Transient Receptor Potential Melastatin 4 (TRPM4) Contributes to High Salt Diet-Mediated Early-Stage Endothelial Injury

Abstract

Background/Aims: The present study investigated whether the transient receptor potential melastatin 4 (TRPM4) channel plays a role in high salt diet (HSD)-induced endothelial injuries. Methods: Western blotting and immunofluorescence were used to examine TRPM4 expression in the mesenteric endothelium of Dahl salt-sensitive (SS) rats fed a HSD. The MTT, TUNEL, and transwell assays were used to evaluate the cell viability, cell apoptosis, and cell migration, respectively, of human umbilical vein endothelial cells (HUVECs). Enzyme-linked immunosorbent assays were used to determine the concentrations of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion protein 1 (VCAM-1), and E-selectin. Carboxy-H2DCFDA, a membrane-permeable reactive oxygen species (ROS)-sensitive fluorescent probe, was used to detect intracellular ROS levels. Results: TRPM4 was mainly expressed near the plasma membrane of mesenteric artery endothelial cells, and its expression level increased in SS hypertensive rats fed a HSD. Its protein expression was significantly upregulated upon treatment with exogenous hydrogen peroxide (H₂O₂) and aldosterone in cultured HUVECs. Cell viability decreased upon treatment with both agents in a concentration-dependent manner, which could be partially reversed by 9-phenanthrol, a specific TRPM4 inhibitor. Exogenous H₂O₂ induced apoptosis, enhanced cell migration, and increased the release of adhesion molecules, including ICAM-1, VCAM-1, and E-selectin, all of which were significantly attenuated upon treatment with 9-phenanthrol. Aldosterone and H₂O₂ induced the accumulation of intracellular ROS, which was significantly inhibited by 9-phenanthrol, suggesting that oxidative stress is one of the mechanisms underlying aldosterone-induced endothelial injury. Conclusions: Given the fact that oxidative stress and high levels of circulating aldosterone are present in hypertensive patients, we suggest that the upregulation of TRPM4 in the vascular endothelium may be involved in endothelial injuries caused by these stimuli.

Endothelial dysfunction in pulmonary arterial hypertension: an evolving landscape (2017 Grover Conference Series)

“…postulated that upregulation of endothelial TRPM4 channel in response to oxidative stress is connected with endothelial lesions. 141 The authors suggest that oxidative stress is one of the mechanisms underlying aldosterone-induced endothelial injury in hypertensive patients. Downregulation of TRPM7 prevents endotoxin-induced endothelial fibrosis, suggesting that the involvement of the subunit in the EndMT mechanism.…”

Role of the TRPM4 Channel in Cardiovascular Physiology and Pathophysiology

“…Due to the research conducted by Gerzanich et al, Becerra et al, and Ding et al, the expression of TRPM4 could be upregulated when the vascular endothelium is damaged under a variety of pathological conditions. For example, TRPM4 expression levels increase by more than 33% in endothelial cells damaged owing to a high-salt diet [ 138 , 139 , 140 , 141 ]. Moreover, the expression of TRPM4 in both protein and mRNA forms increases in human umbilical vein endothelial cells under hypoxic and ischemic conditions [ 10 , 142 ].…”

“…Furthermore, the expression of TRPM4 is significantly upregulated upon treatment with exogenous ROS (H 2 O 2 ), which results in endothelial cell apoptosis. However, this could be reversed through the inhibition of TRPM4 activity with 9-Phe [ 138 ]. Thus, it is implied that the involvement of TRPM4 in endothelial injury is also mediated by ROS [ 131 , 133 , 134 , 144 ].…”

“…It is clear that under the influence of various vascular injury factors, the upregulation of TRPM4 in vascular endothelial cells produces complete or maximal depolarization, resulting in the continuous influx of sodium ions [ 137 , 138 , 139 ]. Soon afterwards, the rise of intracellular Na + and Cl − is able to cause enlargement of osmotic pressure, which drives the influx of H 2 O, inducing cell swelling or rupture [ 140 ].…”

A Novel Approach to Estimate ROS Origination by Hyperbaric Oxygen Exposure, Targeted Probes and Specific Inhibitors

“…For instance, in endothelial cells ROS are the main cause of many vascular pathologies, such as diabetic and hyperpietic endothelial dysfunction, on the other hand, angiogenesis and endotheliumdependent vasorelaxation are under tight redox control [4][5][6]. Owing to their active and short-lived character, ROS must be generated at the precise subcellular compartment close to the molecules modified in ROS-dependent cell signaling and regulation processes [7,8].…”