Structural mechanisms of TRPM7 activation and inhibition

Abstract

The transient receptor potential channel TRPM7 is a master regulator of the organismal balance of divalent cations that plays an essential role in embryonic development, immune responses, cell mobility, proliferation, and differentiation. TRPM7 is implicated in neuronal and cardiovascular disorders, tumor progression and has emerged as a new drug target. Here we use cryo-EM, functional analysis, and molecular dynamics simulations to uncover two distinct structural mechanisms of TRPM7 activation by a gain-of-function mutation and by the agonist naltriben, which show different conformational dynamics and domain involvement. We identify a binding site for highly potent and selective inhibitors and show that they act by stabilizing the TRPM7 closed state. The discovered structural mechanisms provide foundations for understanding the molecular basis of TRPM7 channelopathies and drug development.

Structural basis of selective TRPM7 inhibition by the anticancer agent CCT128930

“…The pore radius profile of TRPM7 CCT is very similar to the ones previously obtained for TRPM7 apo , TRPM7 VER , and TRPM7 NS ( Figure 5B ), indicating that the CCT-bound structure represents the closed, non-conducting state. This pore profile is in stark contrast with the profile obtained for the open-state structures of TRPM7, activated as a result of either the introduced gain-of-function mutation N1098Q (TRPM7 N1098Q ) or binding of agonist NTB (TRPM7 NTB ), 21 where the gate region is substantially wider ( Figure 5B ). Therefore, we propose that, in analogy to VER and NS, CCT acts by allosterically stabilizing the closed state of the TRPM7 channel.…”

“…Since the homologous site in TRPV channels is known as the vanilloid site, we will refer to this site as VL. 21 , 23 …”

“…To compare the effect of inhibitor binding on the ion channel pore, we measured the pore radius in TRPM7 CCT and compared it with the pore radius in the previously solved structures of TRPM7 obtained in the absence of ligands (TRPM7 apo ) or in complex with its pharmacological modulators VER (TRPM7 VER ), NS (TRPM7 NS ), and NTB (TRPM7 NTB ). 21 The pore radius of TRPM7 has two narrow constrictions: one at the selectivity filter and the second at the gate region that allows or stops permeation of water and ions through the pore ( Figure 5A ). The pore radius profile of TRPM7 CCT is very similar to the ones previously obtained for TRPM7 apo , TRPM7 VER , and TRPM7 NS ( Figure 5B ), indicating that the CCT-bound structure represents the closed, non-conducting state.…”

“… 18 - 20 Recently, cryo-EM structures of TRPM7 were solved in the active open and inactive closed states. 21 , 22 One of these studies 21 identified the site of NS and VER binding, located near the cytoplasmic side of the membrane at the interface between the S3 , S4 , S5 and TRP helices. It was referred to as a vanilloid-like (VL) site because the homologous site in the vanilloid subfamily TRP channels is known as the vanilloid site.…”

Proteomic studies of VEGFR2 in human placentas reveal protein associations with preeclampsia, diabetes, gravidity, and labor

“…A possible explanation was offered by the discovery [48] that MDMX interacts with TRPM7, a bi-functional cation channel protein fused with a kinase domain. TRPM7 is a master regulator of the cellular balance of divalent cations, that mediates the uptake of Zn 2+ , Mg 2+ and Ca 2+ [49], and senses oxidative stress to release Zn 2+ from intracellular vesicles [50]. TRPM7 regulates MDMX levels by modulating Zn 2+ concentration, and induces the formation of faster moving forms of MDMX on SDS-PAGE gels [48].…”