Knockdown of pyruvate carboxylase or fatty acid synthase lowers numerous lipids and glucose-stimulated insulin release in insulinoma cells

• Published in: Archives of biochemistry and biophysics Vol. 532; no. 1; pp. 23 - 31
• Main Authors: MacDonald, Michael J., Hasan, Noaman M., Dobrzyn, Agnieszka, Stoker, Scott W., Ntambi, James M., Liu, Xueqing, Sampath, Harini
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2013
• Subjects: Animals; Cell Line, Tumor; Cholesterol esters; Fatty acid synthase; Fatty Acid Synthases - genetics; Fatty Acid Synthases - metabolism; Gene Knockdown Techniques; Glucose - metabolism; Insulin - metabolism; Insulin-Secreting Cells - metabolism; Insulinoma - metabolism; Insulinoma cells; Lipid Metabolism; Lipid remodeling; Phospholipids; Pyruvate carboxylase; Pyruvate Carboxylase - genetics; Pyruvate Carboxylase - metabolism; Rats; shRNA; Cholesterol esters; shRNA; Lipid remodeling; Fatty acid synthase; Phospholipids; Insulinoma cells; Pyruvate carboxylase
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2013.01.002

► Pyruvate carboxylase and fatty acid synthase were knocked down in insulin cells. ► Insulin secretion, phospholipid and cholesterol esters were lowered. ► De novo lipid synthesis from glucose was lowered. ► The results suggest rapid lipid modification is necessary for insulin secretion. We previously showed that knockdown of the anaplerotic enzyme pyruvate carboxylase in the INS-1 832/13 insulinoma cell line inhibited glucose-stimulated insulin release and glucose carbon incorporation into lipids. We now show that knockdown of fatty acid synthase (FAS) mRNA and protein also inhibits glucose-stimulated insulin release in this cell line. Levels of numerous phospholipids, cholesterol esters, diacylglycerol, triglycerides and individual fatty acids with C14–C24 side chains were acutely lowered about 20% in glucose-stimulated pyruvate carboxylase knockdown cells over a time course that coincides with insulin secretion. In FAS knockdown cells glucose carbon incorporation into lipids and the levels of the subclasses of phospholipids and cholesterol ester species were lower by 20–30% without inhibition of glucose oxidation. These studies suggest that rapid lipid modification is essential for normal glucose-stimulated insulin secretion.