Smooth Muscle Specific Glyceraldehyde‐3′‐phosphate dehydrogenase (GAPDH) Reduces DNA Damage, Decreases Cell Apoptosis, Suppresses Atherosclerosis and Promotes the Stable Plaque Phenotype

Abstract

GAPDH is a glycolytic enzyme with a multiple glycolysis‐unrelated functions. We have shown that GAPDH protected smooth muscle cells (SMC) against oxidant‐induced apoptosis via upregulation of Ape1 endonuclease, the major DNA repair enzyme. We also found that GAPDH levels were reduced in atherosclerotic plaque SMC. We hypothesized that SMC‐specific GAPDH overexpression will reduce atherosclerosis. We generated Apoe‐null mice with SM22α promoter‐driven GAPDH overexpression (SM‐GAPDH mice). GAPDH protein levels were increased >2‐fold (P<0.05) in aortas isolated from SM‐GAPDH vs. 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 Ape1 endonuclease (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 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. Stimulation of GAPDH/Ape1 axis is a novel potential anti‐atherosclerotic therapy.Support or Funding InformationNIH/NHLBI R01HL070241 (P.D.), American Heart Association Grant‐in‐Aid 13GRNT17230069 (S.S.), and University of Missouri School of Medicine Bridge Fund (S.S.)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.