Project description:To fully quantify differences in the lymph composition and associated dendritic cells antigenic load, from different anatomical districts and in physiological and pathological conditions, we collected the afferent lymph draining to the cervical and mesenteric lymph nodes in healthy mice. Most of the proteome present in the mesenteric afferent lymph, showed a profile of proteins involved in different metabolic pathways associated with lipoproteintransport, and lipid metabolism, such as adipocyte-type fatty acid binding protein, Apolipoproteins A, B, C and E, and phospholipid transfer proteins, consistent with the known role of the mesenteric lymph in chylomicron transport. Network analysis on the mesenteric afferent lymph unique/enriched proteome highlighted pathways associated with lipase and hydrolase activity, lipoproteins remodeling, fat digestion and absorption, triglyceride catabolism and gut-associated immune cells and cytokines responses. Among the proteome shared across tissue a brain-specific or highly enriched proteome including glia maturation factor, nerve growth factor, mesencephalic astrocyte-derived neurotrophic factor, alpha-crystallin, brain-specific isoform of glycogen phosphorylase, and proteins associated with voltage-dependent channels, were uniquely observed in the lymph harvested from the afferent lymphatics entering the deep cervical nodes. Network analysis on the afferent cervical unique/enriched proteome highlighted pathways associated with neurotransmitter release cycle, synaptic transmission, neuronal development, mitochondrial activity, and an overall CNS proteome.
Project description:In Dendritic cells (DC), the MHC II eluted immunopeptidome reflects the antigenic composition of the microenvironment. Proteins are transported and processed into peptides in endosomal MHC II compartments through autophagy or phagocytosis; extracellular peptides can also directly bind MHC II proteins at the cell surface. Altogether, these mechanisms allow DC to sample both the intra and extracellular environment. To understand the contribution of the lymph proteome to the MHC-II immunopeptidome we eluted I-Ab complexes from DCs harvested from the deep cervical or mesenteric nodes and investigated whether the I-Ab presented peptidome reflects the anatomical distribution of the proteomes carried by the lymph collected from the same anatomical districts. Heatmap representation and cluster analysis indicated differences among the two immunopeptidome. Similarly, regression analysis showed a much higher regression coefficient among MHC II immunopeptidomes eluted from the same anatomical district (r=0.699) as compared to the one eluted from the two different anatomical districts (deep cervical, average r = 0.877 and mesenteric, average r = 0.937). Overall, all analyzed peptides displayed the expected I-Ab binding motives, binding affinity and expected range of peptide length. A combination of data dependent (DDA) and data independent (DIA) analysis indicated that around 36% of the eluted peptides were shared by both the cervical and mesenteric lymph nodes. The rest of the eluted peptides were distinct to each lymph node reflecting the qualitatively different proteome associated with each of the two anatomical districts: peptides unique to the cervical lymph nodes displayed many proteins known to be enriched in brain tissue, whereas those unique to mesenteric lymph nodes were enriched in mesenteric organ proteins. As such, the quantitative analysis of the I-Ab-eluted immunopeptidomes pinpoint important differences in peptide presentation and epitope selection in distinct anatomical districts.
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:Microarray analysis of isolated lymphatic endothelial cells from cervical lymph nodes (CLNs) of ischemic mice showed the activation of transmembrane tyrosine kinase pathways.