Calcium-Sensing Receptor Participates in High Glucose-Induced EndMT in Primary Human Aortic Endothelial Cells

Experimental Models to Study Endothelial to Mesenchymal Transition in Myocardial Fibrosis and Cardiovascular Diseases

Fibrosis is a common feature of cardiovascular diseases and targets multiple organs, such as the heart and vessels. Endothelial to mesenchymal transition is a complex, vital process that occurs during embryonic formation and plays a crucial role in cardiac development. It is also a fundamental process implicated in cardiac fibrosis and repair, but also in other organs. Indeed, in numerous cardiovascular diseases, the endothelial-to-mesenchymal transition has been shown to be involved in the generation of fibroblasts that are able to produce extracellular matrix proteins such as type I collagen. This massive deposition results in tissue stiffening and organ dysfunction. To advance our understanding of this process for the development of new specific diagnostic and therapeutic strategies, it is essential to develop relevant cellular and animal models of this process. In this review, our aim was to gain an in-depth insight into existing in vitro and in vivo models of endothelial to mesenchymal transition in cardiovascular diseases with a focus on cardiac fibrosis. We discuss important parameters impacting endothelial to mesenchymal transition, and we give perspectives for the development of relevant models to decipher the underlying mechanisms and ultimately find new treatments specific to fibrosis happening in cardiovascular diseases.

METTL3 Promotes Endothelium-Mesenchymal Transition of Pulmonary Artery Endothelial Cells by Regulating TRPC6/Calcineurin/NFAT Signaling Pathways

Background

Endothelium-mesenchymal transition (EndMT) is a process of phenotypic and functional transition from activated endothelial cells to mesenchymal cells. Recently, EndMT has been proved to be one of the main pathological mechanisms of pulmonary artery hypertension (PAH). However, the molecular mechanism is not clear.

Methods

Primary rat pulmonary arterial endothelial cells (rPAECs) were isolated from Sprague-Dawley rats and verified by CD31 immunofluorescence staining. rPAECs were exposed to hypoxic conditions to induce EndMT. RNA and protein levels in cells were detected by RT-qPCR and Western blot. The migration ability was verified by the transwell assay. The RIP experiment was used to test the m6A modification of TRPC6 mRNA and the binding relationship between TRPC6 and METTL3. Calcineurin/NFAT signaling was measured by using commercial kits.

Results

METTL3 was found to be highly expressed by hypoxia treatment in a time-dependent manner. Knockdown of METTL3 significantly suppressed cell migration, downregulated the levels of interstitial cell-related markers like α-SMA and vimentin, and increased the levels of endothelial cell markers including CD31 and VE-cadherin. Mechanistically, METTL3 increased TRPC6 expression by enhancing the m6A modification of TRPC6 mRNA, thus activating calcineurin/NFAT signaling. Our experiments showed that METTL3 silencing mediated the inhibitory roles in the hypoxia-mediated EndMT process, which were significantly reversed by TRPC6/calcineurin/NFAT signaling activation.

Conclusion

Our results elucidated that METTL3 knockdown inhibited the hypoxia-mediated EndMT process by inactivating TRPC6/calcineurin/NFAT signaling.

Pathological role of the calcium-sensing receptor in sepsis-induced hypotensive shock: Therapeutic possibilities and unanswered questions

Sepsis is a life-threatening disease involving multiorgan dysfunction, prompted by an unregulated host response to infection. Shock is a complication of sepsis in which the circulatory and cellular metabolism anomalies are significant enough to raise the risk of death. Calcium dyshomeostasis occurs during sepsis condition due to imbalance between calcium uptake and excessive release induced by inflammatory cytokines. This calcium imbalance can cause activation of calcium-sensing receptors (CaSRs) located on the surface of T cells and thereby promote release of reactive oxygen species (ROS). The elevated ROS and inflammatory cytokines during sepsis condition have been reported to directly damage the endothelial cells, disrupt the barrier functions that might result in leakage of fluids, and inflammatory cells in tissues Moreover, several evidence have revealed that the calcium mediated activation of CaSR could produce systemic vasodilatory response by stimulating the nitric oxide production and opening of calcium-activated potassium channels, while infusion of its antagonist elevated the blood pressure. These evidence indicate that activation of CaSR during sepsis conditions results in release of ROS and inflammatory cytokines, which could produce an endothelial barrier damage, cardiomyocyte apoptosis. These pathological events could produce loss of fluid in tissues and cardiac dysfunction. Further the direct vasodilatory effects of CaSR activation might add to the shock-like condition. Thus, we hereby propose that inhibition of CaSR could suppress the release of ROS, inflammatory mediators, and thereby prevent the endothelial damage, cardiac dysfunction, and maintain systemic vascular tone.