title: Contribution of Nrf2 to Atherogenic Phenotype Switching of Coronary Arterial Smooth Muscle Cells Lacking CD38 Gene.
abstract: OBJECTIVE
  Recent studies have indicated that CD38 gene deficiency results in dedifferentiation or transdifferentiation of arterial smooth muscle cells upon atherogenic stimulations. However, the molecular mechanisms mediating this vascular smooth muscle (SMC) phenotypic switching remain unknown. Methods &amp;
  
  
  RESULTS
  In the present study, we first characterized the phenotypic change in the primary cultures of coronary arterial myocytes (CAMs) from CD38-/- mice. It was shown that CD38 deficiency decreased the expression of contractile marker calponin, SM22α and α-SMA but increased the expression of SMC dedifferentiation marker, vimentin, which was accompanied by enhanced cell proliferation. This phenotypic change in CD38-/- CAMs was enhanced by 7-ketocholesterol (7-Ket), an atherogenic stimulus. We further found that the CD38 deficiency decreased the expression and activity of nuclear factor E2-related factor 2 (Nrf2), a basic leucine zipper (bZIP) transcription factor sensitive to redox regulation. Similar to CD38 deletion, Nrf2 gene silencing increased CAM dedifferentiation upon 7-Ket stimulation. In contrast, the overexpression of Nrf2 gene abolished 7-Ket-induced dedifferentiation in CD38-/- CAMs. Given the sensitivity of Nrf2 to oxidative stress, we determined the role of redox signaling in the regulation of Nrf2 expression and activity associated with CD38 effect in CAM phenotype changes. It was demonstrated that in CD38-/- CAMs, 7-Ket failed to stimulate the production of O2-., while in CD38+/+ CAMs 7-Ket induced marked O2-. production and enhancement of Nrf2 activity, which was substantially attenuated by NOX4 gene silencing. Finally, we demonstrated that 7-Ket-induced and NOX4-dependent O2-. production was inhibited by 8-Br-cADPR, an antagonist of cADPR or NED-19, an antagonist of NAADP as product of CD38 ADP-ribosylcyclase, which significantly inhibited the level of cytosolic Ca2+ and the activation of Nrf2 under 7-Ket.
  
  
  CONCLUSIONS
  Taken together, these results suggest that CD38 activity is required for 7-Ket-induced Ca2+ and consequently O2-. production in CAMs, which increases Nrf2 activity to maintain their differentiated status. When CD38 gene expression and function are deficient, the Nrf2 activity is suppressed, thereby leading to phenotypic switching of CAMs.
authors: Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA.
authors: Ming
authors: M
authors: Xu
authors: Xiao-Xue
authors: XX
authors: Li
authors: Lei
authors: L
authors: Wang
authors: Mi
authors: M
authors: Wang
authors: Yang
authors: Y
authors: Zhang
authors: Pin-Lan
authors: PL
authors: Li
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000172:deficiency*; D000818:Animals; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D049109:Cell Proliferation; D054338:Cell Transdifferentiation / Q000187:drug effects; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007653:Ketocholesterols / Q000494:pharmacology*; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency*; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects
chemical_list: D007653:Ketocholesterols; D008562:Membrane Glycoproteins; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; C498155:Cd38 protein, mouse; D051997:ADP-ribosyl Cyclase 1; C003001:7-ketocholesterol; D002118:Calcium