Glycoprotein M6B Interacts with TßRI to Activate TGF-ß-Smad2/3 Signaling and Promote Smooth Muscle Cell Differentiation.

Smooth muscle cells (SMCs), which form the walls of blood vessels, play an important role in vascular development and the pathogenic process of vascular remodeling. However, the molecular mechanisms governing SMC differentiation remain poorly understood. Glycoprotein M6B (GPM6B) is a four-transmembrane protein that belongs to the proteolipid protein family and is widely expressed in neurons, oligodendrocytes, and astrocytes. Previous studies have revealed that GPM6B plays a role in neuronal differentiation, myelination, and osteoblast differentiation. In the present study, we found that the GPM6B gene and protein expression levels were significantly upregulated during transforming growth factor-ß1 (TGF-ß1)-induced SMC differentiation. The knockdown of GPM6B resulted in the downregulation of SMC-specific marker expression and repressed the activation of Smad2/3 signaling. Moreover, GPM6B regulates SMC Differentiation by Controlling TGF-ß-Smad2/3 Signaling. Furthermore, we demonstrated that similar to p-Smad2/3, GPM6B was profoundly expressed and coexpressed with SMC differentiation markers in embryonic SMCs. Moreover, GPM6B can regulate the tightness between TßRI, TßRII, or Smad2/3 by directly binding to TßRI to activate Smad2/3 signaling during SMC differentiation, and activation of TGF-ß-Smad2/3 signaling also facilitate the expression of GPM6B. Taken together, these findings demonstrate that GPM6B plays a crucial role in SMC differentiation and regulates SMC differentiation through the activation of TGF-ß-Smad2/3 signaling via direct interactions with TßRI. This finding indicates that GPM6B is a potential target for deriving SMCs from stem cells in cardiovascular regenerative medicine. Stem Cells 2018 Stem Cells 2019;37:190-201.

BCKA down-regulates mTORC2-Akt signal and enhances apoptosis susceptibility in cardiomyocytes.

Diabetic mellitus (DM) portends poor prognosis concerning pressure overloaded heart disease. Branched-chain amino acids (BCAAs), elements of essential amino acids, have been found altered in its catabolism in diabetes decades ago. However, the relationship between BCAAs and DM induced deterioration of pressure overloaded heart disease remains controversial. This study is aimed to investigate the particular effect of BCKA, a metabolite of BCAA, on myocardial injury induced by pressure overloaded. Primary cardiomyocytes were incubated with or without BCKA and followed by treatment with isoproterenol (ISO); then cell viability was detected by CCK8 and apoptosis was examined by TUNNEL stain and caspase-3 activity analysis. Compared to non-BCKA incubated group, BCKA incubation decreased cell survival and increased apoptosis concentration dependently. Furthermore, Western blot assay showed that mTORC2-Akt pathway was significantly inactivated by BCKA incubation. Moreover, overexpression of rictor, a vital component of mTORC2, significantly abolished the adverse effects of BCKA on apoptosis susceptibility of cardiomyocytes. These results indicate that BCKA contribute to vulnerability of cardiomyocytes in stimulated stress via inactivation of mTORC2-Akt pathway.

[Role of homocysteine in the pathogenesis of alcoholic cardiomyopathy].

OBJECTIVE: To explore the role of homocysteine in the pathogenesis of alcoholic cardiomyopathy. METHODS: A total of 69 male Wistar rats were randomly assigned into two groups: alcohol-fed group and the control. Cardiac function was assessed by pulse Doppler. Plasma Hcy levels were examined using automatic biochemical instrument (chemiluminescence). The protein expression of MMP-9 was evaluated using immunohistochemical method, and collagen fiber of myocardium was quantitative analyzed by Masson stain. RESULTS: After heavy drinking, the LVEDd of alcohol-fed group were larger than the control group [(7.0±0.6) mm vs (5.0±0.4) mm, P<0.05], the LVEF and FS were lower in the 4th month (52%±8% vs 78%±4%, 31%±3% vs 47%±2%, P<0.05), the data changed more significantly (P<0.01) in the 6th month. The level of plasma Hcy from alcohol-fed group was significantly higher from the 2nd month than that before the experiment [(18.1±3.1) µmol/L vs (9.8±2.1) µmol/L, P<0.01], and it was higher in 4th month than that in 2nd month [(26.3±4.0) µmol/L vs (18.1±3.1) µmol/L, P<0.05], it was highest in 6 months. After 4-month and 6-month drinking, the expression of MMP-9 protein from alcohol group was higher than before the experiment (0.161%±0.019%, 0.263%±0.014% vs 0.050%±0.008%, P<0.01). Masson staining showed myocardial collagen of alcohol group was more after 4-month and 6-month drinking than those before the experiment (10.23%±1.20% vs 0.50%±0.09%; 22.41%±2.57% vs 0.50%±0.09%, P<0.01). Plasma Hcy and cardiac tissue MMP-9 is a significant positive correlation (r=0.848, P<0.01). CONCLUSION: Long-term and large drink liquor can lead to plasma Hcy levels significantly increased, and participate cardiac remodeling and the pathogenesis of ACM through increasing the expression of myocardial tissue MMP-9 protein.

Tailorable Hydrogel Improves Retention and Cardioprotection of Intramyocardial Transplanted Mesenchymal Stem Cells for the Treatment of Acute Myocardial Infarction in Mice.

Background Poor engraftment of intramyocardial stem cells limits their therapeutic efficiency against myocardial infarction (MI)-induced cardiac injury. Transglutaminase cross-linked Gelatin (Col-Tgel) is a tailorable collagen-based hydrogel that is becoming an excellent biomaterial scaffold for cellular delivery in vivo. Here, we tested the hypothesis that Col-Tgel increases retention of intramyocardially-injected stem cells, and thereby reduces post-MI cardiac injury. Methods and Results Adipose-derived mesenchymal stem cells (ADSCs) were co-cultured with Col-Tgel in a 3-dimensional system in vitro, and Col-Tgel encapsulated ADSCs were observed using scanning electron microscopy and confocal microscopy. Vitality, proliferation, and migration of co-cultured ADSCs were evaluated. In addition, mice were subjected to MI and were intramyocardially injected with ADSCs, Col-Tgel, or a combination thereof. ADSCs engraftment, survival, cardiac function, and fibrosis were assessed. In vitro MTT and Cell Counting Kit-8 assays demonstrated that ADSCs survive and proliferate up to 4 weeks in the Col-Tgel. In addition, MTT and transwell assays showed that ADSCs migrate outside the edge of the Col-Tgel sphere. Furthermore, when compared with ADSCs alone, Col-Tgel-encapsulated ADSCs significantly enhanced the long-term retention and cardioprotective effect of ADSCs against MI-induced cardiac injury. Conclusions In the current study, we successfully established a 3-dimensional co-culture system using ADSCs and Col-Tgel. The Col-Tgel creates a suitable microenvironment for long-term retention of ADSCs in an ischemic area, and thereby enhances their cardioprotective effects. Taken together, this study may provide an alternative biomaterial for stem cell-based therapy to treat ischemic heart diseases.

Branched-Chain Amino Acids Exacerbate Obesity-Related Hepatic Glucose and Lipid Metabolic Disorders via Attenuating Akt2 Signaling.

Branched chain amino acids (BCAAs) are associated with the progression of obesity-related metabolic disorders, including type 2 diabetes and nonalcoholic fatty liver disease. However, whether BCAAs disrupt the homeostasis of hepatic glucose and lipid metabolism remains unknown. In this study, we observed that BCAAs supplementation significantly reduced high-fat (HF) diet-induced hepatic lipid accumulation while increasing the plasma lipid levels and promoting muscular and renal lipid accumulation. Further studies demonstrated that BCAAs supplementation significantly increased hepatic gluconeogenesis and suppressed hepatic lipogenesis in HF diet-induced obese (DIO) mice. These phenotypes resulted from severe attenuation of Akt2 signaling via mTORC1- and mTORC2-dependent pathways. BCAAs/branched-chain α-keto acids (BCKAs) chronically suppressed Akt2 activation through mTORC1 and mTORC2 signaling and promoted Akt2 ubiquitin-proteasome-dependent degradation through the mTORC2 pathway. Moreover, the E3 ligase Mul1 played an essential role in BCAAs/BCKAs-mTORC2-induced Akt2 ubiquitin-dependent degradation. We also demonstrated that BCAAs inhibited hepatic lipogenesis by blocking Akt2/SREBP1/INSIG2a signaling and increased hepatic glycogenesis by regulating Akt2/Foxo1 signaling. Collectively, these data demonstrate that in DIO mice, BCAAs supplementation resulted in serious hepatic metabolic disorder and severe liver insulin resistance: insulin failed to not only suppress gluconeogenesis but also activate lipogenesis. Intervening BCAA metabolism is a potential therapeutic target for severe insulin-resistant disease.

Application of ozone therapy in interventional medicine.

Ozone therapy has been gradually accepted by doctors in various fields because it has been safe, convenient, and inexpensive since the twentieth century. It has been used in the treatment of various diseases with satisfactory results, especially in the application of interventional surgery. For lumbar disc herniation, knee osteoarthritis, tissue ischemia-reperfusion after revascularization, stroke, and cancer, ozone therapy can improve the efficacy of interventional surgery and reduce postoperative acute and chronic complications. Prospects of ozone therapy in interventional therapy and the underlying mechanisms of efficacy need further exploration.

Nicotine induces H9C2 cell apoptosis via Akt protein degradation.

Smoking is highly associated with cardiovascular diseases. However, the effect of nicotine, a key ingredient in smoking products, on cardiomyocyte apoptosis remains controversial. The present study aims to clarify the role of nicotine on cardiomyocyte cell apoptosis and to investigate the underlying mechanism. In the present study, H9C2 cells were exposed to nicotine at various concentrations (0, 10 and 100 µM) for 48 h. Cell Counting Kit­8 and TUNEL assays were performed to assess cell viability and apoptosis, respectively, and reverse transcription­quantitative polymerase chain reaction and western blot analysis were used to investigate the mRNA and protein expression. PYR­41, a ubiquitin E1 inhibitor, was employed to investigate whether the ubiquitin­proteasome system was involved in the downregulation of Akt. An Akt1 overexpression plasmid was used to demonstrate the role of Akt in H9C2 cells apoptosis. Tetratricopeptide repeat domain 3 (TTC3) small interfering RNA (siRNA) was used to investigate the effect of TTC3 on Akt protein degradation. The results demonstrated that nicotine induced apoptosis in H9C2 cells compared with control cells (P<0.05). The protein level of Akt was downregulated by nicotine in a concentration­dependent manner (P<0.05). PYR­41 treatment restored the protein level of Akt. The cell viability was significantly improved by Akt overexpression when cells were exposed to nicotine at 10 µM, compared with control cells. Nicotine also upregulated the level of TTC3 mRNA (P<0.05) and the protein level of Akt, and cell viability was recovered by TTC3 siRNA. In conclusion, the current study demonstrated that nicotine induced H9C2 cell apoptosis via Akt protein degradation, which may be mediated by TTC3.

Hemodynamic effect of apelin in a canine model of acute pulmonary thromboembolism.

The peptide apelin is expressed in the pulmonary vasculature and is involved in the pathogenesis of many cardiovascular diseases. It has a biphasic role in the regulation of vasomotor tone related to the vascular endothelium. In this study, we induced acute pulmonary embolism (APE) in dogs with autologous blood clots to assess the effect of apelin on pulmonary and systemic circulation in the acute phase of APE. The expression of apelin mRNA was found to be upregulated in the lung tissue in the early several hours after APE induction and decreased at 24 h. The expression of apelin protein in the pulmonary arteries did not change within 24 h after APE, but significantly increased in the bronchial epithelial cells as early as 1h and decreased at 24 h. In normal anesthetized dogs, intravenous bolus administration of apelin significantly reduced the mean arterial pressure (MAP), but did not significantly affect the mean pulmonary arterial pressure (MPAP). In the dogs with APE, apelin decreased MPAP, whereas its impact on MAP was not significantly different from that in the control group. Taken together, the level of endogenous apelin did not change significantly in the pulmonary arterial wall, whereas its expression in the bronchial epithelium was upregulated in the early stage of APE. The effect of exogenous apelin on vasomotor tone was complicated: it resulted in differential changes in the pulmonary and systemic arterial pressures under different physiological and pathological conditions.