Down-regulation of rat mitochondrial branched-chain 2-oxoacid dehydrogenase kinase gene expression by glucocorticoids

Yi Shuian Huang, David T. Chuang

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The mammalian mitochondrial branched-chain 2-oxoacid dehydrogenase (BCOD) complex is regulated by a reversible phosphorylation (inactivation)/dephosphorylation (activation) cycle. In the present study, the effects of glucocorticoids on the level of BCOD kinase mRNA were investigated in rat hepatoma cell lines (H4IIE and FTO-2B), as well as in the rat. In H4IIE cells, dexamethasone was found to significantly reduce steady state concentrations of BCOD kinase mRNA after a 48 h culture, and this was correlated with a 2-fold increase in the dephosphorylated form of the BCOD complex. The half-life of the kinase mRNA in H4IIE cells was not affected by dexamethasone treatment. Therefore, the decrease in the steady-state kinase mRNA level resulting from dexamethasone treatment was not caused by changes in mRNA stability, which raised the possibility of regulation at the level of gene transcription. To identify the negative glucocorticoid-responsive element in the kinase promoter, nested deletion constucts in the 3.0 kb promoter region were examined in H4IIE cells cultured in the presence or absence of dexamethasone. No significant differences in promoter activity were observed on either transient or stable transfection. The data showed that the glucocorticoid-responsive element was located outside the 3.0 kb promoter region. At the physiological level, hepatic BCOD kinase mRNA levels were reduced in rats injected intraperitoneally with dexamethasone. This effect was liver-specific, and was not detected in other tissues. These results suggest that the down-regulation of kinase gene expression by glucocorticoids is mediated through a liver-specific or -enriched transcription factor(s).

Original languageEnglish (US)
Pages (from-to)503-510
Number of pages8
JournalBiochemical Journal
Volume339
Issue number3
DOIs
StatePublished - May 1 1999

Fingerprint

Gene expression
Dexamethasone
Glucocorticoids
Rats
Down-Regulation
Gene Expression
Phosphotransferases
Messenger RNA
Keto Acids
Genetic Promoter Regions
Liver
Oxidoreductases
RNA Stability
Gene Expression Regulation
Phosphorylation
Transfection
Half-Life
Transcription
Hepatocellular Carcinoma
Cultured Cells

Keywords

  • Dexamethasone
  • H4IIE cells
  • Kinase mRNA
  • Kinase promoter
  • Liver-specific factor

ASJC Scopus subject areas

  • Biochemistry

Cite this

Down-regulation of rat mitochondrial branched-chain 2-oxoacid dehydrogenase kinase gene expression by glucocorticoids. / Huang, Yi Shuian; Chuang, David T.

In: Biochemical Journal, Vol. 339, No. 3, 01.05.1999, p. 503-510.

Research output: Contribution to journalArticle

@article{f4c74a2ace074864b72c56ee74519a71,
title = "Down-regulation of rat mitochondrial branched-chain 2-oxoacid dehydrogenase kinase gene expression by glucocorticoids",
abstract = "The mammalian mitochondrial branched-chain 2-oxoacid dehydrogenase (BCOD) complex is regulated by a reversible phosphorylation (inactivation)/dephosphorylation (activation) cycle. In the present study, the effects of glucocorticoids on the level of BCOD kinase mRNA were investigated in rat hepatoma cell lines (H4IIE and FTO-2B), as well as in the rat. In H4IIE cells, dexamethasone was found to significantly reduce steady state concentrations of BCOD kinase mRNA after a 48 h culture, and this was correlated with a 2-fold increase in the dephosphorylated form of the BCOD complex. The half-life of the kinase mRNA in H4IIE cells was not affected by dexamethasone treatment. Therefore, the decrease in the steady-state kinase mRNA level resulting from dexamethasone treatment was not caused by changes in mRNA stability, which raised the possibility of regulation at the level of gene transcription. To identify the negative glucocorticoid-responsive element in the kinase promoter, nested deletion constucts in the 3.0 kb promoter region were examined in H4IIE cells cultured in the presence or absence of dexamethasone. No significant differences in promoter activity were observed on either transient or stable transfection. The data showed that the glucocorticoid-responsive element was located outside the 3.0 kb promoter region. At the physiological level, hepatic BCOD kinase mRNA levels were reduced in rats injected intraperitoneally with dexamethasone. This effect was liver-specific, and was not detected in other tissues. These results suggest that the down-regulation of kinase gene expression by glucocorticoids is mediated through a liver-specific or -enriched transcription factor(s).",
keywords = "Dexamethasone, H4IIE cells, Kinase mRNA, Kinase promoter, Liver-specific factor",
author = "Huang, {Yi Shuian} and Chuang, {David T.}",
year = "1999",
month = "5",
day = "1",
doi = "10.1042/0264-6021:3390503",
language = "English (US)",
volume = "339",
pages = "503--510",
journal = "Biochemical Journal",
issn = "0264-6021",
publisher = "Portland Press Ltd.",
number = "3",

}

TY - JOUR

T1 - Down-regulation of rat mitochondrial branched-chain 2-oxoacid dehydrogenase kinase gene expression by glucocorticoids

AU - Huang, Yi Shuian

AU - Chuang, David T.

PY - 1999/5/1

Y1 - 1999/5/1

N2 - The mammalian mitochondrial branched-chain 2-oxoacid dehydrogenase (BCOD) complex is regulated by a reversible phosphorylation (inactivation)/dephosphorylation (activation) cycle. In the present study, the effects of glucocorticoids on the level of BCOD kinase mRNA were investigated in rat hepatoma cell lines (H4IIE and FTO-2B), as well as in the rat. In H4IIE cells, dexamethasone was found to significantly reduce steady state concentrations of BCOD kinase mRNA after a 48 h culture, and this was correlated with a 2-fold increase in the dephosphorylated form of the BCOD complex. The half-life of the kinase mRNA in H4IIE cells was not affected by dexamethasone treatment. Therefore, the decrease in the steady-state kinase mRNA level resulting from dexamethasone treatment was not caused by changes in mRNA stability, which raised the possibility of regulation at the level of gene transcription. To identify the negative glucocorticoid-responsive element in the kinase promoter, nested deletion constucts in the 3.0 kb promoter region were examined in H4IIE cells cultured in the presence or absence of dexamethasone. No significant differences in promoter activity were observed on either transient or stable transfection. The data showed that the glucocorticoid-responsive element was located outside the 3.0 kb promoter region. At the physiological level, hepatic BCOD kinase mRNA levels were reduced in rats injected intraperitoneally with dexamethasone. This effect was liver-specific, and was not detected in other tissues. These results suggest that the down-regulation of kinase gene expression by glucocorticoids is mediated through a liver-specific or -enriched transcription factor(s).

AB - The mammalian mitochondrial branched-chain 2-oxoacid dehydrogenase (BCOD) complex is regulated by a reversible phosphorylation (inactivation)/dephosphorylation (activation) cycle. In the present study, the effects of glucocorticoids on the level of BCOD kinase mRNA were investigated in rat hepatoma cell lines (H4IIE and FTO-2B), as well as in the rat. In H4IIE cells, dexamethasone was found to significantly reduce steady state concentrations of BCOD kinase mRNA after a 48 h culture, and this was correlated with a 2-fold increase in the dephosphorylated form of the BCOD complex. The half-life of the kinase mRNA in H4IIE cells was not affected by dexamethasone treatment. Therefore, the decrease in the steady-state kinase mRNA level resulting from dexamethasone treatment was not caused by changes in mRNA stability, which raised the possibility of regulation at the level of gene transcription. To identify the negative glucocorticoid-responsive element in the kinase promoter, nested deletion constucts in the 3.0 kb promoter region were examined in H4IIE cells cultured in the presence or absence of dexamethasone. No significant differences in promoter activity were observed on either transient or stable transfection. The data showed that the glucocorticoid-responsive element was located outside the 3.0 kb promoter region. At the physiological level, hepatic BCOD kinase mRNA levels were reduced in rats injected intraperitoneally with dexamethasone. This effect was liver-specific, and was not detected in other tissues. These results suggest that the down-regulation of kinase gene expression by glucocorticoids is mediated through a liver-specific or -enriched transcription factor(s).

KW - Dexamethasone

KW - H4IIE cells

KW - Kinase mRNA

KW - Kinase promoter

KW - Liver-specific factor

UR - http://www.scopus.com/inward/record.url?scp=0033136244&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033136244&partnerID=8YFLogxK

U2 - 10.1042/0264-6021:3390503

DO - 10.1042/0264-6021:3390503

M3 - Article

C2 - 10215586

AN - SCOPUS:0033136244

VL - 339

SP - 503

EP - 510

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 3

ER -