Na+/H+ antiporter gene expression during monocytic differentiation of HL60 cells.
During differentiation of human promyelocytic HL60 cells into monocytes there are sustained increases in intracellular pH and Na+/H+ antiporter activity. Here we show that increased transcription and expression of the gene for the Na+/H+ antiporter precedes phorbol 12-myristate 13-acetate (PMA)-induced HL60 cell differentiation. PMA increased steady-state Na+/H+ antiporter mRNA levels approximately 50-fold within 8 h (at which time less than 15% of cells had differentiated). This increase was due to an increased transcriptional rate as determined by nuclear run on. Immunoprecipitation of [35S]methionine-labeled Na+/H+ antiporter using an antiporter fusion protein antibody (RP1-c28) showed an equivalent increase in Na+/H+ antiporter protein synthesis. The synthetic diacylglycerol, 1-oleolyl-2-acetylglycerol, an activator of protein kinase C, which unlike PMA did not cause differentiation, failed to induce Na+/H+ antiporter mRNA. Furthermore, inhibition of PMA-induced differentiation by either sphingosine or cycloheximide prevented accumulation of Na+/H+ antiporter mRNA. Together, these findings strongly suggest a close association of Na+/H+ antiporter induction with HL60 cell differentiation. The HL60 cell system is a promising model to study the mechanisms of Na+/H+ antiporter gene regulation and its function in differentiation.
Rao
G N
GN
Cardiology Division, Emory University School of Medicine, Atlanta, Georgia 30322.
de Roux
N
N
Sardet
C
C
Pouysségur
J
J
Berk
B C
BC
D002352:Carrier Proteins / Q000235:genetics*; D002454:Cell Differentiation / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D004075:Diglycerides / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007951:Leukemia, Myeloid; D009000:Monocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D017923:Sodium-Hydrogen Exchangers; D013110:Sphingosine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D004075:Diglycerides; D012333:RNA, Messenger; D017923:Sodium-Hydrogen Exchangers; C038237:1-oleoyl-2-acetylglycerol; D003513:Cycloheximide; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate