Pluto Bioinformatics

GSE147298: BMP signaling: at the gate between activated melanocyte stem cells and differentiation [SMART-Seq2 single cell RNA-seq]

Bulk RNA sequencing

Adult tissue stem cells protect their long-term potential by exerting precise control over their transitions between quiescence, activation, and differentiation. Through cyclic bouts synchronous with the hair cycle, quiescent melanocyte stem cells (McSCs) become activated to generate proliferative progeny that differentiate to produce and transfer pigment to hair cells.The signaling factors orchestrating this process are still poorly understood. Here, we use single cell RNA-sequencing with pseudotime analysis to elucidate the transcriptional trajectory of McSCs through quiescence, activation, and differentiation into mature melanocytes. Unearthing signs of increased WNT and BMP signaling along this progression, we lineage-ablate either pathway and see hair graying.We show that BMP signaling functions downstream of McSCs but upstream of WNT signaling through LEF1. After stem cell activation, the two pathways triggercommitted, proliferative progeny to fuel MITF-dependent differentiation. Analyses of the promoters required for melanosome maturation suggest a specific reliance upon MITF and LEF1 transcription factors, whichwe show are dampened without BMP signaling. Our findings shed light upon the signaling interplay that orchestrates the melanocyte lineage. Moreover, the block in differentiation and enhanced proliferation observed in the absence of BMP signaling raises the disconcerting possibility that BMP may harbor not only tumor promoting but also tumor suppressing activity in melanoma. SOURCE: Katherine StewartElaine Fuchs The Rockefeller University

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