title: Amiloride suppresses erythropoietin-induced proliferation and MAP kinase, but potentiates differentiation of J2E cells.
abstract: The J2E erythroid cell line proliferates and differentiates in response to erythropoietin (epo). Here we demonstrate that the diuretic amiloride can suppress normal and hormone-induced cell division in a dose-dependent manner. In the presence of amiloride, cell numbers did not increase, [3H]thymidine incorporation decreased, and fewer cells were observed in the S, G2, and M phases of the cell cycle. In addition, the levels of proliferating cell nuclear antigen, a subunit of DNA polymerase delta, fell. In marked contrast, epo-initiated differentiation was potentiated when J2E cells were cultured with the drug: the number of benzidine-positive cells increased, hemoglobin content per cell rose, and more morphologically mature cells were produced. Immunoblotting with anti-phosphotyrosine antibodies revealed that amiloride reduced the number of phosphorylated proteins in epo-stimulated cells. Moreover, the protein content of p42 and p44 MAP kinases was noticeably downregulated in amiloride-treated cultures. These data indicate that amiloride may interfere with epo-induced signaling cascades within J2E cells which result in restricted cell division and promotion of maturation.
authors.affiliation: Department of Biochemistry, University of Western Australia, Nedlands.
authors.forename: B
authors.initials: B
authors.lastname: Callus
authors.forename: P A
authors.initials: PA
authors.lastname: Tilbrook
authors.forename: S J
authors.initials: SJ
authors.lastname: Busfield
authors.forename: V S
authors.initials: VS
authors.lastname: Cull
authors.forename: T
authors.initials: T
authors.lastname: Bittorf
authors.forename: S P
authors.initials: SP
authors.lastname: Klinken
mesh_terms: D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004912:Erythrocytes; D004921:Erythropoietin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D019833:Genistein; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007529:Isoflavones / Q000494:pharmacology; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis / Q000378:metabolism; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D006454:Hemoglobins; D007529:Isoflavones; D010750:Phosphoproteins; D011994:Recombinant Proteins; D004921:Erythropoietin; D019000:Phosphotyrosine; D014443:Tyrosine; D000584:Amiloride; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D007930:Leucine; D013936:Thymidine