c-fms mRNA is regulated posttranscriptionally by 1,25(OH)2D3 in HL-60 cells.
Macrophage colony-stimulating factor (MCSF) is required for normal osteoclast and macrophage development. The receptor for MCSF (c-fms) is expressed on the pluripotent precursor and mature osteoclasts and macrophages. We have previously shown in myelomonocytic HL-60 cells that phorbol myristate acetate (PMA) upregulates c-fms mRNA expression. This induction of c-fms is inhibited by 1,25(OH)2D3. The major regulatory control of c-fms mRNA levels by PMA has been identified as posttranscriptional. However, a role of transcript elongation in controlling levels of c-fms mRNA has also been suggested. To better understand the 1,25(OH)2D3 regulation of c-fms mRNA expression we studied nuclear run on, mRNA stability, and transcript elongation in HL-60 cells treated with 10 ng/ml phorbol myristate acetate, 10 nM 1,25(OH)2D3 alone or combined. We demonstrated by nuclear run on that c-fms was constitutively transcribed in 1,25(OH)2D3 as well as control and PMA-treated cells. Transcript elongation was evaluated by RT-PCR for exon 2 or exon 3. Both exons were minimally expressed in control and 1,25(OH)2D3-treated cells, and increased in PMA-treated cells; this increased expression was inhibited by the addition of 1,25(OH)2D3. These results fail to show differential transcript elongation. Measurement of mRNA stability demonstrated decreased mRNA half-life to 5 hours in cells treated with PMA and 1,25(OH)2D3 compared with a half-life of 8 hours in cells treated with PMA alone. Our findings demonstrate that c-fms is regulated by 1,25(OH)2D3 at the posttranscriptional level by changes in mRNA stability. This gives the cell the ability to respond to local signals with rapid changes in c-fms levels altering the ability of the cell to respond to MCSF.
Biskobing
D M
DM
Department of Medicine, Emory Uiversity Medical School and Veterans Administration Medical Center, Atlanta, Georgia 30033, USA.
Fan
D
D
Rubin
J
J
D002117:Calcitriol / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D008934:Mitogens / Q000494:pharmacology; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects*; D012333:RNA, Messenger; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D008934:Mitogens; D012333:RNA, Messenger; D016186:Receptor, Macrophage Colony-Stimulating Factor; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate