[Integrins mediate the increase of concentration of intracellular free calcium in mouse eggs].
For studying the effect of integrin on the [Ca(2+)](i) of mouse eggs and its transmembrane signaling mechanism, zona-free mouse eggs were loaded with calcium probe Fluo-3/AM and the intensity of fluorescence of the eggs treated with different factors was measured through laser confocal microscopy. The results showed that the [Ca(2+)](i) of zona-free mouse eggs was increased when the eggs were treated with RGD peptide, fibronectin (Fn) and anti-mouse integrin subunit alpha(6) and beta(1) monoclonal antibodies, respectively. The [Ca(2+)](i) of the mouse eggs was also increased when the eggs were placed in calcium-free medium and treated with RGD peptide or Fn. The changes in the mouse egg [Ca(2+)](i) caused by RGD and Fn were similar to those caused by sperm. However, the concentration of Ca(2+) of the zona-free mouse eggs pretreated with tyrosine kinase inhibitor was not increased when the eggs were treated in the same way, and, neither was the intracellular calcium increased in those eggs pretreated with PKC inhibitor when the eggs were treated with RGD peptide. It is therefore suggested that the occupancy of integrins on the membrane of mouse eggs by their ligands mediates the release of Ca(2+) and then the increase in the [Ca(2+)](i) of eggs, which is one of the early events of egg activation. The tyrosine kinase signaling pathway and PKC are involved in this process as well.
Yue
Li-Min
LM
Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, China. yuelimin@yahoo.com
Zhang
Lei
L
He
Ya-Ping
YP
Zhang
Jin-Hu
JH
Xie
Yi-Min
YM
Zheng
Yu
Y
Zhang
Li
L
Huang
Ping
P
Wang
Li
L
Liu
Wei-Xin
WX
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D005260:Female; D016023:Integrins / Q000502:physiology*; D017136:Ion Transport / Q000187:drug effects; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism; D010063:Ovum / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction
D015220:Calcium Channels; D016023:Integrins; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D002118:Calcium