Herbimycin A and geldanamycin inhibit okadaic acid-induced apoptosis and p38 activation in NRK-52E renal epithelial cells

Toxicol Appl Pharmacol. 1999 Nov 15;161(1):59-74. doi: 10.1006/taap.1999.8765.


It is important to understand the mechanisms by which phosphorylation-dependent events play a role in regulation of apoptosis in toxicant-metabolizing organs such as the kidney. Our previous work demonstrated that the toxicant and phosphatase inhibitor okadaic acid induces apoptosis of renal epithelial cells via a mechanism that appears to involve the modulation of c-raf-1, p38 kinase, and extracellular regulatory kinase (ERK) cascades. Using the benzoquinone ansamycins and tyrosine kinase inhibitors geldanamycin and herbimycin A, we examined the contribution of tyrosine phosphorylation and c-raf-1 activities to okadaic acid-induced apoptosis. In this report we show that both geldanamycin and herbimycin A protected NRK-52E cells from okadaic acid-induced apoptosis, abrogated the overall okadaic acid-induced kinase activation, and specifically inhibited activation of p38 kinase by okadaic acid. Herbimycin A and geldanamycin also abrogated okadaic-acid induced morphologic changes such as cell rounding and cell membrane blebbing. Herbimycin A and geldanamycin caused pronounced cell spreading, cell flattening, and a decrease in okadaic acid-induced loss of actin filaments. Interestingly, herbimycin A showed more potent inhibitory effect than geldanamycin, and herbimycin A alone inhibited okadaic acid-induced movement of p38 kinase into the cytosol. These results imply that decreased p38 activity and its cytosolic translocation together with cellular resistance to cytoskeletal disorganization may play a significant role in resistance to phosphorylation-dependent apoptosis. Furthermore, the results imply that changes in cell shape may partially modulate the observed alterations in signal transduction induced by okadaic acid.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Actins / metabolism
  • Activating Transcription Factor 2
  • Animals
  • Apoptosis / drug effects*
  • Apoptosis / genetics
  • Benzoquinones
  • Cell Line
  • Cell Size / drug effects
  • Chromatin / drug effects
  • Chromatin / metabolism
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Cytosol / drug effects
  • Cytosol / metabolism
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Epithelial Cells / enzymology
  • Imidazoles / pharmacology
  • Kidney / cytology
  • Kidney / drug effects*
  • Kidney / enzymology
  • Lactams, Macrocyclic
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinases / metabolism*
  • Okadaic Acid / antagonists & inhibitors*
  • Okadaic Acid / pharmacology*
  • Okadaic Acid / toxicity
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-raf / antagonists & inhibitors
  • Proto-Oncogene Proteins c-raf / metabolism
  • Pyridines / pharmacology
  • Quinones / pharmacology*
  • Rats
  • Rifabutin / pharmacology
  • Signal Transduction / drug effects
  • Transcription Factors / metabolism
  • Transfection
  • p38 Mitogen-Activated Protein Kinases


  • Actins
  • Activating Transcription Factor 2
  • Benzoquinones
  • Chromatin
  • Cyclic AMP Response Element-Binding Protein
  • Enzyme Inhibitors
  • Imidazoles
  • Lactams, Macrocyclic
  • Pyridines
  • Quinones
  • Transcription Factors
  • Okadaic Acid
  • Rifabutin
  • herbimycin
  • Proto-Oncogene Proteins c-raf
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • 4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole
  • geldanamycin