TRPC3 is one of the classical members of the mammalian transient receptor potential (TRP) superfamily of ion channels. TRPC3 is a molecule with intriguing sensory features including the direct recognition of and activation by diacylglycerols (DAG). Although TRPC3 channels are ubiquitously expressed, they appear to control functions of the cardiovascular system and the brain in a highly specific manner. Moreover, a role of TRPC3 in immunity, cancer, and tissue remodeling has been proposed, generating much interest in TRPC3 as a target for pharmacological intervention. Advances in the understanding of molecular architecture and structure-function relations of TRPC3 have been the foundations for novel therapeutic approaches, such as photopharmacology and optochemical genetics of TRPC3. This review provides an account of advances in therapeutic targeting of TRPC3 channels.

Lipid-gated TRPC channels are highly expressed in cardiovascular and neuronal tissues. Exerting precise pharmacological control over their activity in native cells is expected to serve as a basis for the development of novel therapies. Here we report on a new photopharmacological tool that enables manipulation of TRPC3 channels by light, in a manner independent of lipid metabolism and with higher temporal precision than lipid photopharmacology. Using the azobenzene photoswitch moiety, we modified GSK1702934A to generate light-controlled TRPC agonists. We obtained one light-sensitive molecule (OptoBI-1) that allows us to exert efficient, light-mediated control over TRPC3 activity and the associated cellular Ca²⁺ signaling. OptoBI-1 enabled high-precision, temporal control of TRPC3-linked cell functions such as neuronal firing and endothelial Ca²⁺ transients. With these findings, we introduce a novel photopharmacological strategy to control native TRPC conductances.

Nongenetic optical control of neurons is a powerful technique to study and manipulate the function of the nervous system. This research has benchmarked the performance of organic electrolytic photocapacitor (OEPC) optoelectronic stimulators at the level of single mammalian cells: human embryonic kidney (HEK) cells with heterologously expressed voltage‐gated K⁺ channels and hippocampal primary neurons. OEPCs act as extracellular stimulation electrodes driven by deep red light. The electrophysiological recordings show that millisecond light stimulation of OEPC shifts conductance‐voltage plots of voltage‐gated K⁺ channels by ≈30 mV. Models are described both for understanding the experimental findings at the level of K⁺ channel kinetics in HEK cells, as well as elucidating interpretation of membrane electrophysiology obtained during stimulation with an electrically floating extracellular photoelectrode. A time‐dependent increase in voltage‐gated channel conductivity in response to OEPC stimulation is demonstrated. These findings are then carried on to cultured primary hippocampal neurons. It is found that millisecond time‐scale optical stimuli trigger repetitive action potentials in these neurons. The findings demonstrate that OEPC devices enable the manipulation of neuronal signaling activities with millisecond precision. OEPCs can therefore be integrated into novel in vitro electrophysiology protocols, and the findings can inspire in vivo applications.

Azobenzene-based photochromic lipids are valuable probes for the analysis of ion channel–lipid interactions. Rapid photoisomerization of these molecules enables the analysis of lipid gating kinetics and provides information on lipid sensing. Thermal relaxation of the metastable cis conformation to the trans conformation of azobenzene photolipids is rather slow in the dark and may be modified by ligand–protein interactions. Cis photolipid-induced changes in pure lipid membranes as visualized from the morphological response of giant unilamellar vesicles indicated that thermal cis–trans isomerization of both PhoDAG-1 and OptoDArG is essentially slow in the lipid bilayer environment. While the currents activated by cis PhoDAG remained stable upon termination of UV light exposure (dark, UV-OFF), cis OptoDArG-induced TRPC3/6/7 activity displayed a striking isoform-dependent exponential decay. The deactivation kinetics of cis OptoDArG-induced currents in the dark was sensitive to mutations in the L2 lipid coordination site of TRPC channels. We conclude that the binding of cis OptoDArG to TRPC channels promotes transition of cis OptoDArG to the trans conformation. This process is suggested to provide valuable information on DAG–ion channel interactions and may enable highly selective photopharmacological interventions.

The transient receptor potential canonical type 3 (TRPC3) channel plays a pivotal role in regulating neuronal excitability in the brain via its constitutive activity. The channel is intricately regulated by lipids and has previously been demonstrated to be positively modulated by PIP₂. Using molecular dynamics simulations and patch clamp techniques, we reveal that PIP₂ predominantly interacts with TRPC3 at the L3 lipid binding site, located at the intersection of pre-S1 and S1 helices. We demonstrate that PIP₂ sensing involves a multistep mechanism that propagates from L3 to the pore domain via a salt bridge between the TRP helix and S4-S5 linker. Notably, we find that both stimulated and constitutive TRPC3 activity require PIP₂. These structural insights into the function of TRPC3 are invaluable for understanding the role of the TRPC subfamily in health and disease, in particular for cardiovascular diseases, in which TRPC3 channels play a major role.

The non-selective cation channel TRPC1 is highly expressed in the brain. Recent research shows that neuronal TRPC1 forms heteromeric complexes with TRPC4 and TRPC5, with a small portion existing as homotetramers, primarily in the ER. Given that most studies have focused on the role of heteromeric TRPC1/4/5 complexes, it is crucial to investigate the specific role of homomeric TRPC1 in maintaining brain homeostasis. This review highlights recent findings on TRPC1 in the brain, with a focus on the hippocampus, and compiles the latest data on modulators and their binding sites within the TRPC1/4/5 subfamily to stimulate new research on more selective TRPC1 ligands.