ABSTRACT
The Mouse Metabolic Phenotyping Center (MMPC)Live Program was established in 2023 by the National Institute for Diabetes, Digestive and Kidney Diseases (NIDDK) at the National Institutes of Health (NIH) to advance biomedical research by providing the scientific community with standardized, high quality phenotyping services for mouse models of diabetes and obesity. Emerging as the next iteration of the MMPC Program which served the biomedical research community for 20 years (2001-2021), MMPCLive is designed as an outwardly-facing consortium of service cores that collaborate to provide reduced-cost consultation and metabolic, physiologic, and behavioral phenotyping tests on live mice for U.S. biomedical researchers. Four MMPCLive Centers located at universities around the country perform complex and often unique procedures in vivo on a fee for service basis, typically on mice shipped from the client or directly from a repository or vendor. Current areas of expertise include energy balance and body composition, insulin action and secretion, whole body carbohydrate and lipid metabolism, cardiovascular and renal function, food intake and behavior, microbiome and xenometabolism, and metabolic pathway kinetics. Additionally, an opportunity arose to reduce barriers to access and expand the diversity of the biomedical research workforce by establishing the VIBRANT Program. Directed at researchers historically underrepresented in the biomedical sciences, VIBRANT-eligible investigators have access to testing services, travel and career development awards, expert advice and experimental design consultation, and short internships to learn test technologies. Data derived from experiments run by the Centers belongs to the researchers submitting mice for testing which can be made publicly available and accessible from the MMPCLive database following publication. In addition to services, MMPCLive staff provide expertise and advice to researchers, develop and refine test protocols, engage in outreach activities, publish scientific and technical papers, and conduct educational workshops and training sessions to aid researchers in unraveling the heterogeneity of diabetes and obesity.
ABSTRACT
As part of the Reproducibility Project: Cancer Biology, we published Registered Reports that described how we intended to replicate selected experiments from 29 high-impact preclinical cancer biology papers published between 2010 and 2012. Replication experiments were completed and Replication Studies reporting the results were submitted for 18 papers, of which 17 were accepted and published by eLife with the rejected paper posted as a preprint. Here, we report the status and outcomes obtained for the remaining 11 papers. Four papers initiated experimental work but were stopped without any experimental outcomes. Two papers resulted in incomplete outcomes due to unanticipated challenges when conducting the experiments. For the remaining five papers only some of the experiments were completed with the other experiments incomplete due to mundane technical or unanticipated methodological challenges. The experiments from these papers, along with the other experiments attempted as part of the Reproducibility Project: Cancer Biology, provides evidence about the challenges of repeating preclinical cancer biology experiments and the replicability of the completed experiments.
Subject(s)
Biomedical Research/methods , Neoplasms , Reproducibility of Results , Animals , Cell Line , Humans , MiceABSTRACT
The mammalian brain relies on neurochemistry to fulfill its functions. Yet, the complexity of the brain metabolome and its changes during diseases or aging remain poorly understood. Here, we generate a metabolome atlas of the aging wildtype mouse brain from 10 anatomical regions spanning from adolescence to old age. We combine data from three assays and structurally annotate 1,547 metabolites. Almost all metabolites significantly differ between brain regions or age groups, but not by sex. A shift in sphingolipid patterns during aging related to myelin remodeling is accompanied by large changes in other metabolic pathways. Functionally related brain regions (brain stem, cerebrum and cerebellum) are also metabolically similar. In cerebrum, metabolic correlations markedly weaken between adolescence and adulthood, whereas at old age, cross-region correlation patterns reflect decreased brain segregation. We show that metabolic changes can be mapped to existing gene and protein brain atlases. The brain metabolome atlas is publicly available ( https://mouse.atlas.metabolomics.us/ ) and serves as a foundation dataset for future metabolomic studies.
Subject(s)
Aging/metabolism , Brain/metabolism , Metabolome , Animals , Cerebellum/metabolism , Female , Male , Metabolic Networks and Pathways , Metabolomics , Mice , SphingolipidsABSTRACT
The mouse is the most commonly used model species in biomedical research. Just as human physical and mental health are influenced by the commensal gut bacteria, mouse models of disease are influenced by the fecal microbiome (FM). The source of mice represents one of the strongest influences on the FM and can influence the phenotype of disease models. The FM influences behavior in mice leading to the hypothesis that mice of the same genetic background from different vendors, will have different behavioral phenotypes. To test this hypothesis, colonies of CD-1 mice, rederived via embryo transfer into surrogate dams from four different suppliers, were subjected to phenotyping assays assessing behavior and physiological parameters. Significant differences in behavior, growth rate, metabolism, and hematological parameters were observed. Collectively, these findings show the profound influence of supplier-origin FMs on host behavior and physiology in healthy, genetically similar, wild-type mice maintained in identical environments.
Subject(s)
Gastrointestinal Microbiome , Mice/microbiology , Animals , Anxiety/metabolism , Anxiety/microbiology , Anxiety/physiopathology , Behavior, Animal , Disease Models, Animal , Exploratory Behavior , Feces/microbiology , Female , Locomotion , Lymphopoiesis , Male , Mice/anatomy & histology , Mice/physiology , Mice, Inbred ICRABSTRACT
Selenium-binding protein 1 (SELENBP1) has been associated with several cancers, although its exact role is unknown. We show that SELENBP1 is a methanethiol oxidase (MTO), related to the MTO in methylotrophic bacteria, that converts methanethiol to H2O2, formaldehyde, and H2S, an activity not previously known to exist in humans. We identified mutations in SELENBP1 in five patients with cabbage-like breath odor. The malodor was attributable to high levels of methanethiol and dimethylsulfide, the main odorous compounds in their breath. Elevated urinary excretion of dimethylsulfoxide was associated with MTO deficiency. Patient fibroblasts had low SELENBP1 protein levels and were deficient in MTO enzymatic activity; these effects were reversed by lentivirus-mediated expression of wild-type SELENBP1. Selenbp1-knockout mice showed biochemical characteristics similar to those in humans. Our data reveal a potentially frequent inborn error of metabolism that results from MTO deficiency and leads to a malodor syndrome.
Subject(s)
Halitosis/genetics , Oxidoreductases/genetics , Selenium-Binding Proteins/genetics , Animals , Breath Tests , Cell Line , Cells, Cultured , Dimethyl Sulfoxide/blood , Dimethyl Sulfoxide/cerebrospinal fluid , Dimethyl Sulfoxide/urine , Halitosis/enzymology , Humans , Mice, Inbred C57BL , Mice, Knockout , Mutation , Selenium-Binding Proteins/deficiency , Selenium-Binding Proteins/metabolismABSTRACT
Successful production of genetically modified mouse lines is dependent on germline transmission (GLT) of mutant alleles from chimeras. When natural mating fails to achieve GLT due to male infertility, sickness, or other problems, sperm can be harvested from chimeras and used for assisted reproductive technologies such as in vitro fertilization (IVF) to attempt to "rescue" GLT. However, a rational, evidence-based approach to determine if such extraordinary efforts should be attempted on a chimera has not been established. Therefore, in the present study we assessed the production, quality and genotype of epididymal sperm harvested from male chimeras generated by blastocyst or morula microinjection of gene targeted embryonic stem (ES) cell clones containing a LacZ expression cassette and that failed to achieve GLT. Results of this analysis enabled us to determine the cause of GLT failure, correlate coat color chimerism with the proportion of LacZ-positive sperm, and test the likelihood of achieving GLT by IVF. In 415 chimeras, 332 (80%) produced no offspring by natural mating ("infertile"), while 83 (20%) produced only wildtype offspring ("fertile"). Of the 332 infertile chimeras, 209 (63%) failed to produce any sperm whatsoever, 48 (15%) had extremely poor quality sperm, and 75 (23%) had good quality sperm. These results indicate that most chimeras that do not achieve GLT by natural mating are infertile, and the primary cause of infertility is failed spermatogenesis. Genotyping of sperm from 519 chimeras revealed a significant positive linear correlation between coat color chimerism and mean percentage of LacZ-positive sperm (R(2) = 0.95). Finally, IVF using good quality, LacZ-positive sperm from fertile and infertile chimeras "rescued" GLT for 19 out of 56 genes. We conclude that an assessment of coat color chimerism together with sperm quality and genotype can better inform the selection of chimeras for IVF to rescue GLT than coat color chimerism alone.
Subject(s)
Chimera/genetics , Germ Cells , Spermatogenesis , Spermatozoa , Animals , Animals, Genetically Modified , Embryo, Mammalian , Embryonic Stem Cells , Fertilization in Vitro , Genotype , Male , MiceABSTRACT
The Hfe(- /-) mouse is a model for human hereditary hemochromatosis (HHH). The accumulation of tissue iron in this condition has led to the suggestion that HHH patients may be at higher risk for neurodegenerative diseases. In this study, adult male Hfe(-/-) mice and wildtype controls (n = 12/group) were evaluated for impairment with motor tests (stride length, landing footsplay, rotarod) as well as a general observational battery (Functional Observational Battery, FOB). Hfe(-/-) mice were characterized by more falls from the rotarod, wider forelimb landing footsplay and hypersensitivity to proximal stimulation. Iron accumulation in brain was not detected by histopathology. These data suggest that a motor syndrome may be associated with HHH that could be further understood through the Hfe(-/-) mouse model.