Thrombin-induced shape change in human megakaryoblastic leukemic cells, MEG-01, is mediated by protein kinase C.
We investigated the intracellular processes of the shape change in human megakaryoblastic leukemic cells, MEG-01, by platelet agonists. Thrombin induced the formation of many pseudopods. This shape change was also induced by phorbol 12-myristate 13 acetate (TPA) and weakly by Ca2+ ionophore, A23187, but not by ADP, collagen, or epinephrine. Electron microscopy and FITC-labeled phalloidin staining revealed thick submembranous microfilament bundles in the pseudopods of the shape-changed cells by thrombin. Shape change was inhibited by cytochalasin B. Since Ca(2+)-dependent phosphorylation reactions play central role on the initiation of shape change of platelet, we examined the effects of protein kinase C (PKC) inhibitor, H-7, and myosin light chain (MLC) kinase inhibitor, ML-9, on the shape change of MEG-01 cells induced by thrombin, and observed that H-7 potently inhibited thrombin-induced shape change, while ML-9 did not. These results suggest that thrombin-induced reorganization of microfilaments and shape change of MEG-01 cells are mediated by PKC, but not by MLC kinase.
Goto
S
S
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Kobayashi
M
M
Murate
T
T
Hotta
T
T
Hagiwara
M
M
Hoshino
T
T
Hidaka
H
H
Saito
H
H
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000199:Actins / Q000032:analysis; D001381:Azepines / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D048429:Cell Size / Q000187:drug effects*; D003571:Cytochalasin B / Q000494:pharmacology; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D008533:Megakaryocytes; D010703:Phorbol Esters / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
D000199:Actins; D001381:Azepines; D007546:Isoquinolines; D010703:Phorbol Esters; D010879:Piperazines; C056218:ML 9; D000001:Calcimycin; D003571:Cytochalasin B; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D013917:Thrombin