N-Glycosylation determines ionic permeability and desensitization of the TRPV1 capsaicin receptor

Veldhuis, Nicholas A., Lew, Michael J., Abogadie, Fe C., Poole, Daniel P., Jennings, Ernest A., Ivanusic, Jason J., Eilers, Helge, Bunnett, Nigel W., and McIntyre, Peter (2012) N-Glycosylation determines ionic permeability and desensitization of the TRPV1 capsaicin receptor. Journal of Biological Chemistry, 287 (28). pp. 21765-21772.

[img] PDF (Published Version) - Published Version
Restricted to Repository staff only

View at Publisher Website: http://dx.doi.org/10.1074/jbc.M112.34202...
 
31
3


Abstract

The balance of glycosylation and deglycosylation of ion channels can markedly influence their function and regulation. However, the functional importance of glycosylation of the TRPV1 receptor, a key sensor of pain-sensing nerves, is not well understood, and whether TRPV1 is glycosylated in neurons is unclear. We report that TRPV1 is N-glycosylated and that N-glycosylation is a major determinant of capsaicin-evoked desensitization and ionic permeability. Both N-glycosylated and unglycosylated TRPV1 was detected in extracts of peripheral sensory nerves by Western blotting. TRPV1 expressed in HEK-293 cells exhibited various degrees of glycosylation. A mutant of asparagine 604 (N604T) was not glycosylated but did not alter plasma membrane expression of TRPV1. Capsaicin-evoked increases in intracellular calcium ([Ca2+]i) were sustained in wild-type TRPV1 HEK-293 cells but were rapidly desensitized in N604T TRPV1 cells. There was marked cell-to-cell variability in capsaicin responses and desensitization between individual cells expressing wild-type TRPV1 but highly uniform responses in cells expressing N604T TRPV1, consistent with variable levels of glycosylation of the wild-type channel. These differences were also apparent when wild-type or N604T TRPV1-GFP fusion proteins were expressed in neurons from trpv1−/− mice. Capsaicin evoked a marked, concentration-dependent increase in uptake of the large cationic dye YO-PRO-1 in cells expressing wild-type TRPV1, indicative of loss of ion selectivity, that was completely absent in cells expressing N604T TRPV1. Thus, TRPV1 is variably N-glycosylated and glycosylation is a key determinant of capsaicin regulation of TRPV1 desensitization and permeability. Our findings suggest that physiological or pathological alterations in TRPV1 glycosylation would affect TRPV1 function and pain transmission.

Item ID: 23044
Item Type: Article (Research - C1)
ISSN: 0021-9258
Keywords: calcium imaging, glycosylation, ion channels, receptor desensitization, TRP channels
Date Deposited: 15 Aug 2012 06:05
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1109 Neurosciences > 110902 Cellular Nervous System @ 50%
11 MEDICAL AND HEALTH SCIENCES > 1109 Neurosciences > 110906 Sensory Systems @ 50%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920111 Nervous System and Disorders @ 30%
92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920113 Oro-Dental Disorders @ 70%
Downloads: Total: 3
More Statistics

Actions (Repository Staff Only)

Item Control Page Item Control Page