Sox9 facilitates proliferation, differentiation and lipogenesis in primary cultured human sebocytes

The transcription factor Sox9 is pivotal in the morphogenesis of hair follicles, but its role in sebocytes is poorly understood.

We investigated the effect of Sox9 on human sebocyte proliferation, differentiation and lipogenesis.

Sox9 expression was detected by immunohistochemistry in normal skin and acne lesion. Primary cultured human sebocytes were transfected with adenovirus expressing GFP-Sox9 or Sox9 microRNA. Sox9 and peroxisome proliferator-activated receptor (PPAR)γ expression in sebocytes was detected by quantitative real-time PCR, Western blot and immunocytofluorescence; cell proliferation was measured by MTS and [³H]-thymidine incorporation assays; cell cycle distribution and apoptosis were evaluated by propidium iodide staining-based flow cytometry; and intracellular lipid levels were assessed by Oil Red O stain.

Sox9 immunostaining was increased in mature sebocytes of acne lesion compared with normal skin. Expression of Sox9 mRNA and protein and PPARγ protein was elevated with cell confluent levels in sebocytes. Sox9 overexpression enhanced proliferation, differentiation, proportion of S and G2/M cells, lipogenesis and PPARγ expression in sebocytes, while Sox9 silencing caused inhibition of differentiation, lipogenesis and PPARγ expression, and increase of G1 and sub-G1 (apoptotic) cell fraction. The suppression of Sox9 knockdown on sebocyte growth was observed using [³H]-thymidine incorporation but not MTS assay.

These results demonstrate that Sox9 can reinforce sebocyte proliferation, differentiation and lipogenesis. The G1/S transition arrest and apoptotic induction might contribute to inhibitory effect of Sox9 silencing on sebocyte proliferation.