To explore the lipogenic effect by TNF-伪 and possible molecular mechanisms in sebocyte.
Using SZ95 human sebocytes, lipid formation by TNF-伪 was assessed by Oil Red O, Nile Red staining and thin layer chromatography (TLC). Expression of lipogenic genes and activation of mitogen-activated protein kinase as well as Akt were examined by real-time polymerase chain reaction and/or Western blot analysis. Activation of peroxisome proliferator-activated receptor (PPAR) was evaluated by luciferase assay using PPAR response element containing reporter plasmids. Involvement of c-Jun N-terminal kinase (JNK) and Akt in TNF-伪-induced lipogenesis was investigated by molecule specific small interfering RNA and inhibitors.
TNF-伪 treatment significantly increased formation of lipid droplets in accordance with up-regulated expression of FAS and activation of SREBP-1, but not PPARs. Suppression of phosphorylated JNK by the JNK inhibitor SP600125 greatly diminished TNF-伪-induced expression of FAS and SREBP-1. TNF-伪 could not induce both expression of lipogenic proteins and lipid synthesis when Akt expression was attenuated with siRNA.
TNF-伪 induces lipogenesis in SZ95 human sebocytes through the JNK and phosphoinositide-3-kinase/Akt pathways. These results will be valuable in developing therapeutic strategies for control of seborrhea and acne.