with a grim prognosis, particularly in elderly patients, frequently involves mutations in the nucleophosmin (NPM1) gene. Importantly, the interaction between Menin, MLL, and MLL fusion proteins play a crucial role in the pathogenesis of AML, both with MLL rearrangements (MLLr) and in leukemias carrying NPM1 mutations. Inhibition of the Menin-MLL interaction using novel Menin inhibitors has demonstrated efficacy in pre-clinical and clinical studies for both AML subsets. In this study, we investigate the effectiveness of the novel Menin-MLL inhibitor DS-1594b, developed by Daiichi Sankyo Co. Ltd., in combination with the BCL-2 antagonist venetoclax (ABT-199), in a patient-derived xenograft (PDX) model of NPM1-mutated acute leukemia. We have previously reported synergistic lethality and differentiation-inducing effects of this drug combination in both AML cell lines and primary leukemia samples in vitro (Ciaurro et al., Blood 2022). Our findings shed light on the potential of this therapeutic combination for the targeted treatment of AML with NPM1 mutations. Methods: NSG mice (female, 8-10 weeks old) were purchased from Jackson Laboratory. Mice were inoculated via the tail vein with NPM1m PDX/luc/GFP (3×10 6 cells). Once leukemia engraftment was confirmed by bioluminescent imaging mice were randomized in 4 groups: vehicle, ABT199, DS-1594b alone, and combination. After 12 days drugs were administered as follows: DS1594b at a dosage of 50 mg/kg by oral gavage for 4 weeks; ABT-199 at a dosage of 50 mg/kg by oral gavage for 2 weeks and 100mg/kg for the other 2 weeks. NSG mice were euthanized by CO 2 inhalation at the endpoint of the study in accordance with IACUC protocols. BM and spleens were harvested in a sterile environment and flushed in HBSS with 1% FBS. For CyTOF data spleen cells were initially barcoded and stained with metal-conjugated antibodies according to Fluidigm's protocols and samples were analyzed by CyTOF (Helios) Mass Cytometer. Results: New in vitro data confirmed synergistic lethality on additional AML cell lines and demonstrated upregulation of PARP-C and Caspase3-C apoptosis pathways using western blot analysis. Further, additional 3 primary AML patient samples showed additive or synergistic growth inhibition when treated with combination of drugs. In the in vivo experiment with NPM1m PDX/luc/GFP AML PDX model, we found that co-treatment with DS-1594b and venetoclax for four weeks resulted in a greater reduction in AML burden compared to treatment with either agent alone or a vehicle control as shown by Bioluminescence imaging. Moreover, weight of mice in the combo group was not significantly affected, while mice lost weight in vehicle and in single agent cohort due to rapid disease progression. The survival curve clearly demonstrated the benefits of the combination treatment, with the DS-1594b group having modest anti-tumor efficacy, and the combination group showing the greatest efficacy (Fig. 1A). To study the effects on cell differentiation, we used CyTOF technique, which allowed us to analyze a complete panel of 30 markers. We found two populations of cells, which we named populations (pop) 3 and pop 4, that were enriched in the group treated with the combination of drugs compared to the control group (Fig 1B). These populations of cells had higher levels of expression of CD33 and CD38, which are well-known markers of cellular differentiation. Conclusions: In this study, we present the in vivo effectiveness of DS-1594b in combination with venetoclax in a PDX model of NPM1-mutated AML. Moreover, the combination treatment exhibits differentiation-inducing effects, which contribute to its therapeutic effectiveness, and was safe. Overall, our findings strongly indicate that the combination of DS-1594b and venetoclax exhibits promising anti-leukemic activity in vivo and holds potential as a therapeutic strategy for AML patients with mtNPM1 mutations.

Tasquinimod Improves Erythropoiesis and Mitigates Bone Loss in Myelodysplastic Mice

Myelodysplastic neoplasms (MDS) are characterized by ineffective hematopoiesis, peripheral cytopenia, and a risk of transforming into acute myeloid leukemia (AML). Interestingly, MDS is also associated with an increased prevalence of osteoporosis. Studies have suggested that dysregulated innate immune responses and a proinflammatory bone marrow (BM) microenvironment play significant roles in the pathogenesis of MDS. Targeting inflammatory pathways, especially in low-risk MDS patients, presents a potential strategy to modulate the progression of the disease. One such candidate is Tasquinimod (TASQ, ABR-215050, Active Biotech AB), a small-molecule oral inhibitor and second-generation quinoline-3-carboxamide compound. TASQ binds to the inflammatory protein S100A9 and inhibits its interaction with the proinflammatory toll-like receptor 4, thereby displaying both immunomodulatory and antitumor properties. Our in vitro data provided evidence for a rescuing effect of TASQ on inflammatory signal-primed MDS stromal cells, leading to enhanced hematopoietic support. This study aims to validate these findings using a transgenic MDS mouse model expressing the NUP98/HOXD13 (NHD13) fusion protein in hematopoietic cells. NHD13 mice, generated on a C57BL/6J background, were obtained from Jackson Laboratory. TASQ was administered orally by adding it to the drinking water at a dose of 30 mg/kg. Both transgenic and littermate control (WT) mice (12 weeks old, n=5-10 per group) were treated with or without TASQ for 12 weeks. Throughout the experiment, peripheral blood cell counts were measured every 4 weeks using Sysmex analysis. In the final analysis, primary BM cells were isolated from the femora, and the number of lineage-negative, sca-1-positive, and c-kit-positive (LSK) cells, as well as erythroid differentiation, were assessed using flow cytometry. Additionally, bone volume, trabecular number, and thickness were analyzed in femora using µCT. Transgenic NHD13 mice displayed MDS-like characteristics, including peripheral cytopenias, dysplasia in blood and BM cells, and microstructural abnormalities in the bone microenvironment. As expected, hemoglobin levels (Hb) and red blood cell (RBC) counts were lower in NHD13 mice compared to WT mice [Hb: 8.9 vs. 9.5 mmol/L; RBC: 9.5 vs. 10.3x1012/L] and showed a consistent decrease in the untreated group from 12 to 24 weeks. Notably, treatment with TASQ significantly improved red blood cell counts in NHD13 mice [+14%; p<0.01] after 24 weeks, while having no effect on WT mice. White blood cells were significantly decreased in WT mice after 4 weeks of TASQ treatment [-19%; p<0.001] until the end of the experiment [-36%; p<0.001]. In contrast, in transgenic mice, the lower white blood cell counts [-76%; p<0.001] were not further diminished. Interestingly, TASQ led to an elevation in neutrophil counts. The platelet count was not affected by the treatment in both transgenic and WT mice. Using flow cytometry, an increase in the total number of LSK cells was detected in the BM of WT mice after TASQ treatment. However, no increase was observed in NHD13 mice, which already had lower LSK numbers compared to WT controls. Late-stage erythropoiesis was slightly increased in both WT and transgenic mice after TASQ treatment, whereas early erythroid differentiation was unaffected or even decreased by TASQ. Moreover, BM cells were used for colony-forming assays ex vivo. NHD13 mice had a lower erythroid differentiation potential compared to WT mice, which was improved after TASQ treatment. To assess the potential influence of the microenvironment, adherent BM cells were assayed for their CFU-F forming capacity. BM cells of transgenic mice exhibited a slightly lower CFU-F forming capacity compared to WT mice, which was partially reversed by TASQ treatment. Finally, the bone microarchitecture was analyzed. NHD13 mice showed a lower bone volume [-43%; p<0.01] compared to WT mice. Notably, treatment with TASQ abolished the bone loss in NHD13 mice by increasing the trabecular number [+35% p<0.001], whereas the trabecular thickness was not affected. In conclusion, this study provides the first evidence for an in vivo effect of TASQ in a murine model of MDS, suggesting improved erythropoiesis and positive effects on the bone phenotype. These results warrant further investigations of TASQ in human trials, particularly in MDS patients in whom anemia and bone loss often coexist.

Age-related changes of auditory sensitivity across the life span of CBA/CaJ mice

The inbred mouse strain CBA/CaJ is a frequently used animal model of age-related hearing loss in humans. These mice display significant hearing loss at a relatively advanced age, similar to most humans, with progressive loss of hearing as the mouse continues to age. While important descriptions of hearing loss in this mouse strain at multiple ages have previously been published, shortcomings persist in the data for hearing over the lifespan of the mouse. Therefore, we analyzed auditory brainstem response threshold data from records maintained by our research group to yield an extensive database of thresholds over nearly the entire life span of the CBA/CaJ mouse (from 79 to 1085 days). Data was collected from in-house bred mice of CBA/CaJ stock, initially from The Jackson Laboratory. Data was collected using BiosigRZ software and TDT System III hardware. Thresholds were routinely measured in conjunction with behavioral and electrophysiological experiments; only responses from baseline or experimentally naïve animals were analyzed. The resulting data set comprised 376 female mice and 441 males. At the lowest and highest frequencies (8 & 32 kHz), initial thresholds were just under 30 dB SPL and increased slowly until they were significantly different at 16-18 months compared to 1-3 months age, with the difference increasing over subsequent ages. At the middle frequencies (12 & 16 kHz), initial thresholds were just under 20 dB SPL and increased until they became different from initial at 16-18 months. At 24 kHz, initial thresholds were just above 20 dB and became different from initial at 13-16 months of age. The rate of change of thresholds with age were similar for all frequencies until about 30 months of age, when 32 kHz threshold changes lagged behind other frequencies. Generally, CBA/CaJ mice in our colony display relatively low thresholds until approximately 16 months of age, depending on frequency. After 16-18 months, thresholds become significantly worse. After approximately 20-22 months thresholds increase linearly with age.

Abstract 16904: Low-Dose Isoproterenol Administration in the Murine MDX Model Unmasks Progression of Duchenne-Associated Cardiomyopathy

Introduction: The cardiovascular phenotype resulting from Duchenne muscular dystrophy (DMD) includes cardiomyopathy (CMP) leading to congestive heart failure and early mortality. CMP is the leading cause of death in DMD. Our objective was to characterize the progression of CMP in a murine model of DMD. We hypothesized that a genetic mouse model of DMD will exhibit significantly lower function over time as measured by ejection fraction when given an isoproterenol (IPT) challenge. Methods: We examined a mouse model of DMD from the Jackson Laboratory: C57BL/10ScSn- Dmd mdx /J (B10.mdx; n=6 female). The genetic group was paired with the wild type control strain C57BL/10ScSnJ (B10; n=6 female mice). B10.mdx (MDX) and B10 (WT) mice received intraperitoneal IPT administered via daily injections at 3 mg/kg. Cardiac function was assessed by 2D ultrasound using a Vevo3100 imaging system (FUJIFILM, VisualSonics) from the baseline, immediate effects of IPT injection at 1 minute, after 7, 14, and 21 days. Results: At 1 minute following the first IPT injection in WT and MDX, we observed increases in EF and HR for both groups ( Figure 1 ). While the changes in EF were notable yet not reaching significance, the differences within groups between baseline and 1 minute after injection were significant due to HR response ( p <0.05).We observed decreases in EF for both groups between baseline and day 7 following IPT injections ( Figure 1 ). The changes in MDX EF between baseline and day 7 approached significance. The EF in both groups was maintained through day 7, day 14, and day 21. 2 deaths in MDX occurred during the treatment period and 1 death followed day 7. A WT sacrifice was made after day 14 due to severe dermatitis. Conclusion: Murine mdx models exhibit DMD-associated CMP comparable to humans. Associated humanlike phenotype includes decreased EF, FS, ESV, EDS, and SV. A low dose of IPT in MDW mice has the potential to unmask these changes within 7 days, reducing the need for longer term murine studies.

Chronic TNF in the Aging Microenvironment Exacerbates TET2-loss-of-Function Myeloid Expansion

Introduction: Age-associated TET2 somatic mutations impart an intrinsic hematopoietic stem cell (HSC) advantage and contribute to the phenomenon of clonal hematopoiesis of indeterminate potential (CHIP). Individuals with TET2-mutantCHIP have a higher risk of developing myeloid neoplasms and other age-related conditions, including heart, lung, liver, kidney and infectious disease, and have increased risk of all-cause mortality. Despite its role in unhealthy aging, the extrinsic mechanisms driving TET2-mutant CHIP clonal expansion remain unclear. We previously showed an environment containing TNF favours TET2-mutant HSC expansion in vitro. We therefore postulated that age-related increases in TNF also provide an advantage to HSC and progeny with TET2-mutations in vivo. Methods: All human and mouse studies met ethics approval. C57Bl/6 background wildtype (WT), TNF-α knockout ( TNF-/-), Tet2 hematopoietic knockout (Vav1-iCre-mediated; Tet2-/-) and floxed control mice ( Tet2f/f) mice were obtained from the Jackson Laboratory. Young (6-mo [n=9]) and old (18-22 mo [n=9]) WT mice, and old TNF-/- mice (n=7) were subjected to nonirradiative myeloablation with busulfan, and retro-orbital injections of 8x10 6 cells/ml T-cell-depleted bone marrow (BM), equally harvested from 4-mo-old WT CD45.1 (n=5) and Tet2-/- CD45.2 donor mice (n=5). Flow cytometry was used to confirm and monitor engraftment. Mice were harvested 8 weeks post-transplant for analysis of HSC, progenitor, monocyte and neutrophil populations, and cytokine analyses. Consenting human research participants diagnosed with rheumatoid arthritis (RA) were recruited from the Greater Hamilton Area (Ontario, Canada) from 2016-2018. Blood draws occurred prior to any immunomodulatory treatment (baseline), and at 3- and 6-months following treatment with Adalimumab (Humira®), an anti-TNF agent. CHIP status was determined with our successful 48-gene, targeted, Ion-Torrent based sequencing approach to isolated genomic DNA from PBMC. Confirmation of calls and increased sensitivity to detect clones with VAF < 0.02 employed our established single molecule molecular inversion probes (smMIP)-targeted genomic capture technique and high-depth (47,500X avg. coverage) paired-end sequencing, employing high-stringency filters for error-suppression. Statistical analyses were performed in GraphPad Prism V9.2 or R 4.1.2. Results: 1. Mixed BM chimeric mice of WT and TNF -/- genotypes reconstituted with WT CD45.1 + and Tet2 -/- CD45.2 + HSC showed that age-associated increases in TNF significantly increased by 2- to 2.5-fold the proportions of HSC in old recipient mice, with myeloid lineage skewing (2- to 2.5-fold more granulocyte-monocyte, monocyte-dendritic and common monocyte progenitor cells in BM, and dramatic expansion of Tet2-/- monocytes and neutrophils in blood). This aberrant myelomonocytic advantage was mitigated in old TNF -/- recipient mice, suggesting that TNF signalling in the BM is essential for Tet2-mutant myeloid expansion. 2. Age-associated TNF predisposed Tet2-/- HSC to the development of Ly6C high inflammatory monocytes, including increased intracellular and serum TNF levels, further exacerbating an inflammatory environment in favor of Tet2-mutantexpansion. 3. Examination of human RA patients (n=7; avg. age 57y) with serial PBMC sampling revealed one patient with CHIP driven by CBL and PPM1D variants, with a 32% reduction in clone size between 3 and 6 months of anti-TNF therapy (adalimumab). Two additional variants were detected at baseline in this RA patient, TP53 R196* (VAF = 1.34%) and ASXL1 P689L (VAF = 3.13%), but these were not detected at 3- and 6-months post-treatment even with high-depth, error suppression sequencing. Two additional patients had detectible low-level CH clones prior to anti-TNF treatment - one with a STAG2 R1033Q variant at baseline (VAF = 1.65%) and the other with a TET2 baseline E798K variant (VAF = 1.68%) - but not detected during anti-TNF treatment. Conclusions: We present novel findings that TNF in the aging BM environment has a causal role in driving TET2-mutant CHIP in vivo, and the first examination of the impact of TNF blockade on CH dynamics in humans, suggesting promise for reducing clonal burden. Larger, prospective studies are required to confirm these findings and to determine if inflammatory cytokine blockade may improve CHIP-comorbid conditions and myeloid cancer risk.

Genetic Polymorphisms in the Ferrireductase STEAP3 Regulate a Ferroptosis-like Process of Lipid Peroxidation-Induced Hemolysis in Murine and Human Red Blood Cells

Red blood cell (RBC) storage in the blood bank induces a series of biochemical and morphological alterations, collectively denoted as the storage lesion(s). Membrane damage by lipid peroxidation is a hallmark of the storage lesion, a process thought to be triggered by oxidant stress. To identify the genetics underlying this phenomenon, we leveraged a novel murine system, the Jackson lab Diversity Outbred (JDO) mouse colony, which was obtained by extensively cross-breeding 8 founder mouse strains with extreme genetically heterogeneity ( Figure 1.A). A total of 350 fresh and stored (up to 7 days) murine RBC samples were tested by mass spectrometry-based metabolomics and lipidomics. At the end of storage, post-transfusion recovery (PTR), which measures intra- and extravascular hemolysis and is a gold standard for determining RBC storage quality, was determined by quantifying the percentage of stored RBCs that were still circulating 24h after their transfusion into Ubi-GFP+ recipient mice ( Figure 1.A). Genome wide-association studies identified a strong association between PTR and a polymorphic region on chromosome 1 ( Figure 1.A), which encodes STEAP3, a ferrireductase. This region was associated with altered metabolism of stored RBCs ( Figure 1.A), especially an elevation of lipid peroxidation products (hive plot in Figure 1.A). Mechanistically, these data support a role for STEAP3 in promoting Fenton and Haber-Weiss chemistry in iron-loaded RBCs. Specifically, ferrous iron participates in this chemistry, becoming oxidized to its ferric state with concomitant generation of hydroxyl or hydroperoxyl radicals; these in turn attack fatty acids (preferentially, poly- and highly-unsaturated fatty acids, such as octadecadienoic and eicosatetraenoic acid), thereby promoting lipid peroxidation (to hydroxyoctadecadienoic (HODE) and hydroxyeicosatetraenoic (HETE) acids, respectively). By reducing Fe 3+ to Fe 2+, STEAP3 can shift the balance of this reaction by increasing the availability of the reactant, thereby favoring the generation of product radicals; this process is analogous to ferroptosis, as described in other biological systems. To extend the relevance of these findings to humans, we performed metabolomics on end-of-storage (i.e., Day 42) packed RBCs from 13,091 human donors in the Recipient Epidemiology and Donor Evaluation Study (REDS RBC Omics; Figure 1.B), enrolled in four blood centers across the United States. We stratified donors based on oxylipin levels (e.g., acids - HETEs - Figure 1.B) and common STEAP3 polymorphisms (e.g., a representative non-synonymous coding single nucleotide polymorphism (SNP), rs17013371, was observed with ~10% prevalence in these donors), along with 37 other common SNPs observed in this study ( Figure 1.B). When correlating metabolic and hematological parameters to common STEAP3 non-synonymous coding SNPs, we found strong associations of such polymorphisms with RBC susceptibility to hemolysis (either osmotic or oxidative), lipid peroxidation, RBC numbers, and hemoglobin levels ( Figure 1.B). These associations held true for a subset of the original donors with extreme hemolytic propensity (n=643) who donated a second RBC unit that was again stored for 42 (i.e., the “recalled donor population”). In the initial (n=13,091) and recalled donor (n=643) populations, lipid peroxidation products, HETEs, and HODEs ranked as the top predictors of hemolysis and vesiculation. In summary, we identified a role for the STEAP3 ferrireductase in contributing to a ferroptosis-like phenotype of lipid peroxidation that is associated with increased susceptibility to hemolysis in vitro and in vivo in murine and human RBCs following storage under blood bank conditions. Figure 1 - A. Jackson Lab diversity outbred (JDO) mice were bred from 8 founder mouse strains with extreme genetic heterogeneity. A total of 350 fresh and stored murine red blood cells (RBCs) were tested for metabolomics, lipidomics, and post-transfusion recovery (PTR). A polymorphic region on chromosome 1, coding for the ferrireductase STEAP3 was associated with heterogeneous PTR and elevation in lipid peroxidation products. B. Metabolomics analyses of 13,091 donors from the REDS RBC Omics identified an association between the end of storage levels of oxylipins and common polymorphisms for STEAP3, both linked to an increased RBC susceptibility to hemolysis (either osmotic or oxidative.

6 Exercise Induced Growth Factor Increases Directly and Indirectly Reduce Systemic Vascular Risk Parameters: Translational Project Amongst Midlife Human and Animal Models of Preclinical Alzheimer’s disease and Vascular Dementia

Objective:Using a humanized APOE3/4 (Alzheimer’s disease genetic risk allele) mouse model we investigated the potential modulating effects of exercise on systemic risk factors and the ability of this mouse model to translate to active or sedentary, midlife, human participants. We present preliminary results of an ongoing, translational pilot study.Participants and Methods:26 Midlife individuals, ages 40-65, were recruited from the community and dichotomized into active or sedentary groups following health screening and cognitive assessment. Blood samples were drawn from human participants for lipid assessment and other general health measures as well as peripheral growth factors concentrations (VEGF, BDNF and FGF21). Traditional, transgenic mouse models have helped the scientific community to understand biological mechanisms of Alzheimer’s disease (AD), but they do not develop significant neuronal loss, a hallmark of AD pathology. The MODEL-AD consortium has created a new “humanized” APOE4 model that has the human APOE4 allelic sequence in place of the mouse APOE gene; the model has shown known human phenotypes including deficits in cholesterol trafficking, amyloid clearance and BBB integrity. Of upmost importance, this model does not develop a full AD phenotype indicating that additional genetics and/or environmental factors are required as would be seen in human populations. We used males and females of this model to complete identical sedentary and active measures of each APOE genotype.Results:Lipid and general health marker assessment between mouse and human were similar and reproduced published literature. In both humans and mice we saw increased total cholesterol and HDL in active females and decreased total cholesterol and HDL in active males. We also saw similar relationships between APOE genotype, sex, and activity with regards to triglycerides. Although total cholesterol, HDL and LDL measures are the primary lipids needed to confirm or deny translation, other lipid measurements were not equivalent between the two models. Growth factor assessment in both species are also similar and reproduce published literature with regards to VEGF and BDNF as we see trending elevated levels in the active group. Less published on is the finding seen between active females and these elevated growth factors levels; our results indicates that although elevated as a result of exercise, this increase may be more prominent in females.Conclusions:Based on the results found here we conclude that The Jackson Laboratory’s humanized APOE3/4 mouse model is a translatable model of vascular dysfunction, dementia and Alzheimer’s disease. We also conclude that exercise modulates these aspects by growth factor activation and increases resulting in downstream effects that reduce peripheral vascular risk factors and therefore reduce the risk of Alzheimer’s disease as a result of neuroinflammation. Complete, APOE genotype results from human participants are still ongoing. Descriptive analysis is limited by human samples size.

Genotyping Protocols for Genetically Engineered Mice.

Historically, the laboratory mouse has been the mammalian species of choice for studying gene function and for modeling diseases in humans. This was mainly due to their availability from mouse fanciers. In addition, their short generation time, small size, and minimal food consumption compared to that of larger mammals were definite advantages. This led to the establishment of large hubs for the development of genetically modified mouse models, such as the Jackson Laboratory. Initial research into inbred mouse strains in the early 1900s revolved around coat color genetics and cancer studies, but gene targeting in embryonic stem cells and the introduction of transgenes through pronuclear injection of a mouse zygote, along with current clustered regularly interspaced short palindromic repeat (CRISPR) RNA gene editing, have allowed easy manipulation of the mouse genome. Originally, to distribute a mouse model to other facilities, standard methods had to be developed to ensure that each modified mouse trait could be consistently identified no matter which laboratory requested it. The task of establishing uniform protocols became easier with the development of the polymerase chain reaction (PCR). This chapter will provide guidelines for identifying genetically modified mouse models, mainly using endpoint PCR. In addition, we will discuss strategies to identify genetically modified mouse models that have been established using newer gene-editing technology such as CRISPR. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Basic Protocol 1: Digestion with proteinase K followed by purification of genomic DNA using phenol/chloroform Alternate Protocol: Digestion with proteinase K followed by crude isopropanol extraction of genomic DNA for tail biopsy and ear punch samples Basic Protocol 2: Purification of genomic DNA using a semi-automated system Basic Protocol 3: Purification of genomic DNA from semen, blood, or buccal swabs Basic Protocol 4: Purification of genomic DNA from mouse blastocysts to assess CRISPR gene editing Basic Protocol 5: Routine endpoint-PCR-based genotyping using DNA polymerase and thermal cycler Basic Protocol 6: T7E1/Surveyor assays to detect insertion or deletions following CRISPR editing Basic Protocol 7: Detecting off-target mutations following CRISPR editing Basic Protocol 8: Detecting genomic sequence deletion after CRISPR editing using a pair of guide RNAs Basic Protocol 9: Detecting gene knock-in events following CRISPR editing Basic Protocol 10: Screening of conditional knockout floxed mice.

First person – Ari Dehn

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Ari Dehn is first author on ‘ Epithelial mechanics are maintained by inhibiting cell fusion with age in Drosophila’, published in JCS. Ari conducted the research described in this article while a Research Associate in Dr Vicki Losick's lab at Boston College, MA, USA. Ari is now a Research Assistant at The Jackson Laboratory, Bar Harbor, ME, USA, where they are interested in exploring new ideas and using science to further understand human health and disease.

SAT386 Constitutive Overexpression Of Microrna-93 As A Cause Of Metabolic Dysfunction And Hyperandrogenism In Polycystic Ovary Syndrome (PCOS): Evidence From A Transgenic (Mir-93+) Murine Model

Abstract Disclosure: Y. Chen: None. H. Wu: None. B.A. Gower: None. R. Azziz: Advisory Board Member; Self; Arora Forge. Consulting Fee; Self; Fortress Biotech, Spruce Biosciences, Core Access Surgical Technologies, Rani Therapeutics. Grant Recipient; Self; Ferring Pharmaceuticals, Foundation for Research and Education Excellence. Stock Owner; Self; Martin Imaging. Background: PCOS appears to result from enhanced stimuli, either increased LH or insulin, and exaggerated responsiveness of ovarian theca cell androgen biosynthesis to these stimuli. However, the etiology of the enhanced stimuli remains unclear. We previously reported that a specific microRNA, miR-93, regulates GLUT4 content in adipocytes; and that in PCOS miR-93 overexpression in adipocytes results in suppressed GLUT4 expression and insulin-meditated glucose uptake in these cells, and is associated with whole-body insulin resistance (IR). These data suggest that constitutive miR-93 overexpression may underly the metabolic dysfunction and, possibly, the hyperandrogenism of PCOS. Objective: To test the hypothesis in a transgenic murine model that miR-93 overexpression results in the metabolic and hyperandrogenic features of PCOS. Materials and methods: We generated a novel miR-93 overexpressed (miR-93+) mouse model in collaboration with InGenious Targeting Laboratory (Ronkonkoma, NY). The mouse miR-93 sequence with the R26/CAG promoter was inserted immediately downstream of loxP flanked stop cassette in intron 1 of ROSA26 locus. miR-93 insertion was not expected to cause unwanted phenotypes resulting from modification of the Rosa26 locus. When mating miR-93+ transgenic mice to whole body Cre mice (The Jackson Lab) the stop code is removed, and miR-93 is overexpressed systemically. Results: In miR-93+ mice, miR-93 was overexpressed in adipose tissue (AT), muscle, liver, heart, kidneys, and ovaries. Phenotypically, miR-93+ mice had reduced GLUT4 expression in AT, and higher fasting serum insulin, higher fasting serum glucose, and higher testosterone levels. In PCOS women, increased CYP17A1 expression in theca cells is associated with excess androgen production. Consistent with this PCOS phenotype, Cyp17a1 expression in miR-93+ mice ovaries were also increased. In addition, the ovaries of miR-93+ mice had reduced expression of Cdkn1a, similar to that observed in granulosa cells from PCOS patients. miR-93+ mice gained more weight and epididymal AT than controls. miR-93+ mice also demonstrated a lesser response to insulin during an insulin tolerance test (ITT) and exhibited altered estrous cycles as compared to wild type. Conclusion: We successfully developed a miR-93 overexpressed (miR93+) murine model, which demonstrates IR, hyperandrogenemia, exaggerated ovarian Cyp17a1 expression, increased weight gain, and abnormal estrous (ovulatory) cyclicity, mimicking the PCOS phenotype. These results provide further evidence to support the role for constitutive overexpression of miR-93 in the metabolic and hyperandrogenic features of PCOS. These data also suggest a potential model to study the mechanisms mediating the effect of miR-93 overexpression on IR and on the PCOS phenotype in tissues and conditions not readily accessible in human subjects. Presentation Date: Saturday, June 17, 2023

The role of intestine in metabolic dysregulation in murine Wilson disease.

The clinical manifestations of Wilson disease (WD) are related to copper accumulation in the liver and the brain, but little is known about other tissue involvement regarding metabolic changes in WD. In vitro studies suggested that the loss of intestinal ATP7B affects metabolic dysregulation in WD. We tested this hypothesis by evaluating the gut microbiota and lipidome in 2 mouse models of WD and by characterizing a new mouse model with a targeted deletion of Atp7b in the intestine. Cecal content 16S sequencing and untargeted hepatic and plasma lipidome analyses in the Jackson Laboratory toxic-milk and the Atp7b null global knockout mouse models of WD were profiled and integrated. Intestine-specific Atp7b knockout mice (Atp7bΔIEC) were generated and characterized using targeted lipidome analysis following a high-fat diet challenge. Gut microbiota diversity was reduced in animal models of WD. Comparative prediction analysis revealed amino acid, carbohydrate, and lipid metabolism functions to be dysregulated in the WD gut microbial metagenome. Liver and plasma lipidomic profiles showed dysregulated triglyceride and diglyceride, phospholipid, and sphingolipid metabolism in WD models. However, Atp7bΔIEC mice did not show gut microbiome differences compared to wild type. When challenged with a high-fat diet, Atp7bΔIEC mice exhibited profound alterations to fatty acid desaturation and sphingolipid metabolism pathways as well as altered APOB48 distribution in intestinal epithelial cells. Gut microbiome and lipidome underlie systemic metabolic manifestations in murine WD. Intestine-specific ATP7B deficiency affected both intestinal and systemic response to a high-fat challenge but not the microbiome profile, at least at early stages. WD is a systemic disease in which intestinal-specific ATP7B loss and diet influence the phenotype and the lipidome profile.

Abstract 033: Innate Lymphoid Cells Mediate Hypertension In T Cell Deficient Hosts

T cells have been shown to contribute to hypertension, however, hypertension occurs in settings of T cell deficiency, such as human immunodeficiency virus infection and following chemotherapy. We studied two colonies of RAG-1 -/- mice with disparate responses to angiotensin II (Ang II) infusion. Ang II increased both systolic and diastolic pressure in RAG-1 -/- mice from Jackson labs (RAG-1 -/-US ) but had no effect in a colony of RAG-1 -/- mice housed at our Pozzilli facility (RAG-1 -/-POZ ) for the past 14 years (SBPs 169 ± 2 vs 114 ± 3 mmHg, p < 0.003). While both lacked T and B cells, the RAG-1 -/-US mice exhibited a striking expansion of natural killer and both type 1 and type 3 innate lymphoid cells, while the RAG-1 -/-POZ mice did not. In RAG-1 -/-US mice, NK cells and ILC1s produced IFNγ, while ILC3s produced IL-17A. Immunoclearing of IL-17A, but not IFNγ prevented the hypertension in RAG-1 -/-US mice. There were differences in global gene expression and DNA methylation status in NK1.1 + /NKp46 + cells between these two colonies and notably β2-AdR and IL-10 expression was significantly lower in RAG-1 -/-US mice. Knockdown of the β2-AdR using intra-splenic infusion of siRNA in RAG-1 -/-POZ mice led to a hypertensive response resembling that observed in wild type and RAG-1 -/-US mice. We also found striking differences in DNA methylation patterns in innate lymphoid cells of RAG-1 -/-US vs RAG-1 -/-POZ mice and treatment with the DNA methyltransferase inhibitor 5-azacytidine prevented hypertension in RAG-1 -/-US mice. Single cell sequencing showed that 5-azacytidine also reduced splenic populations of NK and ILC3 cells and reduced the presence of the transcription factor RORγt, which defines ILC3s. Ang II infusion caused only a transient elevation of blood pressure in NSG/MHCI/II -/- mice that lack T cells and innate lymphoid cells but led to sustained hypertension following adoptive transfer of either T cells or NK1.1 + /NKp46 + cells to these animals. We conclude that DNA methylation likely modulates expansion of NK and innate lymphoid cells. Either T cells or innate lymphoid cells can contribute to hypertension, and the latter can compensate by serving as a source of cytokines like IL-17A when T cells are deficient.

Genetic variation influences the skeletal response to hindlimb unloading in the eight founder strains of the diversity outbred mouse population.

During disuse, mechanical unloading causes extensive bone loss, decreasing bone volume and strength. Variations in bone mass and risk of osteoporosis are influenced by genetics; however, it remains unclear how genetic variation affects the skeletal response to unloading. We previously found that genetic variation affects the musculoskeletal response to 3 weeks of immobilization in the 8 Jackson Laboratory J:DO founder strains: C57Bl/6J, A/J, 129S1/SvImJ, NOD/ShiLtJ, NZO/HlLtJ, CAST/EiJ, PWK/PhJ, and WSB/EiJ. Hindlimb unloading (HLU) is the best model for simulating local and systemic contributors of disuse and therefore may have a greater impact on bones than immobilization. We hypothesized that genetic variation would affect the response to HLU across the eight founder strains. Mice of each founder strain were placed in HLU for 3 weeks, and the femurs and tibias were analyzed. There were significant HLU and mouse strain interactions on body weight, femur trabecular BV/TV, and femur ultimate force. This indicates that unloading only caused significant catabolic effects in some mouse strains. C57BL/6 J mice were most affected by unloading while other strains were more protected. There were significant HLU and mouse strain interactions on gene expression of genes encoding bone metabolism genes in the tibia. This indicates that unloading only caused significant effects on bone metabolism genes in some mouse strains. Different mouse strains respond to HLU differently, and this can be explained by genetic differences. These results suggest the outbred J:DO mice will be a powerful model for examining the effects of genetics on the skeletal response to HLU.

Systemic exposure to bacterial amyloid curli alters the gut mucosal immune response and the microbiome, exacerbating Salmonella-induced arthritis

ABSTRACT The Salmonella biofilm-associated amyloid protein, curli, is a dominant instigator of systemic inflammation and autoimmune responses following Salmonella infection. Systemic curli injections or infection of mice with Salmonella Typhimurium induce the major features of reactive arthritis, an autoimmune disorder associated with Salmonella infection in humans. In this study, we investigated the link between inflammation and microbiota in exacerbating autoimmunity. We studied C57BL/6 mice from two sources, Taconic Farms and Jackson Labs. Mice from Taconic Farms have been reported to have higher basal levels of the inflammatory cytokine IL − 17 than do mice from Jackson Labs due to the differences in their microbiota. When we systemically injected mice with purified curli, we observed a significant increase in diversity in the microbiota of Jackson Labs mice but not in that of the Taconic mice. In Jackson Labs, mice, the most striking effect was the expansion of Prevotellaceae. Furthermore, there were increases in the relative abundance of the family Akkermansiaceae and decreases in families Clostridiaceae and Muribaculaceae in Jackson Labs mice. Curli treatment led to significantly aggravated immune responses in the Taconic mice compared to Jackson Labs counterparts. Expression and production of IL − 1β, a cytokine known to promote IL − 17 production, as well as expression of Tnfa increased in the gut mucosa of Taconic mice in the first 24 hours after curli injections, which correlated with significant increases in the number of neutrophils and macrophages in the mesenteric lymph nodes. A significant increase in the expression of Ccl3 in colon and cecum of Taconic mice injected with curli was detected. Taconic mice injected with curli also had elevated levels of inflammation in their knees. Overall, our data suggest that autoimmune responses to bacterial ligands, such as curli, are amplified in individuals with a microbiome that promote inflammation.

Abstract 267: Vascular Smooth Muscle Cell-specific Deletion Of Protein Kinase R-like Endoplasmic Reticulum Kinase Attenuates Microbiome-enhanced Abdominal Aortic Aneurysm

Background: We have previously linked the microbiome-derived metabolite trimethylamine N-oxide (TMAO) to abdominal aortic aneurysm (AAA) in both associative human and mechanistic mouse studies. TMAO is reported to bind protein kinase R-like endoplasmic reticulum kinase (PERK), resulting in selective activation of the unfolded protein response (UPR). Concordantly, our previous RNA sequencing results indicate that TMAO augments PERK-mediated UPR pathways in the aneurysm wall. Thus, the current study will determine the functional role of TMAO-mediated PERK activation in aortic VSMCs to AAA pathogenesis. Methods & Results: Ldlr -/- mice with VSMC-specific deletion of Perk were produced by breeding hemizygous male mice expressing Cre under the control of the Transgelin promoter ( B6.Cg-TG(Tagln-cre)1Her/J , Jackson Labs) to female Perk floxed mice ( Eif2ak3 tm1.2Drc /J , Jackson Labs). Specific deletion of PERK in VSMCs was validated by western blot. Male mice were subjected to angiotensin II (AngII) infusion via osmotic mini pump (1,000 ng/kg/min; 28 days), while female mice underwent laparotomy and application of topical elastase (10 mg/mL porcine pancreatic elastase 5 minutes) to induce AAA. To augment circulating TMAO levels, mice were fed a high choline diet (0.2% total cholesterol + 1.2% choline supplementation) for one week prior to and throughout the study. Male mice with VSMC specific PERK knockout demonstrated significantly reduced AngII-induced aortic dilation (Cre+: 0.90 ± 0.048 mm; Cre-: 1.57 ± 0.156 mm; P = 0.001) and rupture induced death relative to control. Similarly, female mice with VSMC specific PERK knockout displayed significantly reduced aortic diameter (Cre+: 1.17 ± 0.069 mm; Cre-: 2.65 ± 0.432 mm; P = 0.002) and rupture induced mortality as compared to control. Additionally, male and female mice with VSMC specific PERK knockout had significantly greater Type I collagen and reduced macrophage accumulation compared to control. Conclusions: These results indicate that VSMC specific knockout of PERK blunts AAA formation in two independent murine models. Further studies are needed to elucidate the mechanism of PERK mediated ER stress in AAA, which may reveal novel therapeutic targets for AAA treatment.

Voluntary wheel running and lithium supplementation improves muscle force production without altering SERCA function in the D2 mdx mouse

Background: Duchenne muscular dystrophy (DMD) is an X-linked recessive muscle wasting disease that, with no cure, leads to early mortality (30-40 years of age). Previous studies have shown that voluntary wheel running can mitigate disease pathology and improve muscle contractility in the preclinical mdx mouse model. We have shown that treating wild-type (WT) mice with a low dose of lithium, a natural inhibitor of glycogen synthase kinase 3, enhanced soleus (SOL) and extensor digitorum longus (EDL) muscle contractility. Our objectives were to test our hypothesis of whether combining VWR with low dose lithium supplementation could provide further benefits to muscle contractility in DBA/2J mdx mice – a model that displays far worse disease severity compared with the traditional C57BL/10 mdx mouse. We also examined if this combined intervention could improve muscle calcium regulation in muscle by assessing sarco(endo)plasmic reticulum Ca 2+ -ATPase (SERCA) function as we have recently shown that SERCA function is drastically impaired in D2 mdx mice, which could also contribute to deficits in muscle force production. Methods: Young (5-6 week old) male D2 WT and mdx mice were ordered from Jackson Laboratory. D2 mdx mice were assigned into each of the following conditions: sedentary ( mdxSED), voluntary wheel running ( mdxVWR), or VWR+lithium chloride ( mdxVWR+Li). The VWR groups were given access to a cagewheel for a total of 6 weeks, and the mdxVWR+Li group were provided a low dose of LiCl (50 mg/kg/day) via drinking water for the entire duration of the study. After 6 weeks, all mice were euthanized and the SOL and EDL muscles were subjected to force-frequency curve analysis (1-160 Hz). SERCA function was assessed by performing SERCA activity assays and a Ca 2+ uptake assay. Results: In the SOL, the combined effect of lithium and VWR improved specific force production to near WT levels across submaximal and maximal frequencies. Specific force production in the mdxVWR+Li group was significantly greater compared to the mdxSED group at all stimulation frequencies. Rate of SOL force development was significantly lower in all mdx groups compared to WT. However, rate of relaxation was only significantly reduced (vs. WT) within the mdxSED group, suggesting that VWR and VWR+Li improved relaxation. This could not be explained by any changes in SERCA function. In the EDL, specific force was significantly (p<0.001) reduced across mdx groups compared to WT; however, of all mdx groups, the mdxVWR+Li produced the most force and was significantly different compared to mdxVWR at 80 and 160 Hz. Rates of force development and relaxation were all slower in all mdx groups compared to WT, and there were no differences in SERCA activity. Conclusions: Combining lithium supplementation with VWR improved SOL and EDL force production in the D2 mdx mouse without any changes to SERCA function. V.A.F is a Tier 2 Canada Research Chair in Muscle Plasticity and Tissue-Remodelling. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 155: Platelet-derived Transforming Growth Factor-β1 Ameliorates AAA in a Murine Model

Background: Platelets are rapidly recruited to the forming intraluminal thrombus in abdominal aortic aneurysm (AAA), stabilizing the aortic wall and preventing rupture. Adhesion and activation of platelets releases a mix of inflammatory mediators such as transforming growth factor β (TGFβ), which mediates cellular proliferation, inflammatory signaling, and fibrosis. Importantly, while TGFβ neutralization results in increased rupture and disease progression in mouse models of AAA, the source of protective TGFβ signaling remains controversial. We hypothesized that platelet-derived TGFβ1 attenuates aortic growth in the elastase AAA model. Methods and Results: Ldlr -/- mice with platelet-specific deletion of Tgfβ1 were produced by breeding hemizygous male mice expressing Cre under the control of the Pf4 promoter to female Tgfβ1 floxed mice (Jackson Labs). Mice were subjected to laparotomy and topical elastase application to the abdominal aorta (10 mg/mL porcine pancreatic elastase for 5 minutes) and sacrificed at day 28 to determine AAA progression via aortic diameter. Male TGFβ1-Pf4 Cre+ mice (n=8) had significantly increased abdominal aortic diameters compared to Male TGFβ1-Pf4 Cre- mice (n=7) ( Cre- : 1.70 ± 0.12 mm; Cre+ : 2.66 ± 0.25 mm; P < 0.004). Additionally, 25% of male TGFβ1-Pf4 Cre+ mice died of AAA rupture compared to 0% in the TGFβ1-Pf4 Cre- cohort. To determine if these actions were occurring via TGFβ1 activation of the TGFβ receptor 2 (βr 2 ), Ldlr -/- /βr2 Flox /PF4 Cre+ and Cre- mice were created, similarly to the previously described Tgfβ1 mice. Male βr2-Pf4 Cre+ (n=7) had increased aortic diameter compared to βr2-Pf4 Cre- (n=6) ( Cre- : 1.70± 0.20 mm; Cre+ : 2.45 ± 0.38 mm; P < 0.138). Additionally, female βr2-Pf4 Cre+ (n=9) also had significantly larger aortic diameters compared to βr2-Pf4 Cre- (n = 5) ( Cre- : 1.27± 0.04 mm; Cre+ : 1.90 ± 0.23 mm; P < 0.01). Conclusions: Our results further support TGFβ signaling playing a protective role in AAA. More specifically, platelet-derived TGFβ1 ligand and signaling via platelet TGFβr2 mitigates aortic diameter expansion. Further research into the pertinent TGFβ isoforms and the mechanism of TGFβr2 activation will ideally yield insights into therapeutic targets for an, as yet, intractable disease.

Microenvironment regulates antibody secretion by IgA+ plasma cells.

Abstract IgA secreting plasma cells (PCs) provide a critical supply of antibodies for barrier functions against pathogens. These cells express unique tissue-driven transcriptional profiles in their respective niches in the bone marrow (BM) and gut. We previously demonstrated that both tissues sustain long-lived IgA+ PCs, but the cell intrinsic and extrinsic signals responsible for survival and function in the gut remain largely unknown. Understanding how the microenvironment regulates tissue resident IgA+ PC functions has implications for maintaining intestinal homeostasis and protection from disease. We found that BM IgA+ PCs functionally differ from gut IgA+ PCs as they secrete significantly more antibody. To assess if this phenotype could be due to metabolic consequences, we profiled IgA+ PCs in both tissues. BM and gut IgA+ PCs have similar glucose and fatty acid uptake. However, BM IgA+ PCs have increased mitochondrial dependence, while gut IgA+ PCs have increased glycolytic capacity. We next altered the composition of the microbiome to determine the role of gut microbes in regulating tissue resident PCs. Our initial experiments used C57BL/6J mice with a well-defined low-complexity microbiome (from Jackson Labs). Co-housing Jax mice with animals containing a more diverse set of microbes led to an increase in antibody secretion. Herein, we identified that the tissue microenvironment and gut microbiome influences PC function. We aim to dissect the mechanisms involved in microbiome driven changes in PC phenotype. Ultimately, understanding how the microenvironment regulates intensity of PC antibody secretion provides a tool in targeting induction of systemic and mucosal responses and will improve vaccine design and development. Supported by grants from NIH (R35 GM147560, R03 AI156481)

Meeting report of the annual workshop on Principles and Techniques for Improving Preclinical to Clinical Translation in Alzheimer's Disease research.

The second annual 5-day workshop on Principles and Techniques for Improving Preclinical to Clinical Translation in Alzheimer's Disease Research was held October 7-11, 2019, at The Jackson Laboratory in Bar Harbor, Maine, USA, and included didactic lectures and hands-on training. Participants represented a broad range of research across the Alzheimer's disease (AD) field, and varied in career stages from trainees and early stage investigators to established faculty, with attendance from the United States, Europe, and Asia. In line with the National Institutes of Health (NIH) initiative on rigor and reproducibility, the workshop aimed to address training gaps in preclinical drug screening by providing participants with the skills and knowledge required to perform pharmacokinetic, pharmacodynamics, and preclinical efficacy experiments. This innovative and comprehensive workshop provided training in fundamental skill sets for executing in vivo preclinical translational studies. The success of this workship is expected to translate into practical skills that will enablethe goals of improving preclinical to clinical translational studies for AD. Nearly all preclinical studies in animal models have failed to translate to successful efficacious medicines for Alzheimer's disease (AD) patients. While a wide variety of potential causes of these failures have been proposed,deficiencies in knowledge and best practices for translational research are not being sufficiently addressed by common training practices. Here we present proceedings from an annual NIA-sponsored workshop focused specifically on preclinical testing paradigms for AD translational research in animal models aimed at enabling improved preclinical to clinical translation for AD.

Understanding Patterns of Life History Trait Covariation in an Untapped Resource, the Lab Mouse.

AbstractThrough artificial selection and inbreeding, strains of laboratory mice have been developed that vary in the expression of a single or suite of desired traits valuable to biomedical research. In addition to the selected trait(s), these strains also display variation in pelage color, body size, physiology, and life history. This article exploits the broad phenotypic variation across lab mouse strains to evaluate the relationships between life history and metabolism. Life history variation tends to exist along a fast-slow continuum. There has been considerable interest in understanding the ecological and evolutionary factors underlying life history variation and the physiological and metabolic processes that support them. Yet it remains unclear how these key traits scale across hierarchical levels, as ambiguous empirical support has been garnered at the intraspecific level. Within-species investigations have been thwarted by methodological constraints and environmental factors that obscure the genetic architecture underlying the hypothesized functional integration of life history and metabolic traits. In this analysis, we used the publicly available Mouse Phenome Database by the Jackson Laboratory to investigate the relationships among life history traits (e.g., body size, reproduction, and life span) and metabolic traits (e.g., daily energy expenditure and insulin-like growth factor 1 concentration). Our findings revealed significant variation in reproductive characteristics across strains of mice as well as relationships among life history and metabolic traits. We found evidence of variation along the fast-slow life history continuum, though the direction of some relationships among these traits deviated from interspecific predictions laid out in previous literature. Furthermore, our results suggest that the strength of these relationships are strongest earlier in life.