Project description:The hair follicle misorientation phenotype in Fzd6-/- mice appears to act through the PCP signaling system, but the downstream effectors of Fzd6 remain mysterious. We used microarrays to search for potential downstream effectors of the Fzd6 signaling pathway in regulating hair follicle orientation.
Project description:Posttranslational protein modifications have emerged as a mechanism regulating progenitor cell state transitions during tissue formation. Herein, we exploit the stereotyped hair follicle development to delineate the function of PADI4; an enzyme converting peptidylarginine to citrulline. Single cell-sequencing places Padi4 in both progenitor and differentiated hair lineage cells and indicate that PADI4 acts to repress transcription during hair follicle development. We establish PADI4 as a negative regulator of proliferation, acting on LEF1-positive hair shaft committed progenitor cells. Mechanistically, PADI4 citrullinates proteins associated with mRNA-processing and ribosomal biogenesis, and lack of PADI4 promotes protein synthesis and rRNA transcription in vivo. Characterizing key translational effectors, we demonstrate that PADI4 citrullinates the translational repressor 4E-BP1 and reveal a crosstalk between PADI4 activity and 4E-BP1 phosphorylation. This work sheds new light on how posttranslational modifications impact progenitor cell states and tissue formation.
Project description:Dermal lymphatics form a network that connects all the hair follicles in skin and localize in proximity to the Hair Follicle Stem Cell. RNA sequencing analyses of isolated dermal lymphatics at two different time points of the hair follicle cycle (P55 and P70) indicate the existence of dynamic signaling networks associated with lymphatic remodeling, immune trafficking, and HF signaling.
Project description:Tissue formation requires a coordinated balance of progenitor cell proliferation and differentiation. Posttranslational protein modifications have emerged as a mechanism utilized to regulate progenitor cell state transitions. Herein, we exploit the well characterized and stereotyped hair follicle development to delineate the function of PADI4; an enzyme converting peptidylarginine to citrulline. Single cell-sequencing places Padi4 in both progenitor and differentiated hair lineage cells during hair follicle development. We show that the absence of PADI4 induces gene expression across hair follicle cell clusters, suggesting that PADI4 acts to negatively impact transcription. In addition, we establish PADI4 as a negative regulator of proliferation, acting of LEF1-positive hair shaft committed progenitor cells. Mechanistically, PADI4 citrullinates proteins associated with mRNA-processing and ribosomal biogenesis, and lack of PADI4 promotes protein synthesis and rRNA transcription in vivo, in both hair follicle progenitor and committed lineage cells. Characterizing key translational effectors, we demonstrate that PADI4 interacts with 4E-BP1 and reveal a crosstalk between PADI4 activity and 4E-BP1 phosphorylation. We report that PADI4 contributes to hair follicle development by repressing progenitor cell proliferation and translational activity. This work sheds new light on how posttranslational modifications impact progenitor cell states and tissue formation.
Project description:Mouse hair follicles undergo synchronized cycles. Cyclical regeneration and hair growth is fueled by hair follicle stem cells (HFSCs). We used ChIP-seq to unfold genome-wide chromatin landscapes of Nfatc1 and dissect the biological relevence of its upstream BMP signaling in HFSC aging. Telogen quiescent hair follicle stem cells (HFSCs) were FACS-purified for ChIP-sequcencing.
Project description:Tissue regeneration relies on resident stem cells (SCs), whose activity and lineage choices are influenced by microenvironment. Exploiting the synchronized, cyclical bouts of tissue regeneration in hair follicles (HFs), we investigate how microenvironment dynamics shape the emergence of SC lineages. Employing epigenetic and ChIP-seq profiling, we uncover how signal-dependent transcription factors couple spatio-temporal cues to chromatin dynamics, thereby choreographing SC lineages. Using enhancer-driven reporters, mutagenesis and genetics, we show that simultaneous BMP-inhibitory and WNT signals set the stage for lineage choices by establishing chromatin platforms permissive for diversification. Mechanistically, when binding of BMP-effector pSMAD1 is relieved, super-enhancers driving HF-SC master regulators become silenced. Concomitantly, multipotent, lineage-fated super-enhancers silent in HF-SCs become activated by exchanging WNT-effectors TCF3/4 for LEF1. Throughout regeneration, lineage super-enhancers continue reliance upon LEF1, but then achieve specificity by accommodating additional incoming signaling effectors. Barriers to progenitor plasticity mount as diverse, signal-sensitive transcription factors shape LEF1-regulated super-enhancer dynamics.
Project description:Tissue regeneration relies on resident stem cells (SCs), whose activity and lineage choices are influenced by microenvironment. Exploiting the synchronized, cyclical bouts of tissue regeneration in hair follicles (HFs), we investigate how microenvironment dynamics shape the emergence of SC lineages. Employing epigenetic and ChIP-seq profiling, we uncover how signal-dependent transcription factors couple spatio-temporal cues to chromatin dynamics, thereby choreographing SC lineages. Using enhancer-driven reporters, mutagenesis and genetics, we show that simultaneous BMP-inhibitory and WNT signals set the stage for lineage choices by establishing chromatin platforms permissive for diversification. Mechanistically, when binding of BMP-effector pSMAD1 is relieved, super-enhancers driving HF-SC master regulators become silenced. Concomitantly, multipotent, lineage-fated super-enhancers silent in HF-SCs become activated by exchanging WNT-effectors TCF3/4 for LEF1. Throughout regeneration, lineage super-enhancers continue reliance upon LEF1, but then achieve specificity by accommodating additional incoming signaling effectors. Barriers to progenitor plasticity mount as diverse, signal-sensitive transcription factors shape LEF1-regulated super-enhancer dynamics.