Glycosylated CD147 reduces myocardial collagen cross-linking in cardiac hypertrophy

Inhibition of N-acetylglucosaminyltransferase V alleviates diabetic cardiomyopathy in mice by attenuating cardiac hypertrophy and fibrosis

BACKGROUND

The pathogenesis of diabetic cardiomyopathy is closely linked to abnormal glycosylation modifications. N-acetylglucosaminyltransferase V (GnT-V), which catalyzes the production of N-linked -1-6 branching of oligosaccharides, is involved in several pathophysiological mechanisms of many disorders, including cardiac hypertrophy and heart failure. However, the mechanism by which GnT-V regulates cardiac hypertrophy in diabetic cardiomyopathy is currently poorly understood. In this study, we investigated the role of GnT-V on myocardial hypertrophy in diabetic cardiomyopathy and elucidated the underlying mechanisms.

MATERIAL AND METHODS

Streptozotocin (STZ) was intraperitoneally injected into mice to induce diabetic cardiomyopathy. An adeno-associated virus (AAV) carrying negative control small hairpin RNA (shNC) or GnT-V-specifc small hairpin RNA (shGnT-V) was used to manipulate GnT-V expression. In our study, forty male C57BL/6J mice were randomly divided into four groups (10 mice per group): control mice with AAV-shNC, diabetic cardiomyopathy mice with AAV-shNC, control mice with AAV-shGnT-V, and diabetic cardiomyopathy mice with AAV-shGnT-V. In addition, H9C2 cells and primary neonatal cardiac fibroblasts treated with high glucose were used as a cell model of diabetes. Analysis of cardiac hypertrophy and fibrosis, as well as functional studies, were used to investigate the underlying molecular pathways.

RESULTS

AAV-mediated GnT-V silencing dramatically improved cardiac function and alleviated myocardial hypertrophy and fibrosis in diabetic mice. In vitro experiments demonstrated that GnT-V was elevated in cardiomyocytes and induced cardiomyocyte hypertrophy in response to high glucose stimulation. GnT-V knockdown significantly reduced the expression of the integrinβ1 signaling pathway, as evidenced by decreased downstream ERK1/2 activity, which inhibited cardiomyocyte hypertrophy accompanied by reduced ANP, BNP, and β-MHC expression. Furthermore, knocking down GnT-V expression lowered the TGF-β1-Smads signaling pathway, which reduced the expression of α-SMA, collagen I, and collagen III.

CONCLUSIONS

Overall, our research indicated that GnT-V may be a useful therapeutic target to treat diabetic cardiomyopathy, primarily in the inhibition of myocardial hypertrophy and fibrosis.

Functional ACE2 deficiency leading to angiotensin imbalance in the pathophysiology of COVID-19

SARS-CoV-2, the virus responsible for COVID-19, uses angiotensin converting enzyme 2 (ACE2) as its primary cell-surface receptor. ACE2 is a key enzyme in the counter-regulatory pathway of the broader renin-angiotensin system (RAS) that has been implicated in a broad array of human pathology. The RAS is composed of two competing pathways that work in opposition to each other: the "conventional" arm involving angiotensin converting enzyme (ACE) generating angiotensin-2 and the more recently identified ACE2 pathway that generates angiotensin (1-7). Following the original SARS pandemic, additional studies suggested that coronaviral binding to ACE2 resulted in downregulation of the membrane-bound enzyme. Given the similarities between the two viruses, many have posited a similar process with SARS-CoV-2. Proponents of this ACE2 deficiency model argue that downregulation of ACE2 limits its enzymatic function, thereby skewing the delicate balance between the two competing arms of the RAS. In this review we critically examine this model. The available data remain incomplete but are consistent with the possibility that the broad multisystem dysfunction of COVID-19 is due in large part to functional ACE2 deficiency leading to angiotensin imbalance with consequent immune dysregulation and endothelial cell dysfunction.

N-Glycosylation in progression of skin cancer

Skin cancer can be classified as cutaneous malignant melanoma, basal cell carcinoma, and squamous cell carcinoma. Due to the high level of morbidity and mortality, skin cancer has become a global public health issue worldwide while the pathogenesis of skin cancer is still unclear. It is necessary to further identify the pathogenesis of skin cancer and find candidate targets to diagnose and treat skin cancer. A variety of factors are known to be associated with skin cancer including N-glycosylation, which partly explained the malignant behaviors of skin cancer. In this review, we retrieved databases such as PubMed and Web of Science to elucidate its relationship between glycosylation and skin cancer. We summarized some key glycosyltransferases and proteins during the process of N-glycosylation related to skin cancer, which was helpful to unmask the additional mechanism of skin cancer and find some novel targets of skin cancer.

Raising glass transition temperature of polymer nanofilms as a function of negative interface energy

Based on a thermodynamic approach, glass transition temperature (T_g) of substrate-supported polymer nanofilms (s-PNFs) is investigated for carbon-chain polymers, taking the role of the interface energy into consideration.

Effect of atorvastatin on cardiomyocyte hypertrophy through suppressing MURC induced by volume overload and cyclic stretch

MURC (muscle‐restricted coiled‐coil protein) is a hypertrophy‐related gene. Hypertrophy can be induced by mechanical stress. The purpose of this research was to investigate the hypothesis that MURC mediates hypertrophy in cardiomyocytes under mechanical stress. We used the in vivo model of an aortocaval shunt (AV shunt) in adult Wistar rats to induce myocardial hypertrophy. We also used the in vitro model of cyclic stretch in rat neonatal cardiomyocytes to clarify MURC expression and the molecular regulation mechanism. The flexible membrane culture plate seeding with cardiomyocytes Cardiomyocytes seeded on a flexible membrane culture plate were stretched by vacuum pressure to 20% of maximum elongation at 60 cycles/min. AV shunt induction enhanced MURC protein expression in the left ventricular myocardium. Treatment with atorvastatin inhibited the hypertrophy induced by the AV shunt. Cyclic stretch markedly enhanced MURC protein and mRNA expression in cardiomyocytes. Addition of extracellular‐signal‐regulated kinase (ERK) inhibitor PD98059, ERK small interfering RNA (siRNA), angiotensin II (Ang II) antibody and atorvastatin before stretch, abolished the induction of MURC protein. An electrophoretic mobility shift assay showed that stretch enhanced the DNA binding activity of serum response factor. Stretch increased but MURC mutant plasmid, ERK siRNA, Ang II antibody and atorvastatin reversed the transcriptional activity of MURC induced by stretch. Adding Ang II to the cardiomyocytes also induced MURC protein expression. MURC siRNA and atorvastatin inhibited the hypertrophic marker and protein synthesis induced by stretch. Treatment with atorvastatin reversed MURC expression and hypertrophy under volume overload and cyclic stretch.