Abstract
The endoplasmic reticulum (ER) is an organelle in which important cellular events such as protein synthesis and lipid production occur. Although many lipid molecules are produced in the ER, the effect of ER-organizing proteins on lipid synthesis in sebocytes has not been completely elucidated. Tropomyosin-receptor kinase fused gene (TFG) is located in ER exit sites and participates in COPII-coated vesicle formation along with many scaffold proteins, such as Sec. 13 and Sec. 16. In this study, we investigated the putative role of TFG in lipid production in sebocytes using an immortalized human sebocyte line. During IGF-1-induced lipogenesis, the level of the TFG protein was increased in a time- and dose-dependent manner. When TFG was over-expressed using recombinant adenovirus, lipid production in sebocytes was increased along with an up-regulation of the expression of lipogenic regulators, such as PPAR-γ, SREBP-1 and SCD. Conversely, down-regulation of TFG using a microRNA (miR) decreased lipid production and the expression of lipogenic regulators. Based on these data, TFG is a novel regulator of lipid synthesis in sebocytes.
Highlights
The endoplasmic reticulum (ER) is an organelle in which important cellular events such as protein synthesis and lipid production occur
As an IGF-1-induced lipogenesis model was well-established for studies of sebocytes[12,13], we first assessed whether an IGF-1 treatment induced lipogenesis in our SV-sebocytes
When intracellular lipid droplets were stained with an Oil Red O solution, IGF-1 noticeably increased lipid accumulation in the cytoplasm of SV-sebocytes (Fig. 1b)
Summary
The endoplasmic reticulum (ER) is an organelle in which important cellular events such as protein synthesis and lipid production occur. Results IGF-1 induces lipid production in immortalized sebocytes. We analyzed lipid components using thin layer chromatography (TLC), and results clearly showed that IGF-1 significantly increased the production of lipids such as squalene, wax ester, triglyceride, www.nature.com/scientificreports and cholesterol in both the primary sebocytes and SV-sebocytes (Fig. 1c). Various transcription factors, including PPAR-γ, SREBP-1 and SREBP-2, participate in lipid production by up-regulating the expression of lipogenic enzymes, such as SCD and FDFT1.
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