Differential Regulation of Myocardial E3 Ligases and Deubiquitinases in Ischemic Heart Failure

Leveraging Therapeutic Proteins and Peptides from Lumbricus Earthworms: Targeting SOCS2 E3 Ligase for Cardiovascular Therapy through Molecular Dynamics Simulations

Suppressor of cytokine signaling 2 (SOCS2), an E3 ubiquitin ligase, regulates the JAK/STAT signaling pathway, essential for cytokine signaling and immune responses. Its dysregulation contributes to cardiovascular diseases (CVDs) by promoting abnormal cell growth, inflammation, and resistance to cell death. This study aimed to elucidate the molecular mechanisms underlying the interactions between Lumbricus-derived proteins and peptides and SOCS2, with a focus on identifying potential therapeutic candidates for CVDs. Utilizing a multifaceted approach, advanced computational methodologies, including 3D structure modeling, protein-protein docking, 100 ns molecular dynamics (MD) simulations, and MM/PBSA calculations, were employed to assess the binding affinities and functional implications of Lumbricus-derived proteins on SOCS2 activity. The findings revealed that certain proteins, such as Lumbricin, Chemoattractive glycoprotein ES20, and Lumbrokinase-7T1, exhibited similar activities to standard antagonists in modulating SOCS2 activity. Furthermore, MM/PBSA calculations were employed to assess the binding free energies of these proteins with SOCS2. Specifically, Lumbricin exhibited an average ΔGbinding of -59.25 kcal/mol, Chemoattractive glycoprotein ES20 showed -55.02 kcal/mol, and Lumbrokinase-7T1 displayed -69.28 kcal/mol. These values suggest strong binding affinities between these proteins and SOCS2, reinforcing their potential therapeutic efficacy in cardiovascular diseases. Further in vitro and animal studies are recommended to validate these findings and explore broader applications of Lumbricus-derived proteins.

The role of deubiquitinases in cardiac disease

Deubiquitinases are a group of proteins that identify and digest monoubiquitin chains or polyubiquitin chains attached to substrate proteins, preventing the substrate protein from being degraded by the ubiquitin-proteasome system. Deubiquitinases regulate cellular autophagy, metabolism and oxidative stress by acting on different substrate proteins. Recent studies have revealed that deubiquitinases act as a critical regulator in various cardiac diseases, and control the onset and progression of cardiac disease through a board range of mechanism. This review summarizes the function of different deubiquitinases in cardiac disease, including cardiac hypertrophy, myocardial infarction and diabetes mellitus-related cardiac disease. Besides, this review briefly recapitulates the role of deubiquitinases modulators in cardiac disease, providing the potential therapeutic targets in the future.

Targeting selective E3 ligase for healing cardiac fibrosis

Protein quality control is often disrupted in heart diseases. In this issue of Cell Chemical Biology, Yang et al.1 describe the selective E3 ligase SPOP as a pro-fibrotic factor for inducing cardiac fibrosis through RACK1 degradation-mediated Smad3 activation.

Angiotensin II-induced calcium overload affects mitochondrial functions in cardiac hypertrophy by targeting the USP2/MFN2 axis

Ubiquitination, a common type of post-translational modification, is known to affect various diseases, including cardiac hypertrophy. Ubiquitin-specific peptidase 2 (USP2) plays a crucial role in regulating cell functions, but its role in cardiac functions remains elusive. The present study aims to investigate the mechanism of USP2 in cardiac hypertrophy. Animal and cell models of cardiac hypertrophy were established using Angiotensin II (Ang II) induction. Our experiments revealed that Ang II induced USP2 downregulation in the in vitro and in vivo models. USP2 overexpression suppressed the degree of cardiac hypertrophy (decreased ANP, BNP, and β-MHC mRNA levels, cell surface area, and ratio of protein/DNA), calcium overload (decreased Ca²⁺ concentration and t-CaMKⅡ and p-CaMKⅡ, and increased SERCA2), and mitochondrial dysfunction (decreased MDA and ROS and increased MFN1, ATP, MMP, and complex Ⅰ and II) both in vitro and in vivo. Mechanically, USP2 interacted with MFN2 and improved the protein level of MFN2 through deubiquitination. Rescue experiments confirmed that MFN2 downregulation neutralized the protective role of USP2 overexpression in cardiac hypertrophy. Overall, our findings suggested that USP2 overexpression mediated deubiquitination to upregulate MFN2, thus alleviating calcium overload-induced mitochondrial dysfunction and cardiac hypertrophy.

Myostatin/AKT/FOXO Signaling Is Altered in Human Non-Ischemic Dilated Cardiomyopathy

Disturbances in the ubiquitin proteasome system, and especially changes of the E3 ligases, are subjects of interest when searching for causes and therapies for cardiomyopathies. The aim of this study was to clarify whether the myostatin/AKT/forkhead box O (FOXO) pathway, which regulates the expression of the E3 ligases muscle atrophy F-box gene (MAFbx) and muscle ring-finger protein-1 (MuRF1), is changed in dilated cardiomyopathy of ischemic origin (IDCM) and dilated cardiomyopathy of non-ischemic origin (NIDCM). The mRNA and protein expression of myostatin, AKT, FOXO1, FOXO3, MAFbx and MuRF1 were quantified by real-time polymerase chain reaction and ELISA, respectively, in myocardial tissue from 26 IDCM and 23 NIDCM patients. Septal tissue from 17 patients undergoing Morrow resection served as a control. MAFbx and FOXO1 mRNA and protein expression (all p < 0.05), AKT mRNA (p < 0.01) and myostatin protein expression (p = 0.02) were decreased in NIDCM patients compared to the control group. Apart from decreases of AKT and MAFbx mRNA expression (both p < 0.01), no significant differences were detected in IDCM patients compared to the control group. Our results demonstrate that the myostatin/AKT/FOXO pathway is altered in NIDCM but not in IDCM patients. FOXO1 seems to be an important drug target for regulating the expression of MAFbx in NIDCM patients.