Polydatin protects cardiomyocytes against myocardial infarction injury by activating Sirt3

SIRT3: A New Regulator of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading causes of death worldwide, and defects in mitochondrial function contribute largely to the occurrence of CVDs. Recent studies suggest that sirtuin 3 (SIRT3), the mitochondrial NAD⁺-dependent deacetylase, may regulate mitochondrial function and biosynthetic pathways such as glucose and fatty acid metabolism and the tricarboxylic acid (TCA) cycle, oxidative stress, and apoptosis by reversible protein lysine deacetylation. SIRT3 regulates glucose and lipid metabolism and maintains myocardial ATP levels, which protects the heart from metabolic disturbances. SIRT3 can also protect cardiomyocytes from oxidative stress-mediated cell damage and block the development of cardiac hypertrophy. Recent reports show that SIRT3 is involved in the protection of several heart diseases. This review discusses the progress in SIRT3-related research and the role of SIRT3 in the prevention and treatment of CVDs.

How Hippo Signaling Pathway Modulates Cardiovascular Development and Diseases

Cardiovascular disease remains the leading cause of death around the globe. Cardiac deterioration is associated with irreversible cardiomyocyte loss. Understanding how the cardiovascular system develops and the pathological processes of cardiac disease will contribute to finding novel and preventive therapeutic methods. The canonical Hippo tumor suppressor pathway in mammalian cells is primarily composed of the MST1/2-SAV1-LATS1/2-MOB1-YAP/TAZ cascade. Continuing research on this pathway has identified other factors like RASSF1A, Nf2, MAP4Ks, and NDR1/2, further enriching our knowledge of the Hippo-YAP pathway. YAP, the core effecter of the Hippo pathway, may accumulate in the nucleus and initiate transcriptional activity if the pathway is inhibited. The role of Hippo signaling has been widely investigated in organ development and cancers. A heart of normal size and function which is critical for survival could not be generated without the proper regulation of the Hippo tumor suppressor pathway. Recent research has demonstrated a novel role of Hippo signaling in cardiovascular disease in the context of development, hypertrophy, angiogenesis, regeneration, apoptosis, and autophagy. In this review, we summarize the current knowledge of how Hippo signaling modulates pathological processes in cardiovascular disease and discuss potential molecular therapeutic targets.

Roles of Autophagy in Ischemic Heart Diseases and the Modulatory Effects of Chinese Herbal Medicine

Autophagy is an evolutionarily conserved degradation process which eliminates dysfunctional proteins and cytoplasmic components to maintain homeostasis for cell survival. Increasing evidence has demonstrated the modulatory role of autophagy in ischemic heart diseases (IHDs). Traditionally, this process has been recognized as having protective functions, such as inhibiting atherosclerosis progression and reducing cell death during the ischemic phase. However, recent studies have suggested its dual roles in myocardial ischemia/reperfusion (MIR) injury. Excessive autophagy may play a deleterious role in cardiac function, due to overwhelming clearance of cellular constituents and proteins. Hence modulation of autophagy to increase cardiomyocyte survival and improve cardiac function is meaningful for the treatment of IHD. Chinese herbal medicine, including extractive compounds and patented drugs, has shown its potential role in treating IHD by addressing autophagy-related mechanisms. This review summarizes the updated knowledge on the molecular basis and modulatory role of autophagy in IHD and the recent progress of Chinese herbal medicine in its treatment.

Polydatin alleviated radiation-induced lung injury through activation of Sirt3 and inhibition of epithelial-mesenchymal transition

Radiation-induced lung injury (RILI) is one of the most common and fatal complications of thoracic radiotherapy. It is characterized with two main features including early radiation pneumonitis and fibrosis in later phase. This study was to investigate the potential radioprotective effects of polydatin (PD), which was shown to exert anti-inflammation and anti-oxidative capacities in other diseases. In this study, we demonstrated that PD-mitigated acute inflammation and late fibrosis caused by irradiation. PD treatment inhibited TGF-β1-Smad3 signalling pathway and epithelial-mesenchymal transition. Moreover, radiation-induced imbalance of Th1/Th2 was also alleviated by PD treatment. Besides its free radical scavenging capacity, PD induced a huge increase of Sirt3 in culture cells and lung tissues. The level of Nrf2 and PGC1α in lung tissues was also elevated. In conclusion, our data showed that PD attenuated radiation-induced lung injury through inhibiting epithelial-mesenchymal transition and increased the expression of Sirt3, suggesting PD as a novel potential radioprotector for RILI.

Dihydromyricetin Protects against Diabetic Cardiomyopathy in Streptozotocin-Induced Diabetic Mice

Diabetic cardiomyopathy (DCM) is an important cause of heart failure in diabetic patients. The present study sought to explore the potential effects of dihydromyricetin (DHM) on DCM and its possible mechanism. A diabetic model was induced by intraperitoneal injection of streptozotocin (STZ) in C57BL/6J mice. Two weeks after the STZ injection, mice were randomly allocated into the following 4 groups for treatment: the control group (CON), the control treated with DHM group (CON + DHM), the diabetes group (DM), and the diabetes treated with DHM group (DM + DHM). DHM was dissolved in distilled water and administered daily by gavage. For 14 weeks, the CON + DHM group and DM + DHM group were given a dose of 100 mg/kg/day DHM (Sigma-Aldrich), while the CON and DM groups were intragastrically given equivalent volumes of distilled water. Assessments and comparisons were made among the groups based on cardiac function and structural changes, inflammation factors, markers of oxidative stress, mitochondria function, apoptosis, and autophagy. The DHM treatment normalized body weight, preserved cardiac function, attenuated oxidative stress (MDA, SOD, and GSH-Px), reduced the levels of inflammation factors (IL-6, TNF-α), alleviated pathological changes, improved mitochondrial function (ATP content, CS activity, and complex Ι/ΙΙ/ΙΙΙ/ΙV/V activities), inhibited cardiac apoptosis, and restored autophagy in diabetic mice. DHM may have a great therapeutic potential in the treatment of DCM.

Autophagy, Metabolic Disease, and Pathogenesis of Heart Dysfunction

In normal physiology, autophagy is recognized as a protective housekeeping mechanism that enables elimination of unhealthy organelles, protein aggregates, and invading pathogens, as well as recycling cell components and producing new building blocks and energy for cellular renovation and homeostasis. However, overactive or depressed autophagy is often associated with the pathogenesis of multiple disorders, including cardiac disease. During metabolic disorders, such as diabetes and obesity, dysregulation of autophagy frequently leads to cell death, cardiomyopathy, and cardiac dysfunction. In this article, we summarize the current understanding of autophagy-its classification, progression, and regulation; its roles in both physiological and pathophysiological conditions; and the balance between autophagy and apoptosis. We also explore how dysregulation of autophagy leads to cell death in models of metabolic disease and its contributing factors-including nutrient state, hyperglycemia, dyslipidemia, insulin inefficiency, and oxidative stress-and outline some recent efforts to restore normal autophagy in pathophysiological states. This information could provide potential targets for the prevention of, or intervention in, cardiac failure in metabolic disorders such as diabetes and obesity.