期刊
JOURNAL OF GENERAL PHYSIOLOGY
卷 126, 期 4, 页码 379-392出版社
ROCKEFELLER UNIV PRESS
DOI: 10.1085/jgp.200509355
关键词
-
类别
资金
- NCI NIH HHS [CA 68485, P30 CA068485] Funding Source: Medline
- NEI NIH HHS [EY 08126, P30 EY008126] Funding Source: Medline
- NICHD NIH HHS [P30 HD015052, HD 15052] Funding Source: Medline
- NIDDK NIH HHS [DK 20593, P30 DK020593, P30 DK058404, DK 58404] Funding Source: Medline
- NIGMS NIH HHS [GM 68543] Funding Source: Medline
Defecation in the nematode Caenorhabditis elegans is a readily observable ultradian behavioral rhythm that occurs once every 45-50 s and is mediated in part by posterior body wall muscle contraction (pBoc). pBoc is not regulated by neural input but instead is likely controlled by rhythmic Ca2+ oscillations in the intestinal epithelium. We developed an isolated nematode intestine preparation that allows combined physiological, genetic, and molecular characterization of oscillatory Ca2+ signaling. Isolated intestines loaded with fluo-4 AM exhibit spontaneous rhythmic Ca2+ oscillations with a period of similar to 50 s. Oscillations were only detected in the apical cell pole of the intestinal epithelium and occur as a posterior-to-anterior moving intercellular Ca2+ wave. Loss-of-function mutations in the inositol-1,4,5-trisphosphate (IP3) receptor ITR-1 reduce pBoc and Ca2+ oscillation frequency and intercellular Ca2+ wave velocity. In contrast, gain-of-function mutations in the IP3 binding and regulatory domains of ITR-1 have no effect on pBoc or Ca2+ oscillation frequency but dramatically increase the speed of the intercellular Ca2+ wave. Systemic RNA interference (RNAi) screening of the six C. elegans phospholipase C (PLC)-encoding genes demonstrated that pBoc and Ca2+ oscillations require the combined function of PLC-gamma and PLC-beta homologues. Disruption of PLC-gamma and PLC-beta activity by mutation or RNAi induced arrhythmia in pBoc and intestinal Ca2+ oscillations. The function of the two enzymes is additive. Epistasis analysis suggests that PLC-gamma functions primarily to generate IP3 that controls ITR-1 activity. In contrast, IP3 generated by PLC-beta appears to play little or no direct role in ITR-1 regulation. PLC-beta may function instead to control PIP2 levels and/or G protein signaling events. Our findings provide new insights into intestinal cell Ca2+ signaling mechanisms and establish C. elegans as a powerful model system for defining the gene networks and molecular mechanisms that underlie the generation and regulation of Ca2+ oscillations and intercellular Ca2+ waves in nonexcitable cells.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据