Poly(ADP‐ribose) polymerase 1 induces cardiac fibrosis by mediating mammalian target of rapamycin activity

• Published in: Journal of cellular biochemistry 2019-04, Vol.120 (4), p.4813-4826
• Main Authors: Sun, Shuya, Hu, Yuehuai, Zheng, Qiyao, Guo, Zhen, Sun, Duanping, Chen, Shaorui, Zhang, Yiqiang, Liu, Peiqing, Lu, Jing, Jiang, Jianmin
• Format: Article
• Language: English
• Subjects: Adenine; Adenosine diphosphate; Aorta; Apoptosis; cardiac fibrosis; Cardiovascular diseases; Collagen; Coronary artery disease; Extracellular matrix; Fibroblasts; Fibrosis; Heart diseases; Inhibitors; Initiation factor eIF-4E; mammalian target of rapamycin (mTOR); Mammals; NAD; Nicotinamide; Nicotinamide adenine dinucleotide; p53 Protein; Poly(ADP-ribose) polymerase; poly(ADP‐ribose) polymerase 1 (PARP1); Pretreatment; Proteins; Rapamycin; Ribose; Ribosomal protein S6 kinase; Smad3 protein; Substrates; Supplements; Surgery; Therapeutic applications; TOR protein; Transforming growth factor-b1; transforming growth factor‐β1 (TGF‐β1)
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/jcb.26649

Cardiac fibrosis is involved in nearly all forms of heart diseases and is characterized by excessive deposition of extracellular matrix proteins by cardiac fibroblasts (CFs). We and others have reported the possibility of poly(ADP‐ribose) polymerase 1 (PARP1), the founding subtype of the PARPs enzyme family, as a novel therapeutic target of heart diseases. The cardiac fibrotic induction of mammalian target of rapamycin (mTOR) is mainly due to collagen expression, Smad3‐ and p53/JNK‐mediated apoptosis. However, the possible link between PARP1 and mTOR in the progression of cardiac fibrosis remains unclear. In this study, PARP1 protein expression, and the activity of mTOR and its three target substrates (p70 ribosomal S6 Kinase 1, eukaryotic initiation factor 4E­‐binding protein 1, and UNC­51­like kinase 1) were augmented; meanwhile, the nicotinamide adenine dinucleotide (NAD) content was significantly reduced in the process of cardiac fibrosis in vivo and in vitro. Sprague‐Dawley rats were intraperitoneally injected with 3‐aminobenzamide (3AB) (20 mg/kg/d; a well‐established PARP1 inhibitor) or rapamycin (Rapa; 1 mg/kg/d; used for mTOR inhibition) 7 days after abdominal aortic constriction (AAC) surgery for 6 weeks. Pretreatment of 3AB or Rapa both relieved AAC‐caused cardiac fibrosis and heart dysfunction. Overexpression of PARP1 with adenovirus carrying PARP1 gene specifically transduced into the hearts via intramyocardial multipoint injection caused similar myocardial damage. In CFs, preincubation with PARP1 or mTOR inhibitors all blocked TGF‐β1 induced cardiac fibrosis. PARP1 overexpression evoked cardiac fibrosis, which could be antagonized by mTOR inhibitors or NAD supplementation in CFs. These results provide novel and compelling evidence that PARP1 exacerbated cardiac fibrosis, which was partially attributed to NAD‐dependent activation of mTOR. Transforming growth factor‐β1‐induced cardiac fibrosis is accompanied by upregulation of poly(ADP‐ribose) polymerase 1 (PARP1) and mammalian target of rapamycin (mTOR) activity in vitro. Abdominal aortic constriction induced cardiac fibrosis along with the excessive activation of PARP1 and mTOR in vivo. The inhibition of PARP1 or mTOR both effectively relieved cardiac fibrosis in vivo and in vitro. PARP1 overexpression evoked cardiac fibrosis, while that induction can be greatly slowed by mTOR inhibitors or NAD supplementation. PARP1 exacerbated cardiac fibrosis, which was partially attributed to NAD‐dependen