Regulation of the inositol 1,4,5-trisphosphate receptor type I by O-GlcNAc glycosylation.
The inositol 1,4,5-trisphosphate (InsP3) receptor type I (InsP3R-I) is the principle channel for intracellular calcium (Ca2+) release in many cell types, including central neurons. It is regulated by endogenous compounds like Ca2+ and ATP, by protein partners, and by posttranslational modification. We report that the InsP3R-I is modified by O-linked glycosylation of serine or threonine residues with beta-N-acetylglucosamine (O-GlcNAc). The level of O-GlcNAcylation can be altered in vitro by the addition of the enzymes which add [OGT (O-GlcNActransferase)] or remove (O-GlcNAcase) this sugar or by loading cells with UDP-GlcNAc. We monitored the effects of this modification on InsP3R function at the single-channel level and on intracellular Ca2+ transients. Single-channel activity was monitored with InsP3R incorporated into bilayers; Ca2+ signaling was monitored using cells loaded with a Ca2+-sensitive fluorophore. We found that channel activity was decreased by the addition of O-GlcNAc and that this decrease was reversed by removal of the sugar. Similarly, cells loaded with UDP-GlcNAc had an attenuated response to uncaging of InsP3. These results show that O-GlcNAcylation is an important regulator of the InsP3R-I and suggest a mechanism for neuronal dysfunction under conditions in which O-GlcNAc is high, such as diabetes or physiological stress.
Rengifo
Juliana
J
Department of Pharmacology and Cellular and Molecular Physiology, Yale University, New Haven, Connecticut 06520, USA.
Gibson
Craig J
CJ
Winkler
Eva
E
Collin
Thibault
T
Ehrlich
Barbara E
BE
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002531:Cerebellum / Q000737:chemistry / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006031:Glycosylation; D015544:Inositol 1,4,5-Trisphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000737:chemistry* / Q000378:metabolism*; D007395:Interneurons / Q000187:drug effects / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry; D051379:Mice; D008861:Microsomes / Q000737:chemistry; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry / Q000378:metabolism; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D051381:Rats; D014466:Ultraviolet Rays; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000378:metabolism / Q000494:pharmacology; D001619:beta-N-Acetylhexosaminidases / Q000737:chemistry
D053496:Inositol 1,4,5-Trisphosphate Receptors; D008051:Lipid Bilayers; C061868:inositol 1,4,5-trisphosphate 1-(2-nitrophenyl)ethyl ester; D014537:Uridine Diphosphate N-Acetylglucosamine; C098108:N-acetylglucopyranosylamine; D015544:Inositol 1,4,5-Trisphosphate; D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase; C110628:hexosaminidase C; D001619:beta-N-Acetylhexosaminidases; D005944:Glucosamine