Differential induction of mafF, mafG and mafK expression by electrophile-response-element activators.
The three small Maf proteins, MafF, MafG and MafK, have been implicated in a number of physiological processes, including development, differentiation, haematopoiesis and stress response. Here we report the constitutive expression of mafF, mafG and mafK in six human cell lines derived from various tissues (HepG2, IMR-32, K-562, HEK-293, RD and A549). The expression patterns of mafF, mafG and mafK varied widely among cell lines. Because small Maf proteins have been implicated in electrophile response element (EpRE)-mediated stress response, the ability of three EpRE activators [pyrrolidinedithiocarbamate (PDTC), phenylethyl isothiocyanate (PEITC) and t-butylhydroquinone (tBHQ)] to induce small Maf expression was examined in detail in HepG2 cells. Both PDTC and PEITC induced mafF, mafG and mafK expression, whereas tBHQ failed to markedly induce any of the three small Mafs. Where a response was observed, mafF was induced to the greatest extent compared with mafG and mafK, and this response was transcriptionally mediated. PDTC also induced small Maf expression in the other cell lines examined, with patterns of induction varying among cell lines. The differences in expression among the cell lines examined, coupled with the induction patterns observed, indicate that the three small maf genes are stress-responsive, but may be regulated via differing mechanisms. Furthermore, the fact that tBHQ, PDTC and PEITC induce EpRE activity, but that tBHQ fails to markedly induce any of the small Mafs, suggests that up-regulation of small Mafs is not an absolute requirement for EpRE-mediated gene expression.
Moran
Julie A
JA
Department of Pharmacology, University of Wisconsin Medical School, CSC K4/554, 600 Highland Avenue, Madison, WI 53792, USA.
Dahl
Erica L
EL
Mulcahy
R Timothy
RT
D001483:Base Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D017879:Isothiocyanates / Q000494:pharmacology*; D051260:MafF Transcription Factor; D051259:MafG Transcription Factor; D050985:MafK Transcription Factor; D009687:Nuclear Proteins / Q000235:genetics*; D011392:Proline / Q000031:analogs & derivatives* / Q000494:pharmacology*; D012097:Repressor Proteins / Q000235:genetics*; D013859:Thiocarbamates / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D004268:DNA-Binding Proteins; D006873:Hydroquinones; D017879:Isothiocyanates; C484147:MAFF protein, human; C103944:MAFG protein, human; D051260:MafF Transcription Factor; D051259:MafG Transcription Factor; D050985:MafK Transcription Factor; D009687:Nuclear Proteins; D012097:Repressor Proteins; D013859:Thiocarbamates; C066229:prolinedithiocarbamate; C058305:phenethyl isothiocyanate; D011392:Proline; C018855:2-tert-butylhydroquinone