Transcriptional and post-transcriptional regulation of complement factor I (CFI) gene expression in Hep G2 cells by interleukin-6.
We have investigated the effects of IL-1 and IL-6 on human complement factor I (CFI) production by Hep G2 cells. IL-6 treatment caused a dose- and time-dependent increase in CFI secretion while IL-1 did not demonstrate such effects. The increase in CFI synthesis correlated with increase in CFI mRNA levels. The half-life of CFI mRNA in untreated cells was approx. 23 h and this was increased to 31 h (26% increase) following induction with IL-6. The IL-6 induced increase in CFI gene expression was inhibited by actinomycin D indicating regulatory effects at the level of transcription. Nuclear run-on experiments showed that IL-6 increased the rate of CFI gene transcription 4.2-fold. Transient transfection analysis of chloramphenicol acetyltransferase reporter gene constructs containing truncated segments of the 5'-flanking region of CFI gene showed that the cis-acting sequence(s) controlling the IL-6 inducible transcription resides in an 83 bp region located between -738 bp and -655 bp relative to the transcription start site. Our results indicate that the upregulation of CFI gene expression by IL-6 involves a coordinate effort at the level of transcription and mRNA stability, with the enhanced rate of transcription being the principal mechanism.
Minta
J O
JO
Department of Laboratory Medicine and Pathobiology, Medical Sciences Building, University of Toronto, Toronto, ON M5S 1A8, Canada. joe.minta@utoronto.ca
Fung
M
M
Paramaswara
B
B
D001483:Base Sequence; D006528:Carcinoma, Hepatocellular; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D017244:Complement Factor I / Q000096:biosynthesis / Q000235:genetics*; D016384:Consensus Sequence; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D017930:Genes, Reporter; D006207:Half-Life; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology* / Q000502:physiology; D007700:Kinetics; D008113:Liver Neoplasms; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D014162:Transfection
D007375:Interleukin-1; D015850:Interleukin-6; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D003609:Dactinomycin; D003513:Cycloheximide; D015500:Chloramphenicol O-Acetyltransferase; D017244:Complement Factor I