WWP2 regulates SIRT1-STAT3 acetylation and phosphorylation involved in hypertensive angiopathy

RACK1 enhances STAT3 stability and promotes T follicular helper cell development and function during blood-stage Plasmodium infection in mice

CD4+ T cells are central mediators of protective immunity to blood-stage malaria, particularly for their capacity in orchestrating germinal center reaction and generating parasite-specific high-affinity antibodies. T follicular helper (Tfh) cells are predominant CD4+ effector T cell subset implicated in these processes, yet the factors and detailed mechanisms that assist Tfh cell development and function during Plasmodium infection are largely undefined. Here we provide evidence that receptor for activated C kinase 1 (RACK1), an adaptor protein of various intracellular signals, is not only important for CD4+ T cell expansion as previously implied but also plays a prominent role in Tfh cell differentiation and function during blood-stage Plasmodium yoelii 17XNL infection. Consequently, RACK1 in CD4+ T cells contributes significantly to germinal center formation, parasite-specific IgG production, and host resistance to the infection. Mechanistic exploration detects specific interaction of RACK1 with STAT3 in P. yoelii 17XNL-responsive CD4+ T cells, ablation of RACK1 leads to defective STAT3 phosphorylation, accompanied by substantially lower amount of STAT3 protein in CD4+ T cells, whereas retroviral overexpression of RACK1 or STAT3 in RACK1-deficient CD4+ T cells greatly restores STAT3 activity and Bcl-6 expression under the Tfh polarization condition. Further analyses suggest RACK1 positively regulates STAT3 stability by inhibiting the ubiquitin-proteasomal degradation process, thus promoting optimal STAT3 activity and Bcl-6 induction during Tfh cell differentiation. These findings uncover a novel mechanism by which RACK1 participates in posttranslational regulation of STAT3, Tfh cell differentiation, and subsequent development of anti-Plasmodium humoral immunity.

E3 ubiquitin ligase WWP2 as a promising therapeutic target for diverse human diseases

Mammalian E3 ubiquitin ligases have emerged in recent years as critical regulators of cellular homeostasis due to their roles in targeting substrate proteins for ubiquitination and triggering subsequent downstream signals. In this review, we describe the multiple roles of WWP2, an E3 ubiquitin ligase with unique and important functions in regulating a wide range of biological processes, including DNA repair, gene expression, signal transduction, and cell-fate decisions. As such, WWP2 has evolved to play a key role in normal physiology and diseases, such as tumorigenesis, skeletal development and diseases, immune regulation, cardiovascular disease, and others. We attempt to provide an overview of the biochemical, physiological, and pathophysiological roles of WWP2, as well as open questions for future research, particularly in the context of putative therapeutic opportunities.

Proliferation, migration and phenotypic transformation of VSMC induced via Hcy related to up-expression of WWP2 and p-STAT3

To provide a theoretical basis for the prevention and treatment of atherosclerosis (AS), the current study aimed to investigate the mechanism underlying the effect of homocysteine (Hcy) on regulating the proliferation, migration and phenotypic transformation of vascular smooth muscle cells (VSMC) via sirtuin-1 (SIRT1)/signal transducer and activator of transcription 3 (STAT3) through Nedd4-like E3 ubiquitin-protein ligase WWP2 (WWP2). Here, Based on the establishment of ApoE-/- mouse models of high Hcy As and the model of Hcy stimulation of VSMC in vitro to observe the interaction between WWP2 and STAT3 and its effect on the proliferation, migration, and phenotypic transformation of Hcy-induced VSMC, which has not been previously reported. This study revealed that WWP2 could promote the proliferation, migration, and phenotype switch of Hcy-induced VSMC by up-regulating the phosphorylation of SIRT1/STAT3 signaling. Furthermore, Hcy might up-regulate WWP2 expression by inhibiting histone H3K27me3 expression through up-regulated UTX. These data suggest that WWP2 is a novel and important regulator of Hcy-induced VSMC proliferation, migration, and phenotypic transformation.

Atorvastatin rescues vascular endothelial injury in hypertension by WWP2-mediated ubiquitination and degradation of ATP5A

As a widely used lipid-lowering drug in clinical practice, atorvastatin is widely recognized for its role in protecting vascular endothelium in the cardiovascular system. However, a clear mechanistic understanding of its action is lacking. Here, we found that atorvastatin counteracted angiotensin II-induced vascular endothelial injury in mice with hypertension. Mechanistically, atorvastatin up-regulated WWP2, a E6AP C-terminus (HECT)-type E3 ubiquitin ligase with an essential role in regulating protein ubiquitination and various biological processes, thereby rescuing vascular endothelial injury. By ubiquitinating ATP5A (ATP synthase mitochondrial F1 complex subunit alpha), WWP2 degraded ATP5A via the proteasome pathway, stabilizing Bcl-2/Bax in the mitochondrial pathway of apoptosis. Moreover, atorvastatin further ameliorated death of vascular endothelial cells and improved vascular endothelial functions under WWP2 overexpression, whereas WWP2 knockout abrogated these beneficial effects of atorvastatin. Furthermore, we generated endothelial cell-specific WWP2 knockout mice, and this WWP2-mediated mechanism was faithfully recapitulated in vivo. Thus, we propose that activation of a WWP2-dependent pathway that is pathologically repressed in damaged vascular endothelium under hypertension is a major mechanism of atorvastatin. Our findings are also pertinent to develop novel therapeutic strategies for vascular endothelial injury-related cardiovascular diseases.

Metformin suppresses cardiac fibroblast proliferation under high-glucose conditions via regulating the mitochondrial complex I protein Grim-19 involved in the Sirt1/Stat3 signaling pathway

Hyperglycemia associated with myocardial oxidative stress and fibrosis is the main cause of diabetic cardiomyopathy. Currently, no approved drug is available for preventing or treating diabetes-induced cardiac fibrosis. Metformin has been reported to improve glycemic control and ameliorate diabetic cardiomyopathy. This study aimed to investigate the effects and mechanism of metformin on diabetes-induced cardiac fibrosis and high glucose-induced proliferation of cardiac fibroblasts (CFs). In this study, db/db mice were treated with metformin [250 mg/kg⋅d, gavage]. CFs were cultured in high-glucose medium to mimic an in vitro diabetes model and then subjected to treatment with or without metformin. Cardiac fibrosis was analyzed using immunohistochemistry, Masson's trichrome staining, and Western blot analysis. Cell Counting Kit-8 (CCK-8) assays and cell colony formation assays were used to examine cell proliferation capacity. Transwell and scratch-wound assays were used to detect the migration ability of CFs. Retinoid-interferon-induced mortality-19 (Grim-19), sirtuin1 (Sirt1), and signal transducer and activator of transcription 3 (Stat3) were detected using Western blot analysis. The genes downstream of the Stat3 pathway were detected using quantitative reverse transcription PCR (qRT‒PCR). Metformin treatment markedly attenuated cardiac fibrosis in db/db mice and the proliferation and migration of CFs under high-glucose conditions. Mechanistically, we found an intersection between metformin and Grim-19 using bioinformatics. Metformin was found to suppress the expression of p-Stat3 and elevate the expression of mitochondrial complex I protein Grim-19 and Sirt1, thus inhibiting the proliferation and migration of CFs under high-glucose conditions. Our data suggested that metformin inhibited the proliferation and migration of CFs by regulating the expression of mitochondrial complex I Grim-19 protein involved in the Sirt1/Stat3 signaling pathway under high-glucose conditions, thus providing new ideas for treating diabetes-induced cardiac fibrosis.

Spleen tyrosine kinase (SYK) signals are implicated in cardio-cerebrovascular diseases

Post-translational modifications regulate numerous biochemical reactions and functions through covalent attachment to proteins. Phosphorylation, acetylation and ubiquitination account for over 90% of all reported post-translational modifications. As one of the tyrosine protein kinases, spleen tyrosine kinase (SYK) plays crucial roles in many pathophysiological processes and affects the pathogenesis and progression of various diseases. SYK is expressed in tissues outside the hematopoietic system, especially the heart, and is involved in the progression of various cardio-cerebrovascular diseases, such as atherosclerosis, heart failure, diabetic cardiomyopathy, stroke and others. Knowledge on the role of SYK in the progress of cardio-cerebrovascular diseases is accumulating, and many related mechanisms have been discovered and validated. This review summarizes the role of SYK in the progression of various cardio-cerebrovascular diseases, and aims to provide a theoretical basis for future experimental and clinical research targeting SYK as a therapeutic option for these diseases.

circPTPN22 attenuates immune microenvironment of pancreatic cancer via STAT3 acetylation

Accumulating research implicated that circular RNAs exhibited significant roles in cancer development. Nonetheless, the role regarding circPTPN22 in pancreatic cancer remains unclear. Expression of circPTPN22 in pancreatic cancer cell lines and normal cells was determined with quantitative real-time PCR (qRT-PCR). Cell counting kit-8 assay and colony formation assay were used to measure the proliferation of pancreatic cancer cells. RNA immunoprecipitation and Western blot were employed for investigation the binding between circPTPN22 and STAT3. circPTPN22 expression was highly upregulated in pancreatic cancer tissues and cell lines. Knockdown of circPTPN22 inhibited cell proliferation and attenuates pancreatic cancer immune microenvironment. Furthermore, STAT3 acetylation was involved in these effects. circPTPN22 promoted STAT3 acetylation via inhibiting STAT3/SIRT1 interaction. circPTPN22 attenuates pancreatic cancer immune microenvironment by promoting STAT3 acetylation via inhibiting STAT3/SIRT1 interaction.

WWP2 ameliorates oxidative stress and inflammation in atherosclerotic mice through regulation of PDCD4/HO-1 pathway

WWP2 is a HECT-type E3 ubiquitin ligase that regulates various physiological and pathological activities by binding to different substrates, but its role in atherosclerosis (AS) remains largely unknown. The objective of the present study is to investigate the role and underlying molecular mechanisms of WWP2 in endothelial injury. We found that WWP2 expression is significantly decreased in Apolipoprotein E (ApoE) ^-/- mice. Overexpression of WWP2 attenuates oxidative stress and inflammation in AS mice, while knockdown of WWP2 has opposite effects. WWP2 overexpression alleviates oxidized low-density lipoprotein (ox-LDL)-induced human umbilical vein endothelial cell (HUVEC) injury, evidenced by the decreased oxidative stress levels and the secretion of inflammatory cytokines. Programmed cell death 4 (PDCD4) is identified as a potential substrate of WWP2. Co-immunoprecipitation (Co-IP) further demonstrates that WWP2 interacts with PDCD4, which is enhanced by ox-LDL treatment. Furthermore, the level of PDCD4 ubiquitination is significantly increased by WWP2 overexpression under the condition of MG132 treatment, while WWP2 knockdown shows opposite results. Subsequently, rescue experiments demonstrate that WWP2 knockdown further aggravates oxidative stress and inflammation in ox-LDL-treated HUVECs, while knockdown of PDCD4 alleviates this effect. Moreover, the use of sn-protoporphyrin (SnPP), an inhibitor of HO-1 pathway, confirms that PDCD4 enhances endothelial injury induced by ox-LDL through inhibiting HO-1 pathway. In conclusion, our results suggest that WWP2 protects against atherosclerosis progression via the PDCD4/HO-1 pathway, which may provide a novel treatment strategy for atherosclerosis.

Role of Posttranslational Modifications of Proteins in Cardiovascular Disease

Cardiovascular disease (CVD) has become a leading cause of mortality and morbidity globally, making it an urgent concern. Although some studies have been performed on CVD, its molecular mechanism remains largely unknown for all types of CVD. However, recent in vivo and in vitro studies have successfully identified the important roles of posttranslational modifications (PTMs) in various diseases, including CVD. Protein modification, also known as PTMs, refers to the chemical modification of specific amino acid residues after protein biosynthesis, which is a key process that can influence the activity or expression level of proteins. Studies on PTMs have contributed directly to improving the therapeutic strategies for CVD. In this review, we examined recent progress on PTMs and highlighted their importance in both physiological and pathological conditions of the cardiovascular system. Overall, the findings of this review contribute to the understanding of PTMs and their potential roles in the treatment of CVD.

Hypoxia-induced mesenchymal stem cells inhibit corneal fibroblast proliferation by regulating the WWP2/Notch1 axis

Aim: This study aimed to explore the role of hypoxic mesenchymal stem cells (MSCs) in corneal alkali burns and the underlying mechanism. Materials & methods: Rat corneal fibroblasts were incubated with IL-6, followed by treatment with hypoxic MSC supernatant. A rat corneal alkali burn model was implemented and processed with hypoxic MSCs. The associated factors were detected by corresponding methods. Results: Hypoxic MSCs reduced the Notch1 level and the proliferation of rat corneal fibroblasts. Hypoxic MSCs or WWP2 overexpression in MSCs enhanced ubiquitination of Notch1. WWP2 interacted with Notch1, and WWP2 silencing reversed the effects of the hypoxic MSCs. Hypoxic MSC treatment in vivo decreased the corneal neovascularization scores and opacity scores. Conclusion: Hypoxic MSCs inhibited inflammation and alleviated corneal injury in alkali burns via the WWP2/Notch1 axis.

The role of SIRT2 in vascular-related and heart-related diseases: A review

At present, cardiovascular disease is one of the important factors of human death, and there are many kinds of proteins involved. Sirtuins family proteins are involved in various physiological and pathological activities of the human body. Among them, there are more and more studies on the relationship between sirtuin2 (SIRT2) protein and cardiovascular diseases. SIRT2 can effectively inhibit pathological cardiac hypertrophy. The effect of SIRT2 on ischaemia‐reperfusion injury has different effects under different conditions. SIRT2 can reduce the level of reactive oxygen species (ROS), which may help to reduce the severity of diabetic cardiomyopathy. SIRT2 can affect a variety of cardiovascular diseases, energy metabolism and the ageing of cardiomyocytes, thereby affecting heart failure. SIRT2 also plays an important role in vascular disease. For endothelial cell damage used by oxidative stress, the role of SIRT2 is bidirectional, which is related to the degree of oxidative stress stimulation. When the degree of stimulation is small, SIRT2 plays a protective role, and when the degree of stimulation increases to a certain level, SIRT2 plays a negative role. In addition, SIRT2 is also involved in the remodelling of blood vessels and the repair of skin damage.

WWP2 regulates SIRT1-STAT3 acetylation and phosphorylation involved in hypertensive angiopathy

WWP2 is a HECT‐type E3 ubiquitin ligase that regulates various physiological and pathological activities by binding to different substrates, but its function and regulatory mechanism in vascular smooth muscle cells (VSMCs) are still unknown. Here, we clarified the role of WWP2 in the regulation of SIRT1‐STAT3 and the impact of this regulatory process in VSMCs. We demonstrated that WWP2 expression was significantly increased in angiotensin II‐induced VSMCs model. Knockdown of WWP2 significantly inhibited angiotensin II‐induced VSMCs proliferation, migration and phenotypic transformation, whereas overexpression of WWP2 had opposite effects. In vivo experiments showed that vascular smooth muscle‐specific WWP2 knockout mice significantly relieved angiotensin II‐induced hypertensive angiopathy. Mechanistically, mass spectrometry and co‐immunoprecipitation assays identified that WWP2 is a novel interacting protein of SIRT1 and STAT3. Moreover, WWP2 formed a complex with SIRT1‐STAT3, inhibiting the interaction between SIRT1 and STAT3, then reducing the inhibitory effect of SIRT1 on STAT3, ensuing promoting STAT3‐K685 acetylation and STAT3‐Y705 phosphorylation in angiotensin II‐induced VSMCs and mice. In conclusion, WWP2 modulates hypertensive angiopathy by regulating SIRT1‐STAT3 and WWP2 suppression in VSMCs can alleviate hypertensive angiopathy vitro and vivo. These findings provide new insights into the treatment of hypertensive vascular diseases.