The Role of CD147 in Pathological Cardiac Hypertrophy Is Regulated by Glycosylation.

CD147, also known as EMMPRIN or basigin, is a transmembrane glycoprotein receptor that activates matrix metalloproteinases and promotes inflammation. CD147 function is regulated by posttranslational modifications of which glycosylation has attracted the most attention. In this study, we demonstrated that glycosylated CD147 was the dominant form in heart tissue, and its levels were markedly elevated in response to transverse aortic constriction (TAC). Adeno-associated virus 9-mediated, cardiac-specific overexpression of wild-type CD147 in mice significantly promoted pressure overload-induced pathological cardiac remodeling accompanied by augmented oxidative stress and ferroptosis. By contrast, mutations of CD147 glycosylation sites notably weakened these detrimental effects of CD147. Mechanistically, CD147 exacerbated TAC-induced pathological cardiac remodeling via direct binding with the adaptor molecule TRAF2 and subsequent activation of TAK1 signalling, which was dependent on glycosylation of CD147. Collectively, our findings provide the first evidence that CD147 promoted pathological cardiac remodeling and dysfunction in a glycosylation-dependent manner through binding the adaptor protein TRAF2 and activating the downstream TRAF2-TAK1 signalling pathway. Thus, glycosylation of CD147 may be a potent interventional target for heart failure treatment.

Primary localized tracheobronchial amyloidosis presenting with massive hemoptysis: a case report and literature review.

Primary localized tracheobronchial amyloidosis (TBA) is a rare respiratory tract dysfunction, which is a heterogeneous group of diseases involving abnormal extracellular deposition of amyloid and autologous fibrillar protein material in ß-pleated sheets. A 64-year-old man was referred to our hospital because of hemoptysis. Physical examination showed decreased breath sounds in the right lung on auscultation. Chest computed tomography scan displayed multiple nodules with varied size in main bronchia around bilateral hilus of the lung. After admission, bronchoscopy was performed for this patient, and roughness of mucosa in trachea and multiple nodules in respiratory tract were observed. Through further tissue biopsy, the diagnosis of primary TBA was confirmed.

The ubiquitin E3 ligase TRAF6 exacerbates pathological cardiac hypertrophy via TAK1-dependent signalling.

Tumour necrosis factor receptor-associated factor 6 (TRAF6) is a ubiquitin E3 ligase that regulates important biological processes. However, the role of TRAF6 in cardiac hypertrophy remains unknown. Here, we show that TRAF6 levels are increased in human and murine hypertrophied hearts, which is regulated by reactive oxygen species (ROS) production. Cardiac-specific Traf6 overexpression exacerbates cardiac hypertrophy in response to pressure overload or angiotensin II (Ang II) challenge, whereas Traf6 deficiency causes an alleviated hypertrophic phenotype in mice. Mechanistically, we show that ROS, generated during hypertrophic progression, triggers TRAF6 auto-ubiquitination that facilitates recruitment of TAB2 and its binding to transforming growth factor beta-activated kinase 1 (TAK1), which, in turn, enables the direct TRAF6-TAK1 interaction and promotes TAK1 ubiquitination. The binding of TRAF6 to TAK1 and the induction of TAK1 ubiquitination and activation are indispensable for TRAF6-regulated cardiac remodelling. Taken together, we define TRAF6 as an essential molecular switch leading to cardiac hypertrophy in a TAK1-dependent manner.

Ubiquitin-Specific Protease 4 Is an Endogenous Negative Regulator of Pathological Cardiac Hypertrophy.

Dysregulation of the ubiquitin proteasome system components ubiquitin ligases and proteasome plays an important role in the pathogenesis of cardiac hypertrophy. However, little is known about the role of another ubiquitin proteasome system component, the deubiquitinating enzymes, in cardiac hypertrophy. Here, we revealed a crucial role of ubiquitin specific protease 4 (USP4), a deubiquitinating enzyme prominently expressed in the heart, in attenuating pathological cardiac hypertrophy and dysfunction. USP4 levels were consistently decreased in human failing hearts and in murine hypertrophied hearts. Adenovirus-mediated gain- and loss-of-function approaches indicated that deficiency of endogenous USP4 promoted myocyte hypertrophy induced by angiotensin II in vitro, whereas restoration of USP4 significantly attenuated the prohypertrophic effect of angiotensin II. To corroborate the role of USP4 in vivo, we generated USP4 global knockout mice and mice with cardiac-specific overexpression of USP4. Consistent with the in vitro study, USP4 depletion exacerbated the hypertrophic phenotype and cardiac dysfunction in mice subjected to pressure overload, whereas USP4 transgenic mice presented ameliorated pathological cardiac hypertrophy compared with their control littermates. Molecular analysis revealed that USP4 deficiency augmented the activation of the transforming growth factor ß-activated kinase 1 (TAK1)-(JNK1/2)/P38 signaling in response to hypertrophic stress, and blockage of TAK1 activation abolished the pathological effects of USP4 deficiency in vivo. These findings provide the first evidence for the involvement of USP4 in cardiac hypertrophy, and shed light on the therapeutic potential of targeting USP4 in the treatment of cardiac hypertrophy.

Calcitriol attenuates cardiac remodeling and dysfunction in a murine model of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a complex reproductive and metabolic disorder affecting 10 % of reproductive-aged women, and is well associated with an increased prevalence of cardiovascular risk factors. However, there are few data concerning the direct association of PCOS with cardiac pathologies. The present study aims to investigate the changes in cardiac structure, function, and cardiomyocyte survival in a PCOS model, and explore the possible effect of calcitriol administration on these changes. PCOS was induced in C57BL/6J female mice by chronic dihydrotestosterone administration, as evidenced by irregular estrous cycles, obesity and dyslipidemia. PCOS mice progressively developed cardiac abnormalities including cardiac hypertrophy, interstitial fibrosis, myocardial apoptosis, and cardiac dysfunction. Conversely, concomitant administration of calcitriol significantly attenuated cardiac remodeling and cardiomyocyte apoptosis, and improved cardiac function. Molecular analysis revealed that the beneficial effect of calcitriol was associated with normalized autophagy function by increasing phosphorylation levels of AMP-activated protein kinase and inhibiting phosphorylation levels of mammalian target of rapamycin complex. Our findings provide the first evidence for the presence of cardiac remodeling in a PCOS model, and vitamin D supplementation may be a potential therapeutic strategy for the prevention and treatment of PCOS-related cardiac remodeling.

[Farnesoid-X-receptor blockade reduces myocardial reperfusion injury in cholesterol-fed apolipoprotein E knockout mice].

OBJECTIVE: To investigate the effect of farnesoid-X-receptor (FXR) antagonist Z-guggulsterone in an in vivo high-fat fed apolipoprotein E knockout (ApoE(-/-)) mice model of myocardial ischemia/reperfusion (I/R). METHODS: Male ApoE(-/-) mice were randomly divided into three groups: standard ApoE(-/-) group (fed with standard mouse diet for 12 weeks before myocardial I/R procedure, n = 18), high-fat ApoE(-/-) group (fed with high-fat mouse diet for 12 weeks before myocardial I/R procedure, n = 22), and high-fat ApoE(-/-) + FXR antagonist group(fed with high-fat mouse diet for 12 weeks and received FXR antagonist Z-Guggulsterone 30 minutes before myocardial I/R procedure, n = 17). The expression of FXR was detected by real-time quantitative-PCR. Myocardial infarct size was determined by Evans blue/TTC double staining methods. Myocardial apoptosis was determined by in situ TUNEL technique. Markers of the mitochondrial-mediated apoptotic pathway (cytochrome c release, caspase-9 activity, and BAX and BCL-2 levels), endoplasmic reticulum stress apoptotic pathway (caspase-12 activity and CHOP level), and death receptor apoptotic pathway (caspase-8 activity, and Fas and FasL levels) were also measured. RESULT: FXR expression (3.7-fold higher, P < 0.01), myocardial infarct size [(62.1 ± 7.0)% vs. (33.8 ± 5.8)%, P < 0.01] and myocardial apoptosis index[ (36.8 ± 5.7)% vs. (17.2 ± 3.8)%, P < 0.01]were all significantly higher in high-fat ApoE(-/-) group than those in standard ApoE(-/-) group. Compared with high-fat ApoE(-/-) group, myocardial infarct size [(24.4 ± 4.7)% vs. (62.1 ± 7.0)%, P < 0.01] and myocardial apoptosis index [(13.8 ± 2.7)% vs. (36.8 ± 5.7)%, P < 0.01] were significantly reduced in high-fat ApoE(-/-) + FXR antagonist group. Moreover, levels of mitochondrial-mediated apoptotic pathway markers (cytochrome c release, caspase-9 activity, and BAX/BCL-2 levels) and endoplasmic reticulum stress apoptotic pathway markers (caspase-12 activity and CHOP level) were significantly lower in high-fat ApoE(-/-) + FXR antagonist group than those in high-fat ApoE(-/-) group (all P < 0.01). Levels of death receptor apoptotic pathway markers (caspase-8 activity, and Fas and FasL levels) were similar between high-fat ApoE(-/-) group and high-fat ApoE(-/-) + FXR antagonist group. CONCLUSION: FXR antagonist alleviates myocardial reperfusion injury in cholesterol-fed ApoE(-/-) mice via inhibition of the mitochondrial-mediated and endoplasmic-reticulum stress pathway.