GADD34 activates p53 and may have utility as a marker of atherosclerosis

Abstract

We previously identified growth arrest and DNA-damage-inducible gene 34 (GADD34) as a marker of ischemic stroke. In the present study, serum levels of anti-GADD34 antibodies were found to be significantly higher in patients with acute ischemic stroke or chronic kidney disease compared to healthy donors. We then examined the biological function of GADD34 by transfection into human osteosarcoma U2OS cells. Knockdown of GADD34 by siRNA resulted in enhanced cell proliferation, which was suppressed by knockdown of MDM2. Luciferase reporter assays revealed that the transactivation ability of p53 enhanced by genotoxic anticancer drugs such as camptothecin and etoposide was further potentiated by the presence of GADD34 and attenuated by co-transfection with p53 shRNA expression plasmids. Western blotting demonstrated increased p53 protein levels after treatment with camptothecin, which was also potentiated by GADD34 but suppressed by GADD34 siRNA, ATM siRNA, and wortmannin, an ATM inhibitor. GADD34 levels increased in response to treatment with camptothecin or adriamycin, and this increase was attenuated by MDM2 siRNA. Immunoprecipitation with anti-GADD34 antibodies followed by Western blotting with anti-MDM2 antibodies indicated ubiquitination of GADD34 is mediated by MDM2. Accordingly, GADD34 may function as a ubiquitination decoy to reduce p53 ubiquitination and increase p53 protein levels. Increased neuronal death due to activation of p53 by GADD34 may account for the elevated serum levels of anti-GADD34 antibodies observed in patients with acute ischemic stroke.

Serum anti‑KIAA0513 antibody as a common biomarker for mortal atherosclerotic and cancerous diseases

“…In terms of biomarker species, studies have reported enzyme, antigen, and, in recent years, nucleotide markers (1-3). However, there are still some reports on antibody markers, which include heat-shock 60-kD protein 1 (4), replication protein A2 (5), programmed cell death 11 (6), metalloproteinase 1, chromobox homolog 1, chromobox homolog 5 (7), DnaJ heat shock protein family (Hsp40) member C2 (8), adaptor-related protein complex 3 subunit delta 1 (9), serpin peptidase inhibitor, clade E member 1 (10), death-inducer obliterator 1, cleavage and polyadenylation specificity factor 2, forkhead box J2 (11) and thiosulfate sulfurtransferase-like domain-containing 2 (12) for acute ischemic stroke (AIS); ATPase, Ca ++ transporting, plasma membrane 4 (10), bone morphogenetic protein 1 (3,13), deoxyhypusine synthase (14), SH3 domain-binding protein 5 (15), prolyl carboxypeptidase (16), low-density lipoprotein receptor-related protein-associated protein 1 (17) and additional sex combs-like 2 (18) for atherosclerosis; nardilysin (19) for acute cardiac syndrome; and insulin (20), glutamic acid decarboxylase (21), adiponectin (22) and growth arrest and DNA-damage-inducible gene 34 (23,24), and proprotein convertase subtilisin/kexin type 9 (25) for diabetes mellitus (DM).…”