PKCζ interacts with STAT3 and promotes its activation in cardiomyocyte hypertrophy

A Novel Therapeutic Strategy for Ameliorating Hyperglycemia-Induced Liver Injury via Overexpression of the Carboxyl Terminus of HSP70-Interacting Protein in Wharton's Jelly Mesenchymal Stem Cells

Diabetes is a widespread metabolic disorder that significantly affects modern society. The liver plays a vital role in metabolism; however, hyperglycemia can induce liver damage and disrupt its normal functions. Wharton's jelly mesenchymal stem cells (WJMSCs) engineered to express the carboxyl terminus of HSP70-interacting protein (CHIP) have demonstrated protective effects against hyperglycemia-induced damage in various organs. Nonetheless, the potential hepatoprotective effects and underlying mechanisms of these modified stem cells in diabetic livers remain unclear. Therefore, this study aimed to evaluate the efficacy of CHIP-transfected WJMSCs in mitigating hyperglycemia-induced hepatic injury in diabetic rats and to elucidate the associated protective mechanisms. Diabetic rats received tail vein injections of WJMSCs either overexpressing or silenced for CHIP. Seven weeks post-transplantation, all rats were sacrificed, and liver tissues were harvested for histological staining and Western blot analysis. The findings indicated that CHIP-overexpressing WJMSCs significantly reversed hyperglycemia-induced liver damage, reducing tissue injury, fibrosis, and glycogen deposition. These cells also alleviated hepatic inflammation and apoptosis. Moreover, they regulated oxidative stress pathways by lowering gp91-phox, Rac1, and phosphorylated PKCζ levels, while enhancing phosphorylated Nrf2 and SOD-2 expression. Additionally, the modified WJMSCs suppressed STAT3 activation and downregulated FOXO3a, suggesting a role in attenuating fibrosis and triglyceride accumulation in diabetic livers. Overall, CHIP-overexpressing WJMSCs reversed hyperglycemia-induced hepatic alterations by mitigating inflammation and oxidative stress while also modulating pathways related to fibrosis and lipid metabolism. These results highlight the therapeutic potential of CHIP-modified WJMSCs in managing diabetic liver complications and offer promising avenues for future treatment strategies.

STAT protein family and cardiovascular diseases: overview of pathological mechanisms and therapeutic implications

Globally, cardiovascular diseases (CVD) are one of the significant causes of death and are considered a major concern of human society. One of the most crucial objectives of scientists is to reveal the mechanisms associated with the pathogenesis of CVD, which has attracted the attention of many scientists. Accumulating evidence showed that the signal transducer and activator of transcription (STAT) signaling pathway is involved in various physiological and pathological processes. According to research on the molecular mechanisms of CVDs, the STAT family of proteins is one of the most crucial players in these diseases. Numerous studies have demonstrated the undeniable relevance of STAT family proteins in various CVDs. The aim of this review is to shed light on how STAT signaling pathways are related to CVD and the potential for using these signaling pathways as therapeutic targets.

The water extract of Amydrium sinense (Engl.) H. Li ameliorates Isoproterenol-induced cardiac hypertrophy through inhibiting the NF-κB signaling pathway

OBJECTIVE

Pathologic cardiac hypertrophy (PCH) is a precursor to heart failure. Amydrium sinense (Engl.) H. Li (AS), a traditional Chinese medicinal plant, has been extensively utilized to treat chronic inflammatory diseases. However, the therapeutic effect of ASWE on PCH and its underlying mechanisms are still not fully understood.

METHODS

A cardiac hypertrophy model was established by treating C57BL/6 J mice and neonatal rat cardiomyocytes (NRCMs) in vitro with isoprenaline (ISO) in this study. The antihypertrophic effects of AS water extract (ASWE) on cardiac function, histopathologic manifestations, cell surface area and expression levels of hypertrophic biomarkers were examined. Subsequently, the impact of ASWE on inflammatory factors, p65 nuclear translocation and NF-κB activation was investigated to elucidate the underlying mechanisms.

RESULTS

In the present study, we observed that oral administration of ASWE effectively improved ISO-induced cardiac hypertrophy in mice, as evidenced by histopathological manifestations and the expression levels of hypertrophic markers. Furthermore, the in vitro experiments demonstrated that ASWE treatment inhibited cardiac hypertrophy and suppressed inflammation response in ISO-treated NRCMs. Mechanically, our findings provided evidence that ASWE suppressed inflammation response by repressing p65 nuclear translocation and NF-κB activation. ASWE was found to possess the capability of inhibiting inflammation response and cardiac hypertrophy induced by ISO.

CONCLUSION

To sum up, ASWE treatment was shown to attenuate ISO-induced cardiac hypertrophy by inhibiting cardiac inflammation via preventing the activation of the NF-kB signaling pathway. These findings provided scientific evidence for the development of ASWE as a novel therapeutic drug for PCH treatment.

Aqueous extract of Amydrium sinense (Engl.) H. Li alleviates hepatic fibrosis by suppressing hepatic stellate cell activation through inhibiting Stat3 signaling

Background: The present study aimed to investigate the protective effect of the water extract of Amydrium sinense (Engl.) H. Li (ASWE) against hepatic fibrosis (HF) and clarify the underlying mechanism. Methods: The chemical components of ASWE were analysed by a Q-Orbitrap high-resolution mass spectrometer. In our study, an in vivo hepatic fibrosis mouse model was established via an intraperitoneal injection of olive oil containing 20% CCl₄. In vitro experiments were conducted using a hepatic stellate cell line (HSC-T6) and RAW 264.7 cell line. A CCK-8 assay was performed to assess the cell viability of HSC-T6 and RAW264.7 cells treated with ASWE. Immunofluorescence staining was used to examine the intracellular localization of signal transducer and activator of transcription 3 (Stat3). Stat3 was overexpressed to analyse the role of Stat3 in the effect of ASWE on HF. Results: Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that candidate targets of ASWE, associated with protective effects against hepatic fibrosis, were related to inflammation response. ASWE ameliorated CCl₄-induced liver pathological damage and reduced the liver index and alanine transaminase (ALT) and aspartate transaminase (AST) levels. ASWE also decreased the serum levels of collagen Ⅰ (Col Ⅰ) and hydroxyproline (Hyp) in CCl₄-treated mice. In addition, the expression of fibrosis markers, including α-SMA protein and Acta2, Col1a1, and Col3a1 mRNA, was downregulated by ASWE treatment in vivo. The expression of these fibrosis markers was also decreased by treatment with ASWE in HSC-T6 cells. Moreover, ASWE decreased the expression of inflammatory markers, including the Tnf-α, Il6 and Il1β, in RAW264.7 cells. ASWE decreased the phosphorylation of Stat3 and total Stat3 expression and reduced the mRNA expression of the Stat3 gene in vivo and in vitro. ASWE also inhibited the nuclear shuttling of Stat3. Overexpression of Stat3 weakened the therapeutic effect of ASWE and accelerated the progression of HF. Conclusion: The results show that ASWE protects against CCl₄-induced liver injury by suppressing fibrosis, inflammation, HSC activation and the Stat3 signaling pathway, which might lead to a new approach for preventing HF.

Uncovering the Effect and Mechanism of Rhizoma Corydalis on Myocardial Infarction Through an Integrated Network Pharmacology Approach and Experimental Verification

Background: Myocardial infarction (MI), characterized by reduced blood flow to the heart, is a coronary artery disorder with the highest morbidity and mortality among cardiovascular diseases. Consequently, there is an urgent need to identify effective drugs to treat MI. Rhizoma Corydalis (RC) is the dry tuber of Corydalis yanhusuo W.T. Wang, and is extensively applied in treating MI clinically in China. Its underlying pharmacological mechanism remains unknown. This study aims to clarify the molecular mechanism of RC on MI by utilizing network pharmacology and experimental verification.

Methods: Based on network pharmacology, the potential targets of the RC ingredients and MI-related targets were collected from the databases. Furthermore, core targets of RC on MI were identified by the protein-protein interaction (PPI) network and analyzed with Gene Ontology (GO) analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Molecular docking was used to validate the binding affinity between the core targets and the bioactive components. Oxygen-glucose deprivation (OGD) was performed on H9c2 cells to mimic MI in vitro. A Cell Counting Kit-8 assay was used to assess the cardioprotective effect of the active ingredient against OGD. Western blot analysis and RT-qPCR were used to measure the cell apoptosis and inflammation level of H9c2 cells.

Results: The network pharmacology obtained 60 bioactive components of RC, 431 potential targets, and 1131 MI-related targets. In total, 126 core targets were screened according to topological analysis. KEGG results showed that RC was closely related to the phosphatidylinositol 3-kinase (PI3K)/Protein kinase B (PKB, also called Akt) signaling pathway. The experimental validation data showed that tetrahydropalmatine (THP) pretreatment preserved cell viability after OGD exposure. THP suppressed cardiomyocyte apoptosis and inflammation induced by OGD, while LY294002 blocked the inhibition effect of THP on OGD-induced H9c2 cell injury. Moreover, the molecular docking results indicated that THP had the strongest binding affinity with Akt over berberine, coptisine, palmatine, and quercetin.

Conclusion: THP, the active ingredient of RC, can suppress OGD-induced H9c2 cell injury by activating the PI3K/Akt pathway, which in turn provides a scientific basis for a novel strategy for MI therapy and RC application.

Aqueous extract of Solanum nigrum attenuates Angiotensin-II induced cardiac hypertrophy and improves cardiac function by repressing protein kinase C-ζ to restore HSF2 deSUMOlyation and Mel-18-IGF-IIR signaling suppression

ETHNOPHARMACOLOGICAL RELEVANCE

Solanum nigrum, commonly known as Makoi or black shade has been traditionally used in Asian countries and other regions of world to treat liver disorders, diarrhoea, inflammatory conditions, chronic skin ailments (psoriasis and ringworm), fever, hydrophobia, painful periods, eye diseases, etc. It has been observed that S. nigrum contains substances, like steroidal saponins, total alkaloid, steroid alkaloid, and glycoprotein, which show anti-tumor activity. However; there is no scientific evidence of the efficacy of S. nigrum in the treatment of cardiac hypertrophy.

AIM

To investigate the ability of S. nigrum to attenuate Angiotensin II - induced cardiac hypertrophy and improve cardiac function through the suppression of protein kinase PKC-ζ and Mel-18-IGF-IIR signaling leading to the restoration of HSF2 desumolyation.

MATERIALS AND METHODS

Cardiomyoblast cells (H9c2) were challenged with 100 nM Angiotensin-II (AngII) for 24 h and were then treated with different concentration of S.nigrum or Calphostin C for 24 h. The hypertrophic effect in cardiomyoblast cells were determined by immunofluorescence staining and the modulations in hypertrophic protein marker along with Protein Kinase C-ζ, MEL18, HSF2, and Insulin like growth factor II (IGFIIR), markers were analyzed by western blotting. In vivo experiments were performed using 12 week old male Wistar Kyoto rats (WKY) and Spontaneously hypertensive rats (SHR) separated into five groups. [1]Control WKY, [2] WKY -100 mg/kg of S.nigrum treatment, [3] SHR, [4] SHR-100 mg/kg of S.nigrum treatment, [5] SHR-300 mg/kg of S.nigrum treatment. S. nigrum was administered intraperitoneally for 8 week time interval.

RESULTS

Western blotting results indicate that S. nigrum significantly attenuates AngII induced cardiac hypertrophy. Furthermore, actin staining confirmed the ability of S. nigrum to ameliorate AngII induced cardiac hypertrophy. Moreover, S. nigrum administration suppressed the hypertrophic signaling mediators like Protein Kinase C-ζ, Mel-18, and IGFIIR in a dose-dependent manner and HSF2 activation (restore deSUMOlyation) that leads to downregulation of IGF-IIR expression. Additionally in vivo experiments demonstrate the reduced heart sizes of S. nigrum treated SHRs rats when compared to control WKY rats.

CONCLUSION

Collectively, the data reveals the cardioprotective effect of S. nigrum inhibiting PKC-ζ with alleviated IGF IIR level in the heart that profoundly remits cardiac hypertrophy for hypertension-induced heart failure.

Histone H4R3 symmetric di-methylation by Prmt5 protects against cardiac hypertrophy via regulation of Filip1L/β-catenin

BACKGROUND AND PURPOSE

Although histone lysine methylation has been extensively studied for their participation in pathological cardiac hypertrophy, the potential regulatory role of histone arginine methylation remains to be elucidated. The present study focused on H4R3 symmetric di-methylation (H4R3me2s) induced by protein arginine methyltransferase 5 (Prmt5), and explored its epigenetic regulation and underlying mechanisms in cardiomyocyte hypertrophy.

METHODS AND RESULTS

1. The expressions of Prmt5 and H4R3me2s were suppressed in cardiac hypertrophy models in vivo and in vitro; 2. Prmt5 silencing or its inhibitor EPZ, or knockdown of cooperator of Prmt5 (Copr5) to disrupt H4R3me2s, facilitated cardiomyocyte hypertrophy, whereas overexpression of wild type Prmt5 rather than the inactive mutant protected cardiomyocytes against hypertrophy; 3. ChIP-sequence analysis identified Filip1L as a target gene of Prmt5-induced H4R3me2s; 4. Knockdown or inhibition of Prmt5 impaired Filip1L transcription and subsequently prevented β-catenin degradation, thus augmenting cardiomyocyte hypertrophy.

CONCLUSIONS

The present study reveals that Prmt5-induced H4R3me2s ameliorates cardiomyocyte hypertrophy by transcriptional upregulation of Filip1L and subsequent enhancement of β-catenin degradation. Deficiency of Prmt5 and the resulting suppression of H4R3me2s might facilitate the development of pathological cardiac hypertrophy. Prmt5 might serve as a key epigenetic regulator in pathological cardiac hypertrophy.

Palmitic acid is an intracellular signaling molecule involved in disease development

Emerging evidence shows that palmitic acid (PA), a common fatty acid in the human diet, serves as a signaling molecule regulating the progression and development of many diseases at the molecular level. In this review, we focus on its regulatory roles in the development of five pathological conditions, namely, metabolic syndrome, cardiovascular diseases, cancer, neurodegenerative diseases, and inflammation. We summarize the clinical and epidemiological studies; and also the mechanistic studies which have identified the molecular targets for PA in these pathological conditions. Activation or inactivation of these molecular targets by PA controls disease development. Therefore, identifying the specific targets and signaling pathways that are regulated by PA can give us a better understanding of how these diseases develop for the design of effective targeted therapeutics.

PKC and PKN in heart disease

The protein kinase C (PKC) and closely related protein kinase N (PKN) families of serine/threonine protein kinases play crucial cellular roles. Both kinases belong to the AGC subfamily of protein kinases that also include the cAMP dependent protein kinase (PKA), protein kinase B (PKB/AKT), protein kinase G (PKG) and the ribosomal protein S6 kinase (S6K). Involvement of PKC family members in heart disease has been well documented over the years, as their activity and levels are mis-regulated in several pathological heart conditions, such as ischemia, diabetic cardiomyopathy, as well as hypertrophic or dilated cardiomyopathy. This review focuses on the regulation of PKCs and PKNs in different pathological heart conditions and on the influences that PKC/PKN activation has on several physiological processes. In addition, we discuss mechanisms by which PKCs and the closely related PKNs are activated and turned-off in hearts, how they regulate cardiac specific downstream targets and pathways, and how their inhibition by small molecules is explored as new therapeutic target to treat cardiomyopathies and heart failure.

Sirtuin 1 represses PKC-ζ activity through regulating interplay of acetylation and phosphorylation in cardiac hypertrophy

BACKGROUND AND PURPOSE

Activation of PKC-ζ is closely linked to the pathogenesis of cardiac hypertrophy. PKC-ζ can be activated by certain lipid metabolites such as phosphatidylinositol (3,4,5)-trisphosphate and ceramide. However, its endogenous negative regulators are not well defined. Here, the role of the sirtuin1-PKC-ζ signalling axis and the underlying molecular mechanisms were investigated in cardiac hypertrophy.

EXPERIMENTAL APPROACH

Cellular hypertrophy in cultures of cardiac myocytes, from neonatal Sprague-Dawley rats, was monitored by measuring cell surface area and the mRNA levels of hypertrophic biomarkers. Interaction between sirtuin1 and PKC-ζ was investigated by co-immunoprecipitation and confocal immunofluorescence microscopy. Sirtuin1 activation was enhanced by resveratrol treatment or Ad-sirtuin1 transfection. A model of cardiac hypertrophy in Sprague-Dawley rats was established by abdominal aortic constriction surgery or induced by isoprenaline in vivo.

KEY RESULTS

Overexpression of PKC-ζ led to cardiac hypertrophy and increased activity of NF-κB, ERK1/2 and ERK5, which was ameliorated by sirtuin1 overexpression. Enhancement of sirtuin1 activity suppressed acetylation of PKC-ζ, hindered its binding to phosphoinositide-dependent kinase 1 and inhibited PKC-ζ phosphorylation in cardiac hypertrophy. Consequently, the downstream pathways of PKC-ζ' were suppressed in cardiac hypertrophy. This regulation loop suggests a new role for sirtuin1 in mediation of cardiac hypertrophy.

CONCLUSIONS AND IMPLICATIONS

Sirtuin1 is an endogenous negative regulator for PKC-ζ and mediates its activity via regulating the acetylation and phosphorylation in the pathogenesis of cardiac hypertrophy. Targeting the sirtuin1-PKC-ζ signalling axis may suggest a novel therapeutic approach against cardiac hypertrophy.

PARP1 interacts with STAT3 and retains active phosphorylated-STAT3 in nucleus during pathological myocardial hypertrophy

The activation of signal transducer and activator of transcription 3 (STAT3) positively regulates myocardial hypertrophy, and its transcriptional activity is finely conditioned by diverse extracellular growth factors and cytokines. Here, we introduce novel evidence that poly(ADP-ribose) polymerase 1 (PARP1) interacts with STAT3 and promotes its activation in cardiomyocytes and rat heart tissues. PARP1 activity and phosphorylated STAT3 were augmented by hypertrophic stimuli both in vitro and in vivo. Infection of PARP1 adenovirus induced cardiomyocyte hypertrophy, which could be prevented by STAT3 knockdown or inhibition. Additionally, PARP1 enhanced STAT3 phosphorylation level, nuclear accumulation and transcriptional activity. Mechanistically, PARP1 interacts with STAT3 and retains active phosphorylated-STAT3 in nucleus. In conclusion, our findings provide the first evidence that PARP1 exacerbates cardiac hypertrophy by stabilizing active phosphorylated-STAT3, which suggests that multi-target therapeutic strategies counteracting PARP1 activity and STAT3 activation would be potential for treating cardiovascular diseases.

Oleanonic acid ameliorates pressure overload-induced cardiac hypertrophy in rats: The role of PKCζ-NF-κB pathway

It has been reported that inflammation is closely related with cardiac hypertrophy. Some inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, and interleukin-6 directly induce cardiac hypertrophy, which is associated with the activation of nuclear factorkappa B (NF-κB). Thus, NF-κB is an attractive target for cardiac hypertrophy. In the present study, oleanonic acid inhibited the elevation of transcriptional activity of NF-κB and reduced the mRNA expressions of hypertrophic genes such as atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) in a concentration-dependent manner in phenylephrine (PE)-treated cardiomyocytes. Furthermore, we found that oleanonic acid inhibited the phosphorylation of protein kinase C ζ (PKCζ) at Thr410 site and then reduced the activation of NF-κB using gain- and loss-of-function approaches in PE-treated cardiomyocytes. In vivo, similar results were observed in abdominal aortic constriction (AAC) rats that were intragastrically administered with oleanonic acid, and the pathological changes accompanying cardiac hypertrophy were relieved. In conclusion, oleanonic acid can effectively ameliorate cardiac hypertrophy by inhibiting PKCζ-NF-κB signaling pathway.