Gene Deletion Mice Research Articles

GJA4 gene inhibition may represent a potential target for novel antithrombotic therapies

Abstract The GJA4 gene encodes a protein called connexin 37, a component of gap junctions in vascular endothelial cells, crucial in regulating endothelial function and influencing inflammation, platelet adhesion and thrombus formation. This gene deletion in mice diminished thrombus formation in vitro in human blood. In these circumstances, connexin inhibition with pharmacological agents may represent potential avenues for developing novel antithrombotic agents. Aim To investigate whether the GJA4 rs618675 T>C variant is a risk factor for progressing atherosclerosis and cardiovascular (CV) events in an asymptomatic free of apparent CAD from a Portuguese population. Methods A prospective study was performed with 1421 individuals without apparent CV disease (73.6% male, aged 52.2±8.3 years) followed during an extended period of 7.2±5.1 years). GJA4 rs618675 T>C variant was genotyped by TaqMan real-time PCR technique (Applied Biosystems). Conventional, anthropometric, biochemical and clinical risk factors were studied. Bivariate analysis and multivariate Cox regression adjusted for age, gender, traditional risk factors, biochemical markers, and the genotypes under study was performed to determine which variables were, significantly and independently, associated with CV events. Kaplan-Meier's estimate assessed the prognosis. Results Bivariate analysis showed that 50.6% of wild genotype (TT) carriers had CV events vs. 66.2% without events. Of the risk genotype (CC) carriers, 10.1% had CV events, and 3.4% did not. After the Kaplan-Meier analysis, the TT carriers had 90% CV event-free survival time and the CC risk carriers had only 64% of event-free survival. Finally, after adjustment, CC genotype remained in the equation with an HR of 3.1 (p=0.003) and CT heterozygous with HR of 1.6 (p=0.043), together with Hypertension (HR 3.0; p<0.0001), Smoking habits (HR 2.3; p=0.001) and Diabetes (HR 1.9; p=0.015). Conclusion: The CC risk genotype of the GJA4 rs618675 represented an independent risk factor for progressing atherosclerosis and CV events in a Portuguese Population. Thrombus formation often begins with the adhesion of platelets to the endothelium, and connexin 37 may influence this process. The inhibition of connexin 37 emerges as a promising candidate for future cardiovascular prevention as well as for the development of new antithrombotic drugs.

Intestinal epithelial Cldn-7 regulates intestinal inflammation by altering the gut microbiota

Background and aimTight junctions maintain gut homeostasis by forming a physical barrier that protects the gut from invasion by microbiota. Cldn-7 is an important component involved in this protection, but the relationship between Cldn-7, intestinal inflammation, and gut microbiota has not been clarified. Here, we hypothesize that Cldn-7 depletion affects intestinal inflammation by altering the gut microbiota. MethodsBased on the induced intestinal condition of Cldn-7 knockout mice (Cldn7fl/fl;villin-CreaERT2), we established the intestinal flora depletion model and colitis model by antibiotic drinking and feeding with dextran sodium sulfate (DSS). The environment of Cldn-7 gene deletion mice was changed by co-housing experiment. AB-PAS staining and Muc2 were used to detect the effect of co-housing and Cldn-7 deficiency on the mucus layer after flora depletion. qRT-PCR was used to detect the expression of intestinal inflammatory factors and AMPs in mice. Feces were collected and proportions of microbiota were analyzed by 16 S rRNA amplicon sequencing. ResultsMice in the co-housing experiment had altered intestinal microbiota, including diversity, composition, and functional prediction, compared to controls. Intestinal inflammation was restored to some extent following altered intestinal microbiota. The intestinal inflammation caused by Cldn-7 deficiency and susceptibility to DSS could be reduced after antibiotic administration compared to controls, in terms of phenotype, pathological changes, inflammatory factors, mucus barrier, and expression of AMPs. ConclusionsIn analyses of intestinal tissues, colitis induction, and gut microbiota in mice with intestinal disruption of Cldn-7, we found this protein to prevent intestinal inflammation by regulating the gut microbiota. Cldn-7might therefore be an important mediator of host–microbiome interactions. Our research has revealed that Cldn-7 plays an indispensable role in maintaining intestinal homeostasis by regulating the gut microbiota and impacting intestinal inflammation. These findings provide new insights into the pathogenesis of ulcerative colitis.

Abstract 5581: The DACH1 gene, frequently co-deleted with BRCA2 in prostate cancer, governs PARP inhibitor resistance

Abstract Background: Prostate cancer (PCa), the second leading cause of death in American men, includes distinct genetic subtypes with distinct therapeutic vulnerabilities (1,2). The DACH1 gene, in the 13q21.31-q21.33 region, encodes a winged helix/Forkhead DNA-binding protein that governs cell-fate determination that is deleted in ~ 18% of human PCa, where it is associated with poor prognosis (3). Prostate-specific deletion of the Dach1 gene enhanced prostatic intraepithelial neoplasia (PIN). Methods: Analysis of DACH1 gene deletion and expression was conducted from public data bases and human prostate cancer samples. Cells derived from Dach1 gene deletion mice and human prostate cancer cell lines with DACH1 overexpression were analyzed for PARP inhibitor responses and mechanisms of PARPi resistance. Transgenic prostate Oncomice were generated in which the Dach1 gene was deleted in the prostate. Results: Herein, DACH1 was shown to be co-deleted with BRCA2 in each of 8 separate cohorts (N=2,186 patients), in ~3-12% of patients. Dach1 gene deletion or knockdown conferred PARP inhibitor resistance (talazoparib > niraparib > olaparib > rucaparib > veliparib). DACH1 enhanced PARP sensitivity through several mechanisms affecting replication stress, PARP1 binding, inhibiting G9a (reducing H3K9me2), inhibiting CHK1p and CDK1p and inducing expression of snoRNA, specifically the snoRNA known to bind PARP. PARP1 has a BRCT (BRCA1 C-terminus 1) homology domain governing PARP1 dimerization and binding to intact DNA in a complex within a nucleosome. DACH1 binding to PARP1 requires the BRCT domain. Conclusions: There is a correlation between DACH1a-/- and PARPi resistance, correlating with PARPi trapping ability. As reduced Dach1a expression may define a subclass of PCa that warrants specific therapies, testing for DACH1a may be warranted.

RGS4 controls airway hyperresponsiveness through GAP-independent mechanisms

Regulators of G protein signaling (RGS proteins) constrain G protein-coupled receptor (GPCR)-mediated and other responses throughout the body primarily, but not exclusively, through their GTPase activating (GAP) activity. Asthma is a highly prevalent condition characterized by airway hyper-responsiveness (AHR) to environmental stimuli resulting in part from amplified GPCR-mediated airway smooth muscle (ASM) contraction. Rgs2 or Rgs5 gene deletion in mice enhances AHR and ASM contraction whereas RGS4 knockout (KO) mice unexpectedly have decreased AHR due to increased production of the bronchodilator prostaglandin E2 (PGE2) by lung epithelial cells. Here we found that knockin mice harboring Rgs4 alleles encoding a point mutation (N128A) that sharply curtails RGS4 GAP activity had increased AHR, reduced airway PGE2 levels, and augmented GPCR-induced bronchoconstriction compared to either RGS4 KO mice or WT controls. RGS4 interacted with the p85α subunit of PI3 kinase (PI3K) and inhibited PI3K-dependent PGE2 secretion elicited by TGFβ in airway epithelial cells. Together these findings suggest that RGS4 affects asthma severity in part by regulating the airway inflammatory milieu in a G protein-independent manner.

Death receptor 5 is required for intestinal stem cell activity during intestinal epithelial renewal at homoeostasis

Intestinal epithelial renewal, which depends on the proliferation and differentiation of intestinal stem cells (ISCs), is essential for epithelial homoeostasis. Understanding the mechanism controlling ISC activity is important. We found that death receptor 5 (DR5) gene deletion (DR5-/-) mice had impaired epithelial absorption and barrier function, resulting in delayed weight gain, which might be related to the general reduction of differentiated epithelial cells. In DR5-/- mice, the expression of ISC marker genes, the number of Olfm4+ ISCs, and the number of Ki67+ and BrdU+ cells in crypt were reduced. Furthermore, DR5 deletion inhibited the expression of lineage differentiation genes driving ISC differentiation into enterocytes, goblet cells, enteroendocrine cells, and Paneth cells. Therefore, DR5 gene loss may inhibit the intestinal epithelial renewal by dampening ISC activity. The ability of crypts from DR5-/- mice to form organoids decreased, and selective DR5 activation by Bioymifi promoted organoid growth and the expression of ISC and intestinal epithelial cell marker genes. Silencing of endogenous DR5 ligand TRAIL in organoids down-regulated the expression of ISC and intestinal epithelial cell marker genes. So, DR5 expressed in intestinal crypts was involved in the regulation of ISC activity. DR5 deletion in vivo or activation in organoids inhibited or enhanced the activity of Wnt, Notch, and BMP signalling through regulating the production of Paneth cell-derived ISC niche factors. DR5 gene deletion caused apoptosis and DNA damage in transit amplifying cells by inhibiting ERK1/2 activity in intestinal crypts. Inhibition of ERK1/2 with PD0325901 dampened the ISC activity and epithelial regeneration. In organoids, when Bioymifi’s effect in activating ERK1/2 activity was completely blocked by PD0325901, its role in stimulating ISC activity and promoting epithelial regeneration was also eliminated. In summary, DR5 in intestinal crypts is essential for ISC activity during epithelial renewal under homoeostasis.

Trans-Palmitoleic acid promotes adipose thermogenesis to reduce obesity via hypothalamic FFAR1 signaling.

Diet-induced thermogenesis (DIT) is crucial for maintaining body weight homeostasis, and the role of dietary fatty acids in modulating DIT is essential. However, the underlying mechanism of fatty acid regulated diet-induced thermogenesis remains elusive. Utilizing the diet- and genetic ablation-induced obese mice models, we found that the C16 unsaturated fatty acids, trans-palmitoleic acid (TPA) and cis-palmitoleic acid (CPA), significantly increased the energy expenditure by promoting the thermogenesis of brown adipose tissues and the production of beige cells in white adipose. As a result, there is a significant reduction in the occurrence of obesity, associated hepatic steatosis and hyperglycemia. Notably, TPA exhibited more potent effects on promoting DIT and alleviating obesity than CPA did. Using inhibitor and gene deletion mice models, we unveiled that TPA acted as a signaling molecule to play a biological function, which could be sensed by the hypothalamic FFAR1 to activate the sympathetic nervous system in promoting adipose tissue thermogenesis. Together, these results demonstrate the underlying mechanism of free fatty acids associated-DIT and will provide fresh insights into the roles of trans-fatty acids in the development of obesity.

Co-expression of prepulse inhibition and Schizophrenia genes in the mouse and human brain

Schizophrenia is a complex psychiatric disorder with genetic and phenotypic heterogeneity. Accumulating rare and genome-wide association study (GWAS) common risk variant information has yet to yield robust mechanistic insight. Leveraging large-scale gene deletion mouse phenomic data thus has potential to functionally interrogate and prioritize human disease genes. To this end, we applied a cross-species network-based approach to parse an extensive mouse gene set (188 genes) associated with disrupted prepulse inhibition (PPI), a Schizophrenia endophenotype. Integrating PPI genes with high-resolution mouse and human brain transcriptomic data, we identified functional and disease coherent co-expression modules through hierarchical clustering and weighted gene co-expression network analysis (WGCNA). In two modules, Schizophrenia risk and mouse PPI genes converged based on telencephalic patterning. The associated neuronal genes were highly expressed in cingulate cortex and hippocampus; implicated in synaptic function and neurotransmission and overlapped with the greatest proportion of rare variants. Concordant neuroanatomical patterning revealed novel core Schizophrenia-relevant genes consistent with the Omnigenic hypothesis of complex traits. Among other genes discussed, the developmental and post-synaptic scaffold TANC2 (Tetratricopeptide repeat, ankyrin repeat and coiled-coil containing 2) emerged from both networks as a novel core genetic driver of Schizophrenia altering PPI. Aspects of psychiatric disease comorbidity and phenotypic heterogeneity are also explored. Overall, this study provides a framework and galvanizes the value of mouse preclinical genetics and PPI to prioritize both existing and novel human Schizophrenia candidate genes as druggable targets.

Hematopoietic Stem/Progenitor Cell Intrinsic SAM Synthesis Is Required to Prevent p53 Pathway Activation By Maintaining DNA Stability

S-adenosylmethionine (SAM) is a principle methyl group donor to maintain epigenetic status. SAM is synthesized from methionine and ATP via the enzymatic activity of Mat2a (Methionine adenosyltransferase 2a). It has been reported that SAM reduction by methionine restriction or Mat2a inhibition suppresses the proliferation of leukemia cells to attract attentions as a potential therapeutic target for leukemia. To develop the therapy targeting methionine metabolism in leukemia, it is essential to elucidate the significance of methionine metabolism in non-leukemic hematopoiesis. However, still little is known about the importance of SAM synthesis in hematopoiesis, including hematopoietic stem/progenitor cells (HSPCs), in vivo. By using Mx1-Cre mediated Mat2a gene deletion in mice ( Mat2a fl/fl;Mx1-Cre mice), we investigated the roles of Mat2a in hematopoiesis in vivo. Reduction of Mat2a activity in Mat2a knockout (KO) mice in bone marrow (BM) was confirmed by ultra-high performance liquid chromatography tandem mass spectrometry analysis. Mat2a KO mice displayed severe pancytopenia in peripheral blood (PB). Mature cell fractions (Myeloid cells, B cells and T cells) and HSPCs (HSCs, MPP2s, MPP3s and MPP4s) in BM were also significantly decreased in Mat2a KO mice, suggesting that Mat2a is essential for the maintenance of hematopoiesis from HSPCs in vivo. To exclude the possible contributions of the effects induced by Mat2a KO in non-hematopoietic cells, we performed BM transplantation analyses in which hematopoietic cell specific KO or non-hematopoietic cell specific KO were achieved. These analyses clearly confirmed that HSPC intrinsic SAM synthesis is inevitable for the maintenance of hematopoiesis. To reveal the mechanistic insights of the regulatory roles for Mat2a in HSPCs, we performed RNA sequencing analysis ( Mat2a WT vs KO in HSPCs). GSEA (Gene Set Enrichment Analysis) using the Hallmark gene sets showed that p53 pathway was most highly enriched in Mat2a KO. In depth, genes downstream of p53 ( Bax, Apaf1, Bbc3, Casp3, Casp8, Fas, Cdkn1a etc.) were up-regulated by Mat2a KO, causing cell cycle arrest and apoptosis in HSPCs. On the other hand, gene expressions of the upstream of p53 ( Atr, Atm, Chek1, Chek2 etc.) were unchanged, suggesting that p53 activity was not increased at mRNA expression levels. In line with this, mRNA expression levels of Trp53 was unchanged, but total protein amount of p53 was increased in Mat2a KO HSPCs. Since DNA stability is known as a critical regulator of p53 pathway, we analyzed gH2AX levels as DNA damage marker and found that gH2AX levels were increased in Mat2a KO HSPCs. To be noted, expressions of genes involved in Fanc pathway ( Fanca, Fancc, Fancd2, Fance, Fancg, Fancl, Fanci etc), which is responsible for the DNA maintenance, were broadly down-regulated in Mat2a KO HSPCs at transcriptomic levels. Therefore, the Fanc pathway repression by SAM synthesis inhibition could cause DNA damage and p53 pathway dependent loss of maintenance in Mat2a KO HSPCs. To further understand the importance of SAM synthesis under stress hematopoiesis. We analyzed Mat2a expression changes in HSPCs by irradiation (5.5 Gy/mouse). Intriguingly, Mat2a expression was up-regulated by irradiation. We also found that dietary methionine restriction (MR) in mice prevents its hematopoietic recovery from irradiation stress. To be noted, long term MR (24 weeks) did not show any particular compared to control diet. Therefore, methionine metabolism possesses significant roles at least in the situation where acute hematopoietic recovery is required. Collectively, in this study, we found that cell intrinsic SAM synthesis is required for the maintenance (proliferation and survival) of HSPCs in vivo. SAM might be required for the prevention of DNA damage and p53 pathway activation by supporting Fanc pathway gene expressions. Methionine and/or SAM availability might possess critical roles for the regeneration of non-leukemic hematopoiesis. Further investigation about the significance of SAM synthesis in non-leukemic hematopoiesis is required for the proper establishment of SAM synthesis targeting therapy in cancers.

Fast, multiplexable and efficient somatic gene deletions in adult mouse skeletal muscle fibers using AAV-CRISPR/Cas9

Molecular screens comparing different disease states to identify candidate genes rely on the availability of fast, reliable and multiplexable systems to interrogate genes of interest. CRISPR/Cas9-based reverse genetics is a promising method to eventually achieve this. However, such methods are sorely lacking for multi-nucleated muscle fibers, since highly efficient nuclei editing is a requisite to robustly inactive candidate genes. Here, we couple Cre-mediated skeletal muscle fiber-specific Cas9 expression with myotropic adeno-associated virus-mediated sgRNA delivery to establish a system for highly effective somatic gene deletions in mice. Using well-characterized genes, we show that local or systemic inactivation of these genes copy the phenotype of traditional gene-knockout mouse models. Thus, this proof-of-principle study establishes a method to unravel the function of individual genes or entire signaling pathways in adult skeletal muscle fibers without the cumbersome requirement of generating knockout mice.

Metabolomics and transcriptomics analysis of prefrontal cortex in the Pax2 neuron-specific deletion mice

Restricted and repetitive behaviors (RRBs) are one of the characteristics of various neuropsychiatric disorders with complex and diverse molecular mechanisms. Repetitive self-grooming behavior is one of the manifestations of RRBs in humans and rodents. Research on the neural mechanism of repetitive self-grooming behavior is expected to reveal the underlying logic of the occurrence of RRBs. Pax2 is an important member of the paired-box transcription factor family. It is expressed in different regions of the developing central nervous system. Our previous study showed that Pax2 heterozygous gene knockout mice (Pax2+/− KO mice) exhibit significantly increased self-grooming, which suggests that the Pax2 gene is involved in the control of self-grooming behavior, but the molecular mechanism is still unclear. In this study, we further constructed the Pax2 neuron-specific deletion mice (Nestin-Pax2 mice). Targeted metabolomics and transcriptomics techniques was used to analyze. The results showed that there is an excitatory/inhibitory imbalance of the neurotransmitter system and the Arc gene was significantly up-regulated in the prefrontal cortex (PFC) of Nestin-Pax2 mice. This study suggests that the potential regulatory mechanism of the increased repetitive self-grooming behavior in Pax2 gene deletion mice is that the deletion of the Pax2 gene affects the expression of Arc in the PFC, leading to impaired synaptic plasticity and excitatory/inhibitory imbalance, and participating in the occurrence of repetitive self-grooming behavior.

Bifidobacterium longum 68S mediated gut-skin axis homeostasis improved skin barrier damage in aging mice

BackgroundBifidobacterium as probiotics, play important roles in skin status, while the potential mechanisms interaction remains unknown. The study further explored the potential mechanism of B. longum 68S in ameliorating skin barrier damage from the perspective of the gut-skin axis in aging mice. MethodsB. longum 68S supplied natural aging mouse model and fecal microbiota transplantation (FMT) experiment proves the key role of intestinal microbiota in B. longum 68S up-regulating the production of ceramide synthesis key enzyme (SPT1) and ceramide level and improving skin barrier damage. Moreover, B. longum 68S supplied SPT1 gene deletion mouse model to investigate the mechanism of B. longum 68S on improving skin barrier damage. ResultsTranscriptome analysis and 16S rRNA high-throughput pyrosequencing demonstrated that aging mice exhibited skin barrier dysfunction and intestinal dysbiosis. Meanwhile, aging mice exhibited an up-regulation in the trans epidermal water loss (TEWL) and a down-regulation in the level of SPT1, ceramide and skin barrier-related proteins (Loricrin, Keratin 10 and Desmoglein 1). Similarity, the FMT from aging mice to normal mice and SPT1 gene deletion mice could rebuild skin barrier damage and B. longum 68S supplementation exerted a positive effect on it. Further, B. longum 68S-mediated SPT1-derived ceramide production prevented impaired ceramide synthesis-induced endoplasmic reticulum stress and apoptotic response, ultimately improving skin barrier damage in vitro. ConclusionEmerging anti-aging therapies are necessary given the poor safety profiles of current pharmaceutical drugs. B. longum 68S may be better alternatives, considering the association between the gut microbiota and healthy aging. The findings suggested that B. longum 68S-mediated gut-skin axis homeostasis, thereby exhibiting an anti-aging effect and facilitate a better understanding of the mechanisms governing the various beneficial effects of B. longum 68S.

Metabolic and Proteomic Divergence Is Present in Circulating Monocytes and Tissue-Resident Macrophages from Berkeley Sickle Cell Anemia and β-Thalassemia Mice.

Sickle cell disease and β-thalassemia represent hemoglobinopathies arising from dysfunctional or underproduced β-globin chains, respectively. In both diseases, red blood cell injury and anemia are the impetus for end organ injury. Because persistent erythrophagocytosis is a hallmark of these genetic maladies, it is critical to understand how macrophage phenotype polarizations in tissue compartments can inform on disease progression. Murine models of sickle cell disease and β-thalassemia allow for a basic understanding of the mechanisms and provide for translation to human disease. A multi-omics approach to understanding the macrophage metabolism and protein changes in two murine models of β-globinopathy was performed on peripheral blood mononuclear cells as well as spleen and liver macrophages isolated from Berkley sickle cell disease (Berk-ss) and heterozygous B1/B2 globin gene deletion (Hbbth3/+) mice. The results from these experiments revealed that the metabolome and proteome of macrophages are polarized to a distinct phenotype in Berk-ss and Hbbth3/+ compared with each other and their common-background mice (C57BL6/J). Further, spleen and liver macrophages revealed distinct disease-specific phenotypes, suggesting that macrophages become differentially polarized and reprogrammed within tissue compartments. We conclude that tissue recruitment, polarization, and metabolic and proteomic reprogramming of macrophages in Berk-ss and Hbbth3/+ mice may be relevant to disease progression in other tissue.

Effects of chronic sleep restriction on the neuro-phenotypes of Ctnnd2 knockout mice.

Sleep abnormalities are highly correlated with neurodevelopmental disorders, such as intellectual disability, attention deficit hyperactivity disorder, and autism spectrum disorders (ASD). The severity of behavioral abnormalities is correlated with the presence of sleep abnormalities. Based on previous research, we investigated that Ctnnd2 gene deletion in mice lead to ASD-like behaviors and cognitive defects. Given the importance of sleep in individuals with ASD, this study aimed to determine the effects of chronic sleep restriction (SR) on wild-type (WT) mice and on Ctnnd2 deletion-induced, neurologically related phenotypes in mice. WT and Ctnnd2 knockout (KO) mice were both subjected to manual SR (5h per day) for 21 consecutively days separately, then we compared neurologically related phenotypes of WT mice, WT mice subjected to SR, KO mice, and KO mice subjected to SR using a three-chamber assay, direct social interaction test, open-field test, Morris water maze, Golgi staining, and Western blotting. The effects of SR on WT and KO mice were different. After SR, social ability and cognition were impaired in both WT and KO mice. Repetitive behaviors were increased, and exploration abilities were decreased in KO mice but not in WT mice. Moreover, SR reduced the density and area of mushroom-type dendritic spines in WT rather than KO mice. Finally, the PI3K/Akt-mTOR pathway was found to be involved in the effects induced by SR-impaired phenotypes in WT and KO mice. Overall, results of the present study may have implications for the role of disrupted sleep in patients with CTNND2 gene-related autism and the evolution of neurodevelopmental disorders.

Endothelial tip/stalk cell selection requires BMP9-induced βIV-spectrin expression during sprouting angiogenesis.

βIV-Spectrin is a membrane cytoskeletal protein with specialized roles in the nervous system and heart. Recent evidence also indicates a fundamental role for βIV-spectrin in angiogenesis as its endothelial-specific gene deletion in mice enhances embryonic lethality due to hypervascularization and hemorrhagic defects. During early vascular sprouting, βIV-spectrin is believed to inhibit tip cell sprouting in favor of the stalk cell phenotype by mediating VEGFR2 internalization and degradation. Despite these essential roles, mechanisms governing βIV-spectrin expression remain unknown. Here we identify bone morphogenetic protein 9 (BMP9) as a major inducer of βIV-spectrin gene expression in the vascular system. We show that BMP9 signals through the ALK1/Smad1 pathway to induce βIV-spectrin expression, which then recruits CaMKII to the cell membrane to induce phosphorylation-dependent VEGFR2 turnover. Although BMP9 signaling promotes stalk cell behavior through activation of hallmark stalk cell genes ID-1/3 and Hes-1 and Notch signaling cross-talk, we find that βIV-spectrin acts upstream of these pathways as loss of βIV-spectrin in neonate mice leads to retinal hypervascularization due to excessive VEGFR2 levels, increased tip cell populations, and strong Notch inhibition irrespective of BMP9 treatment. These findings demonstrate βIV-spectrin as a BMP9 gene target critical for tip/stalk cell selection during nascent vessel sprouting.

Abstract 2598: The DACH1 gene is frequently deleted in prostate cancer, restrains prostatic intraepithelial neoplasia, augments DNA damage repair and predicts therapy responses

Abstract Background: Prostate cancer (PCa), the second leading cause of death in American men, includes distinct genetic subtypes with distinct therapeutic vulnerabilities. The DACH1 gene encodes a winged helix/Forkhead DNA-binding protein that competes for binding to FOXM1 sites. Methods: Analysis of DACH1 gene deletion and gene expression was conducted from public data bases and human prostate cancer samples. Transgenic mice were generated in which the Dach1 gene was deleted in the prostate of prostate Oncomice. Cells derived from Dach1 gene deletion mice and human prostate cancer cell lines with Dach1 knockdown were analyzed for DNA damage repair responses. Results: DACH1 gene deletion within the 13q21.31-q21.33 region, occurred in up to 18% of human PCa, and was associated with increased AR activity, and poor prognosis. DACH1 homozygous deletions more frequent in the metastatic site than in the primary tumors (Mich: 10% vs. 18%, N=59; FHCRC: 4% vs.11%, N= 54, SU2C: not profiled vs. 3.3, N=150). The prevalence of DACH1 heterozygous deletions was higher in the metastatic lesions than in primary tumors within a given cohort for three of six cohorts (Mich: 27.3% vs. 36%, N=59; FHCRC: 15% vs. 59%, N=54; SU2C: 0% vs. 26%, N=150, respectively). The patients with homozygous DACH1 deletions had reduced overall survival (medians of 84 vs. 120 months, N=667, log rank test P=9.3x10-3). Low DACH1 gene expression (expressed as a z-score with a z-score threshold of -1.25) was significantly correlated with earlier biochemical recurrence (BCR, log rank p value = 4.7x10-4, n=79). In prostate OncoMice, prostate-specific deletion of the Dach1 gene enhanced prostatic intraepithelial neoplasia (PIN) and was associated with increased DNA damage. Reduced Dach1 increased DNA damage in responses to genotoxic stresses. DACH1 was recruited to sites of DNA damage, augmenting recruitment of Ku70/Ku80. Reduced Dach1 expression was associated with resistance to TGFβ kinase and PARP inhibitors. Conclusions: Reduced Dach1 expression may define a subclass of PCa that warrants specific therapies. Citation Format: Zhiping Li, Xuanmao Jiao, Gordon Robertson, Gabriele Di Sante, Anthony W. Ashton, Agnese DiRocco, Min Wang, Jun Zhao, Sankar Addya, Chenguang Wang, Peter A. McCue, Andrew P. South, Carlos Cordon-Cardo, Runzhi Liu, Kishan Patel, Rasha Hamid, Jorim Parmar, James B. DuHadaway, Nikolaus Schultz, Andrew Kossenkov, Lai Yee Phoon, Hao Chen, Li Lan, Yunguang Sun, Kenneth A. Iczkowski, Hallgeir Rui, Richard G. Pestell. The DACH1 gene is frequently deleted in prostate cancer, restrains prostatic intraepithelial neoplasia, augments DNA damage repair and predicts therapy responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2598.

Gut microbe-derived milnacipran enhances tolerance to gut ischemia/reperfusion injury

There are significant differences in the susceptibility of populations to intestinal ischemia/reperfusion (I/R), but the underlying mechanisms remain elusive. Here, we show that mice exhibit significant differences in susceptibility to I/R-induced enterogenic sepsis. Notably, the milnacipran (MC) content in the enterogenic-sepsis-tolerant mice is significantly higher. We also reveal that the pre-operative fecal MC content in cardiopulmonary bypass patients, including those with intestinal I/R injury, is associated with susceptibility to post-operative gastrointestinal injury. We reveal that MC attenuates mouse I/R injury in wild-type mice but not in intestinal epithelial aryl hydrocarbon receptor (AHR) gene conditional knockout mice (AHRflox/flox) or IL-22 gene deletion mice (IL-22-/-). Collectively, our results suggest that gut microbiota affects susceptibility to I/R-induced enterogenic sepsis and that gut microbiota-derived MC plays a pivotal role in tolerance to intestinal I/R in an AHR/ILC3/IL-22 signaling-dependent manner, revealing the pathological mechanism, potential prevention and treatment drugs, and treatment strategies for intestinal I/R.

Important Role of Endogenous Nerve Growth Factor Receptor in the Pathogenesis of Hypoxia-Induced Pulmonary Hypertension in Mice.

Pulmonary arterial hypertension (PAH) remains a disease with poor prognosis; thus, a new mechanism for PAH treatment is necessary. Circulating nerve growth factor receptor (Ngfr)-positive cells in peripheral blood mononuclear cells are associated with disease severity and the prognosis of PAH patients; however, the role of Ngfr in PAH is unknown. In this study, we evaluated the function of Ngfr using Ngfr gene-deletion (Ngfr-/-) mice. To elucidate the role of Ngfr in pulmonary hypertension (PH), we used Ngfr-/- mice that were exposed to chronic hypoxic conditions (10% O2) for 3 weeks. The development of hypoxia-induced PH was accelerated in Ngfr-/- mice compared to littermate controls. In contrast, the reconstitution of bone marrow (BM) in Ngfr-/- mice transplanted with wild-type BM cells improved PH. Notably, the exacerbation of PH in Ngfr-/- mice was accompanied by the upregulation of pulmonary vascular remodeling-related genes in lung tissue. In a hypoxia-induced PH model, Ngfr gene deletion resulted in PH exacerbation. This suggests that Ngfr may be a key molecule involved in the pathogenesis of PAH.

Rpl3l gene deletion in mice reduces heart weight over time.

Introduction: The ribosomal protein L3-like (RPL3L) is a heart and skeletal muscle-specific ribosomal protein and paralogue of the more ubiquitously expressed RPL3 protein. Mutations in the human RPL3L gene are linked to childhood cardiomyopathy and age-related atrial fibrillation, yet the function of RPL3L in the mammalian heart remains unknown. Methods and Results: Here, we observed that mouse cardiac ventricles express RPL3 at birth, where it is gradually replaced by RPL3L in adulthood but re-expressed with induction of hypertrophy in adults. Rpl3l gene-deleted mice were generated to examine the role of this gene in the heart, although Rpl3l -/- mice showed no overt changes in cardiac structure or function at baseline or after pressure overload hypertrophy, likely because RPL3 expression was upregulated and maintained in adulthood. mRNA expression analysis and ribosome profiling failed to show differences between the hearts of Rpl3l null and wild type mice in adulthood. Moreover, ribosomes lacking RPL3L showed no differences in localization within cardiomyocytes compared to wild type controls, nor was there an alteration in cardiac tissue ultrastructure or mitochondrial function in adult Rpl3l -/- mice. Similarly, overexpression of either RPL3 or RPL3L with adeno-associated virus -9 in the hearts of mice did not cause discernable pathology. However, by 18months of age Rpl3l -/- null mice had significantly smaller hearts compared to wild type littermates. Conclusion: Thus, deletion of Rpl3l forces maintenance of RPL3 expression within the heart that appears to fully compensate for the loss of RPL3L, although older Rpl3l -/- mice showed a mild but significant reduction in heart weight.

Induction of whole-body gene deletion via R26-regulated tamoxifen-inducible Cre recombinase activity.

Germline deletion of certain genes causes embryonic lethality, therefore, understanding the effect of deletion of such genes on mammalian pathophysiology remains challenging. Tamoxifen (TAM)-inducible Cre recombinase is widely used for tissue-specific and temporal induction of gene deletion in mice. However, the tamoxifen treatment regimen for the generation of whole-body deletion of a gene is not yet fully standardized for the majority of organs/tissues. Accordingly, we employed GtROSA26 (R26) promoter-regulated Cre and a reporter gene expression strategy. GtROSA26 (R26) is an ubiquitous promoter and mice carrying the R26Cre-ERT2 transgene express Cre-ERT2 in all the cells. Similarly, mice carrying the R26mTOM-mEGFP transgene express mTOM (membrane-targeted tdTomato), in the absence of Cre or mEGFP (membrane-targeted enhanced green fluorescent protein), in the presence of Cre, in all the cells. The progeny carrying one allele of both transgenes were subjected to different TAM regimens, i.e., IP injections (4 injections; 1.35mg/injection), diet (400mg TAM-citrate/kg food), or diet (400mg TAM-citrate/kg food) combined with either TAM-oral gavage (4 gavages; 1.35mg/gavage) or TAM IP injections (4 injections; 1.35mg/injection) for 2-weeks beginning at postnatal day (PND) 21 and the extent of Cre recombination in different tissues was determined at PND35. Tamoxifen administration resulted in a transient loss of body weight in all the treatment regimens with a relatively slower rate of weight gain in the TAM-diet plus TAM-oral gavage group compared to other groups. While the efficiency of Cre recombination, as determined by the expression of mEGFP protein, was variable among tissues, major tissues such as the liver, heart, lungs, spleen, and thymus-showed almost complete recombination. No recombination was evident in any of the tissues examined from the control mice. In general, the efficiency of Cre recombination was better with a combined regimen of TAM-diet with either TAM-injections or TAM-oral gavage compared to TAM-diet alone or TAM-injections alone. Our results demonstrate that a combination of TAM-diet with either TAM-injections or TAM-oral gavage can be employed for the efficient deletion of a gene in the whole body. Our findings will provide technical expertise to the researchers employing TAM-inducible Cre for the deletion of floxed genes in varied tissues.

Fkbp38 deletion induces premature ovarian insufficiency in mice by activating mTOR signaling and inducing granulosa cell apoptosis

To investigate the role of tacrolimus-binding protein 38 (FKBP38) in follicle development and the mechanism by which Fkbp38 gene deletion causes premature ovarian insufficiency (POI). The Cre-loxp system was used to construct oocyte-specific Fkbp38 knockout transgenic mice. The genotype of the transgenic mice was identified using PCR, and the expression of FKBP38 in the oocytes was verified. The numbers of primordial follicles, primary follicles, secondary follicles and antral follicles in Fkbp38 knockout mice and non-transgenic littermate control mice were counted with HE staining under a microscope for analyzing the effect of Fkbp38 deletion on follicular development. The fertility and serum sex hormone levels of the mice were determined by reproduction experiments and ELISA to assess ovarian function. Ovarian granulosa cell apoptosis of the mice was assessed using TUNEL assay. The activity of the downstream target protein of phosphorylated ribosomal S6 (PS6) of mTOR signaling pathway was detected, and the expressions of BCL-2 and BAX proteins were determined using immunofluorescence assay for assessing oocyte development in the mice. The oocyte-specific Fkbp38 knockout transgenic mouse model was successfully constructed, which showed decreased fertility, disordered sex hormone levels, and significantly reduced primordial follicles, primary follicles and secondary follicles in the ovary (P < 0.05), demonstrating POI-like changes. Compared with the control mice, oocyte-specific Fkbp38 knockout caused activation of the mTOR signaling pathway, significantly increased apoptosis of the granulosa cells, and obviously increased the BAX/BCL- 2 ratio by increasing BAX expression and reducing BCL-2 expression in the oocytes (P < 0.05). FKBP38 plays an important role in follicle development, and Fkbp38 gene deletion in mice causes POI possibly by activating the mTOR signaling pathway and inducing granulosa cell apoptosis.