Project description:Hepatocyte nuclear factor 4alpha (HNF4α) is a nuclear receptor with an emerging role in the gut. While HNF4α has been implicated in colitis and colon cancer in humans, deciphering its functional role is complicated by the existence of two promoters (P1 and P2) in theHNF4A gene that drive the expression of multiple isoforms in the adult intestine. In this study we investigate the roles of P1- and P2-driven HNF4α under conditions of homeostasis, colitis and colitis-associated colon cancer (CAC). P1- and P2-HNF4α are differentially expressed in the differentiated and proliferative compartments of the normal colonic crypt, respectively. Expression profiling of untreated exon swap mice suggests distinct functions of the isoforms that were corroborated in migration and ion transport assays.
Project description:To describe the protein profile in hippocampus, colon and ileum tissue’ changing after the old faeces transplants, we adopted a quantitative label free proteomics approach.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:Background & Aims: HNF4α is an important transcriptional regulator of hepatocyte and pancreatic function. Hnf4α deletion is embryonically lethal with severe defects in visceral endoderm formation, liver maturation and colon development. However, the precise role of this transcription factor in maintaining homeostasis of the adult intestine remains unclear. Herein, we aimed to elucidate the adult intestinal functions of Hnf4α. Methods: A conditional intestinal epithelial Hnf4α knockout mouse was generated. Histological abnormality of the colonic mucosa was assessed by immunodetection and Western. Changes in global gene expression and biological network were analyzed. Results: Hnf4α intestine null mice developed normally until reaching young adulthood. Crypt distortion became apparent in the Hnf4α null colon at 3 months of age followed by focal areas of crypt dropout, increased immune cell infiltrates, crypt hyperplasia and early signs of polyposis later in life. A gene profiling analysis identified cell death and cell cycle related to cancer as the most significant sets of genes altered in the Hnf4α colon null mice. Expression levels of the tight junction proteins claudin 4, 8 and 15 were altered early in the colon epithelium of Hnf4α mutants and correlated with increased barrier permeability to a molecular tracer that does not normally penetrate normal mucosa. Conclusion: These observations support a functional role for Hnf4α in protecting the colonic mucosa against the initiation of the changes resembling inflammatory bowel diseases and polyp formation.
Project description:HNF4α is a nuclear receptor regulating the transcription of genes involved mainly in development, cell differentiation and metabolism. Opposite functions for the two classes of P1 and P2 isoforms of HNF4α have recently been highlighted. These classes include 12 variants of HNF4α that can be expressed by the use of two promoters and by alternative splicing. Until now, the characterization of this transcription factor has ignored this diversity and has remained confined to the study of a fraction of the isoforms. We therefore wanted to clarify the situation by specifically characterizing the transcriptional functions of the 12 isoforms of HNF4α. We have generated for this purpose stable lines expressing each isoform of HNF4α in HCT 116 cells. We analyzed the whole transcriptome associated with each isoform by sequencing RNA, as well as their proteome by a BioID approach coupled to quantitative mass spectrometry. We noted major differences in the transcriptional function of the 12 isoforms. The α4, α5 and α6 isoforms have been characterized for the first time, and show a greatly reduced transcriptional potential. We have shown that these isoforms are unable to recognize the consensus response element of HNF4α. The α1 and α2 isoforms are the most potent regulators of gene expression, while the α3 isoform exhibits significantly reduced activity. Several transcription factors and coregulators have been identified as potential specific partners for certain HFH4α isoforms. The IRF-2BP2 co-repressor interacts specifically with isoforms which include the long form of the F domain of HNF4α. This specific interaction could explain the large number of genes modulated negatively by α1 and α2 compared to α3. The analysis integrating the vast amount of transcriptomic and proteomic data allows the identification of transcriptional regulatory mechanisms specific to certain isoforms, demonstrating the importance of considering all isoforms which can have diverse functions.