Thioredoxin increases the proliferation of human B-cell lines through a protein kinase C-dependent mechanism.
Thioredoxin (Trx) catalyzes thiol-disulfide oxidoreductions. We and others recently showed that human Trx could function as an autocrine growth factor for human lymphoid cells immortalized by the human T-lymphotrophic virus type I or the Epstein-Barr virus. Here we report that reduced Trx from Escherichia coli generated by NADPH and thioredoxin reductase increases the proliferation of an Epstein-barr virus(+)-B cell line 1G8, which constitutively produces low amounts of human Trx. This proliferative effect involved the activation of protein kinase C through its translocation to the membrane. Staurosporin and calphostin C, two inhibitors of protein kinase C, but not of H8, a protein kinase A inhibitor, were able to block Trx-dependent proliferation. The addition of Trx to 1G8 cells resulted in the formation of inositol 1,4,5-triphosphate and sn-1,2-diacylglycerol by a phosphoinositide-specific phospholipase C, as well as increased free calcium concentration. Diacylglycerol showed a biphasic increase; the first phase, corresponding to an early peak (30 s) of inositol 1,4,5-triphosphate and a second larger, prolonged phase. The second phase was inhibited by propranolol, a specific inhibitor of phosphohydrolase, indicating that it is most likely derived from phosphatidylcholine hydrolysis by the sequential action of phospholipase D and phosphatidic acid phosphohydrolase. Our data suggest that enhanced phosphoinositide-specific phospholipase C activity induced by the dithiol form of Trx in 1G8 cells is associated to protein kinase C activation, and thus plays a role in the permanent growth of Epstein-Barr virus-infected B cells.
Biguet
C
C
Laboratoire de Biologie des Tumeurs Humaines, U.R.A. C.N.R.S., Institut Gustave-Roussy, Villejuif, France.
Wakasugi
N
N
Mishal
Z
Z
Holmgren
A
A
Chouaib
S
S
Tursz
T
T
Wakasugi
H
H
D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D004075:Diglycerides / Q000096:biosynthesis; D004926:Escherichia coli; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction; D013879:Thioredoxins / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D004075:Diglycerides; D013879:Thioredoxins; D015544:Inositol 1,4,5-Trisphosphate; D011493:Protein Kinase C; D002118:Calcium