Involvement of Insulin/Phosphoinositide 3-Kinase/Akt Signal Pathway in 17β-Estradiol-mediated Neuroprotection

Autor: Xiaorui Yu, Xiaohong Zhou, Feng Li, James McGinnis, R. Elias, Sheng Li, Raju V. S. Rajala, Robert E. Anderson, Ryan R. Knapp, W. Cao, Xiaorong Yan
Rok vydání: 2004
Předmět:
Light
Tetrazolium Salts
Estrogen receptor
Apoptosis
Biochemistry
Rats
Sprague-Dawley
Phosphatidylinositol 3-Kinases
chemistry.chemical_compound
Recoverin
Insulin
LY294002
Enzyme Inhibitors
Phosphorylation
Coloring Agents
Cells
Cultured
Progesterone
Glutathione Transferase
Neurons
Estradiol
biology
Immunohistochemistry
Cell biology
Electrophoresis
Polyacrylamide Gel
Signal transduction
Protein Binding
Signal Transduction
medicine.medical_specialty
Lipoproteins
Morpholines
Blotting
Western
Nerve Tissue Proteins
DNA Fragmentation
Protein Serine-Threonine Kinases
Retina
src Homology Domains
Proto-Oncogene Proteins
Internal medicine
Hippocalcin
Electroretinography
In Situ Nick-End Labeling
medicine
Animals
Eye Proteins
Molecular Biology
Protein kinase B
PI3K/AKT/mTOR pathway
Dose-Response Relationship
Drug
Akt/PKB signaling pathway
Calcium-Binding Proteins
Retinal
Hydrogen Peroxide
Cell Biology
Receptor
Insulin
Rats
Tamoxifen
Thiazoles
Insulin receptor
Endocrinology
chemistry
Chromones
biology.protein
Proto-Oncogene Proteins c-akt
Zdroj: Journal of Biological Chemistry. 279:13086-13094
ISSN: 0021-9258
DOI: 10.1074/jbc.m313283200
Popis: In the present study, we tested the hypothesis that 17beta-estradiol (betaE2) is a neuroprotectant in the retina, using two experimental approaches: 1) hydrogen peroxide (H(2)O(2))-induced retinal neuron degeneration in vitro, and 2) light-induced photoreceptor degeneration in vivo. We demonstrated that both betaE2 and 17alpha-estradiol (alphaE2) significantly protected against H(2)O(2)-induced retinal neuron degeneration; however, progesterone had no effect. betaE2 transiently increased the phosphoinositide 3-kinase (PI3K) activity, when phosphoinositide 4,5-bisphosphate and [(32)gammaATP] were used as substrate. Phospho-Akt levels were also transiently increased by betaE2 treatment. Addition of the estrogen receptor antagonist tamoxifen did not reverse the protective effect of betaE2, whereas the PI3K inhibitor LY294002 inhibited the protective effect of betaE2, suggesting that betaE2 mediates its effect through some PI3K-dependent pathway, independent of the estrogen receptor. Pull-down experiments with glutathione S-transferase fused to the N-Src homology 2 domain of p85, the regulatory subunit of PI3K, indicated that betaE2 and alphaE2, but not progesterone, identified phosphorylated insulin receptor beta-subunit (IRbeta) as a binding partner. Pretreatment with insulin receptor inhibitor, HNMPA, inhibited IRbeta activation of PI3K. Systemic administration of betaE2 significantly protected the structure and function of rat retinas against light-induced photoreceptor cell degeneration and inhibited photoreceptor apoptosis. In addition, systemic administration of betaE2 activated retinal IRbeta, but not the insulin-like growth factor receptor-1, and produced a transient increase in PI3K activity and phosphorylation of Akt in rat retinas. The results show that estrogen has retinal neuroprotective properties in vivo and in vitro and suggest that the insulin receptor/PI3K/Akt signaling pathway is involved in estrogen-mediated retinal neuroprotection.
Databáze: OpenAIRE
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