A novel transcriptional repressor, Rhit, is involved in heat-inducible and age-dependent expression of Mpv17-like protein, a participant in reactive oxygen species metabolism.
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-LP(S) and M-LP(L), are generated by the alternative usage of promoters. M-LP(S) is expressed exclusively in kidneys after the age of 6 weeks, whereas M-LP(L) is expressed ubiquitously. To elucidate the molecular basis of M-LP(S) expression, we searched for cis-regulatory elements in the promoter region of M-LP(S) 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-LP(S) promoter by DNA affinity chromatography and confirmed its participation in the transcriptional regulation of M-LP(S) by RNA interference (RNAi). Sequence analysis revealed that Rhit contains a KRAB (Krüppel-associated box) domain and a DNA-binding domain composed of eight C(2)H(2)-type zinc fingers. Interestingly, exposure to heat shock stress resulted in the upregulation of M-LP(S) expression concurrent with the downregulation of Rhit expression. Moreover, the age-dependent expression of M-LP(S) 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-LP(S).
Division of Life Science, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan. riida@u-fukui.ac.jp
Reiko
R
Iida
Misuzu
M
Ueki
Toshihiro
T
Yasuda
D000375:Aging / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D005786:Gene Expression Regulation; D006358:Hot Temperature; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D008565:Membrane Proteins; C065292:Mpv17 protein, mouse; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D012097:Repressor Proteins; C549621:Rhit protein, mouse