Structure of human TRPV4 in complex with GTPase RhoA

Abstract

Transient receptor potential (TRP) channel TRPV4 is a polymodal cellular sensor that responds to moderate heat, cell swelling, shear stress, and small-molecule ligands. It is involved in thermogenesis, regulation of vascular tone, bone homeostasis, renal and pulmonary functions. TRPV4 is implicated in neuromuscular and skeletal disorders, pulmonary edema, and cancers, and represents an important drug target. The cytoskeletal remodeling GTPase RhoA has been shown to suppress TRPV4 activity. Here, we present a structure of the human TRPV4-RhoA complex that shows RhoA interaction with the membrane-facing surface of the TRPV4 ankyrin repeat domains. The contact interface reveals residues that are mutated in neuropathies, providing an insight into the disease pathogenesis. We also identify the binding sites of the TRPV4 agonist 4α-PDD and the inhibitor HC-067047 at the base of the S1-S4 bundle, and show that agonist binding leads to pore opening, while channel inhibition involves a π-to-α transition in the pore-forming helix S6. Our structures elucidate the interaction interface between hTRPV4 and RhoA, as well as residues at this interface that are involved in TRPV4 disease-causing mutations. They shed light on TRPV4 activation and inhibition and provide a template for the design of future therapeutics for treatment of TRPV4-related diseases.

Gain-of-function mutations of TRPV4 acting in endothelial cells drive blood-CNS barrier breakdown and motor neuron degeneration in mice

“…Elucidation of the molecular pathways by which mutant TRPV4 channel activity alters NVEC tight junction integrity and barrier function will be an important focus for future work. We and others have shown that TRPV4 interacts with the small guanosine triphosphatase RhoA ( 14 , 16 , 17 ) and that motor neuron disease–causing mutations in TRPV4 disrupt this binding and the reciprocal inhibitory interactions between TRPV4 and RhoA ( 14 , 16 ) . Because RhoA activation can drive endothelial junctional complex disassembly by promoting actin cytoskeleton remodeling ( 51 , 52 ), these findings suggest a potential mechanism through which TRPV4 may regulate BSCB permeability.…”

“…Structurally, each TRPV4 protomer comprises six transmembrane domains and intracellular N and C termini. Motor neuron disease–causing mutations occur primarily on the convex face of a prominent ankyrin repeat domain within the N terminus ( 5 , 14 – 17 ). In heterologous expression systems, mutant TRPV4 channels exhibit elevated channel activity ( 5 , 6 , 14 , 16 , 18 ), suggesting that TRPV4 antagonism may represent a therapeutic strategy for patients with TRPV4 mutations.…”

Recent advances on the structure and the function relationships of the TRPV4 ion channel

“…b, examples of some types of cells that express TRPV4, along with their corresponding functions are depicted. PDB: 8T1B (3.0-Å resolution) [ 52 ]. Created with PyMOL and BioRender.com.…”

“…Currently, we know that TRPV4 is assembled as a homotetramer [ 45 , 52 , 53 , 84 ]; although, it has been described that it can form heteromeric channels with the TRPP2 in an alternating 2:2 stoichiometry [ 39 ]; TRPC1 [ 85–88 ]; TRPC1 and TRPP2 [ 89 ], and most recently with TRPV3 [ 90 ].…”

“…In the case of the human TRPV4 homotetramer, each subunit consists of 871 residues and contains two layers: the bottom, also known as the cytoplasmic layer, which encompasses the amino- and carboxyl-terminal regions of the protein [ 67 , 91 ]; while the top layer, or transmembrane region, consists of six helices, where the first four α-helices (S1-S4) form a voltage sensor-like domain (VSLD), similar to other tetrameric voltage-gated ion channels (VGIC), while the S5 and S6 α-helices form the pore domain [ 45 , 52 , 53 ]. The N - and C-termini contain very characteristic domains such as a phosphoinositide binding domain (PDB), the ankyrin repeat domain (ARD), the proline-rich domain (PRD), the coupling domain (CD), the TRP box, the calmodulin-binding domain (CAM) and the PDZ-like domain Figure 2(a) .…”