Complex functions of phosphatidylinositol 4,5-bisphosphate in regulation of TRPC5 cation channels

• Published in: Pflügers Archiv Vol. 457; no. 4; pp. 757 - 769
• Main Authors: Trebak, Mohamed, Lemonnier, Loic, DeHaven, Wayne I., Wedel, Barbara J., Bird, Gary S., Putney, James W.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.02.2009; Springer Nature B.V; Springer Verlag
• Subjects: Androstadienes - metabolism; Animals; Antibiotics, Antineoplastic - metabolism; Biomedical and Life Sciences; Biomedicine; Calcium - metabolism; Calcium Signaling - physiology; Carbachol - metabolism; Cell Biology; Cell Line; Cells; Cholinergic Agonists - metabolism; Chromones - metabolism; Enzyme Inhibitors - metabolism; Human Physiology; Humans; Ion Channel Gating - physiology; Ion Channels; Kinases; Life Sciences; Methacholine Chloride - metabolism; Molecular Medicine; Morpholines - metabolism; Neurosciences; Patch-Clamp Techniques; Phosphatidylinositol 4,5-Diphosphate - metabolism; Phosphodiesterase Inhibitors - metabolism; Receptors; Receptors and Transporters; Sirolimus - metabolism; TRPC Cation Channels - genetics; TRPC Cation Channels - metabolism; Type C Phospholipases - metabolism; Wortmannin; Ion channels; 5-bisphosphate; Non-selective cation channels; Phosphatidylinositol 4; TRPC5 channels; Phospholipase C
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/s00424-008-0550-1

The canonical transient receptor potential (TRPC) proteins have been recognized as key players in calcium entry pathways activated through phospholipase-C-coupled receptors. While it is clearly demonstrated that members of the TRPC3/6/7 subfamily are activated by diacylglycerol, the mechanism by which phospholipase C activates members of the TRPC1/4/5 subfamily remains a mystery. In this paper, we provide evidence for both negative and positive modulatory roles for membrane polyphosphoinositides in the regulation of TRPC5 channels. Depletion of polyphosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate (PIP 2 ) through inhibition of phosphatidylinositol 4-kinase activates calcium entry and membrane currents in TRPC5-expressing but not in TRPC3- or TRPC7-expressing cells. Inclusion of polyphosphatidylinositol 4-phosphate or PIP 2 , but not phosphatidylinositol 3,4,5-trisphosphate, in the patch pipette inhibited TRPC5 currents. Paradoxically, depletion of PIP 2 with a directed 5-phosphatase strategy inhibited TRPC5. Furthermore, when the activity of single TRPC5 channels was examined in excised patches, the channels were robustly activated by PIP 2 . These findings indicate complex functions for regulation of TRPC5 by PIP 2 , and we propose that membrane polyphosphoinositides may have at least two distinct functions in regulating TRPC5 channel activity.