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Induction of stress proteins in cultured myogenic cells. Molecular signals for the activation of heat shock transcription factor during ischemia. J Clin Invest 1992 May;89(5):1685-9

Date

05/01/1992

Pubmed ID

1569208

Pubmed Central ID

PMC443048

DOI

10.1172/JCI115768

Scopus ID

2-s2.0-0026653034   100 Citations

Abstract

Expression of major stress proteins is induced rapidly in ischemic tissues, a response that may protect cells from ischemic injury. We have shown previously that transcriptional induction of heat-shock protein 70 by hypoxia results from activation of DNA binding of a preexisting, but inactive, pool of heat shock factor (HSF). To determine the intracellular signals generated in hypoxic or ischemic cells that trigger HSF activation, we examined the effects of glucose deprivation and the metabolic inhibitor rotenone on DNA-binding activity of HSF in cultured C2 myogenic cells grown under normoxic conditions. Whole-cell extracts were examined in gel mobility shift assays using a 39-bp synthetic oligonucleotide containing a consensus heat-shock element as probe. ATP pools were determined by high-pressure liquid chromatography and intracellular pH (pHi) was measured using a fluorescent indicator. Glucose deprivation alone reduced the cellular ATP pool to 50% of control levels but failed to activate HSF. However, 2 x 10(-4) M rotenone induced DNA binding of HSF within 30 min, in association with a fall in ATP to 30% of control levels, and a fall in pHi from 7.3 to 6.9. Maneuvers (sodium propionate and amiloride) that lowered pHi to 6.7 without ATP depletion failed to activate HSF. Conversely, in studies that lowered ATP stores at normal pH (high K+/nigericin) we found induction of HSF-DNA binding activity. Our data indicate that the effects of ATP depletion alone are sufficient to induce the DNA binding of HSF when oxidative metabolism is impaired, and are consistent with a model proposed recently for transcriptional regulation of stress protein genes during ischemia.

Author List

Benjamin IJ, Horie S, Greenberg ML, Alpern RJ, Williams RS

Author

Ivor J. Benjamin MD Center Director, Professor in the Medicine department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Acidosis
Adenosine Triphosphate
Amiloride
Base Sequence
Cells, Cultured
DNA-Binding Proteins
Glucose
Heat-Shock Proteins
In Vitro Techniques
Molecular Sequence Data
Muscles
Oligodeoxyribonucleotides
Oxidative Phosphorylation
Propionates
Regulatory Sequences, Nucleic Acid
Rotenone
Transcription Factors
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a