1. Ubiquitin Carboxyl Terminal Hydrolyase L1 -Suppressed Autophagic Degradation of p21WAF1/Cip1 as a Novel Feedback Mechanism in the Control of Cardiac Fibroblast Proliferation.
- Author
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Zhang, Xiaoming, Guo, Linlin, Niu, Ting, Shao, Lei, Li, Huanjie, Wu, Weiwei, Wang, Wenjuan, Lv, Linmao, Qin, Qingyun, Wang, Fang, Tang, Dongqi, Wang, Xing Li, and Cui, Taixing
- Subjects
UBIQUITIN ,C-terminal residues ,AUTOPHAGY ,FIBROBLASTS ,CELL proliferation ,GENE expression ,BLOOD pressure - Abstract
Aims: Deubiquitinating enzymes (DUBs) appear to be critical regulators of a multitude of processes such as proliferation, apoptosis, differentiation, and inflammation; however, the potential roles of DUBs in the heart remain to be determined. This study was aimed to explore the role of a DUB, ubiquitin carboxyl terminal hydrolyase L1 (UCH-L1) in maladaptive cardiac remodeling and dysfunction. Methods and Results: Maladaptive cardiac remodeling and dysfunction were induced in mice by transverse aortic constriction (TAC). UCH-L1 expression was transiently increased and then declined near to the basal level while impairment of cardiac function proceeded. The upregulation of UCH-L1 was observed in cardiac myocytes and fibroblasts. In primary culture of cardiac fibroblasts, UCH-L1 was upregulated by platelet-derived growth factor (PDGF)-BB and PDGF-DD. Adenoviral overexpession of UCH-L1 inhibited the PDGF-induced cardiac fibroblast proliferation without affecting the activation of mitogen activated protein kinases (MAPKs), Akt, and signal transducers and activators of transcription 3 (STAT3). Further signaling dissection revealed that PDGF-BB posttranscriptional upregulated p21
WAF1/Cip1 protein expression, which was inhibited by rapamycin, an activator of autophagy via suppressing mammalian target of rapamycin (mTOR), rather than MG132, a proteasome inhibitor. Overexpression of UCH-L1 enhanced PDGF-BB-induced mTOR phosphorylation and upregulation of p21WAF1/Cip1 protein expression while suppressed autophagic flux in cardiac fibroblasts. Conclusion: UCH-L1 facilitates PDGF-BB-induced suppression of autophagic degradation of p21WAF1/Cip1 proteins in cardiac fibroblasts, which may serve as a novel negative feedback mechanism in the control of cardiac fibroblast proliferation contributing to cardiac fibrosis and dysfunction. [ABSTRACT FROM AUTHOR]- Published
- 2014
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