In:
American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 295, No. 4 ( 2008-10), p. H1743-H1752
Abstract:
CD38 contains an ADP ribosylcyclase domain that mediates intracellular Ca 2+ signaling by the production of cyclic ADP-ribose (cADPR), but the mechanisms by which the agonists activate this enzyme remain unclear. The present study tested a hypothesis that a special lipid-raft (LR) form, ceramide-enriched lipid platform, contributes to CD38 activation to produce cADPR in response to muscarinic type 1 (M 1 ) receptor stimulation in bovine coronary arterial myocytes (CAMs). By confocal microscopic analysis, oxotremorine (Oxo), an M 1 receptor agonist, was found to increase LR clustering on the membrane with the formation of a complex of CD38 and LR components such as GM 1 , acid sphingomyelinase (ASMase), and ceramide, a typical ceramide-enriched macrodomain. At 80 μM, Oxo increased LR clustering by 78.8%, which was abolished by LR disruptors, methyl-β-cyclodextrin (MCD), or filipin. With the use of a fluorescence resonance energy transfer (FRET) technique, 15.5 ± 1.9% energy transfer rate (vs. 5.3 ± 0.9% of control) between CD38 and LR component, ganglioside M 1 was detected, further confirming the proximity of both molecules. In the presence of MCD or filipin, there were no FRET signals detected. In floated detergent-resistant membrane fractions, CD38 significantly increased in LR fractions of CAMs treated by Oxo. Moreover, MCD or filipin attenuated Oxo-induced production of cADPR via CD38. Functionally, Oxo-induced intracellular Ca 2+ release and coronary artery constriction via cADPR were also blocked by LR disruption or ASMase inhibition. These results provide the first evidence that the formation of ceramide-enriched lipid macrodomains is crucial for Oxo-induced activation of CD38 to produce cADPR in CAMs, and these lipid macrodomains mediate transmembrane signaling of M 1 receptor activation to produce second messenger cADPR.
Type of Medium:
Online Resource
ISSN:
0363-6135
,
1522-1539
DOI:
10.1152/ajpheart.00617.2008
Language:
English
Publisher:
American Physiological Society
Publication Date:
2008
detail.hit.zdb_id:
1477308-9
SSG:
12
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