Mouse Strains Research Articles

Influence of Mitochondrial NAD(P) + Transhydrogenase (NNT) on Hypothalamic Inflammation and Metabolic Dysfunction Induced by a High-Fat Diet in Mice.

The mitochondrial protein NAD(P)+ transhydrogenase (NNT) has been implicated in the metabolic derangements observed in obesity. Mice with the C57BL/6J genetic background bear a spontaneous mutation in the Nnt gene and are known to exhibit increased susceptibility to diet-induced metabolic disorders. Most of the studies on NNT in the context of diet-induced obesity have compared C57BL/6J mice with other mouse strains, where differences in genetic background can serve as confounding factors. Moreover, these studies have predominantly employed a high-fat diet (HFD) consisting of approximately 60% of calories from fat, which may not accurately mimic real-world fat-rich diets. In this study, we sought to examine the role of NNT in diet-induced hypothalamic inflammation and metabolic syndrome by using a congenic mice model lacking NNT, along with a HFD providing approximately 45% of calories from fat. Our findings indicate that mice lacking NNT were more protected from HFD-induced weight gain but presented a worse performance on glucose tolerance test, albeit not in insulin tolerance test. Interestingly, the brown adipose tissue of HFD-fed Nnt +/+ mice presented a greater mass and a higher whole-tissue ex-vivo oxygen consumption rate. Also, HFD increased the expression of the inflammatory markers Il1β, Tlr4 and Iba1 in the hypothalamus of Nnt -/- mice. In conclusion, our study highlights the importance of NNT in the context of diet-induced obesity and metabolic syndrome, indicating its contribution to mitigate hypothalamic inflammation and suggesting its role in the brown adipose tissue increased mass.

Mycobacterium abscessus pulmonary infection and associated respiratory function in cystic fibrosis-like βENaC mice

IntroductionChronic pulmonary infection with Mycobacterium abscessus (M. abscessus) is a significant cause of morbidity and mortality in people with cystic fibrosis (CF). Developing an animal model of M. abscessus pulmonary infection, especially under CF conditions, is essential to understanding clinical pulmonary M. abscessus infection. βENaC transgenic mice are known to develop spontaneous CF-like disease characterized by airway mucus obstruction and inflammation. The aim of this study was to evaluate the suitability of βENaC mice as a preclinical model and characterize their respiratory function during M. abscessus lung infection.MethodsMice received an intrapulmonary aerosol of M. abscessus using a high-pressure syringe device (Penn-Century) for subsequent characterization of disease progression and respiratory function. Whole body unrestrained plethysmography (WBP) data was collected to monitor lung function and endpoints determined organ bacterial burden and associated pathology.ResultsEndpoint CFU data in the lung and spleen showed that there was no significant difference in bacterial clearance between βENaC and WT mice. WBP data showed an impairment in overall respiratory function during and after M. abscessus infection in both strains of mice. Interestingly, even in wildtype control mice, lung dysfunction persisted after bacterial clearance.DiscussionEven with CF-like features, the βENaC transgenic mice cleared M. abscessus at a similar rate than WT mice, however, the associated respiratory monitoring revealed that there are long-term implications of M. abscessus lung exposure. The clear decline in respiratory function, even after M. abscessus clearance, suggests that WBP coupled animal modeling provides important insight that is relevant to disease burden and treatment efficacy. The M. abscessus clearance in the βENaC mice may help improve the fields understanding of CF-modulated immune deficiencies in M. abscessus pulmonary infection.

Functional characterization of human IL-8 in vascular stenosis using a novel humanized transgenic mouse model

IL-8 (aka interleukin 8, CXCL8) is a prototypic cytokine that is highly expressed in the diseased vessel wall and its plasma concentration is strongly associated with cardiovascular events. However, whether IL-8 plays a causative role in cardiovascular diseases remains largely unknown. In this study we used a human IL-8 transgenic (Tg) mouse strain with a bacterial artificial chromosome (BAC) integrated into its genome. This BAC encompasses 166 kb of sequence encompassing the human IL-8 gene locus as well as upstream and downstream DNA sequences containing regulatory elements. This BAC ensured a pathophysiologically regulated, rather than forced constitutive, expression of human IL-8 in the mouse. Tg mice were subjected to complete carotid ligation injury. IL-8 was highly expressed in the ligation-injured carotid artery from 3 days until 2 weeks after injury. As a result, exacerbated neointimal hyperplasia and increased Mac2 and PCNA positive cells were observed in Tg mice. To further confirm its role in promoting neointimal formation, IL-8 was neutralized by anti-IL8 treatment at the ligation site. Consequently, the size of neointima was significantly reduced. Our results provided new insights into the regulation and function of IL-8 in response to vascular insult and during neointima formation.

Spiny mice are primed but fail to regenerate volumetric skeletal muscle loss injuries

BackgroundIn recent years, the African spiny mouse Acomys cahirinus has been shown to regenerate a remarkable array of severe internal and external injuries in the absence of a fibrotic response, including the ability to regenerate full-thickness skin excisions, ear punches, severe kidney injuries, and complete transection of the spinal cord. While skeletal muscle is highly regenerative in adult mammals, Acomys displays superior muscle regeneration properties compared with standard laboratory mice following several injuries, including serial cardiotoxin injections of skeletal muscle and volumetric muscle loss (VML) of the panniculus carnosus muscle following full-thickness excision injuries. VML is an extreme muscle injury defined as the irrecoverable ablation of muscle mass, most commonly resulting from combat injuries or surgical debridement. Barriers to the treatment of VML injury include early and prolonged inflammatory responses that promote fibrotic repair and the loss of structural and mechanical cues that promote muscle regeneration. While the regeneration of the panniculus carnosus in Acomys is impressive, its direct relevance to the study of VML in patients is less clear as this muscle has largely been lost in humans, and, while striated, is not a true skeletal muscle. We therefore sought to test the ability of Acomys to regenerate a skeletal muscle more commonly used in VML injury models.MethodsWe performed two different VML injuries of the Acomys tibialis anterior muscle and compared the regenerative response to a standard laboratory mouse strain, Mus C57BL6/J.ResultsNeither Acomys nor Mus recovered lost muscle mass or myofiber number within three months following VML injury, and Acomys also failed to recover force production better than Mus. In contrast, Acomys continued to express eMHC within the injured area even three months following injury, whereas Mus ceased expressing eMHC less than one-month post-injury, suggesting that Acomys muscle was primed, but failed, to regenerate.ConclusionsWhile the panniculus carnosus muscle in Acomys regenerates following VML injury in the context of full-thickness skin excision, this regenerative ability does not translate to regenerative repair of a skeletal muscle.

Inhibiting chondroitin sulfate synthase 1 ameliorates hyperplastic arterial remodelling

Abstract Introduction Hyperplastic arterial remodelling is characterized by intima-media thickening, lumen narrowing, inflammation and increased extracellular matrix (ECM) deposition. Chondroitin sulfate (CS) glycosaminoglycans, the unbranched polysaccharide chains of proteoglycans, are important components of ECM. We previously found CS accumulated in adversely remodelled heart and artery, aggravating cardiac deterioration. Objective We aim to explore a therapeutic strategy to interfere with CS synthesis and investigate its potential in ameliorating hyperplastic arterial remodelling. Methods Through single-cell RNA sequencing of non-cardiomyocytes cardiac cells from mouse myocardial infarction model, chondroitin sulfate synthase 1 (CHSY1) was identified as the primary CS synthase and was increased during disease progression. A Chsy1 knockout (KO) mouse strain was generated. Fibrosis and arterial remodelling were induced using: (i) 4 weeks of angiotensin II/phenylephrine (AngII/PE) infusion through subcutaneous osmotic minipumps; and (ii) transverse aortic constriction surgery. To assess the therapeutic potential of CHSY1 inhibition in ameliorating hyperplastic arterial remodelling, Chsy1 was knockdown by dsiRNA post disease onset. Mechanism of action was investigated using primary vascular smooth muscle cells (VSMCs). Results Chsy1 KO reduced CS and its stereoisomer dermatan sulfate in the heart to 42 ± 22% and 36 ± 7% respectively, whereas other types of glycosaminoglycans remain intact. KO mice were protected against phenotypes of hyperplastic arterial remodelling induced by the two disease models in both the coronary and carotid arteries. For example, 90.1% of coronary arterial fibrosis and 79.7% of macrophage infiltration induced by AngII/PE was declined in KO mice compared to WT mice, while cardiac function as stroke volume was augmented by 41.3%. Concomitantly, carotid arterial wall thickening was lower by 36.5% and distensibility was higher by 36.7%, validating Chsy1 as a potent target. As a therapeutic approach, weekly intravenous injection of dsiRNA achieved Chsy1 reduced to 30.2 ± 5.5% in the carotid artery and 72.5 ± 4.7% in the heart. Post disease onset, Chsy1 KD therapy reduced fibrosis by 59.9% in the coronary artery (P = 0.006) and improved stroke volume by 25.6% (P = 0.036). The structural integrity and function of carotid arteries were well-reserved, manifesting as improved distensibility (29%, P = 0.016), increased elastin/perimeter ratio (15%, P = 0.002), and reduced macrophage infiltration (38%, P = 0.029). In vitro, CHSY1 inhibition suppressed migration and cytokine production of macrophages, fibroblast-to-myofibroblast transition, and VSMC hyperproliferation. NOTCH3 signalling was found to be positively correlated with CHSY1 modulation. Conclusions We demonstrated that inhibiting CHSY1 is necessary and sufficient to block CS synthesis. Chsy1 KD by dsiRNA is an effective therapy to ameliorate hyperplastic arterial remodelling.

The reconstruction of evolutionary dynamics of processed pseudogenes indicates deep silencing of “retrobiome” in naked mole rat

Approximately half of mammalian genomes are occupied by retrotransposons, highly repetitive interspersed genetic elements expanded through the mechanism of reverse transcription. The evolution of this "retrobiome" involved a series of explosive amplifications, presumably associated with high mutation rates, interspersed with periods of silencing. A by-product of retrotransposon activity is the formation of processed pseudogenes (PPGs)-intron-less, promoter-less DNA copies of messenger RNA (mRNA). We examined the proportion of PPGs with varying degrees of deviation from their ancestor mRNAs as an indicator of the intensity of retrotranspositions at different times in the past. Our analysis revealed a high proportion of "young'' (recently acquired) PPGs in the DNA of mice and rats, indicating significant retrobiome activity during the recent evolution of these species. The ongoing process of new PPG entries in mouse germ line DNA was confirmed by identifying diversity in PPG content within the single strain of mice, C57BL/6. In contrast, the highly abundant PPGs of the naked mole rat (NMR) exhibited substantial deviation from their mRNAs, with a near-complete lack of PPGs without mutations, indicative of the silencing of the retrobiome in the most recent evolutionary past, preceded by a period of high activity. This distinctive feature of the NMR genome was confirmed through the analysis of a broad range of mammalian species. The peculiar evolutionary dynamics of PPGs in the NMR, an organism with exceptional longevity and resistance to cancer, may reflect the role played by the retrobiome in aging and cancer.

Circadian rhythm disruption modulates enteric neural precursor cells differentiation leading to gastrointestinal motility dysfunction via the NR1D1/NF-κB axis

ObjectivesCircadian rhythm disruption (CRD) is implicated with numerous gastrointestinal motility diseases, with the enteric nervous system (ENS) taking main responsibility for the coordination of gastrointestinal motility. The purpose of this study is to explore the role of circadian rhythms in ENS remodeling and to further elucidate the underlying mechanisms.MethodsFirst, we established a jet-lagged mice model by advancing the light/dark phase shift by six hours every three days for eight weeks. Subsequent changes in gastrointestinal motility and the ENS were then assessed. Additionally, a triple-transgenic mouse strain (Nestin-creERT2 × Ngfr-DreERT2: DTRGFP) was utilized to track the effects of CRD on the differentiation of enteric neural precursor cells (ENPCs). RNA sequencing was also performed to elucidate the underlying mechanism.ResultsCompared to the control group, CRD significantly accelerated gastrointestinal motility, evidenced by faster intestinal peristalsis (P < 0.01), increased fecal output (P < 0.01), and elevated fecal water content (P < 0.05), as well as enhanced electrical field stimulation induced contractions (P < 0.05). These effects were associated with an increase in the number of glial cells and nitrergic neurons in the colonic myenteric plexus. Additionally, ENPCs in the colon showed a heightened differentiation into glial cells and nitrergic neurons. Notably, the NR1D1/nuclear factor-kappaB (NF-κB) axis played a crucial role in the CRD-mediated changes in ENPCs differentiation. Supplementation with NR1D1 agonist or NF-κB antagonist was able to restore gastrointestinal motility and normalize the ENS in jet-lagged mice.ConclusionsCRD regulates the differentiation of ENPCs through the NR1D1/NF-κB axis, resulting in dysfunction of the ENS and impaired gastrointestinal motility in mice.

Chronic interferon-stimulated gene transcription promotes oncogene-induced breast cancer.

The MRE11 complex (comprising MRE11, RAD50, and NBS1) is integral to the maintenance of genome stability. We previously showed that a hypomorphic Mre11 mutant mouse strain (Mre11 ATLD1/ATLD1 ) was highly susceptible to oncogene-induced breast cancer. Here we used a mammary organoid system to examine which MRE11-dependent responses are tumor-suppressive. We found that Mre11 ATLD1/ATLD1 organoids exhibited an elevated interferon-stimulated gene (ISG) signature and sustained changes in chromatin accessibility. This Mre11 ATLD1/ATLD1 phenotype depended on DNA binding of a nuclear innate immune sensor, IFI205. Ablation of Ifi205 in Mre11 ATLD1/ATLD1 organoids restored baseline and oncogene-induced chromatin accessibility patterns to those observed in WT. Implantation of Mre11 ATLD1/ATLD1 organoids and activation of the oncogene led to aggressive metastatic breast cancer. This outcome was reversed in implanted Ifi205 -/- Mre11 ATLD1/ATLD1 organoids. These data reveal a connection between innate immune signaling and tumor development in the mammary epithelium. Given the abundance of aberrant DNA structures that arise in the context of genome instability syndromes, the data further suggest that cancer predisposition in those contexts may be partially attributable to chronic innate immune transcriptional programs.

AKTIVITAS ANTITUMOR KOMBINASIEKSTRAKTyphonium flagelliformeDENGANINTERFERON ALAMIANJING DAN KUCING PADA MENCITDENGAN TUMORKULIT YANG DIINDUKSIDMBA

Indonesia has various plants with potential activities and uses as antitumor agents, one of which is Typhonium flagelliforme. This study aimed to examine in vivo the effects of combination therapy of T. flagelliforme leaf-ethanolic extract and natural interferon of canine or feline as an antitumor agent. In this study, 18 female mice of ddY strain induced with 7.12-dimethyl-benz(?)anthracene (DMBA) carcinogenic substance were divided into six treatment groups. All tumor tissues formed were collected and made for histopathological slides. The slides were stained with Hematoxylin-Eosin (HE) and immunohistochemistry (IHC) procedure using antibodies for proliferating cell nuclear antigen (PCNA) and Caspase-3. The macroscopic observations showed that the skin surface of the mice groups with tumors had alopecia with a reddish color. The microscopic observations showed three tumors types: anaplastic carcinoma, fibrosarcoma, and squamous cell carcinoma. The mitotic, angiogenesis, PCNA and Caspase-3 tests showed significant differences among the groups administered with the single and combination test materials. The combination therapy of T. flagelliforme leaf-ethanolic extract and natural interferon can stabilize mice’s body weight, inhibit tumor growth, reduce mitosis and angiogenesis, and reduce PCNA and Caspase-3 expression.

Characterization of Collaborative Cross mouse founder strain CAST/EiJ as a novel model for lethal COVID-19

Mutations in SARS-CoV-2 variants of concern (VOCs) have expanded the viral host range beyond primates, and a few other mammals, to mice, affording the opportunity to exploit genetically diverse mouse panels to model the broad spectrum of responses to infection in patient populations. Here we surveyed responses to VOC infection in genetically diverse Collaborative Cross (CC) founder strains. Infection of wild-derived CC founder strains produced a broad range of viral burden, disease susceptibility and survival, whereas most other strains were resistant to disease despite measurable lung viral titers. In particular, CAST/EiJ, a wild-derived strain, developed high lung viral burdens, more severe lung pathology than seen in other CC strains, and a dysregulated cytokine profile resulting in morbidity and mortality. These inbred mouse strains may serve as a valuable platform to evaluate therapeutic countermeasures against severe COVID-19 and other coronavirus pandemics in the future.

Generation and Characterization of Three Novel Mouse Mutant Strains Susceptible to Audiogenic Seizures.

The mechanisms of epileptogenesis after brain injury, ischemic stroke, or brain tumors have been extensively studied. As a result, many effective antiseizure drugs have been developed. However, there are still many patients who are resistant to therapy. The molecular and genetic bases regarding such drug-resistant seizures have been poorly elucidated. In many cases, heavy seizures are instigated by brain development malformations and often caused by gene mutations. Such malformations can be demonstrated in mouse models by generating mutant strains. One of the most potent mutagens is ENU (N-ethyl-N-nitrosourea). In the present study, we describe three novel mutant strains generated by ENU-directed mutagenesis. Two of these strains present a very strong epileptic phenotype triggered by audiogenic stimuli (G9-1 and S5-1 strains). The third mouse strain is characterized by behavioral disorders and hyperexcitation of neuronal networks. We identified changes in the expression of those genes encoding neurotransmission proteins in the cerebral cortexes of these mice. It turned out that the G9-1 strain demonstrated the strongest disruptions in the expression of those genes encoding plasma membrane channels, excitatory glutamate receptors, and protein kinases. On the other hand, the number of GABAergic neurons was also affected by the mutation. All three lines are characterized by increased anxiety, excitability, and suppressed motor and orientational-exploratory activities. On the other hand, the strains with an epileptic phenotype-G9-1 and S5-1ave reduced learning ability, and the A9-2 mice line retains high learning ability.

NUMB dysfunction defines a novel mechanism underlying hyperuricemia and gout

Defective renal excretion and increased production of uric acid engender hyperuricemia that predisposes to gout. However, molecular mechanisms underlying defective uric acid excretion remain largely unknown. Here, we report a rare genetic variant of gout-unprecedented NUMB gene within a hereditary human gout family, which was identified by an unbiased genome-wide sequencing approach. This dysfunctional missense variant within the conserved region of the NUMB gene (NUMBR630H) underwent intracellular redistribution and degradation through an autophagy-dependent mechanism. Mechanistically, we identified the uric acid transporter, ATP Binding Cassette Subfamily G Member 2 (ABCG2), as a novel NUMB-binding protein through its intracellular YxNxxF motif. In polarized renal tubular epithelial cells (RTECs), NUMB promoted ABCG2 trafficking towards the apical plasma membrane. Genetic loss-of-function of NUMB resulted in redistribution of ABCG2 in the basolateral domain and ultimately defective excretion of uric acid. To recapitulate the clinical situation in human gout patients, we generated a NUMBR630H knock-in mouse strain, which showed marked increases of serum urate and decreased uric acid excretion. The NUMBR630H knock-in mice exhibited clinically relevant hyperuricemia. In summary, we have uncovered a novel NUMB-mediated mechanism of uric acid excretion and a functional missense variant of NUMB in humans, which causes hyperuricemia and gout.

Activation of Gs signaling in mouse enteroendocrine K-cells greatly improves obesity- and diabetes-related metabolic deficits.

Following a meal, glucagon-like peptide-1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP), the two major incretins promoting insulin release, are secreted from specialized enteroendocrine cells (L- and K-cells, respectively). Although GIP is the dominant incretin in humans, the detailed molecular mechanisms governing its release remain to be explored. GIP secretion is regulated by the activity of G protein-coupled receptors (GPCRs) expressed by K-cells. GPCRs couple to one or more specific classes of heterotrimeric G proteins. In the present study, we focused on the potential metabolic roles of K-cell Gs. First, we generated a mouse model that allowed us to selectively stimulate K-cell Gs signaling. Second, we generated a mouse strain harboring an inactivating mutation of Gnas, the gene encoding the alpha-subunit of Gs, selectively in K-cells. Metabolic phenotyping studies showed that acute or chronic stimulation of K-cell Gs signaling greatly improved impaired glucose homeostasis in obese mice and in a mouse model of type 2 diabetes, due to enhanced GIP secretion. In contrast, K-cell-specific Gnas knockout mice displayed markedly reduced plasma GIP levels. These data strongly suggest that strategies aimed at enhancing K-cell Gs signaling may prove useful for the treatment of diabetes and related metabolic diseases.

Comparative Study of Cutaneous Squamous Cell Carcinogenesis in Different Hairless Murine Models

Background: In recent decades, a significant global increase in the incidence of non-melanoma skin cancer has been observed. To explore the pathogenesis of and potential therapeutic approaches for squamous cell carcinoma, various in vivo studies using mouse models have been conducted. However, investigations comparing different hairless mouse models, with or without melanin, as well as models with hypercholesterolemia and immunosuppression, in terms of their ability to induce squamous cell carcinoma have yet to be undertaken. Methods: Four mouse strains, namely SKH-hr1, SKH-hr2, SKH-hr2+ApoE, and immunodeficient Nude (Foxn1 knockout), were exposed to UVA and UVB radiation three times per week, initially to 1 Minimal Erythemal Dose (MED), incrementally increased weekly to a maximum dose of 3 MED. Clinical evaluation, photodocumentation, and biophysical parameters were monitored, along with proteasome protein activity and histopathological assessments. Results: The SKH-hr1 model primarily developed actinic keratosis without significant progression to invasive squamous cell carcinoma (SCC), while the SKH-hr2 and SKH-hr2+ApoE models exhibited a higher likelihood and intensity of papilloma and aggressive SCC formation, with the latter showing upregulated proteasome activity. Histopathological analysis confirmed the presence of poorly differentiated, invasive SCCs in the SKH-hr2 and SKH-hr2+ApoE models, contrasting with the less aggressive SCCs in the Nude mice and the mixed lesions observed in the SKH-hr1 mice. Conclusions: The SKH-hr2+ApoE and SKH-hr2 mice were identified as the most suitable for further exploration of squamous cell carcinogenesis. In contrast, the SKH-hr1 mice were found to be the least suitable, even though they are albino. Notably, proteasome analysis revealed a potential role of proteasome activity in squamous cell carcinogenesis.

Regulator of G-Protein Signaling 2 Knockout in CD4+ T Cells Promotes Anti-Inflammatory T Cells, Enhancing Ovulation, and Oocyte Yield.

To determine the downstream effects on ovarian function and immune cell differentiation in the ovary and uterus using a model in which RGS2 was knocked out specifically in CD4+ T cells. Laboratory based experiments with female mice. Female congenic (fully backcrossed) and non-congenic (mixed strain) mice with CD4 T cell-specific RGS2 knockout. Four-week-old female CD4 RGS2 knockout (CD4 RGS2 KO ) mice and their littermate controls (CD4 RGS2 CTL ) were subjected to superovulation using pregnant mare serum gonadotropins. Oocyte numbers, lymphocyte populations in the ovary and uterus, and serum estradiol and progesterone concentrations. In non-congenic (mixed strain) mice, CD4 RGS2 knockout (KO) promoted higher oocyte ovulation and increased uterine total leukocyte numbers. Similarly, congenic (fully backcrossed strain) mice showed higher oocyte numbers and increased uterine total leukocytes in the CD4 RGS2 KO mice compared to CD4 RGS2 CTL mice. Pro-inflammatory CD4+ T helper (T H ) 1 and T H 17 cell frequencies in the ovary and uterus were unchanged, while Treg and T H 2 cell frequencies were elevated, along with increased concentrations of estradiol and progesterone in the serum of CD4 RGS2 KO mice. Our study highlights the important role of RGS2 in CD4+ T cells within the context of reproduction. The dysregulation of immune responses due to RGS2 knockout in CD4+ T cells appears to enhance oocyte production. Further research is warranted to elucidate the precise mechanisms by which RGS2 influences reproductive outcomes, including its impact on fecundability, endometrial receptivity, and successful implantation.

A novel animal model of spontaneous epilepsy: Cdk5 knockout in pericyte-specific mice.

Changes in neurovascular unit components and their interactions play a crucial role in epileptogenesis and the pathological process of epilepsy. Currently, there is a lack of animal models that can accurately reflect the etiological impact of cerebrovascular lesions on epilepsy. In this study, we constructed cyclin-dependent kinase 5 conditional knockout mice in Cspg4 (pericyte marker)-positive cells using the Cre-LoxP system. The results revealed that this strain of mice exhibited significant seizure behaviors and epileptiform brain waves, loss of hippocampal and amygdala neurons, astrogliosis, decreased pericyte coverage, and reduced AQP4 polar distribution. Herein, we have developed a novel mouse model of spontaneous epilepsy, providing a critical animal model for studying the involvement of neurovascular unit factors in the development and progression of epilepsy.

Extra-cerebral recombination activity of Emx1-Cre and nestin-Cre in the kidney.

Individuals with neurodevelopmental disorders (NDDs) are frequently diagnosed with comorbidities in other organs, indicating that NDD risk genes may have extra-cerebral functions. The engineered mouse models are pivotal in understanding the functions of candidate NDD genes. Here, we report that Emx1-Cre and nestin-Cre mouse strains, the popular tools to study brain development, also exhibit recombination activity in the kidney. We find that both Emx1-Cre and nestin-Cre can drive recombination in epithelial cells lining proximal and distal convoluted tubules of the nephron. Additionally, nestin-Cre drives recombination in the glomerulus of the nephron. Furthermore, we use Emx1-Cre and nestin-Cre to knock out Larp7, a gene linked to a human NDD called Alazami syndrome. We find that Larp7 knockout using nestin-Cre, but not Emx1-Cre, results in elevated blood urea nitrogen. This result suggests a compromised kidney function, reminiscent of recently revealed renal anomalies in Alazami syndrome patients. Many genes have been knocked out using Emx1-Cre and nestin-Cre to study their roles during embryonic neurogenesis. It will be of great interest to reinvestigate whether the renal development and function is affected in these existing mouse models.

Sympathetic Innervation of Interscapular Brown Adipose Tissue Is Not a Predominant Mediator of Oxytocin-Induced Brown Adipose Tissue Thermogenesis in Female High Fat Diet-Fed Rats.

Recent studies have indicated that hindbrain [fourth ventricle (4V)] administration of the neurohypophyseal hormone, oxytocin (OT), reduces body weight, energy intake and stimulates interscapular brown adipose tissue temperature (TIBAT) in male diet-induced obese (DIO) rats. What remains unclear is whether chronic hindbrain (4V) OT can impact body weight in female high fat diet-fed (HFD) rodents and whether this involves activation of brown adipose tissue (BAT). We hypothesized that OT-elicited stimulation of sympathetic nervous system (SNS) activation of interscapular brown adipose tissue (IBAT) contributes to its ability to activate BAT and reduce body weight in female high HFD-fed rats. To test this hypothesis, we determined the effect of disrupting SNS activation of IBAT on OT-elicited stimulation of TIBAT and reduction of body weight in DIO rats. We first measured the impact of bilateral surgical SNS denervation to IBAT on the ability of acute 4V OT (0.5, 1, and 5 µg ≈ 0.5, 0.99, and 4.96 nmol) to stimulate TIBAT in female HFD-fed rats. We found that the high dose of 4V OT (5 µg ≈ 4.96 nmol) stimulated TIBAT similarly between sham rats and denervated rats (p = NS). We subsequently measured the effect of bilateral surgical denervation of IBAT on the effect of chronic 4V OT (16 nmol/day ≈ 16.1 μg/day) or vehicle infusion to reduce body weight, adiposity and energy intake in female HFD-fed rats (N = 7-8/group). Chronic 4V OT reduced body weight gain (sham: -18.0 ± 4.9 g; denervation: -15.9 ± 3.7 g) and adiposity (sham: -13.9 ± 3.7 g; denervation: -13.6 ± 2.4 g) relative to vehicle treatment (p < 0.05) and these effects were similar between groups (p = NS). These effects were attributed, in part, to reduced energy intake evident during weeks 2 (p < 0.05) and 3 (p < 0.05). To test whether these results translate to other female rodent species, we also examined the effect of chronic 4V infusion of OT on body weight and adiposity in two strains of female HFD-fed mice. Similar to what we found in the HFD-fed rat model, we also found that chronic 4V OT (16 nmol/day) infusion resulted in reduced body weight gain, adiposity and energy intake in female DIO C57BL/6J and DBA/2J mice (p < 0.05 vs. vehicle). Together, these findings suggest that (1) sympathetic innervation of IBAT is not necessary for OT-elicited increases in BAT thermogenesis and weight loss in female HFD-fed rats and (2) the effects of OT to reduce weight gain and adiposity translate to other female mouse models of diet-induced obesity (DIO).

Alterations in cellular metabolic pathway and epithelial cell maturation induced by MYO5B defects are partially reversible by LPAR5 activation.

Functional loss of the motor protein, Myosin Vb (MYO5B), induces various defects in intestinal epithelial function and causes a congenital diarrheal disorder, microvillus inclusion disease (MVID). Utilizing the MVID model mice, Vil1-CreERT2;Myo5bflox/flox (MYO5B∆IEC) and Vil1-CreERT2;Myo5bflox/G519R (MYO5B(G519R)), we previously reported that functional MYO5B loss disrupts progenitor cell differentiation and enterocyte maturation that result in villus blunting and deadly malabsorption symptoms. In this study, we determined that both absence and a point mutation of MYO5B impair lipid metabolism and alter mitochondrial structure, which may underlie the progenitor cell malfunction observed in MVID intestine. Along with a decrease in fatty acid oxidation, the lipogenesis pathway was enhanced in the MYO5B∆IEC small intestine. Consistent with these observations in vivo, RNA-sequencing of enteroids generated from the two MVID mouse strains showed similar downregulation of energy metabolic enzymes, including mitochondrial oxidative phosphorylation genes. In our previous studies, lysophosphatidic acid (LPA) signaling ameliorates epithelial cell defects in MYO5B∆IEC tissues and enteroids. The present study demonstrated that the highly soluble LPAR5-preferred agonist, Compound-1, improved sodium transporter localization and absorptive function, and tuft cell differentiation in patient-modeled MVID animals that carry independent mutations in MYO5B. Body weight loss in male MYO5B(G519R) mice was ameliorated by Compound-1. These observations suggest that Compound-1 treatment has a trophic effect on intestine with MYO5B functional loss through epithelial cell-autonomous pathways that can accelerate the differentiation of progenitor cells and the maturation of enterocytes. Targeting LPAR5 may represent an effective therapeutic approach for treatment of MVID symptoms induced by different point mutations in MYO5B.

Mucosal BCG delivery provides a spectrum of protection from different Mycobacterium tuberculosis strains across susceptible and resistant mouse backgrounds

Mycobacterium bovis Bacille Calmette-Guérin (BCG) is the sole globally licensed vaccine against tuberculosis despite its relatively moderate protection of acute disease through adolescence. We hypothesize that vaccine efficacy from a mucosal BCG vaccination will be directly influenced by Mycobacterium tuberculosis (M.tb) strain and mouse background. Here we investigated the effectiveness of mucosal BCG vaccination via the intranasal route, in resistant and susceptible mouse strains, to protect against laboratory strain H37Rv and clinical strain HN878 M.tb aerosol challenge. We evaluated both pulmonary and disseminated CFU at 4-weeks post-infection in addition to survival endpoints in C57BL/6, SWR, and C3HeB/FeJ mice. Antigen specific T cell responses in the lung post-infection were also evaluated. We observed that in each case intranasal BCG afforded a significant reduction in pulmonary CFU at 4-weeks post-infection compared to matched untreated controls. However, only susceptible mouse strains, SWR and C3HeB/FeJ, demonstrated similarly robust control from bacterial dissemination when CFU in the spleen was evaluated at the same timepoint. In the case of both M.tb H37Rv and M.tb HN878 challenge, intranasal BCG significantly improved survival of each mouse cohort compared to unvaccinated controls. Together these data suggest that there is still much to be learned from the century old vaccine, BCG, and how it drives protection.