Activating transcription factor 4 regulates stearate-induced vascular calcification.
Previously, we reported that stearate, a saturated fatty acid, promotes osteoblastic differentiation and mineralization of vascular smooth muscle cells (VSMC). In this study, we examined the molecular mechanisms by which stearate promotes vascular calcification. ATF4 is a pivotal transcription factor in osteoblastogenesis and endoplasmic reticulum (ER) stress. Increased stearate by either supplementation of exogenous stearic acid or inhibition of stearoyl-CoA desaturase (SCD) by CAY10566 induced ATF4 mRNA, phosphorylated ATF4 protein, and total ATF4 protein. Induction occurred through activation of the PERK-eIF2α pathway, along with increased osteoblastic differentiation and mineralization of VSMCs. Either stearate or the SCD inhibitor but not oleate or other fatty acid treatments also increased ER stress as determined by the expression of p-eIF2α, CHOP, and the spliced form of XBP-1, which were directly correlated with ER stearate levels. ATF4 knockdown by lentiviral ATF4 shRNA blocked osteoblastic differentiation and mineralization induced by stearate and SCD inhibition. Conversely, treatment of VSMCs with an adenovirus containing ATF4 induced vascular calcification. Our results demonstrated that activation of ATF4 mediates vascular calcification induced by stearate.
Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, USA.
Masashi
M
Masuda
Tabitha C
TC
Ting
Moshe
M
Levi
Sommer J
SJ
Saunders
Shinobu
S
Miyazaki-Anzai
Makoto
M
Miyazaki
D051701:Activating Transcription Factor 4 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D051379:Mice; D008903:Minerals / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013229:Stearic Acids / Q000494:pharmacology*; D051742:Transcription Factor CHOP / Q000378:metabolism; D061205:Vascular Calcification / Q000139:chemically induced* / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D019892:eIF-2 Kinase / Q000235:genetics
D051701:Activating Transcription Factor 4; D008903:Minerals; D017346:Protein Serine-Threonine Kinases; D013229:Stearic Acids; D051742:Transcription Factor CHOP; D019892:eIF-2 Kinase; C497250:Ddit3 protein, mouse; C031183:stearic acid; C531557:eIF2alpha kinase, mouse