Thresholds for cellular disruption and activation of the stress response in renal epithelia.
Renal ischemia causes a rapid fall in cellular ATP, increased intracellular calcium (Ca(i)), and dissociation of Na(+)-K(+)-ATPase from the cytoskeleton along with initiation of a stress response. We examined changes in Ca(i), Na(+)-K(+)-ATPase detergent solubility, and activation of heat-shock transcription factor (HSF) in relation to graded reduction of ATP in LLC-PK(1) cells to determine whether initiation of the stress response was related to any one of these perturbations alone. Ca(i) increased first at 75% of control ATP. Triton X-100 solubility of Na(+)-K(+)-ATPase increased below 70% control ATP. Reducing cellular ATP below 50% control consistently activated HSF. Stepped decrements in cellular ATP below the respective thresholds caused incremental increases in Ca(i), Na(+)-K(+)-ATPase solubility, and HSF activation. ATP depletion activated both HSF1 and HSF2. Proteasome inhibition caused activation of HSF1 and HSF2 in a pattern similar to ATP depletion. Lactate dehydrogenase release remained at control levels irrespective of the degree of ATP depletion. Progressive accumulation of nonnative proteins may be the critical signal for the adaptive induction of the stress response in renal epithelia.
van Why
S K
SK
Departments of Pediatrics, Pathology and Surgery, Yale University School of Medicine, New Haven, Connecticut 06520-8064, USA.
Kim
S
S
Geibel
J
J
Seebach
F A
FA
Kashgarian
M
M
Siegel
N J
NJ
D000255:Adenosine Triphosphate / Q000172:deficiency; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D003902:Detergents; D004056:Differential Threshold; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D007668:Kidney / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018374:LLC-PK1 Cells; D009097:Multienzyme Complexes / Q000187:drug effects / Q000378:metabolism; D017830:Octoxynol; D046988:Proteasome Endopeptidase Complex; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000737:chemistry; D012995:Solubility; D013312:Stress, Physiological / Q000378:metabolism / Q000503:physiopathology*; D013552:Swine; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D003902:Detergents; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D009097:Multienzyme Complexes; D014157:Transcription Factors; C070389:HSF2 protein, human; D000255:Adenosine Triphosphate; D017830:Octoxynol; D007770:L-Lactate Dehydrogenase; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium