Hair Follicles’ Transit-Amplifying Cells Govern Concurrent Dermal Adipocyte Production Through Sonic Hedgehog

The study conducted on October 15, 2016, demonstrated that hair follicle transit-amplifying cells (HF-TACs) play a pivotal role in promoting dermal adipogenesis through the secretion of Sonic Hedgehog (SHH). Depletion of Shh in HF-TACs led to inhibited growth of both hair follicles and the dermal adipose layer. The research showed that SHH directly influences adipocyte precursors by encouraging their proliferation and the expression of the adipogenic gene Pparg. The study involved experiments with 2 control mice and 4 knockout mice for Shh deletion, and 3 mice for denervation experiments. It was also found that SHH signaling is not necessary in mature adipocytes or hair follicles for adipogenesis, but is required in adipocyte precursors. Overexpression of SHH resulted in thicker skin and more adipocytes, indicating its importance in dermal adipogenesis. Additionally, the absence of SHH in embryonic hair follicles significantly reduced adipocyte formation, highlighting the critical role of SHH signaling from hair follicles in the regulation of the dermal environment and adipogenesis.