Calcium oscillation and phosphatidylinositol 3-kinase positively regulate integrin alpha(IIb)beta3-mediated outside-in signaling.
The frequency of calcium oscillation reveals the platelet activation status, however, the biological significance of the periodic calcium responses and methods of communication with other integrin-mediated signals are not clear. RGD-containing disintegrin rhodostomin coated substrates were employed to enhance platelet spreading and calcium oscillation through direct binding and clustering of the receptor integrin alpha(IIb)beta3. The results showed that the activation of phosphatidylinositol 3-kinase (PI3-K) and internal calcium pathways were crucial for alpha(IIb)beta3 outside-in signaling. PI3-K antagonists wortmannin and LY294002 inhibited disintegrin substrates and induced platelet spreading and calcium oscillation. At the same time, pretreatment of platelets with the microsomal calcium-ATPase inhibitor thapsigargin to deplete internal calcium stores severely impaired the calcium oscillation as well as PI3-K activation and spreading on disintegrin substrates. Because inhibition of one pathway could inhibit the other, our data indicates that PI3-K and calcium oscillation are synergistically operated and form a positive-feedback regulation in integrin alpha(IIb)beta3-mediated outside-in signaling.
Sun
Der-Shan
DS
Institute of Molecular and Cellular Biology, Tzu-Chi University, Hualien, Taiwan.
Lo
Szecheng J
SJ
Lin
Chi-Hung
CH
Yu
Mei-Shiuan
MS
Huang
Ching-Yi
CY
Chen
Yao-Fong
YF
Chang
Hsin-Hou
HH
D000199:Actins / Q000378:metabolism; D000730:Androstadienes / Q000494:pharmacology; D001792:Blood Platelets / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D016023:Integrins / Q000378:metabolism; D018613:Microscopy, Confocal; D018715:Microscopy, Video; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D009842:Oligopeptides / Q000737:chemistry; D009991:Oscillometry; D010455:Peptides / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry; D010973:Platelet Adhesiveness; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D015398:Signal Transduction; D013997:Time Factors; D000077191:Wortmannin
D000199:Actins; D000730:Androstadienes; D002867:Chromones; D016023:Integrins; D009025:Morpholines; D009842:Oligopeptides; D010455:Peptides; D010743:Phospholipids; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D011993:Recombinant Fusion Proteins; C072026:rhodostomin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C047981:arginyl-glycyl-aspartic acid; D019869:Phosphatidylinositol 3-Kinases; D002118:Calcium; D000077191:Wortmannin