FBXW5 acts as a negative regulator of pathological cardiac hypertrophy by decreasing the TAK1 signaling to pro-hypertrophic members of the MAPK signaling pathway

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.

FBXL8 inhibits post-myocardial infarction cardiac fibrosis by targeting Snail1 for ubiquitin-proteasome degradation

Abnormal cardiac fibrosis is the main pathological change of post-myocardial infarction (MI) heart failure. Although the E3 ubiquitin ligase FBXL8 is a key regulator in the cell cycle, cell proliferation, and inflammation, its role in post-MI ventricular fibrosis and heart failure remains unknown. FBXL8 was primarily expressed in cardiac fibroblasts (CFs) and remarkably decreased in CFs treated by TGFβ and heart subjected to MI. The echocardiography and histology data suggested that adeno-associated viruses (AAV9)-mediated FBXL8 overexpression had improved cardiac function and ameliorated post-MI cardiac fibrosis. In vitro, FBXL8 overexpression prevented TGFβ-induced proliferation, migration, contraction, and collagen secretion in CFs, while knockdown of FBXL8 demonstrated opposite effects. Mechanistically, FBXL8 interacted with Snail1 to promote Snail1 degradation through the ubiquitin-proteasome system and decreased the activation of RhoA. Moreover, the FBXL8ΔC3 binding domain was indispensable for Snail1 interaction and degradation. Ectopic Snail1 expression partly abolished the effects mediated by FBXL8 overexpression in CFs treated by TGFβ. These results characterized the role of FBXL8 in regulating the ubiquitin-mediated degradation of Snail1 and revealed the underlying molecular mechanism of how MI up-regulated the myofibroblasts differentiation-inducer Snail1 and suggested that FBXL8 may be a potential curative target for improving post-MI cardiac function.

DPP2/7 is a Potential Predictor of Prognosis and Target in Immunotherapy in Colorectal Cancer: An Integrative Multi-omics Analysis

BACKGROUND

Colorectal cancer (CRC) ranks among the leading causes of cancerrelated deaths.

OBJECTIVE

This study aimed to illuminate the relationship between DPP7 (also known as DPP2) and CRC through a combination of bioinformatics and experimental methodologies.

METHODS

A multi-dimensional bioinformatic analysis on DPP7 was executed, covering its expression, survival implications, clinical associations, functional roles, immune interactions, and drug sensitivities. Experimental validations involved siRNA-mediated DPP7 knockdown and various cellular assays.

RESULTS

Data from the Cancer Genome Atlas (TCGA) identified high DPP7 expression in solid CRC tumors, with elevated levels adversely affecting patient prognosis. A shift from the N0 to the N2 stage in CRC was associated with increased DPP7 expression. Functional insights indicated the involvement of DPP7 in cancer progression, particularly in extracellular matrix disassembly. Immunological analyses showed its association with immunosuppressive entities, and in vitro experiments in CRC cell lines underscored its oncogenic attributes.

CONCLUSION

DPP7 could serve as a CRC prognosis marker, functioning as an oncogene and representing a potential immunotherapeutic target.

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.

Identification of hypertrophy-modulating Cullin-RING ubiquitin ligases in primary cardiomyocytes

Cullin-RING ubiquitin ligases (CRL) regulate numerous biological processes in the heart and have been implicated in regulating cardiac hypertrophy. This study aimed to identify novel hypertrophy-modulating CRLs in cardiomyocytes (CM). A functional genomic approach using siRNA-mediated depletion and automated microscopy was employed to screen for cell size-modulating CRLs in neonatal rat CM. Screening hits were confirmed by ³H-isoleucine incorporation. Of 43 targets screened, siRNA-mediated depletion of Fbxo6, Fbxo45, and Fbxl14 resulted in decreased cell size, whereas depletion of Fbxo9, Fbxo25, Fbxo30, Fbxo32, Fbxo33, Cullin1, Roc1, Ddb1, Fbxw4, and Fbxw5 led to a markedly increased cell size under basal conditions. In CM stimulated with phenylephrine (PE), depletion of Fbxo6, Fbxo25, Fbxo33, Fbxo45, and Fbxw4 further augmented PE-induced hypertrophy. As a proof-of-concept, the CRL^Fbox25 was analysed by transverse aortic constriction (TAC) resulting in a 4.5-fold increase in Fbxo25 protein concentrations compared to control animals. In cell culture, siRNA-mediated depletion of Fbxo25 resulted in a ∼ 37% increase in CM cell size and ∼41% increase in ³H-isoleucine incorporation. Depleting Fbxo25 resulted in upregulation of Anp and Bnp. In summary, we identified 13 novel CRLs as positive or negative regulators of CM hypertrophy. Of these, CRL^Fbox25 was further characterized, as a potential modulator of cardiac hypertrophy.

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.

GCN5-mediated regulation of pathological cardiac hypertrophy via activation of the TAK1-JNK/p38 signaling pathway

Pathological cardiac hypertrophy is a process of abnormal remodeling of cardiomyocytes in response to pressure overload or other stress stimuli, resulting in myocardial injury, which is a major risk factor for heart failure, leading to increased morbidity and mortality. General control nonrepressed protein 5 (GCN5)/lysine acetyltransferase 2 A, a member of the histone acetyltransferase and lysine acetyltransferase families, regulates a variety of physiological and pathological events. However, the function of GCN5 in pathological cardiac hypertrophy remains unclear. This study aimed to explore the role of GCN5 in the development of pathological cardiac hypertrophy. GCN5 expression was increased in isolated neonatal rat cardiomyocytes (NRCMs) and mouse hearts of a hypertrophic mouse model. GCN5 overexpression aggravated the cardiac hypertrophy triggered by transverse aortic constriction surgery. In contrast, inhibition of GCN5 impairs the development of pathological cardiac hypertrophy. Similar results were obtained upon stimulation of NRCMs (having GCN5 overexpressed or knocked down) with phenylephrine. Mechanistically, our results indicate that GCN5 exacerbates cardiac hypertrophy via excessive activation of the transforming growth factor β-activated kinase 1 (TAK1)-c-Jun N-terminal kinase (JNK)/p38 signaling pathway. Using a TAK1-specific inhibitor in rescue experiments confirmed that the activation of TAK1 is essential for GCN5-mediated cardiac hypertrophy. In summary, the current study elucidated the role of GCN5 in promotion of cardiac hypertrophy, thereby implying it to be a potential target for treatment.

Different activation of MAPKs and Akt/GSK3β after preload vs. afterload elevation

Aims

Pressure overload (PO) and volume overload (VO) lead to concentric or eccentric hypertrophy. Previously, we could show that activation of signalling cascades differ in in vivo mouse models. Activation of these signal cascades could either be induced by intrinsic load sensing or neuro‐endocrine substances like catecholamines or the renin‐angiotensin‐aldosterone system.

Methods and results

We therefore analysed the activation of classical cardiac signal pathways [mitogen‐activated protein kinases (MAPKs) (ERK, p38, and JNK) and Akt‐GSK3β] in in vitro of mechanical overload (ejecting heart model, rabbit and human isolated muscle strips). Selective elevation of preload in vitro increased AKT and GSK3β phosphorylation after 15 min in isolated rabbit muscles strips (AKT 49%, GSK3β 26%, P < 0.05) and in mouse ejecting hearts (AKT 51%, GSK49%, P < 0.05), whereas phosphorylation of MAPKs was not influenced by increased preload. Selective elevation of afterload revealed an increase in ERK phosphorylation in the ejecting heart (43%, P < 0.05), but not in AKT, GSK3β, and the other MAPKs. Elevation of preload and afterload in the ejecting heart induced a significant phosphorylation of ERK (95%, P < 0.001) and showed a moderate increased AKT (P = 0.14) and GSK3β (P = 0.21) phosphorylation, which did not reach significance. Preload and afterload elevation in muscles strips from human failing hearts showed neither AKT nor ERK phosphorylation changes.

Conclusions

Our data show that preload activates the AKT–GSK3β and afterload the ERK pathway in vitro, indicating an intrinsic mechanism independent of endocrine signalling.