Project description:The mammary gland (MG) is composed of basal cells (BCs) and luminal cells (LCs). While it is generally believed that MG arises from embryonic multipotent progenitors (EMPs), it remains unclear when lineage restriction occurs and what are the mechanisms responsible for the switch from multipotency to unipotency during MG morphogenesis. Here, we performed multicolor lineage tracing and assessed the fate of single embryonic progenitors during mouse MG development. We demonstrated the existence of a developmental switch from multipotency to unipotency during embryonic MG development. Molecular profiling and single cell RNA-seq revealed the hybrid gene expression of EMPs, and the gene trajectory and lineage segregation occurring during MG development. In situ characterization showed that one of the earliest signs of lineage segregation consists in the restricted expression of p63 in the future BCs. Sustained p63 expression during MG development promotes unipotent BC fate in EMPs. Altogether, this study identifies the timing and the mechanisms mediating the switch from multipotency to unipotency during MG development. To understand the molecular mechanisms regulating multipotency during embryonic development, we isolated EMPs by FACS at E14, performed their transcriptional profiling by microarray and compared their transcriptome to adult BCs and LCs
Project description:The mammary gland (MG) is composed of basal cells (BCs) and luminal cells (LCs). While it is generally believed that MG arises from embryonic multipotent progenitors (EMPs), it remains unclear when lineage restriction occurs and what are the mechanisms responsible for the switch from multipotency to unipotency during MG morphogenesis. Here, we performed multicolor lineage tracing and assessed the fate of single embryonic progenitors during mouse MG development. We demonstrated the existence of a developmental switch from multipotency to unipotency during embryonic MG development. Molecular profiling and single cell RNA-seq revealed the hybrid gene expression of EMPs, and the gene trajectory and lineage segregation occurring during MG development. In situ characterization showed that one of the earliest signs of lineage segregation consists in the restricted expression of p63 in the future BCs. Sustained p63 expression during MG development promotes unipotent BC fate in EMPs. Altogether, this study identifies the timing and the mechanisms mediating the switch from multipotency to unipotency during MG development. To understand the molecular mechanisms regulating multipotency during embryonic development, we isolated EMPs by FACS at E14, performed their transcriptional profiling by microarray and compared their transcriptome to adult BCs and LCs
Project description:The mammary gland (MG) is composed of basal cells (BCs) and luminal cells (LCs). While it is generally believed that MG arises from embryonic multipotent progenitors (EMPs), it remains unclear when lineage restriction occurs and what are the mechanisms responsible for the switch from multipotency to unipotency during MG morphogenesis. Here, we performed multicolor lineage tracing and assessed the fate of single progenitors and demonstrated the existence of a developmental switch from multipotency to unipotency during embryonic MG development. Molecular profiling and single cell RNA-seq revealed that EMPs express a unique hybrid basal and luminal signature and the factors associated with the different lineages. Sustained p63 expression in EMPs promotes unipotent BC fate and was sufficient to reprogram adult LCs into BCs by promoting an intermediate hybrid multipotent like state. Altogether, this study identifies the timing and the mechanisms mediating the early lineage segregation of multipotent progenitors during MG development.
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:We demonstrate for the first time that the extracellular matrix glycoprotein Tenascin-C regulates the expression of key patterning genes during late embryonic spinal cord development, leading to a timely maturation of gliogenic neural precursor cells. We first show that Tenascin-C is expressed by gliogenic neural precursor cells during late embryonic development. The loss of Tenascin-C leads to a sustained generation and delayed migration of Fibroblast growth factor receptor 3 expressing immature astrocytes in vivo. Furthermore, we could demonstrate an upregulation of Nk2 transcription factor related locus 2 (Nkx2.2) and its downstream target Sulfatase 1 in vivo. A dorsal expansion of Nkx2.2-positive cells within the ventral spinal cord indicates a potential progenitor cell domain shift. Moreover, Sulfatase 1 is known to regulate growth factor signalling by cleaving sulphate residues from heparan sulphate proteoglycans. Consistent with this possibility we observed changes in both Fibroblast growth factor 2 and Epidermal growth factor responsiveness of spinal cord neural precursor cells. Taken together our data clearly show that Tenascin-C promotes the astroglial lineage progression during spinal cord development.
Project description:Glandular epithelia, including mammary gland (MG) and prostate, are composed of luminal and basal cells. During embryonic development, glandular epithelia arise from multipotent stem cells (SCs) giving rise to basal and luminal cells. However, these multipotent SCs are replaced after birth by unipotent basal and unipotent luminal SCs. Different conditions, such as basal cell transplantation, luminal cell ablation, and oncogene expression, can reinduce multipotency in adult basal SC (BaSCs) of different glandular epithelia. The mechanisms regulating the reactivation of multipotency in BaSCs are incompletely understood. Here, we compared the transcriptional signature of BaSCs from MG and prostate in different conditions associated with multipotency in adult mice and uncovered that Collagen I expression was commonly upregulated across the different conditions associated with multipotency. Using MG and prostate organoids, we demonstrated that increasing collagen concentration or stiffness of the extracellular matrix (ECM) promote BaSC multipotency. Single cell RNA-seq of MG organoids in the presence of high concentration of Collagen I or in a stiffer ECM activate a hybrid bipotent state and uncovered a gene signature and signaling pathways associated with bipotent BaSCs. Finally, we demonstrated the importance of 1integrin/FAK/AP-1 axis in the regulation of BaSC multipotency in response to Col1 signaling and ECM stiffness. Altogether our study uncovers the key role of Collagen signaling and ECM stiffness in the regulation of multipotency in glandular epithelia.
Project description:Glandular epithelia, including mammary gland (MG) and prostate, are composed of luminal and basal cells. During embryonic development, glandular epithelia arise from multipotent stem cells (SCs) giving rise to basal and luminal cells. However, these multipotent SCs are replaced after birth by unipotent basal and unipotent luminal SCs. Different conditions, such as basal cell transplantation, luminal cell ablation, and oncogene expression, can reinduce multipotency in adult basal SC (BaSCs) of different glandular epithelia. The mechanisms regulating the reactivation of multipotency in BaSCs are incompletely understood. Here, we compared the transcriptional signature of BaSCs from MG and prostate in different conditions associated with multipotency in adult mice and uncovered that Collagen I expression was commonly upregulated across the different conditions associated with multipotency. Using MG and prostate organoids, we demonstrated that increasing collagen concentration or stiffness of the extracellular matrix (ECM) promote BaSC multipotency. Single cell RNA-seq of MG organoids in the presence of high concentration of Collagen I or in a stiffer ECM activate a hybrid bipotent state and uncovered a gene signature and signaling pathways associated with bipotent BaSCs. Finally, we demonstrated the importance of 1integrin/FAK/AP-1 axis in the regulation of BaSC multipotency in response to Col1 signaling and ECM stiffness. Altogether our study uncovers the key role of Collagen signaling and ECM stiffness in the regulation of multipotency in glandular epithelia.
Project description:We demonstrate for the first time that the extracellular matrix glycoprotein Tenascin-C regulates the expression of key patterning genes during late embryonic spinal cord development, leading to a timely maturation of gliogenic neural precursor cells. We first show that Tenascin-C is expressed by gliogenic neural precursor cells during late embryonic development. The loss of Tenascin-C leads to a sustained generation and delayed migration of Fibroblast growth factor receptor 3 expressing immature astrocytes in vivo. Furthermore, we could demonstrate an upregulation of Nk2 transcription factor related locus 2 (Nkx2.2) and its downstream target Sulfatase 1 in vivo. A dorsal expansion of Nkx2.2-positive cells within the ventral spinal cord indicates a potential progenitor cell domain shift. Moreover, Sulfatase 1 is known to regulate growth factor signalling by cleaving sulphate residues from heparan sulphate proteoglycans. Consistent with this possibility we observed changes in both Fibroblast growth factor 2 and Epidermal growth factor responsiveness of spinal cord neural precursor cells. Taken together our data clearly show that Tenascin-C promotes the astroglial lineage progression during spinal cord development. in total 6 probes: 3 replica of TNC_wt and 3 replica of TNC_ko