Geldanamycin activates Hsp70 response and attenuates okadaic acid-induced cytotoxicity in human retinal pigment epithelial cells.

• Reversible protein phosphorylation regulates the biological activities of many human proteins involved in crucial cellular processes, e.g., protein-protein interactions, cell signaling, gene transcription, cell growth, and death. A malfunction of cellular homeostasis in retinal pigment epithelial (RPE) cells is involved in the age-related retinal degeneration. In this study, we examined cytotoxicity in human RPE cells subjected to the protein phosphatase inhibitor, okadaic acid (OA). Moreover, the influence of Hsp90 inhibitor geldanamycin (GA), a benzoquinone ansamycin, in cytoprotection was assessed. Hsp70 protein levels were analyzed by Western blot. Cellular viability was determined by LDH and MTT assays. To study apoptotic cell death, caspase-3 enzyme activity was measured by assaying the cleavage of a fluorescent peptide substrate and Hoechst dye was used to visualize nuclear morphology. OA treatment caused morphological changes and induced cytotoxicity by caspase-3-independent manner in the RPE cells. No evidence of nuclear fragmentation was observed in response to OA. Interestingly, GA treatment accumulated Hsp70 protein and attenuated OA-induced cytotoxicity. This study suggests that Hsp70 and Hsp90 are closely related to cytoprotection of RPE cells in response to protein phosphatase inhibition.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Cell- och molekylärbiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Cell and Molecular Biology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Oftalmologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Ophthalmology (hsv//eng)

Nyckelord

Opthalmology

retinal pigment epithelial cells

geldanamycin

heat shock protein

cell viability

biokemi

Biochemistry

cell research

cellforskning

oftalmiatrik

Ophtalmology

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