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J Biol Chem. 2005 Mar 25;280(12):11723-30. Epub 2005 Jan 6.

Amplification of Ca2+ signaling by diacylglycerol-mediated inositol 1,4,5-trisphosphate production.

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  • 1Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI) 2-1 Hirosawa, Wako City, Saitama 351-0198, Japan. chihiro@brain.riken.jp

Abstract

Stimulation of various cell surface receptors leads to the production of inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) through phospholipase C (PLC) activation, and the IP3 and DAG in turn trigger Ca2+ release through IP3 receptors and protein kinase C activation, respectively. The amount of IP(3) produced is particularly critical to determining the spatio-temporally coordinated Ca(2+)-signaling patterns. In this paper, we report a novel signal cross-talk between DAG and the IP3-mediated Ca(2+)-signaling pathway. We found that a DAG derivative, 1-oleoyl-2-acyl-sn-glycerol (OAG), induces Ca2+ oscillation in various types of cells independently of protein kinase C activity and extracellular Ca2+. The OAG-induced Ca2+ oscillation was completely abolished by depletion of Ca2+ stores or inhibition of PLC and IP3 receptors, indicating that OAG stimulates IP3 production through PLC activation and thereby induces IP3-induced Ca2+ release. Furthermore, intracellular accumulation of endogenous DAG by a DAG-lipase inhibitor greatly increased the number of cells responding to agonist stimulation at low doses. These results suggest a novel physiological function of DAG, i.e. amplification of Ca2+ signaling by enhancing IP3 production via its positive feedback effect on PLC activity.

PMID:
15637078
[PubMed - indexed for MEDLINE]
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