Atheroprotective Effects Induced by Glyceraldehyde‐3′‐phosphate Dehydrogenase (GAPDH) in Murine Model of Atherosclerosis

Abstract

GAPDH was shown to protect smooth muscle cells (SMC) against oxidant‐induced apoptosis via stimulation of DNA repair. GAPDH levels were reduced in atherosclerotic plaque SMC and therefore we hypothesized that SMC‐specific GAPDH overexpression will reduce atherosclerosis. GAPDH protein levels were increased >2‐fold (P<0.05) in aortas isolated from Apoe‐null mice with SM22α promoter‐driven GAPDH overexpression (SM‐GAPDH mice) compared to Apoe‐null controls. SM‐GAPDH mice have BW and BP similar to control. Aortic circumference, lumen area and media area were not changed by GAPDH overexpression. SMC GAPDH did not change pulse wave velocity (SM‐GAPDH, 1.1±0.1 m/s, control, 1.2±0.3 m/s) (ultrasound imaging) as well as endothelium‐dependent and ‐independent vascular responses to PE, Ach or SNP (organ chamber assay with thoracic aortic rings). High‐cholesterol fed SM‐GAPDH had reduced atherosclerotic burden (H&E‐stained aortic valve cross‐sections: 28±3% decrease, P<0.05), elevated plaque SMC levels (IHC for a‐SM actin, 3.1‐fold increase, P<0.01; IHC for calponin, 3.8‐fold increase, P<0.05), increased plaque collagen (Trichrome, 2.1‐fold increase, P<0.05), reduced plaque SMC apoptosis (TUNEL assay with IHC for calponin, 3.2‐fold decrease, IHC for cleaved caspase‐3, 2.6‐fold decrease both are P<0.05) without changes in macrophages (IHC with Mac3, P=NS). Aortas isolated from SM‐GAPDH have increased expression of Ape1 endonuclease (major DNA repair enzyme, 31±5% increase, P<0.05), reduced cleaved PARP (apoptotic marker, 74±12% decrease, P<0.001) and decreased oxidative DNA damage (AP sites assay, 2.5‐fold decrease, P<0.05; pSer139 histone H2AX, 33±3% decrease, P<0.05) compared to controls. Plaques in SM‐GAPDH mice had thicker SMC‐rich fibrous plaque cap (3.5‐fold increase, P<0.05) and decreased area of necrotic core (1.8‐fold reduction, P<0.05) suggesting enhanced plaque stability. These data taken together with our in vitro findings indicate that Ape1 upregulation mediates GAPDH effect on DNA and apoptosis. Our results suggest that stimulation of GAPDH/Ape1 axis is a novel potential anti‐atherosclerotic therapy.Support or Funding InformationStudy was supported by NIH/NHLBI 1R01HL142796‐01A1 (SS), AHA Grant‐in‐aid (SS) and NIH/NHLBI 7R01HL070241 (PD).