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Transmission and activation of cytomegalovirus with blood transfusion: a mouse model.

A mouse model that mimics many features of human cytomegalovirus (CMV) infections associated with transfusion and perfusion is described. The concept of antigenic activation of CMV was tested by infusion of blood from latently infected mice, which were found to be virus-negative by tissue culture asssay, into uninfected allogeneic and isogenic hosts. After a latent period, virus was detectable invariably in allogeneic and only rarely in isogenic recipients. Transfusions from uninfected donors into latently infected mice activated CMV in heterologous and homologous recipients. These observations should assist in definition of relevant pathogenetic principles and may explain the failure to recover CMV from healthy human blood donors in spite of predictions of a carrier state based on epidemiologic observations.

Animals

A mouse model of influenza protection.

A mouse model has been developed in order to examine the parts played by humoral and cellular mechanisms in influenza immunity. Protection is assessed in terms of the amount of virus detectable in the lungs within 48 h of challenge. This system has two major advantages over the more common mouse lethality models. It is no longer necessary to use a mouse-lethal strain of virus; and protection is measured within days rather than weeks of challenge. Thus it is possible to determine the ability of the immune system to limit infection at an early stage, as distinct from curing a pre-existing infection and so preventing death. Transfer of spleen cells from an immune donor to a normal recipient will significantly reduce the amount of virus found in the lungs 24 h after challenge. The transferred cells are, however, capable of producing significant serum levels of anti-influenza antibody. Administration of serum from immune mice to normal recipients also results in a significant degree of protection within 24 h of challenge. These results give additional evidence that in the mouse significant protection is provided by serum antibody very soon after infection, but do not exclude the possibility that a part may be played by other mechanisms.

Animals

Experimental studies of the pathogenesis of infections due to Pseudomonas aeruginosa: description of a burned mouse model.

An experimental burned mouse model is described that is clinically relevant to burn wound sepsis caused by Pseudomonas aeruginosa. Mice subjected to a nonlethal burn by flame were challenged with P. aeruginosa. The LD50 after subcutaneous injection in the skin of the burn up to 24 hr after the burn was smaller than 10 organisms vs. 10-6 organisms in normal animals. By three days after the burn, the value returned to and exceeded that of normal animals. This dramatic change in the LD50 after the burn was not seen when mice were challenged with other organisms. Challenge with P. aeruginosa by different routes immediately after burning showed less dramatic decreases in the LD50. Enumeration of infecting organisms in the skin of the burn and in major organs suggests the possibility of a toxic event.

Animals

Investigating the genomic landscape of mouse models of breast cancer metastasis.

Metastasis remains a major cause of cancer mortality. AbstractThis study, expanding upon previous findings in the MMTV-PyMT model, investigated four independent mouse models, representing luminal (MMTV-PyMT, MMTV-Myc), HER2-amplified (MMTV-Her2) and triple negative (C3(1)TAg) breast cancer subtypes. Consistent with previous results, limited evidence for metastasis-associated somatic point mutations was found for all models. We also found that oncogenic drivers significantly influenced the number and size of metastasis-specific copy number variations (MSCNVs), but common driver-independent MSCNVs were rare. Furthermore, analyzing a cohort with varying genetic backgrounds while maintaining a constant oncogenic driver (PyMT) revealed that genetic background profoundly impacts MSCNVs. Transcriptome analysis demonstrated that oncogenic drivers strongly shaped metastasis-specific gene expression (MSGE), with each driver exhibiting distinct expression profiles. In contrast, MSGE in the PyMT-F1 cohort was more variable across strains. Despite the diversity of MSCNV and MSGE, functional analysis revealed that both mechanisms converge on the modulation of key cellular processes, including immune responses, metabolism, and extracellular matrix interactions. These findings emphasize the complex interplay between oncogenic drivers and genetic background in shaping the genomic and transcriptional landscapes of metastatic lesions.

Journal Article

Inhaled xenon modulates microglia and ameliorates disease in mouse models of amyloidosis and tauopathy.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder. Antiamyloid antibody treatments modestly slow disease progression in mild dementia due to AD. Emerging evidence shows that homeostatic dysregulation of the brain immune system, especially that orchestrated by microglia, plays an important role in disease onset and progression. Thus, a major question is how to modulate the phenotype and function of microglia to treat AD. Xenon (Xe) gas is a noble gas used in human patients as an anesthetic and a neuroprotectant used for treating brain injuries. Xe penetrates the blood-brain barrier, which could make it an effective therapeutic. To assess the effect of Xe on microglia and AD pathology, we designed a custom Xe inhalation chamber and treated several mouse models of AD with Xe gas. Xe treatment induced mouse microglia to adopt an intermediate activation state that we have termed pre-neurodegenerative microglia (pre-MGnD). This microglial phenotypic transition was observed in mouse models of acute neurodegeneration and amyloidosis (APP/PS1 and 5xFAD mice) and tauopathy (P301S mice). This microglial state enhanced amyloid plaque compaction and reduced dystrophic neurites in the APP/PS1 and 5xFAD mouse models. Moreover, Xe inhalation reduced brain atrophy and neuroinflammation and improved nest-building behavior in P301S mice. Mechanistically, Xe inhalation induced homeostatic brain microglia toward a pre-MGnD state through IFN-γ signaling that maintained the microglial phagocytic response in APP/PS1 and 5xFAD mice while suppressing the microglial proinflammatory phenotype in P301S mice. These results support the translation of Xe inhalation as an approach for treating AD.

Animals

Intrahepatic Exhausted Antiviral Immunity in an Immunocompetent Mouse Model of Chronic Hepatitis B.

BACKGROUND & AIMS: Targeting exhausted immune systems would be a promising therapeutic strategy to achieve a functional cure for HBV infection in patients with chronic hepatitis B (CHB). However, animal models recapitulating the immunokinetics of CHB are very limited. We aimed to develop an immunocompetent mouse model of CHB for intrahepatic immune profiling. METHODS: CHB mice were created by intrahepatic delivery of the Sleeping Beauty transposon vector tandemly expressing the hepatitis B virus (HBV) genome and fumarylacetoacetate hydrolase (FAH) cDNA into C57BL/6J congenic FAH knockout mice via hydrodynamic tail vein injection. We profiled the viral and intrahepatic immune kinetics in CHB mice with or without treatment with recombinant IFNα or the hepatotropic Toll-like receptor 7 agonist SA-5 using single-cell RNA-seq. RESULTS: CHB mice exhibited sustained HBV viremia and persistent hepatitis. They showed intrahepatic expansion of exhausted CD8+ T (Tex) cells, the frequency of which was positively associated with viral load. Recruited macrophages increased in number but impaired inflammatory responses in the liver. The cytotoxicity of mature natural killer (NK) cells also increased in CHB mice. IFNα and SA-5 treatment both resulted in viral suppression with mild hepatic flares in CHB mice. Although both treatments activated NK cells, SA-5 had the capacity to revitalize the impaired function of Tex cells and liver-recruited macrophages. CONCLUSIONS: Our novel CHB mouse model recapitulated the intrahepatic exhausted antiviral immunity in patients with CHB, which might be able to be reinvigorated by a hepatotropic TLR7 agonist.

Animals

A novel mouse model recapitulates the effects of rs2254524 variant in the lanosterol synthase gene on salt sensitivity and organ damage.

OBJECTIVE: The blood pressure (BP) response to salt intake (salt sensitivity) shows great variability among individuals and is more frequent in hypertensive patients. Elevated levels of the steroid hormone Endogenous Ouabain (EO) are associated with hypertension (HT) and salt sensitivity. The lanosterol synthase gene ( LSS ) plays a key role in the biosynthesis of steroids and its rs2254524 variant (Val642Leu) is linked to salt sensitivity in humans. This study aims to investigate the pathophysiological significance of the Lss missense variation in a new knock-in mouse model of salt-sensitive HT onset. METHODS: We generated a mouse model carrying the murine homolog (Val643Leu) of the human LSS variant. C57BL/6N LssV643L/V643L mice were fed different NaCl diets (low-salt, LSD; normal-salt, NSD; high-salt, HSD) and were characterized at functional, histological, and molecular levels. RESULTS: At baseline, mutant mice showed an enlarged kidney compared to the wild-type (WT) counterpart, but the Lss V643L variant did not affect EO biosynthesis nor systolic BP at 3 and 12 months. In HSD, we observed an increased systolic BP only in 12-month-old LssV643L/V643L mice, compared to NSD. Moreover, only the HSD LssV643L/V643L mice showed cardiac hypertrophy and a higher incidence of cardiac fibrosis compared to WT at 12 months. Finally, the Lss mRNA level was differentially regulated by HSD in the adrenal gland, liver, and heart of LssV643L/V643L mice compared to WT. CONCLUSIONS: The novel Lss mouse model resembles the salt-sensitive HT phenotype observed in hypertensive patients and provides a good model of salt-sensitive HT and HT-mediated organ damage.

Animals

Indirect mouse model for the evaluation of potential antiviral compounds: results with Venezuelan equine encephalomyelitis virus.

An indirect mouse model was utilized to evaluate the antiviral activity of several compounds against Venezuelan equine encephalomyelitis (VEE) virus infection in mice. Mice were given various dosages of lysine-stabilized polyriboinosinic acid-polyribocytidylic acid, a tilorone analogue, kethoxal, or mepacrine before and/or shortly after receiving one of several dose levels of attenuated strain TC-83 VEE virus. Twenty-one days later, the same mice were rechallenged intracranially with virulent Trinidad donkey strain VEE virus. Susceptibility to rechallenge was interpreted as evidence of drug effectiveness in completely preventing the initial immunizing virus infection. In contrast, if a drug lacked antiviral effectiveness, the initial attenuated infection stimulated sufficient immunity to protect mice against the virulent rechallenge. Both of the interferon inducers, lysine-stabilized polyriboinosinic acid-polyribocytidylic acid and tilorone analogue 11,567, possessed significant (P < 0.01) antiviral activity based upon this indirect model, whereas mepacrine and kethoxal were inactive. Results using the indirect method were confirmed by using the conventional direct method for evaluating the effectiveness of potentially useful antiviral compounds. The indirect mouse model described should prove useful for studying drug efficacy against certain viruses that are lethal only by intracranial inoculation.

Animals

Retinal Proteome Profiling of Inherited Retinal Degeneration Across Three Different Mouse Models Suggests Common Drug Targets in Retinitis Pigmentosa.

Inherited retinal degenerations (IRDs) are a leading cause of blindness among the population of young people in the developed world. Approximately half of IRDs initially manifest as gradual loss of night vision and visual fields, characteristic of retinitis pigmentosa (RP). Due to challenges in genetic testing, and the large heterogeneity of mutations underlying RP, targeted gene therapies are an impractical largescale solution in the foreseeable future. For this reason, identifying key pathophysiological pathways in IRDs that could be targets for mutation-agnostic and disease-modifying therapies (DMTs) is warranted. In this study, we investigated the retinal proteome of three distinct IRD mouse models, in comparison to sex- and age-matched wild-type mice. Specifically, we used the Pde6&#x3b2;Rd10 (rd10) and RhoP23H/WT (P23H) mouse models of autosomal recessive and autosomal dominant RP, respectively, as well as the Rpe65-/- mouse model of Leber's congenital amaurosis type 2 (LCA2). The mice were housed at two distinct institutions and analyzed using LC-MS in three separate facilities/instruments following data-dependent and data-independent acquisition modes. This cross-institutional and multi-methodological approach signifies the reliability and reproducibility of the results. The large-scale profiling of the retinal proteome, coupled with in&#xa0;vivo electroretinography recordings, provided us with a reliable basis for comparing the disease phenotypes and severity. Despite evident inflammation, cellular stress, and downscaled phototransduction observed consistently across all three models, the underlying pathologies of RP and LCA2 displayed many differences, sharing only four general KEGG pathways. The opposite is true for the two RP models in which we identify remarkable convergence in proteomic phenotype even though the mechanism of primary rod death in rd10 and P23H mice is different. Our data highlights the cAMP and cGMP second-messenger signaling pathways as potential targets for therapeutic intervention. The proteomic data is curated and made publicly available, facilitating the discovery of universal therapeutic targets for RP.

Animals

Revisiting endothelial tropism of SARS-CoV-2 using a cell-specific hACE2 mouse model.

UNLABELLED: Severe COVID-19 is frequently associated with vascular complications, raising ongoing debate about whether SARS-CoV-2 can directly infect endothelial cells and thereby contribute to disease pathogenesis. Although endothelial cells express angiotensin-converting enzyme 2 (ACE2), the in vivo relevance of endothelial-restricted viral tropism remains unclear. To directly assess the consequences of endothelial-restricted SARS-CoV-2 tropism in vivo, we generated a transgenic mouse model expressing human ACE2 under control of the endothelial-specific Cdh5 promoter (Cdh5-hACE2). Despite confirmed pulmonary endothelial expression and protein presence of hACE2, SARS-CoV-2 infection of Cdh5-hACE2 mice did not induce clinical illness, detectable viral replication, immune cell influx in the lung, or histopathological abnormalities in the lung or brain. These findings indicate that endothelial-restricted SARS-CoV-2 tropism alone is insufficient to drive productive infection and clinical disease in vivo, suggesting that endothelial involvement in COVID-19 likely arises in the context of broader cellular infection or systemic host responses rather than from primary endothelial infection. IMPORTANCE: Although SARS-CoV-2 primarily infects the upper and lower airways, COVID-19 was quickly recognized as a multi-organ disease, in which vascular complications are a recurring feature. This has raised the possibility that direct infection of endothelial cells contributes to disease pathogenesis. However, whether vascular injury arises from productive endothelial infection or instead represents a secondary consequence of systemic inflammation remains unresolved. To directly disentangle these possibilities and define the in vivo consequences of endothelial-restricted viral tropism, we generated a transgenic mouse model expressing human ACE2 under the control of the endothelial-specific Cdh5 promoter (Cdh5-hACE2).

Animals

Profiling hippocampal neuronal populations reveals unique gene expression mosaics reflective of connectivity-based degeneration in the Ts65Dn mouse model of Down syndrome and Alzheimer's disease.

INTRODUCTION: Individuals with Down syndrome (DS) exhibit neurological deficits throughout life including the development of in Alzheimer's disease (AD) pathology and cognitive impairment. At the cellular level, dysregulation in neuronal gene expression is observed in postmortem human brain and mouse models of DS/AD. To date, RNA-sequencing (RNA-seq) analysis of hippocampal neuronal gene expression including the characterization of discrete circuit-based connectivity in DS remains a major knowledge gap. We postulate that spatially characterized hippocampal neurons display unique gene expression patterns due, in part, to dysfunction of the integrity of intrinsic circuitry. METHODS: We combined laser capture microdissection to microisolate individual neuron populations with single population RNA-seq analysis to determine gene expression analysis of CA1 and CA3 pyramidal neurons and dentate gyrus granule cells located in the hippocampus, a region critical for learning, memory, and synaptic activity. RESULTS: The hippocampus exhibits age-dependent neurodegeneration beginning at ~6&#x202f;months of age in the Ts65Dn mouse model of DS/AD. Each population of excitatory hippocampal neurons exhibited unique gene expression alterations in Ts65Dn mice. Bioinformatic inquiry revealed unique vulnerabilities and differences with mechanistic implications coinciding with onset of degeneration in this model of DS/AD. CONCLUSIONS: These cell-type specific vulnerabilities may underlie degenerative endophenotypes suggesting precision medicine targeting of individual populations of neurons for rational therapeutic development.

Alzheimer&#x2019;s disease

Motor coordination and behavioural deficits in a mouse model of KMT2B-related dystonia.

INTRODUCTION: Pathogenic variants in KMT2B cause early-onset dystonia, but a mouse model that has undergone comprehensive, dystonia-oriented phenotyping is lacking. METHODS: We conducted detailed phenotyping on heterozygous Kmt2b constitutive knockout mice and wild-type littermates, assessing growth, neurobehavioural traits, motor coordination, sensorimotor gating, social behaviour and metabolic parameters, combined with striatal RNA sequencing. RESULTS: Kmt2b knockout mice of both sexes were viable but significantly smaller and lighter than littermate controls. Knockouts were hyperlocomotive in the open field and showed approximately two-fold larger acoustic startle responses; unexpectedly, prepulse inhibition was enhanced rather than reduced at all prepulse intensities. On the balance beam, knockouts crossed more slowly and paused more frequently; female knockouts also paused more on the ladder rung task. Frame-by-frame video analysis revealed a claw-like hindpaw posture characterized by abnormal inward flexion of the digits. Knockout mice spent less time investigating a novel conspecific, while social recognition memory remained intact. Striatal RNA sequencing confirmed reduction of Kmt2b transcript to approximately half of control levels and identified 177 differentially expressed genes, including Maob, encoding monoamine oxidase B; gene set enrichment analysis implicated neurodevelopmental, glial and mitochondrial processes. Nociception, vision, body-weight-adjusted grip strength, and clinical chemistry and haematological measures were largely unaffected. CONCLUSION: Heterozygous Kmt2b knockout mice show hyperlocomotion, altered sensorimotor gating, impaired motor coordination with dystonic-like paw posturing and reduced sociability, alongside a striatal transcriptomic signature implicating neurodevelopmental processes. The model mirrors aspects of human KMT2B-related dystonia and provides a platform for mechanistic study; environmental or pharmacological challenge may be needed to unmask overt dystonic features.

Dystonia

Optimized AAV5-RPGR ORF15 Gene Therapy Rescues Photoreceptor Structure and Function in X-Linked Retinitis Pigmentosa Mouse Model.

PURPOSE: To develop and evaluate an rAAV5-based gene therapy vector expressing an optimized human RPGR ORF15 transgene (rAAV5-RPGR) for the treatment of X-linked retinitis pigmentosa caused by RPGR mutations, addressing the challenges of cloning the unstable wild-type ORF15 sequence. DESIGN: This was a prospective experimental study. SUBJECTS: This was an animal study. METHODS: An optimized RPGR ORF15 sequence was designed to eliminate problematic secondary structures and cryptic splice sites. In vitro expression was validated in HEK 293T and photoreceptor-like 661 W cells. A complete Rpgr knockout mouse model (Rpgr-knockout [KO]) was generated and characterized phenotypically. Therapeutic efficacy was assessed in Rpgr-KO mice via subretinal injection of rAAV5-RPGR at low (1 &#xd7; 10&#x2079; vg/eye), medium (3 &#xd7; 10&#x2079; vg/eye), or high (1 &#xd7; 10&#xb9;&#x2070; vg/eye) doses. Structural and functional outcomes were evaluated at 12- and 14-month postinjection. Short-term safety was assessed in rabbits 1 month after subretinal injection. MAIN OUTCOME MEASURES: Level of RPGR protein expression and Protein isoform profile (elimination of truncated isoforms), Cellular localization of transgene expression and Dose-dependence of expression, outer nuclear layer thickness, and electroretinography parameters. RESULTS: (1) The optimized vector increased RPGR protein expression 3.3-fold in vitro compared to wild-type and eliminated truncated isoforms. (2) Subretinal delivery of rAAV5-RPGR in mice demonstrated dose-dependent transgene expression localized correctly to photoreceptor inner segments. (3) In Rpgr-KO mice, high-dose treatment significantly preserved outer nuclear layer thickness at the injection site (42% greater than controls at 14 months, P < .01) and central retina (P < .05), reduced aberrant rhodopsin mislocalization (P < .01), and partially restored retinal function. ERG showed significantly improved scotopic a-wave (&#x2265;100 vs <90 &#xb5;V in controls at 10 cd&#xb7;s/m&#xb2;) and photopic b-wave amplitudes (49-66 vs 31-46 &#xb5;V at 30 cd&#xb7;s/m&#xb2;) in treated mice. (4) No vector-related toxicity was observed in rabbits. CONCLUSIONS: rAAV5-RPGR mediated efficiently, targeted expression of optimized RPGR-ORF15, significantly preserved photoreceptor structure and function in a severe X-linked retinitis pigmentosa mouse model, and demonstrated a favorable safety profile. This study provides preclinical proof-of-concept for RPGR-targeted gene replacement therapy.

Animals

Phosphoproteomic analysis in a mouse model reveals ERK signaling as a key modulator of inflammatory response in nasal mucosa associated with childhood allergic rhinitis.

Childhood allergic rhinitis (AR) is a multifactorial condition arising from the interplay between genetic predisposition and environmental exposures. Although protein phosphorylation is widely recognized as a key regulator of gene expression across various physiological and pathological states, its global alterations in the nasal mucosa of pediatric patients with AR and their subsequent impact on mucosal function and inflammatory pathways remain incompletely characterized. Our study aimed to elucidate the molecular mechanisms underlying nasal mucosa dysfunction induced by pediatric AR. Our analysis revealed 3,861 proteins encompassing a total of 15,491 phosphorylation sites. Specifically, we detected 441 downregulated phosphorylation sites on 584 proteins and 531 upregulated phosphorylation sites on 722 proteins in the nasal mucosa of the AR group. Our proteomics findings suggest that the dysregulation of immune activation and metabolic regulation may contribute to AR pathophysiology. Through pathway analysis of the identified phosphorylation sites, we found Extracellular Signal-Regulated Kinase (ERK) signaling emerged as an important pathway; notably, upregulation of ERK1/2 phosphorylation was observed as a significant marker associated with AR. Importantly, targeting ERK inhibitors presents a potential therapeutic strategy for modulating key inflammatory response signaling pathways in the context of AR, although this finding is derived from preclinical mouse models and requires rigorous validation in human pediatric nasal mucosal tissues before any clinical translation can be considered. Collectively, these findings highlight that elucidating the molecular mechanisms underlying AR-induced nasal mucosal dysfunction in the mouse model may inform the novel therapeutic targets for pediatric allergy-related diseases. Overall, elucidating these mechanisms has substantial implications for developing targeted interventions aimed at mitigating inflammation associated with allergic rhinitis.

Animals

Tracking HIV persistence across T cell lineages during early ART-treated HIV-1-infection using a reservoir-marking humanized mouse model.

Human immunodeficiency virus (HIV) infection depletes CD4 T-cells, and long-term persistence of latent virus prevents full clearance of HIV even in the presence of effective antiretroviral therapy (ART), Here we present the HIV-1-induced lineage tracing (HILT) system, a model that irreversibly marks infected cells within a humanized mouse model, which detects rare latently infected cells. Immunodeficient mice transplanted with genetically modified hematopoietic stem cells develop a human immune system, in which CD4 T-cells contain a genetic switch that permanently labels cells infected by HIV-1 expressing cre-recombinase. Through single-cell RNA sequencing of HILT-marked cells during acute infection and post-ART treatment, we identify distinct CD4+ T-cell transcriptional lineages enriched in either active or latent infections. Comparative gene expression analysis highlights common pathways modulated in both states, including EIF2, Sirtuin, and protein ubiquitination. Critical regulators of these pathways, including JUN, BCL2, and MDM2, change to opposite directions in the two states, highlighting gene expression programs that may support HIV persistence across T-cell lineages and states.

Animals

A mouse model of autosomal dominant spastic ataxia and myopathy caused by a mutation in Tuba4a.

Hereditary ataxias are a heterogeneous group of neurodegenerative disorders characterized by impaired balance and coordination, often due to cerebellar dysfunction. Despite advances in identifying genetic causes, animal models remain essential for dissecting underlying mechanisms and testing therapeutic strategies. Here we describe a mouse model of spastic ataxia and myopathy caused by a missense mutation in Tuba4a (n.A626C, p.Gln176Pro). In an ENU mutagenesis screen, a male C57BL/6&#xa0;J mouse exhibiting muscle wasting and an intention tremor starting at approximately 4&#xa0;weeks-of-age was identified. The male was bred by in vitro fertilization to BALB/cByJ oocyte donors. Genetic mapping determined dominant inheritance and localized the mutation to Chromosome 1. Genome sequencing revealed single nucleotide polymorphisms (SNPs) in serine threonine kinase 36 (Stk36Y1003N) and alpha-tubulin 4A (Tuba4aQ176P) in the mapping interval. These SNPs were CRISPR-engineered into C57BL/6&#xa0;J mice, which confirmed the Tuba4aQ176P variant as the causative mutation. Mutant mice are normal at 3&#xa0;weeks, except for decrement in muscle response following repetitive nerve stimulation. However, by 30&#xa0;days these mice have overt ataxia, Purkinje neuron degeneration, and extensive skeletal muscle defects, which contribute to a decreased lifespan. Dominant TUBA4A mutations in humans are associated with spastic ataxia type 11 (SPAX11), congenital myopathy type 26 (CMYO26), and frontotemporal dementia/amyotrophic lateral sclerosis type 9 (FTDALS9). Our mice exhibit hallmark features of SPAX11 and CMYO26, but do not show motor neuron degeneration. This specificity makes this model a valuable tool for studying cell-type selective effects of TUBA4A mutations in neurodegeneration and myopathy.

Animals

Suckling mouse model for detection of heat-stable Escherichia coli enterotoxin: characteristics of the model.

Although the suckling mouse assay is widely used for the detection of heat-stable Escherichia coli enterotoxin (ST), few data have been published concerning the reproducibility, optimal growth, and test conditions of this assay. Four strains of toxigenic E. coli known to elaborate both heat-labile enterotoxin and ST or ST alone were used to study these parameters. ST activity after heat treatment and the effect of purified choleragen were also examined. ST production was optimal in Casamino Acids-yeast extract media, but both Trypticase soy and brain heart infusion broths resulted in several false negative reactions. Growing cultures in roller tubes was the most reliable method of ST production. Shaking-flask cultures and stationary-grown cultures resulted in suboptimal ST production in several strains. Optimal mouse incubation time was 3 h, and fluid secretion did not rise thereafter. Adequate toxin production occurred after 16 to 24 h of incubation. The coefficient of variation of various toxins tested on many occasions varied between 10.5 and 15.7%. Toxin activity was stable for 6 months when frozen at - 20 C. There was no decrease in ST activity when heated at 65 C for 15 min, but a small decrease was observed in two of four strains after heating at 100 C for 30 min. Choleragen, tested at various doses and at multiple times, gave uniformly negative results. These studies indicate that when done under the proper conditions, the suckling mouse assay is a simple, rapid, and reproducible assay for E. coli ST.

Animals

Progressive HNF1A-MODY pathophysiology revealed by a translational mouse model.

HNF1A-MODY, the most common monogenic diabetes, exhibits progressive &#x3b2; cell dysfunction, but existing mouse models fail to recapitulate human disease progression, limiting understanding of pathogenic mechanisms. We developed mice with heterozygous deletion of the Hnf1a transactivation domain (Hnf1a+/&#x394;e4-10) to model human HNF1A haploinsufficiency, conducted cross-sectional metabolic characterization, and validated our findings in HNF1A-deficient human islets. Unlike previous models, Hnf1a+/&#x394;e4-10 mice successfully recapitulated temporal HNF1A-MODY progression. Male mice developed sequential pathophysiology: early insulin resistance in young adults (7 weeks), followed by testosterone deficiency and fasting hyperglycemia in adult mice (10 weeks). Glucose intolerance emerged in middle-aged mice (30 weeks), progressing to multi-organ dysfunction in aged mice (44-70 weeks), characterized by elevated hepatic gluconeogenesis, impaired renal glucose handling, and hepatic steatosis/fibrosis. This dual pathophysiology involving &#x3b2; cell dysfunction and peripheral insulin resistance was associated with dysregulated hormone secretion from both &#x3b1; and &#x3b2; cells in aged mice (40-70 weeks). Human islet studies with HNF1A knockdown confirmed translational relevance, demonstrating reduced SGLT2 protein expression and inappropriate glucagon and insulin secretion. This work established a physiologically relevant HNF1A-MODY model, identified early insulin resistance as a key mechanism triggering hormonal dysfunction, and revealed HNF1A's role in multi-organ pathophysiology beyond traditional &#x3b2; cell dysfunction.

Animals