Administration of USP7 inhibitor P22077 inhibited cardiac hypertrophy and remodeling in Ang II-induced hypertensive mice

USP7 cardiomyocyte specific knockout causes disordered mitochondrial biogenesis and dynamics and early neonatal lethality in mice

BACKGROUND

Ubiquitination is an enzymatic modification involving ubiquitin chains, that can be reversed by deubiquitination (DUB) enzymes. Ubiquitin-specific protease 7 (USP7), which is also known as herpes virus-associated ubiquitin-specific protease (HAUSP), has been shown to play a vital role in cardiovascular diseases. However, the underlying molecular mechanism by which USP7 regulates cardiomyocyte function has not been reported.

METHODS

To understand the physiological function of USP7 in the heart, we constructed cardiomyocyte-specific USP7 conditional knockout mice.

RESULTS

We found that homozygous knockout mice died approximately three weeks after birth, while heterozygous knockout mice grew normally into adulthood. Severe cardiac dysfunction, hypertrophy, fibrosis, and cell apoptosis were observed in cardiomyocyte-specific USP7 knockout mice, and these effects were accompanied by disordered mitochondrial dynamics and cardiometabolic-related proteins.

CONCLUSIONS

In summary, we investigated changes in the growth status and cardiac function of cardiomyocyte-specific USP7 knockout mice, and preliminarily explored the underlying mechanism.

USP7 promotes cardiometabolic disorders and mitochondrial homeostasis dysfunction in diabetic mice via stabilizing PGC1β

Diabetic cardiomyopathy (DCM) is a major complication of diabetes and is characterized by left ventricular dysfunction. Currently, there is a lack of effective treatments for DCM. Ubiquitin-specific protease 7 (USP7) plays a key role in various diseases. However, whether USP7 is involved in DCM has not been established. In this study, we demonstrated that USP7 was upregulated in diabetic mouse hearts and NMCMs co-treated with HG+PA or H9c2 cells treated with PA. Abnormalities in diabetic heart morphology and function were reversed by USP7 silencing through conditional gene knockout or chemical inhibition. Proteomic analysis coupled with biochemical validation confirmed that PCG1β was one of the direct protein substrates of USP7 and aggravated myocardial damage through coactivation of the PPARα signaling pathway. USP7 silencing restored the expression of fatty acid metabolism-related proteins and restored mitochondrial homeostasis by inhibiting mitochondrial fission and promoting fusion events. Similar effects were also observed in vitro. Our data demonstrated that USP7 promoted cardiometabolic metabolism disorders and mitochondrial homeostasis dysfunction via stabilizing PCG1β and suggested that silencing USP7 may be a therapeutic strategy for DCM.

Ubiquitin-specific protease-7 promotes expression of airway mucin MUC5AC via the NF-κB signaling pathway

Chronic obstructive pulmonary disease (COPD) and other respiratory diseases frequently present with airway mucus hypersecretion, which not only affects the patient's quality of life but also poses a constant threat to their life expectancy. Ubiquitin-specific protease 7 (USP7), a deubiquitinating enzyme, affects cell differentiation, tissue growth, and disease development. However, its role in airway mucus hypersecretion induced by COPD remains elusive. In this study, USP7 expression was significantly upregulated in airway epithelial samples from patients with COPD, and USP7 was also overexpressed in mouse lung and human airway epithelial cells in models of airway mucus hypersecretion. Inhibition of USP7 reduced the expression of nuclear factor kappa B (NF-κB), phosphorylated-NF-κB (p-NF-κB), and phosphonated inhibitor of nuclear factor kappa B (p-IκBα), and alleviated the airway mucus hypersecretion in vivo and in vitro. Further research revealed that USP7 stimulated airway mucus hypersecretion through the activation of NF-κB nuclear translocation. In addition, the expression of mucin 5AC (MUC5AC) was suppressed by the NF-κB inhibitor erdosteine. These findings suggest that USP7 stimulates the NF-κB signaling pathway, which promotes airway mucus hypersecretion. This study identifies one of the mechanisms regulating airway mucus secretion and provides a new potential target for its prevention and treatment.

USP36-mediated PARP1 deubiquitination in doxorubicin-induced cardiomyopathy

Doxorubicin (Dox) is a potent antineoplastic agent, but its use is curtailed by severe cardiotoxicity, known as Dox-induced cardiomyopathy (DIC). The molecular mechanism underlying this cardiotoxicity remains unclear. Our current study investigates the role of Ubiquitin-Specific Protease 36 (USP36), a nucleolar deubiquitinating enzyme (DUB), in the progression of DIC and its mechanism. We found increased USP36 expression in neonatal rat cardiomyocytes and H9C2 cells exposed to Dox. Silencing USP36 significantly mitigated Dox-induced oxidative stress injury and apoptosis in vitro. Mechanistically, USP36 upregulation positively correlated with Poly (ADP-ribose) polymerase 1 (PARP1) expression, and its knockdown led to a reduction in PARP1 levels. Further investigation revealed that USP36 could bind to and mediate the deubiquitination of PARP1, thereby increasing its protein stability in cardiomyocytes upon Dox exposure. Moreover, overexpression of wild-type (WT) USP36 plasmid, but not its catalytically inactive mutant (C131A), stabilized PARP1 in HEK293T cells. We also established a DIC model in mice and observed significant upregulation of USP36 in the heart. Cardiac knockdown of USP36 in mice using a type 9 recombinant adeno-associated virus (rAAV9)-shUSP36 significantly preserved cardiac function after Dox treatment and protected against Dox-induced structural changes within the myocardium. In conclusion, these findings suggest that Dox promotes DIC progression by activating USP36-mediated PARP1 deubiquitination. This novel USP36/PARP1 axis may play a significant regulatory role in the pathogenesis of DIC.

Administration of USP7 inhibitor p22077 alleviates Angiotensin II (Ang II)-induced atrial fibrillation in Mice

Atrial fibrillation (AF), the most common cardiac arrhythmia, is an important contributor to mortality and morbidity. Ubquitin-specific protease 7 (USP7), one of the most abundant ubiquitin-specific proteases (USP), participated in many cellular events, such as cell proliferation, apoptosis, and tumourigenesis. However, its role in AF remains unknown. Here, the mice were treated with Ang II infusion to induce the AF model. Echocardiography was used to measure the atrial diameter. Electrical stimulation was programmed to measure the induction and duration of AF. The changes in atrial remodeling were measured using routine histologic analysis. Here, a significant increase in USP7 expression was observed in Ang II-stimulated atrial cardiomyocytes and atrial tissues, as well as in atrial tissues from patients with AF. The administration of p22077, the inhibitor of USP7, attenuated Ang II-induced inducibility and duration of AF, atrial dilatation, connexin dysfunction, atrial fibrosis, atrial inflammation, and atrial oxidase stress, and then inhibited the progression of AF. Mechanistically, the administration of p22077 alleviated Ang II-induced activation of TGF-β/Smad2, NF-κB/NLRP3, NADPH oxidases (NOX2 and NOX4) signals, the up-regulation of CX43, ox-CaMKII, CaMKII, Kir2.1, and down-regulation of SERCA2a. Together, this study, for the first time, suggests that USP7 is a critical driver of AF and revealing USP7 may present a new target for atrial fibrillation therapeutic strategies.

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.

Ginsenoside RH4 inhibits Ang II-induced myocardial remodeling by interfering with NFIL3

Ventricular remodeling refers to the structural and functional changes of the heart under various stimuli or disease influences and may also be accompanied by myocardial fibrosis, where an excessive amount of fibrous tissue appears in the myocardial tissue, affecting the heart's normal contraction and relaxation. Hypertension is posing the potential risk of causing myocardial injury and remodeling. The significance of the renin-angiotensin-aldosterone system (RAAS) in myocardial remodeling cannot be overlooked. Drug targeting of RAAS can effectively lower blood pressure and reduce left ventricular mass. Studies have shown that ginsenoside Rh4 can inhibit oxidative stress and inflammatory responses. In this study, a myocardial remodeling model was established using angiotensin (Ang) II, and the inhibitory effect of RH4 on myocardial hypertrophy and remodeling induced by Ang II was investigated using pathological staining and quantitative polymerase chain reaction (qPCR). Immunofluorescence and qPCR demonstrated that Rh4 causes myocardial hypertrophy and the generation of reactive oxygen species (ROS) in vitro. The Rh4 target was identified using transcriptomics. The findings indicated that RH4 could inhibit myocardial hypertrophy, inflammatory fibrosis, and oxidative stress induced by Ang II, suggesting potential cardiovascular protection effects. In vitro experiments have shown that Rh4 inhibits myocardial hypertrophy. Transcriptomics revealed that nuclear factor interleukin-3 (NFIL3) is a downstream regulator of Rh4. By constructing AAV9-NFIL3 and injecting it into mice, it was found that NFIL3 overexpression interfered with anti-Ang II-induced myocardial remodeling of Rh4. These results indicate that Rh4 demonstrates potential therapeutic effects on myocardial hypertrophy and fibrosis.

Targeting the NLRP3 inflammasome for the treatment of hypertensive target organ damage: Role of natural products and formulations

BACKGROUND AND AIM

Hypertension is a major global health problem that causes target organ damage (TOD) in the heart, brain, kidney, and blood vessels. The mechanisms of hypertensive TOD are not fully understood, and its treatment is challenging. This review provides an overview of the current knowledge on the role of Nod-like receptor pyrin domain containing 3 (NLRP3) inflammasome in hypertensive TOD and the natural products and formulations that inhibit it.

METHODS

We searched PubMed, Web of Science, Google Scholar, and CNKI for relevant articles using the keywords "hypertension," "target organ damage," "NLRP3 inflammasome," "natural products," and "formulations." We reviewed the effects of the NLRP3 inflammasome on hypertensive TOD in different organs and discussed the natural products and formulations that modulate it.

KEY RESULTS

In hypertensive TOD, the NLRP3 inflammasome is activated by various stimuli such as oxidative stress and inflammation. Activation of NLRP3 inflammasome leads to the production of pro-inflammatory cytokines that exacerbate tissue damage and dysfunction. Natural products and formulations, including curcumin, resveratrol, triptolide, and allicin, have shown protective effects against hypertensive TOD by inhibiting the NLRP3 inflammasome.

CONCLUSIONS AND IMPLICATIONS

The NLRP3 inflammasome is a promising therapeutic target in hypertensive TOD. Natural products and formulations that inhibit the NLRP3 inflammasome may provide novel drug candidates or therapies for hypertensive TOD. Further studies are needed to elucidate the molecular mechanisms and optimize the dosages of these natural products and formulations and evaluate their clinical efficacy and safety.

A review of deubiquitinases and thier roles in tumorigenesis and development

Ubiquitin is a small protein that can be added onto target protein for inducing target degradation, thereby modulating the activity and stability of protein. Relatively, deubiquitinases (DUBs), a class catalase that can remove ubiquitin from substrate protein, provide a positive regulation of the protein amount at transcription level, post-translational modification, protein interaction, etc. The reversible and dynamic ubiquitination-deubiquitination process plays an essential role in maintaining protein homeostasis, which is critical to almost all the biological processes. Therefore, the metabolic dysregulation of deubiquitinases often lead to serious consequences, including the growth and metastasis of tumors. Accordingly, deubiquitinases can be served as key drug targets for the treatment of tumors. The small molecule inhibitors targeting deubiquitinases has become one of the hot spots of anti-tumor drug research areas. This review concentrated on the function and mechanism of deubiquitinase system in the proliferation, apoptosis, metastasis and autophagy of tumor cells. The research status of small molecule inhibitors of specific deubiquitinases in tumor treatment is introduced, aiming to provide reference for the development of clinical targeted drugs.