Extracellular signal-regulated kinases and g protein-coupled receptors in megakaryocytic human erythroleukemia cells: selective activation, differential regulation, and dissociation from mitogenesis.
Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are a group of kinases that play an important role in proliferation and differentiation. In megakaryocyte-like human erythroleukemia (HEL) cells, ERK2 was found to be predominantly expressed and strongly activated by prostaglandin (PG) E(2), thrombin, and epinephrine. On the other hand, adenosine, ADP, ATP, and UTP did not significantly increase ERK1/2 phosphorylation. However, of the agonists tested, only ADP was able to stimulate thymidine uptake. Pretreatment with pertussis toxin abolished the PGE(2) response but had less of an effect on thrombin. PGE(2)- and thrombin-induced ERK1/2 activation was mimicked by 4-beta-phorbol-12-myristate-13-acetate and ionomycin and blocked by mitogen-activated protein kinase kinase inhibitor 1,4 diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene but displayed differential sensitivity to protein kinase C inhibitor bisindolylmaleimide I and Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. Analogs of cAMP or agents that stimulate cAMP production were either weak or ineffective activators. Further studies indicate that the effect of thrombin was blocked by the phosphoinositide 3-kinase inhibitor wortmannin but not by agents inhibiting tyrosine kinase activity. On the contrary, herbimycin, but not wortmannin, attenuated the effect of PGE(2). Collectively, these results indicate that ERK1/2 are selectively activated by G protein-coupled receptors and not functionally associated with proliferation in HEL cells. ERK1/2 activation in response to PGE(2) and thrombin is mediated by distinctive types of G proteins and is differentially regulated by multiple pathways, including calcium mobilization, protein kinase C, phosphoinositide 3-kinase, and tyrosine kinases.
Wu
Hung
H
Department of Pharmacy, Chia Nan University of Pharmacy and Science, Tainan, Taiwan. hungwu@mail.chna.edu.tw
Shen
Huang-Wei
HW
Wu
Tin-Feng
TF
Brass
Lawrence F
LF
Sung
Kuo-Chun
KC
D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D008533:Megakaryocytes / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis / Q000378:metabolism*; D008938:Mitosis / Q000187:drug effects*; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D020536:Enzyme Activators; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D019204:GTP-Binding Proteins; D002118:Calcium; D013936:Thymidine