Project description:We sorted melanocyte nuclei from quiescent (telogen) skin, skin actively producing hair shafts (anagen), and skin exposed to UVB. With these sorted nuclei, we then utilized single-nucleus assay for transposase-accessible chromatin with high-throughput sequencing (snATAC-seq) and characterized three melanocyte lineages: quiescent McSCs (qMcSCs), activated McSCs (aMcSCs), and differentiated melanocytes (dMCs) that co-exist in all three skin conditions. Furthermore, we successfully identified differentially accessible genes and enriched transcription factor binding motifs for each melanocyte lineage. Our findings reveal potential gene regulators that determine these melanocyte cell states and provide new insights into how aMcSC chromatin states are regulated differently under divergent intrinsic and extrinsic cues. We also provide a publicly available online tool with a user-friendly interface to explore this comprehensive dataset, which will provide a resource for further studies on McSC regulation upon natural or UVB-mediated stem cell activation.
Project description:This study focuses on understanding the role of Tnf signaling in regulating UVB induced melanocyte stem cell activation and epidermal migration
Project description:Dysfunctions in melanocytes can lead to pigmentation disorders, such as albinism, or contribute to the development of melanoma, the most aggressive form of skin cancer. Epidermal melanocytes typically interact with the collagen IV-rich basement membrane, but upon injury or in pathological conditions, they can encounter environments rich in collagen I or fibronectin. While alterations in ECM composition and stiffness are known to impact cell behavior, the specific roles of each of these cues for melanocyte functions remain unclear. To explore the impact of these extrinsic cues, we here exposed murine melanocytes to different ECM proteins as well as varying substrate stiffnesses. This study identified MITF, a key regulator of melanocyte differentiation and function, as an ECM- and mechanosensitive transcription factor. We further revealed that distinct ECM proteins and substrate stiffness engage a FAK/MEK/ERK/MITF signaling axis to control melanocyte functions. Exposure of melanocytes to collagen I restricted FAK and ERK activation, promoting high nuclear MITF levels associated with melanocyte proliferation and differentiation. Conversely, fibronectin elicited elevated FAK and ERK activation, leading to low nuclear MITF, correlating with a dedifferentiated and motile phenotype. Consistent with these observations, RNA sequencing revealed that COL I supports a differentiated gene expression program, whereas FN induces a neural crest-like and dedifferentiated transcriptomic signature. Importantly, inhibiting MEK or ERK activity in melanocytes cultured on fibronectin led to increased MITF nuclear localization, and enhanced melanogenesis. Additionally, we uncovered that melanocyte mechanoresponses differ depending on the specific ECM environment. Together, these findings reveal a synergistic effect of extrinsic cues on melanocyte function, with a context-dependent MITF regulation downstream of ERK, offering new perspectives for our understanding of melanocyte-related pathologies.
Project description:Dynamic regulation of chromatin accessibility by pluripotency transcription factors across the cell cycle [OCT4OFF SOX2OFF ChIP-seq]
Project description:Dynamic regulation of chromatin accessibility by pluripotency transcription factors across the cell cycle [OCT4OFF SOX2OFF ATAC-seq]