Phenobarbitone-mediated translocation of the cytosolic proteins interacting with the 5'-proximal region of rat liver CYP2B1/B2 gene into the nucleus.
The positive element (PE) (-69 to -98 bp) within the 5'-proximal region of the CYP2B1/B2 gene (+1 to -179 bp) of rat liver is essential for phenobarbitone (PB) response and gives a single major complex with the rat liver cytosol in gel shift analysis. This complex corresponds to complex I (top) of the three complexes given by the nuclear extracts. PB treatment of rats leads to a decrease in complex I formation with the cytosol and PE and an increase in the same with the nuclear extract in gel shift analysis. Both the changes are counteracted by simultaneous okadaic acid administration. The nuclear protein giving rise to complex I has been isolated and has an M(r) of 26 kDa. The cytosolic counterpart consists of two species, 26 and 28 kDa, as revealed by Southwestern blot analysis using labeled PE. It is concluded that PB treatment leads to the translocation accompanied by processing of the cytosolic protein species into the nucleus that requires protein dephosphorylation. It is suggested that PB may exert a global regulation on the transcription of many genes by modulating the phosphorylation status of different protein factors involved in transcriptional regulation.
Samudre
Kalpana R
KR
Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
Mani
S A
SA
Vathsala
P G
PG
Rangarajan
P N
PN
Padmanaban
G
G
D024506:5' Flanking Region; D021581:Active Transport, Cell Nucleus; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D019362:Cytochrome P-450 CYP2B1 / Q000235:genetics*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D010634:Phenobarbital / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D020218:Response Elements; D013250:Steroid Hydroxylases / Q000235:genetics*
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D019319:Okadaic Acid; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; D019362:Cytochrome P-450 CYP2B1; C025619:steroid 16-beta-hydroxylase; D010634:Phenobarbital