Ubiquitin C-terminal hydrolase L1 (UCHL1) regulates post-myocardial infarction cardiac fibrosis through glucose-regulated protein of 78 kDa (GRP78)

Abstract

Abnormal cardiac fibrosis indicates cardiac dysfunction and poor prognosis in myocardial infarction (MI) patients. Many studies have demonstrated that the ubiquitin proteasome system (UPS) plays a significant role in the pathogenesis of fibrosis. Ubiquitin C-terminal hydrolase L1 (UCHL1), a member of the UPS, is related to fibrosis in several heart diseases. However, whether UCHL1 regulates cardiac fibrosis following MI has yet to be determined. In the present study, we found that UCHL1 was dramatically increased in infarct hearts and TGF-β1-stimulated cardiac fibroblasts (CFs). Inhibition of UCHL1 with LDN57444 (LDN) reversed the myocardial fibrosis in post-MI heart and improved cardiac function. Treatment of LDN or UCHL1 siRNA abolished the TGF-β1-induced fibrotic response of CFs. We further identified GRP78 as an interactor of UCHL1 through screening using immunoprecipitationmass spectrometer. We determined that UCHL1 interacted with glucose-regulated protein of 78 kDa (GRP78) and prompted GRP78 degradation via ubiquitination. Furthermore, we found that GRP78 was upregulated after UCHL1 knockdown and that the GRP78 inhibitor HA15 diminished the antifibrotic function exerted by UCHL1 knockdown in CFs stimulated with TGF-β1. This suggests that UCHL1 regulates cardiac fibrosis post MI through interactions with GRP78. This work identifies that the UCHL1-GRP78 axis is involved in cardiac fibrosis after MI. Myocardial infarction (MI) has been the main cause of cardiovascular diseases for centuries and remains a major issue. Although improved survival from acute MI has been observed due to the effectiveness of revascularisation and other therapies, the incidence of heart failure has increased as a consequence of adverse ventricular remodelling 1,2. Among the factors involved in ventricular remodelling, cardiac fibrosis, which results from the disequilibrium of synthesis and deregulation of extracellular matrix, is a pivotal 3,4. In the acute stage, cardiac fibrosis, is a repairing process that protects the infarct heart from rupture; at the subacute and chronic stage, in cases where cardiac fibrosis abnormally persists, it inevitably leads to cardiac dysfunction and ventricular wall stiffness increasing the risk of heart failure 4,5. Thus, it is essential to control levels of cardiac fibrosis. Cardiac fibroblasts (CFs) are central mediators of the cardiac fibrotic response 6. CFs are mainly stimulated by TGFβ-1 following MI and differentiate into activated myofibroblasts which express α-smooth muscle actin (α-SMA). This results in the secretion of a large amount of extracellular matrix, including fibronectin and collagen I (Col1), which is, in part, regulated by the activation of Smad2/3 4,7,8. To date, no studies have fully elucidated how this process is regulated. The ubiquitin proteasome system (UPS), which consists of E1 ubiquitin-activating enzymes, E2 conjugating enzymes and E3 ubiquitin ligases and deubiquitinating enzymes, is responsible for the degradation and stability of the majority of proteins 9,10. Rece...

Investigation of candidate genes and mechanisms underlying obesity associated type 2 diabetes mellitus using bioinformatics analysis and screening of small drug molecules

“…The GO and pathway enrichment analysis of DEG are closely related to obesity associated type 2 diabetes mellitus. Genes such as KCNE5 [ 45 ], SHANK3 [ 46 ], CASQ2 [ 47 ], EDNRA (endothelin receptor type A) [ 48 ], EPHB4 [ 49 ], ALPK3 [ 50 ], WNT11 [ 51 ], IRAK2 [ 52 ], FBN1 [ 53 ], SFRP2 [ 54 ], CLCA2 [ 55 ], NEXN (nexilin F-actin binding protein) [ 56 ], PALLD (palladin, cytoskeletal associated protein) [ 57 ], DAB2 [ 58 ], NRP2 [ 59 ], THBS2 [ 60 ], CSF1R [ 61 ], KCNA2 [ 62 ], CACNA1C [ 63 ], F2R [ 64 ], UCHL1 [ 65 ], CCL18 [ 66 ], ITGB1BP2 [ 67 ] and FMOD (fibromodulin) [ 68 ] were reportedly involved in cardio vascular diseases, but these genes might be key for progression of obesity associated type 2 diabetes mellitus. Hu et al [ 69 ], Liu et al [ 70 ], Eltokhi et al [ 71 ], Cai et al [ 72 ], Pfeiffer et al [ 73 ], Lin et al [ 74 ], Royer-Zemmour et al [ 75 ], Pastor et al [ 76 ], Goodspeed et al [ 77 ], Zhang et al [ 78 ], Rogers et al [ 79 ], Su et al [ 80 ] and Foale et al [ 81 ] reported that NRXN1, CRHR1, SHANK2, PSEN2, CKB (creatine kinase B), CD200R1, SRPX2, PTPRZ1, SLC6A1, GABRB2, KCNA1, ASAH1 and LINGO1 were the genes expressed in progression of neuropsychiatric disorders, but these genes might be involved in advancement of obesity associated type 2 diabetes mellitus.…”

Legumain is a predictor of all-cause mortality and potential therapeutic target in acute myocardial infarction

“…It is also possible that the legumain-mediated degradation is related to non-lysosomal proteolysis, such as the UPS which is present in all eukaryotic cells and is believed to be responsible for non-lysosomal proteolysis 44 and thus could modulate the remodelling of ECM after MI 45 , 46 . We thus checked the expression of E3 ubiquitin ligase—a key enzyme in ubiquitination that promotes protein ubiquitination and degradation in the cardiac tissue post-MI—and found that E3 expression was increased in the cardiac tissue post-MI; however, E3 expression was not affected by RR-11a treatment (Supplementary Fig.…”

Investigation of Candidate Genes and Mechanisms Underlying Obesity Associated Type 2 Diabetes Mellitus Using Bioinformatics Analysis and Screening of Small Drug Molecules 

“…The GO and pathway enrichment analysis of DEG are closely related to obesity associated type 2 diabetes mellitus genes and advancement. KCNE5 [45], SHANK3 [46], CASQ2 [47], EDNRA (endothelin receptor type A) [48], EPHB4 [49], ALPK3 [50], WNT11 [51], IRAK2 [52], FBN1 [53], SFRP2 [54], CLCA2 [55], NEXN (nexilin F-actin binding protein) [56], PALLD (palladin, cytoskeletal associated protein) [57], DAB2 [58], NRP2 [59], THBS2 [60], CSF1R [61], KCNA2 [62], CACNA1C [63], F2R [64], UCHL1 [65], CCL18 [66], ITGB1BP2 [67] and FMOD ( bromodulin) [68] were reportedly involved in cardio vascular diseases, but these genes might be key for progression of obesity associated type 2 diabetes mellitus. Hu et al [69], Liu et al [70], Eltokhi et al [71], Cai et al [72], Pfeiffer et al [73], Lin et al [74], Royer-Zemmour et al [75], Pastor et al [76], Goodspeed et al [77], Zhang et al [78], Rogers et al [79], Su et al [80] and Foale et al [81] reported that NRXN1, CRHR1, SHANK2, PSEN2, CKB (creatine kinase B), CD200R1, SRPX2, PTPRZ1, SLC6A1, GABRB2, KCNA1, ASAH1 and LINGO1 were linked with progression of neuropsychiatric disorders, but these genes might be involved in advancement of obesity associated type 2 diabetes mellitus.…”