scholarly journals Arsenite induces a cell stress-response gene, RTP801, through reactive oxygen species and transcription factors Elk-1 and CCAAT/enhancer-binding protein

2005 ◽  
Vol 392 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Lin Lin ◽  
Teresa M. Stringfield ◽  
Xianglin Shi ◽  
Yan Chen

RTP801 is a newly discovered stress-response gene that is induced by hypoxia and other cell stress signals. Arsenic is a heavy metal that is linked to carcinogenesis in humans. Here, we investigated the mechanism by which arsenic induces RTP801 transcription. In HaCaT human keratinocytes, arsenite was able to induce a rapid rise in the RTP801 mRNA level. Correspondingly, arsenite treatment was capable of stimulating a 2.5 kb human RTP801 promoter. Such a stimulatory effect was inhibited by co-expression of superoxide dismutase or glutathione peroxidase, and was abrogated by N-acetylcysteine, implying that ROS (reactive oxygen species) were involved in transcriptional regulation of the RTP801 gene. A series of deletion studies with the promoter revealed a critical arsenic-responsive region between −1057 and −981 bp of the promoter. Point mutations of the putative Elk-1 site and the C/EBP (CCAAT/enhancer-binding protein) site within this region were able to reduce the stimulatory effect of arsenite, indicating that Elk-1 and C/EBP are involved in transcriptional regulation of the RTP801 gene by arsenite. Furthermore, a gel mobility-shift assay demonstrated that arsenite was able to mount the rapid formation of a protein complex that bound the arsenic-responsive region as well as the C/EBP-containing sequence. The arsenite stimulation on RTP801 transcription was partly mediated by the ERK (extracellular-signal-regulated kinase) pathway, since the effect of RTP801 was inhibited by a selective ERK inhibitor. In addition, overexpression of Elk-1 and C/EBPβ was able to elevate the promoter activity. Therefore these studies indicate that RTP801 is a transcriptional target of arsenic in human keratinocytes, and that arsenic and ROS production are linked to Elk-1 and C/EBP in the transcriptional control.

2016 ◽  
Vol 171 (3) ◽  
pp. 1551-1559 ◽  
Author(s):  
Shaobai Huang ◽  
Olivier Van Aken ◽  
Markus Schwarzländer ◽  
Katharina Belt ◽  
A. Harvey Millar

2010 ◽  
Vol 30 (10) ◽  
pp. 2306-2315 ◽  
Author(s):  
Reiko Iida ◽  
Misuzu Ueki ◽  
Toshihiro Yasuda

ABSTRACT Mpv17-like protein (M-LP) is a protein that has been suggested to be involved in the metabolism of reactive oxygen species. The two M-LP isoforms in mouse, M-LPS and M-LPL, are generated by the alternative usage of promoters. M-LPS is expressed exclusively in kidneys after the age of 6 weeks, whereas M-LPL is expressed ubiquitously. To elucidate the molecular basis of M-LPS expression, we searched for cis-regulatory elements in the promoter region of M-LPS and identified heat shock element half-sites as positive elements and a Tramtrack 69K (Ttk 69K) binding site as a negative element. Furthermore, we isolated a novel transcription repressor, Rhit (regulator of heat-induced transcription), that binds to the Ttk 69K binding site within the M-LPS promoter by DNA affinity chromatography and confirmed its participation in the transcriptional regulation of M-LPS by RNA interference (RNAi). Sequence analysis revealed that Rhit contains a KRAB (Krüppel-associated box) domain and a DNA-binding domain composed of eight C2H2-type zinc fingers. Interestingly, exposure to heat shock stress resulted in the upregulation of M-LPS expression concurrent with the downregulation of Rhit expression. Moreover, the age-dependent expression of M-LPS was inversely correlated with that of Rhit. These observations strongly suggest that Rhit acts as a repressor in the heat-induced and age-dependent transcriptional regulation of M-LPS.


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