Project description:We screened nine genetically diverse inbred mouse strains for differences in axonal growth of adult dorsal root ganglion (DRG) neurons on CNS myelin. Naïve DRG neurite outgrowth on myelin was very limited, but preconditioning the neurons by a prior sciatic nerve crush increased axonal growth substantially across all strains, with by far the greatest change in neurons from CAST/Ei mice. Three independent in vivo CNS injury models revealed greater capacity for CNS axonal regeneration in CAST/Ei than C57BL/6 mice. Full-genome expression profiling of naïve and pre-conditioned DRGs across all strains revealed Activin-βA (Inhba) as the transcript whose expression most closely correlated with axonal growth on myelin. In vitro and in vivo gain- and loss-of-function experiments confirmed that Activin promotes axonal growth in the CNS. Substantial regeneration is possible, therefore, in the injured mammalian CNS when Activin signaling is intrinsically high, as in CAST/Ei or when extrinsically modulated in other strains. 9 strains, 4 replicates per strain, 2 conditions (naïve and axotomy) = 72 samples. 2 samples were excluded because technical outliers (AJ_AX5D_1 and AJ_NAIVE_4 excluded from the normalized data but included in the raw data)
Project description:We screened nine genetically diverse inbred mouse strains for differences in axonal growth of adult dorsal root ganglion (DRG) neurons on CNS myelin. Naïve DRG neurite outgrowth on myelin was very limited, but preconditioning the neurons by a prior sciatic nerve crush increased axonal growth substantially across all strains, with by far the greatest change in neurons from CAST/Ei mice. Three independent in vivo CNS injury models revealed greater capacity for CNS axonal regeneration in CAST/Ei than C57BL/6 mice. Full-genome expression profiling of naïve and pre-conditioned DRGs across all strains revealed Activin-βA (Inhba) as the transcript whose expression most closely correlated with axonal growth on myelin. In vitro and in vivo gain- and loss-of-function experiments confirmed that Activin promotes axonal growth in the CNS. Substantial regeneration is possible, therefore, in the injured mammalian CNS when Activin signaling is intrinsically high, as in CAST/Ei or when extrinsically modulated in other strains.
Project description:The acetylation levels of histones and other proteins change during aging and have been linked to neurodegeneration. Here we show that deletion of the histone acetyltransferase (HAT) co-factor Trrap specifically impairs the function of the transcription factor Sp1, reduces its stability and causes a decrease in histone acetylation at Sp1 target genes. Modulation of Sp1 function by Trrap acts as a hub regulating multiple processes involved in neuron and neural stem cells function and maintenance including microtubule dynamics and the Wnt signaling pathway. Consistently, Trrap conditional mutants exhibit all hallmarks of neurodegeneration including dendrite retraction and axonal swellings, neuron death, astrogliosis, microglia activation, demyelination and decreased adult neurogenesis. Our results uncovered a novel functional network, essential to prevent neurodegeneration, and involving the specific regulation of Sp1 transcription factor and its downstream targets by Trrap-HAT.
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:PURPOSE: To provide a detailed gene expression profile of the normal postnatal mouse cornea. METHODS: Serial analysis of gene expression (SAGE) was performed on postnatal day (PN)9 and adult mouse (6 week) total corneas. The expression of selected genes was analyzed by in situ hybridization. RESULTS: A total of 64,272 PN9 and 62,206 adult tags were sequenced. Mouse corneal transcriptomes are composed of at least 19,544 and 18,509 unique mRNAs, respectively. One third of the unique tags were expressed at both stages, whereas a third was identified exclusively in PN9 or adult corneas. Three hundred thirty-four PN9 and 339 adult tags were enriched more than fivefold over other published nonocular libraries. Abundant transcripts were associated with metabolic functions, redox activities, and barrier integrity. Three members of the Ly-6/uPAR family whose functions are unknown in the cornea constitute more than 1% of the total mRNA. Aquaporin 5, epithelial membrane protein and glutathione-S-transferase (GST) omega-1, and GST alpha-4 mRNAs were preferentially expressed in distinct corneal epithelial layers, providing new markers for stratification. More than 200 tags were differentially expressed, of which 25 mediate transcription. CONCLUSIONS: In addition to providing a detailed profile of expressed genes in the PN9 and mature mouse cornea, the present SAGE data demonstrate dynamic changes in gene expression after eye opening and provide new probes for exploring corneal epithelial cell stratification, development, and function and for exploring the intricate relationship between programmed and environmentally induced gene expression in the cornea. Keywords: other
Project description:Post-transcriptional regulation of gene expression plays important roles in neuron physiology, and likely do so as well in injury response of axons We used microarray to profile expression changes in total and polysome-bound RNA upon spinal cord injury, to elucidate the role of post-transcriptional regulation towards axonal regeneration