Adipose Tissue: SHH and Dermal Adipogenesis

RESEARCH HIGHLIGHTS

Nature Reviews Endocrinology | Published online 18 Nov 2016; doi:10.1038/nrendo.2016.192

ADIPOSE TISSUE SHH and dermal adipogenesis

In the dermis, adipose tissue adipogenesis. SHH is secreted from overexpression increased skin thick- expands in sync with the growth of HF-TACs; by knocking out this ness, which was also associated with hair follicles, but the mechanism that protein specifically in HF-TACs of increased Pparg expression. couples the growth of the two tissues mice, the dermal adipose layer failed Hsu and his colleagues hope is unclear. In new research, investiga- to expand. that their findings will eventually tors have found that sonic hedgehog This effect was specific to SHH help to mitigate the adverse effects (SHH) secreted from hair follicle secreted from HF-TACs and not of chemotherapy, such as thinning transit-amplifying cells (HF-TACs) from hair follicles, as in mice with of the skin, hair loss and increased is required for expansion of both hair follicles lacking smoothened susceptibility to infections. “Some dermal adipocytes and hair follicles. (Smo), a protein that mediates the of these symptoms might be a con- “TACs are stem cell progeny downstream effect of SHH, dermal sequence of a compromised ability responsible for generating a large adipogenesis was unaffected but of HF-TACs to direct changes amount of downstream cell types the follicles are shorter. Moreover, in dermal adipocytes, which are directly,” explains Ya-Chieh Hsu by deleting Smo in different skin important for skin thickening and who led the study. “TACs might be cell types, Hsu and his colleagues innate immunity,” concludes Hsu. well-situated to couple downstream showed that SHH acts on preadipo- Tim Geach tissue production with changes in cytes, but not on mature adipocytes,

surrounding tissues, such as dermal to regulate dermal adipogenesis. ORIGINAL ARTICLE Zhang, B. et al. Hair follicles’ adipogenesis.” In skin lacking SHH or Smo, the transit-amplifying cells govern concurrent dermal The team found that, in mice, key adipogenic gene Pparg was adipocyte production through Sonic Hedgehog. Genes Dev. 30, 2325–2338 (2016) HF-TACs are crucial for dermal downregulated. Moreover, SHH