title: Calcium permeability of transient receptor potential canonical (TRPC) 4 channels measured by TRPC4-GCaMP6s.
abstract: Conflicting evidence has been obtained regarding whether transient receptor potential cation channels (TRPC) are store-operated channels (SOCs) or receptor-operated channels (ROCs). Moreover, the Ca/Na permeability ratio differs depending on whether the current-voltage (I-V) curve has a doubly rectifying shape or inward rectifying shape. To investigate the calcium permeability of TRPC4 channels, we attached GCaMP6s to TRPC4 and simultaneously measured the current and calcium signals. A TRPC4 specific activator, (-)-englerin A, induced both current and calcium fluorescence with the similar time course. Muscarinic receptor stimulator, carbachol, also induced both current and calcium fluorescence with the similar time course. By forming heteromers with TRPC4, TRPC1 significantly reduced the inward current with outward rectifying I-V curve, which also caused the decrease of calcium fluorescence intensity. These results suggest that GCaMP6s attached to TRPC4 can detect slight calcium changes near TRPC4 channels. Consequently, TRPC4-GCaMP6s can be a useful tool for testing the calcium permeability of TRPC4 channels.
authors.affiliation: Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Juyeon
authors.initials: J
authors.lastname: Ko
authors.affiliation: Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Jongyun
authors.initials: J
authors.lastname: Myeong
authors.affiliation: Department of Physiology, College of Medicine, Gachon University, Incheon 21936, Korea.
authors.forename: Dongki
authors.initials: D
authors.lastname: Yang
authors.affiliation: Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Insuk
authors.initials: I
authors.lastname: So
keywords: Calcium; GCaMP6s; Receptor-operated channels; TRPC1/4 heteromer; TRPC4