The Mechanosensitive Ion Channel TRPV4 is a Regulator of Lung Development and Pulmonary Vasculature Stabilization

Abstract

Introduction – Clinical observations and animal models suggest a critical role for the dynamic regulation of transmural pressure and peristaltic airway smooth muscle contractions for proper lung development. However, it is currently unclear how such mechanical signals are transduced into molecular and transcriptional changes at the cell level. To connect these physical findings to a mechanotransduction mechanism, we identified a known mechanosensor, TRPV4, as a component of this pathway. Methods – Embryonic mouse lung explants were cultured on membranes and in submersion culture to modulate explant transmural pressure. Time-lapse imaging was used to capture active changes in lung biology, and whole-mount images were used to visualize the organization of the epithelial, smooth muscle, and vascular compartments. TRPV4 activity was modulated by pharmacological agonism and inhibition. Results – TRPV4 expression is present in the murine lung with strong localization to the epithelium and major pulmonary blood vessels. TRPV4 agonism and inhibition resulted in hyper- and hypoplastic airway branching, smooth muscle differentiation, and lung growth, respectively. Smooth muscle contractions also doubled in frequency with agonism and were reduced by 60% with inhibition demonstrating a functional role consistent with levels of smooth muscle differentiation. Activation of TRPV4 increased the vascular capillary density around the distal airways, and inhibition resulted in a near complete loss of the vasculature. Conclusions – These studies have identified TRPV4 as a potential mechanosensor involved in transducing mechanical forces on the airways to molecular and transcriptional events that regulate the morphogenesis of the three essential tissue compartments in the lung.

Role of Transient Receptor Potential Vanilloid 4 in Vascular Function

“…Thus, TRPV4 might become a therapeutic target in hypertension treatment. Additionally, TRPV4 is involved in converting mechanical forces on the airways to molecular and transcriptional events, regulating the development of lung and stabilization of pulmonary vasculature ( Morgan et al, 2018 ). Recent evidence suggests that activating pulmonary capillary endothelial TRPV4 channels enhance pulmonary venous pressure-induced edema and TRPV4 blockade prevents the increased vascular permeability and pulmonary edema ( Thorneloe et al, 2012 ), highlighting a pharmacological therapeutic potential of TRPV4 inhibition for pulmonary edema induced by heart failure.…”

Significant Unresolved Questions and Opportunities for Bioengineering in Understanding and Treating COVID-19 Disease Progression

“…While these platforms are highly complex and challenging to develop, there is a corresponding increase in control and ability to separate spatiotemporal responses, with less sacrifice of physiologic conditions. These models are common for studying organ development 91 , 165 , 168 , 200 and bioreactors for organ and lung conditioning for transplant, 96 , 188 but less common with applications to studying disease pathophysiology. This is especially critical in studying SARS-CoV-2 pathology and the progression of COVID-19.…”

Mechanochemical coupling and junctional forces during collective cell migration

“…In branching morphogenesis occurring in the lung, kidney, vascular system, prostate, mammary gland, and kidney to form tubular branching structures, a leader or "tip" cell responds to a chemotactic or durotactic gradient and protrudes while bringing along follower or "stalk" cells through adhesion junctions. Several studies have shown that mechanically sensitive molecules such as YAP (43), integrin 1 (44), and the TRPV4 ion channel (45), are needed for proper branching morphogenesis, yet measurement of cell-cell force during this process in vivo is limited. Since in vivo collective cell migration is di cult to quantify, especially with respect to cell-cell and cell-matrix forces, our model provides a method for understanding this fundamental aspect of development and disease.…”