Dual-Specificity Phosphatase 26 Protects Against Cardiac Hypertrophy Through TAK1

Dual-specificity phosphatase 26 protects against kidney injury caused by ischaemia-reperfusion through restraint of TAK1-JNK/p38-mediated apoptosis and inflammation of renal tubular epithelial cells

Dual-specificity phosphatase 26 (DUSP26) acts as a pivotal player in the transduction of signalling cascades with its dephosphorylating activity. Currently, DUSP26 attracts extensive attention due to its particular function in several pathological conditions. However, whether DUSP26 plays a role in kidney ischaemia-reperfusion (IR) injury is unknown. Aims of the current work were to explore the relevance of DUSP26 in kidney IR damage. DUSP26 levels were found to be decreased in renal tubular epithelial cells following hypoxia-reoxygenation (HR) and kidney samples subjected to IR treatments. DUSP26-overexpressed renal tubular epithelial cells exhibited protection against HR-caused apoptosis and inflammation, while DUSP26-depleted renal tubular epithelial cells were more sensitive to HR damage. Upregulation of DUSP26 in rat kidneys by infecting adenovirus expressing DUSP26 markedly ameliorated kidney injury caused by IR, while also effectively reducing apoptosis and inflammation. The mechanistic studies showed that the activation of transforming growth factor-β-activated kinase 1 (TAK1)-JNK/p38 MAPK, contributing to kidney injury under HR or IR conditions, was restrained by increasing DUSP26 expression. Pharmacological restraint of TAK1 markedly diminished DUSP26-depletion-exacebated effects on JNK/p38 activation and HR injury of renal tubular cells. The work reported a renal-protective function of DUSP26, which protects against IR-related kidney damage via the intervention effects on the TAK1-JNK/p38 axis. The findings laid a foundation for understanding the molecular pathogenesis of kidney IR injury and provide a prospective target for treating this condition.

Inhibition of Sema4D attenuates pressure overload-induced pathological myocardial hypertrophy via the MAPK/NF-κB/NLRP3 pathways

Sema4D (CD100) is closely related to pathological and physiological processes, including tumor growth, angiogenesis and cardiac development. Nevertheless, the role and mechanism of Sema4D in cardiac hypertrophy are still unclear to date. To assess the impact of Sema4D on pathological cardiac hypertrophy, TAC surgery was performed on C57BL/6 mice which were transfected with AAV9-mSema4D-shRNA or AAV9-mSema4D adeno-associated virus by tail vein injection. Our results indicated that Sema4D knockdown mitigated cardiac hypertrophy, fibrosis and dysfunction when exposed to pressure overload, and Sema4D downregulation markedly inhibited cardiomyocyte hypertrophy induced by angiotensin II. Meanwhile, Sema4D overexpression had the opposite effect in vitro and in vivo. Furthermore, analysis of signaling pathways showed that Sema4D activated the MAPK pathway during cardiac hypertrophy induced by pressure overload, and the pharmacological mitogen-activated protein kinase kinase 1/2 inhibitor U0126 almost completely reversed Sema4D overexpression-induced deteriorated phenotype, resulting in improved cardiac function. Further research indicated that myocardial hypertrophy induced by Sema4D was closely related to the expression of the pyroptosis-related proteins PP65, NLRP3, caspase-1, ASC, GSDMD, IL-18 and IL-1β. In conclusion, our study demonstrated that Sema4D regulated the process of pathological myocardial hypertrophy through modulating MAPK/NF-κB/NLRP3 pathway, and Sema4D may be the promising interventional target of cardiac hypertrophy and heart failure.

TBC1 domain family member 25 protects against myocardial apoptosis and the proinflammatory response triggered by ischemia-reperfusion injury through suppression of the TAK1-JNK/p38 MAPK signaling cascade

TBC1 domain family member 25 (TBC1D25) is a crucial mediator of signal transduction involved in the development of several diseases. Particularly, a cardioprotective role of TBC1D25 has been raised due to its antagonistic action on cardiac hypertrophy. However, whether TBC1D25 protects the myocardium from ischemia-reperfusion injury has not been reported. This work aimed to determine the role of TBC1D25 in myocardial ischemia-reperfusion (MIR) injury and to explore the potential mechanisms involved. Marked decreases in TBC1D25 levels occurred in cardiomyocytes suffering hypoxia/reoxygenation (H/R) injury in vitro and myocardium tissues of rats with MIR injury in vivo. Cardiomyocytes overexpressing TBC1D25 were protected from apoptosis and inflammation triggered by H/R, whereas TBC1D25-deficient cardiomyocytes were more sensitive to H/R injury. Intramyocardial injection of recombinant adenovirus expressing TBC1D25 into rats reduced infarct size and cardiac injury triggered by MIR injury accompanied by decreased myocardial apoptosis and inflammation. A subsequent mechanistic investigation revealed that the signaling cascade of transforming growth factor-β-activated kinase 1 (TAK1)-c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK) activated under H/R or MIR conditions was markedly restrained by TBC1D25 overexpression. Moreover, TAK1 blockade remarkably reversed the TBC1D25 deficiency-induced aggravating effect on H/R injury. The work concludes that TBC1D25 protects against MIR injury through action on the TAK1-JNK/p38 MAPK signaling cascade. This work suggests TBC1D25 as a potential therapeutic target for MIR injury.

Transforming growth factor-β and bone morphogenetic protein signaling pathways in pathological cardiac hypertrophy

Pathological cardiac hypertrophy (referred to as cardiac hypertrophy) is a maladaptive response of the heart to a variety of pathological stimuli, and cardiac hypertrophy is an independent risk factor for heart failure and sudden death. Currently, the treatments for cardiac hypertrophy are limited to improving symptoms and have little effect. Elucidation of the developmental process of cardiac hypertrophy at the molecular level and the identification of new targets for the treatment of cardiac hypertrophy are crucial. In this review, we summarize the research on multiple active substances related to the pathogenesis of cardiac hypertrophy and the signaling pathways involved and focus on the role of transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signaling in the development of cardiac hypertrophy and the identification of potential targets for molecular intervention. We aim to identify important signaling molecules with clinical value and hope to help promote the precise treatment of cardiac hypertrophy and thus improve patient outcomes.

CTRP12 ameliorates post-myocardial infarction heart failure through down-regulation of cardiac apoptosis, oxidative stress and inflammation by influencing the TAK1-p38 MAPK/JNK pathway

OBJECTIVE

C1q/tumour necrosis factor-related protein 12 (CTRP12) is closely related to coronary artery disease and has an outstanding cardioprotective effect. However, whether CTRP12 participates in heart failure (HF) has not been well studied. This work aimed to explore the role and mechanism of CTRP12 in post-myocardial infarction (MI) HF.

METHODS

Rats were subjected to left anterior descending artery ligation and then raised for six weeks to establish post-MI HF. Recombinant adeno-associated virus-mediated gene transfer was applied to overexpress or silence CTRP12 in rat hearts. RT-qPCR, Immunoblot, Echocardiography, Haematoxylin-eosin (HE) staining, Masson's trichrome staining, TUNEL staining and ELISA were carried out.

RESULTS

CTRP12 levels were decreased in the hearts of rats with post-MI HF. The overexpression of CTRP12 improved cardiac function and attenuated cardiac hypertrophy and fibrosis in rats with post-MI HF. CTRP12 silencing exacerbated cardiac dysfunction, hypertrophy and fibrosis in rats with post-MI HF. The cardiac apoptosis, oxidative stress and inflammatory response induced by post-MI HF were weakened by CTRP12 overexpression or aggravated by CTRP12 silencing. CTRP12 inhibited the activation of the transforming growth factor-β activated kinase 1 (TAK1)-p38 mitogen-activated protein kinase (MAPK)/c-Jun N-terminal kinase (JNK) pathway in the hearts of rats with post-MI HF. Treatment with the TAK1 inhibitor reversed the adverse effects of CTRP12 silencing on post-MI HF.

CONCLUSIONS

CTRP12 protects against post-MI HF by modulating the TAK1-p38 MAPK/JNK pathway. CTRP12 may be a therapeutic target for the treatment of post-MI HF.

DUSP12 ameliorates myocardial ischemia-reperfusion injury through HSPB8-induced mitophagy

This study aimed to explore the role of dual specificity phosphatase 12 (DUSP12) in regulating myocardial ischemia-reperfusion (I/R) injury and the underlying mechanism. The expression of DUSP12 in myocardial tissues and heat-shock protein beta-8 (HSPB8) and mitophagy-related proteins in myocardial tissues and H9c2 cells were detected by western blot analysis. The serum creatine kinase isoenzymes (CK-MB) and lactate dehydrogenase (LDH), levels of reactive oxygen species and malondialdehyde, superoxide dismutase activity in myocardial tissues and H9c2 cells, and caspase-3 activity in H9c2 cells were analyzed by corresponding assay kits. The infarct area in the rat's heart was observed by triphenyl tetrazolium chloride staining. The apoptosis of myocardial cells in myocardial tissues and H9c2 cells was detected by terminal-deoxynucleotidyl transferase dUTP-biotin nick-end labeling assay. The interaction between DUSP12 and HSPB8 was clarified by the coimmunoprecipitation assay. The transfection efficacy of si-HSPB8#1 and si-HSPB8#2 in H9c2 cells was confirmed by real-time quantitative-polymerase chain reaction and western blot analysis. As a result, DUSP12 expression was downregulated in I/R rats, which was promoted by lentivirus-expressing DUSP12. DUSP12 overexpression reduced the serum creatine kinase isoenzymes (CK-MB) and LDH, decreased the infarct area in the rat's heart, and suppressed the apoptosis and oxidative stress in myocardial tissues. DUSP12 overexpression also upregulated the expression of HSPB8 to promote mitophagy. The coimmunoprecipitation assay indicated that DUSP12 could be combined with HSPB8. In addition, DUSP12 overexpression could inhibit hypoxia/reoxygenation-elicited apoptosis as well as oxidative stress in H9c2 cells by upregulating HSPB8 expression to promote mitophagy, which was countervailed by HSPB8 deficiency. In conclusion, DUSP12 overexpression decreased the apoptosis and oxidative stress in myocardial I/R injury through HSPB8-induced mitophagy.

Dual-specificity phosphatase 26-dificient neurons are susceptible to oxygen-glucose deprivation/reoxygenation-evoked apoptosis and proinflammatory response by affecting the TAK1-medaited JNK/P38 MAPK pathway

Dual-specificity phosphatase 26 (DUSP26) is linked to a broad range of human disorders as it affects numerous signaling cascades. However, the involvement of DUSP26 in ischemic stroke has not been explored. Here, we investigated DUSP26 as a key mediator of oxygen-glucose deprivation/reoxygenation (OGD/R)-associated neuronal injury, an in vitro model for investigating ischemic stroke. A decline in DUSP26 occurred in neurons suffering from OGD/R. A deficiency in DUSP26 rendered neurons more susceptible to OGD/R by aggravating neuronal apoptosis and inflammation, while the overexpression of DUSP26 blocked OGD/R-evoked neuronal apoptosis and inflammation. Mechanistically, enhanced phosphorylation of transforming growth factor-β-activated kinase 1 (TAK1), c-Jun N-terminal kinase (JNK) and P38 mitogen-activated protein kinase (MAPK) was evidenced in DUSP26-deficient neurons suffering from OGD/R, whereas the opposite effects were observed in DUSP26-overexpressed neurons. Moreover, the inhibition of TAK1 abolished the DUSP26-deficiency-elicited activation of JNK and P38 MAPK and exhibited anti-OGD/R injury effects in DUSP26-deficiency neurons. Results from these experiments show that DUSP26 is essential for neurons in defending against OGD/R insult, while neuroprotection is achieved by restraining the TAK1-mediated JNK/P38 MAPK pathway. Therefore, DUSP26 may serve as a therapeutic target for the management of ischemic stroke.

Tabersonine alleviates obesity-induced cardiomyopathy by binding to Transforming growth factor activated kinase 1 (TAK1) and inhibiting TAK1-mediated inflammation

Obesity-induced cardiomyopathy (OIC) is an increasingly serious global disease caused by obesity. Chronic inflammation greatly contributes to the pathogenesis of OIC. This study aimed to explore the role and mechanism of tabersonine (Tab), a natural alkaloid with antiinflammatory activity, in the treatment of OIC. High fat diet (HFD)-induced obese mice were administered with Tab. The results showed that Tab significantly inhibit inflammation, myocardial fibrosis, and hypertrophy to prevent heart dysfunction, without the alteration of body weight and hyperlipidemia, in HFD-induced obese mice. H9c2 cells and primary cardiomyocytes stimulated by palmitic acid (PA) were used to explore the molecular mechanism and target of Tab. We examined the effect of Tab on key proteins involved in HFD/PA-induced inflammatory signaling pathway and found that Tab significantly inhibits TAK1 phosphorylation in cardiomyocytes. We further detected the direct interaction between Tab and TAK1 at the cellular, animal, and molecular levels. We found that Tab directly binds to TAK1 to inhibit TAK1 phosphorylation, which then blocks TAK1-TAB2 interaction and then NF-κB pro-inflammatory pathway in cultured cardiomyocytes. Our results indicate that Tab is a potential agent for the treatment of OIC, and TAK1 is an effective therapeutic target for this disease.

Dual Specific Phosphatase 7 Exacerbates Dilated Cardiomyopathy, Heart Failure, and Cardiac Death by Inactivating the ERK1/2 Signaling Pathway

Heart failure is one of the most common but complicated end-stage syndromes in clinical practice. Dilated cardiomyopathy is a myocardial structural abnormality that is associated with heart failure. Dual-specificity phosphatases (DUSPs) are a group of protein phosphatases that regulate signaling pathways in numerous diseases; however, their physiological and pathological impact on cardiovascular disease remains unknown. In the present study, we generated two transgenic mouse models, a DUSP7 knockout and a cardiac-specific DUSP7 overexpressor. Mice overexpressing DUSP7 showed an exacerbated disease phenotype, including severe dilated cardiomyopathy, heart failure, and cardiac death. We further demonstrated that high levels of DUSP7 inhibited ERK1/2 phosphorylation and influenced downstream c-MYC, c-FOS, and c-JUN gene expression but did not affect upstream activators. Taken together, our study reveals a novel molecular mechanism for DUSP7 and provides a new therapeutic target and clinical path to alleviate dilated cardiomyopathy and improve cardiac function.

Tabersonine attenuates Angiotensin II-induced cardiac remodeling and dysfunction through targeting TAK1 and inhibiting TAK1-mediated cardiac inflammation

BACKGROUND

Angiotensin II (Ang II)-induced cardiac inflammation contribute to pathological cardiac remodeling and hypertensive heart failure (HF). Tabersonine (Tab) is an indole alkaloid mainly isolated from Catharanthus roseus and exhibits anti-inflammatory activity in various systems. However, the role of Tab in hypertensive HF and its molecular targets remains unknown.

HYPOTHESIS/PURPOSE

We aimed to investigate potential cardioprotective effects and mechanism of Tab against Ang II-induced cardiac injuries.

METHODS

C57BL/6 mice were administered Ang II (at 1000 ng/kg/min) by micro-osmotic pump infusion for 30 days to develop hypertensive HF. Tab at 20 and 40 mg/kg/day was administered during the last 2 weeks to elucidate the cardioprotective properties. Cultured cardiomyocyte-like H9c2 cells and rat primary cardiomyocytes were used for mechanistic studies of Tab.

RESULTS

We demonstrate for the first time that Tab provides protection against Ang II-induced cardiac dysfunction in mice, associated with reduced cardiac inflammation and fibrosis. Mechanistically, we show that Tab may interacts with TAK1 to inhibit Ang II-induced TAK1 ubiquitination and phosphorylation. Disruption of TAK1 activation by Tab blocked downstream NF-κB and JNK/P38 MAPK signaling activation and decreased cardiac inflammation and fibrosis both in vitro and in vivo. TAK1 knockdown also blocked Ang II-induced cardiomyocytes injuries and prevented the innately pharmacological effects of Tab.

CONCLUSION

Our results indicate that Tab protects hearts against Ang II-mediated injuries through targeting TAK1 and inhibiting TAK1-mediated inflammatory cascade and response. Thus, Tab may be a potential therapeutic candidate for hypertensive HF.

DUSP26 induces aortic valve calcification by antagonizing MDM2-mediated ubiquitination of DPP4 in human valvular interstitial cells

AIMS

The morbidity and mortality rates of calcific aortic valve disease (CAVD) remain high while treatment options are limited. Here, we evaluated the role and therapeutic value of dual-specificity phosphatase 26 (DUSP26) in CAVD.

METHODS AND RESULTS

Microarray profiling of human calcific aortic valves and normal controls demonstrated that DUSP26 was significantly up-regulated in calcific aortic valves. ApoE-/- mice fed a normal diet or a high cholesterol diet (HCD) were infected with adeno-associated virus serotype 2 carrying DUSP26 short-hairpin RNA to examine the effects of DUSP26 silencing on aortic valve calcification. DUSP26 silencing ameliorated aortic valve calcification in HCD-treated ApoE-/- mice, as evidenced by reduced thickness and calcium deposition in the aortic valve leaflets, improved echocardiographic parameters (decreased peak transvalvular jet velocity and mean transvalvular pressure gradient, as well as increased aortic valve area), and decreased levels of osteogenic markers (Runx2, osterix, and osteocalcin) in the aortic valves. These results were confirmed in osteogenic medium-induced human valvular interstitial cells. Immunoprecipitation, liquid chromatography-tandem mass spectrometry, and functional assays revealed that dipeptidyl peptidase-4 (DPP4) interacted with DUSP26 to mediate the procalcific effects of DUSP26. High N6-methyladenosine levels up-regulated DUSP26 in CAVD; in turn, DUSP26 activated DPP4 by antagonizing mouse double minute 2-mediated ubiquitination and degradation of DPP4, thereby promoting CAVD progression.

CONCLUSION

DUSP26 promotes aortic valve calcification by inhibiting DPP4 degradation. Our findings identify a previously unrecognized mechanism of DPP4 up-regulation in CAVD, suggesting that DUSP26 silencing or inhibition is a viable therapeutic strategy to impede CAVD progression.

ERK1/2: An Integrator of Signals That Alters Cardiac Homeostasis and Growth

Integration of cellular responses to extracellular cues is essential for cell survival and adaptation to stress. Extracellular signal-regulated kinase (ERK) 1 and 2 serve an evolutionarily conserved role for intracellular signal transduction that proved critical for cardiomyocyte homeostasis and cardiac stress responses. Considering the importance of ERK1/2 in the heart, understanding how these kinases operate in both normal and disease states is critical. Here, we review the complexity of upstream and downstream signals that govern ERK1/2-dependent regulation of cardiac structure and function. Particular emphasis is given to cardiomyocyte hypertrophy as an outcome of ERK1/2 activation regulation in the heart.

Dual-Specificity Phosphatase 26 Protects Against Cardiac Hypertrophy Through TAK1

Background Heart pathological hypertrophy has been recognized as a predisposing risk factor for heart failure and arrhythmia. DUSP (dual-specificity phosphatase) 26 is a member of the DUSP family of proteins, which has a significant effect on nonalcoholic fatty liver disease, neuroblastoma, glioma, and so on. However, the involvement of DUSP26 in cardiac hypertrophy remains unclear. Methods and Results Our study showed that DUSP26 expression was significantly increased in mouse hearts in response to pressure overload as well as in angiotensin II-treated cardiomyocytes. Cardiac-specific overexpression of DUSP26 mice showed attenuated cardiac hypertrophy and fibrosis, while deficiency of DUSP26 in mouse hearts resulted in increased cardiac hypertrophy and deteriorated cardiac function. Similar effects were also observed in cellular hypertrophy induced by angiotensin II. Importantly, we showed that DUSP26 bound to transforming growth factor-β activated kinase 1 and inhibited transforming growth factor-β activated kinase 1 phosphorylation, which led to suppression of the mitogen-activated protein kinase signaling pathway. In addition, transforming growth factor-β activated kinase 1-specific inhibitor inhibited cardiomyocyte hypertrophy induced by angiotensin II and attenuated the exaggerated hypertrophic response in DUSP26 conditional knockout mice. Conclusions Taken together, DUSP26 was induced in cardiac hypertrophy and protected against pressure overload induced cardiac hypertrophy by modulating transforming growth factor-β activated kinase 1-p38/ c-Jun N-terminal kinase-signaling axis. Therefore, DUSP26 may provide a therapeutic target for treatment of cardiac hypertrophy and heart failure.