Formation of novel TRPC channels by complex subunit interactions in embryonic brain.
Mammalian short TRP channels (TRPCs) are putative receptor- and store-operated cation channels that play a fundamental role in the regulation of cellular Ca2+ homeostasis. Assembly of the seven TRPC homologs (TRPC1-7) into homo- and heteromers can create a large variety of different channels. However, the compositions as well as the functional properties of native TRPC complexes are largely undefined. We performed a systematic biochemical study of TRPC interactions in mammalian brain and identified previously unrecognized channel heteromers composed of TRPC1, TRPC4, or TRPC5 and the diacylglycerol-activated TRPC3 or TRPC6 subunits. The novel TRPC heteromers were found exclusively in embryonic brain. In heterologous systems, we demonstrated that assembly of these novel heteromers required the combination of TRPC1 plus TRPC4 or TRPC5 subunits along with diacylglycerol-sensitive subunits in the channel complexes. Functional interaction of the TRPC subunits was verified using a dominant negative TRPC5 mutant (TRPC5DN). Co-expression of TRPC5DN suppressed currents through TRPC5- and TRPC4-containing complexes; TRPC3-associated currents were unaffected by TRPC5DN unless TRPC1 was also co-expressed. This complex assembly mechanism increases the diversity of TRPC channels in mammalian brain and may generate novel heteromers that have specific roles in the developing brain.
Strübing
Carsten
C
Howard Hughes Medical Institute, Department of Cardiovascular Research, Children's Hospital and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Krapivinsky
Grigory
G
Krapivinsky
Luba
L
Clapham
David E
DE
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000196:embryology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry*; D002217:Carbachol / Q000494:pharmacology; D027682:Cation Transport Proteins; D002412:Cations; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D004075:Diglycerides / Q000737:chemistry; D019281:Dimerization; D004594:Electrophysiology; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins; D006801:Humans; D007473:Ion Channels / Q000737:chemistry*; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; D014162:Transfection
D015220:Calcium Channels; D027682:Cation Transport Proteins; D002412:Cations; D004075:Diglycerides; D007473:Ion Channels; D008164:Luminescent Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; C491780:TRPC5 protein, human; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C503500:Trpc5 protein, rat; C492146:Trpc6 protein, mouse; C492145:Trpc6 protein, rat; C096351:transient receptor potential cation channel, subfamily C, member 1; D049452:Green Fluorescent Proteins; D002217:Carbachol; D002118:Calcium