Interleukin-3 dependent mitogenesis in murine cells involves a predominant non-protein kinase C (pKC) dependent pathway for c-myc transcription. Role of a myc expression vector in rescuing pKC dependent mitogenesis.
The signaling pathways used by interleukin-3 (IL-3) and by active phorbol ester (12-0-tetradecanoyl phorbol-13-acetate, TPA) to stimulate mitogenesis in the growth factor dependent myeloid cell line FDC-P1 were studied by 'reporter' analysis of nuclear proto-oncogene expression. These studies revealed that IL-3 strongly stimulated c-myc expression by a transcriptional mechanism but IL-3 poorly stimulated c-jun expression, a measure of protein kinase C dependent signals. On the other hand, the protein kinase C agonist, TPA, strongly activated c-jun expression but poorly promoted expression (transcription) of c-myc in FDC-P1. These findings appeared to correlate with the poor mitogenic capacity of TPA for FDC-P1. However, stable transfection of FDC-P1 with a c-myc expression vector driven by a human methallothionein IIA promoter containing the TPA responsive element (TRE), led to a cell clone, FDMT myc.A1, in which TPA mediated selective transcription of the transfected TRE driven c-myc vector and down-regulated expression of the endogenous c-myc gene. IL-3 selectively failed to stimulate expression of the TRE driven c-myc vector in FDMT myc.A1. Augmented TPA dependent vector derived c-myc expression was accompanied by enhanced mitogenesis of the cell line FDMT myc.A1 compared with FDC-P1. In addition, TPA mediated expression of the transfected c-myc gene in FDMT myc.A1 was accompanied by augmented transcription of c-jun and c-fos in response to TPA. These studies show the importance of a non-protein kinase C dependent pathway for IL-3 mediated c-myc transcription. However, these studies reveal that protein kinase C mediated pathways can be promitogenic, especially when complemented by unregulated c-myc expression (in this case driven by an alternative, TRE containing promoter).
Nahreini
T S
TS
Department of Medicine, Indiana University School of Medicine, Indianapolis.
Litz-Jackson
S
S
Burgess
G S
GS
Helvering
L M
LM
Manolagas
S C
SC
Boswell
H S
HS
D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D002460:Cell Line; D005786:Gene Expression Regulation; D016758:Genes, jun; D016259:Genes, myc; D005822:Genetic Vectors; D066298:In Vitro Techniques; D007377:Interleukin-3 / Q000494:pharmacology*; D051379:Mice; D008938:Mitosis / Q000187:drug effects; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000502:physiology; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic
D007377:Interleukin-3; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D011994:Recombinant Proteins; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate