Short time exposure to hypoxia promotes H9c2 cell growth

Increased Extracellular Matrix Protein Production in Chronic Diabetic Complications: Implications of Non-Coding RNAs

Management of chronic diabetic complications remains a major medical challenge worldwide. One of the characteristic features of all chronic diabetic complications is augmented production of extracellular matrix (ECM) proteins. Such ECM proteins are deposited in all tissues affected by chronic complications, ultimately causing organ damage and dysfunction. A contributing factor to this pathogenetic process is glucose-induced endothelial damage, which involves phenotypic transformation of endothelial cells (ECs). This phenotypic transition of ECs, from a quiescent state to an activated dysfunctional state, can be mediated through alterations in the synthesis of cellular proteins. In this review, we discussed the roles of non-coding RNAs, specifically microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), in such processes. We further outlined other epigenetic mechanisms regulating the biogenesis and/or function of non-coding RNAs. Overall, we believe that better understanding of such molecular processes may lead to the development of novel biomarkers and therapeutic strategies in the future.

Mitochondrial Lon protease controls ROS-dependent apoptosis in cardiomyocyte under hypoxia

Apoptosis of cardiomyocytes, under ischemic conditions, has been identified as an essential process in the progression of heart failure. Under hypoxic conditions, mitochondria can become a threat to the cell because of their capacity to generate reactive oxygen species (ROS). As ROS appear to have a critical role in heart failure, there has been considerable interest in identifying the candidate proteins involved and in developing strategies to reduce oxidative stress. Lon protease (Lon) is a multifunctional protein that mediates protein quality control and stress response in mitochondria. However, comprehensive and detailed studies, on the role of Lon in hypoxia-induced cardiomyocyte apoptosis, have yet to be carried out. In the present study, we demonstrated that hypoxia induced ROS-dependent cardiomyocyte apoptosis. Lon was upregulated in hypoxia-induced cardiomyocytes. Lon downregulation attenuated hypoxia-induced cardiomyocyte apoptosis through a reduction of ROS level. Moreover, overexpression of Lon stimulated ROS production and induced apoptosis under normoxic conditions in cardiomyocytes. Our results identify Lon as a novel regulator of cardiomyocyte fate and offers exciting new insights into the therapeutic potential of hypoxia-induced cardiomyocyte apoptosis.

Role of FAK phosphorylation in hypoxia-induced hMSCS migration: involvement of VEGF as well as MAPKS and eNOS pathways

Here we show that the effect of hypoxia on human umbilical cord blood mesenchymal stem cell (hMSC) migration is via the modulation of focal adhesion kinase (FAK) and its related signaling pathways. Hypoxia increased hMSC migration and cell viability, whereas lactate dehydrogenase (LDH) release was not affected for up to 48 h (data not shown). In addition, hypoxia increased the level of reactive oxygen species (ROS) generation in a time-dependent manner. Hypoxia-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and stress-activated protein kinase/c-Jun NH(2)-terminal kinase (SAPK/JNK) were inhibited by the antioxidant (N-acetylcysteine, NAC, 10(-6) M) and (taurine, 4x10(-6) M). Hypoxia-induced endothelial nitric oxide synthase (eNOS) phosphorylation was regulated by p38 MAPK and SAPK/JNK activation. In addition, hypoxia increased the level of hypoxia inducible factor (HIF)-1alpha expression, which was blocked by inhibition of eNOS. Also, hypoxia-induced expression of Flk-1, vascular endothelial growth factor (VEGF), and its secreted form were inhibited by HIF-1alpha small interfering RNA (siRNA). In this hypoxic condition, FAK and Src phosphorylation were increased in a time-dependent manner. Inhibition of Src with specific inhibitor (PP2, 10(-8) M) blocked hypoxia-induced FAK activation. Subsequently, hypoxia-induced FAK phosphorylation was blocked by VEGF siRNA. Finally, hypoxia-induced increase of hMSC migration was inhibited by FAK siRNA. The results indicate that hypoxia increases migration of hMSCs via VEGF-mediated FAK phospholylation and involves the cooperative activity of the ROS, MAPK, eNOS and HIF-1alpha pathways.