Retinoic acid-mediated decrease of G (alpha S) protein expression: involvement of G (alpha S) in the differentiation of HL-60 myeloid cells.
The amount of the heterotrimeric G protein subunit G (alpha S) decreases after the induction of human myeloblastic leukemia HL-60 cells to become granulocyte-like cells in the presence of retinoic acid (RA). Compared to untreated control cells, HL-60 cells expressed decreased levels of G (alpha S) protein and mRNA levels after addition of RA to the cultures as shown by immunoblot and Northern blot analysis. The reduction of the G (alpha S) protein in HL-60 cells by antisense RNA expression was associated with (i) decreased cell doubling time; (ii) induction of a granulocyte-like phenotype; (iii) and expression of a surface marker characteristic of myeloid differentiation. Expression of a constitutively active mutant G (alpha S) (Q227L) in HL-60 cells blocked RA-induced differentiation. In contrast, treatment with forskolin, prostaglandin E2, or 8-bromo-cyclic AMP, which increase intracellular cyclic AMP (cAMP) levels, did not inhibit the RA-mediated differentiation process. No changes in cAMP levels occurred in response to RA. The present study provides insights into the involvement of G (alpha S) protein in growth regulation during differentiation of the human myeloid cell line HL-60. These data suggest that in HL-60 human myeloid cells RA-mediated decrease of G (alpha S) plays a critical role in the regulation of differentiation which is independent of intracellular cAMP.
Meissner
J D
JD
Zentrum Biochemie, Department of Clinical Chemistry, Medizinische Hochschule Hannover, Germany.
Brown
G A
GA
Mueller
W H
WH
Scheibe
R J
RJ
D000262:Adenylyl Cyclases / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D015536:Down-Regulation; D019205:GTP-Binding Protein alpha Subunits, Gs; D019204:GTP-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D006098:Granulocytes / Q000166:cytology; D018922:HL-60 Cells; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016372:RNA, Antisense; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*
D009838:Oligodeoxyribonucleotides; D016372:RNA, Antisense; D014212:Tretinoin; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases