Expression of Heat Shock Protein 90 (hsp90) in Neural and Nonneural Tissues of the Control and Hyperthermic Rabbit

Abstract

Tissue-specific differences were apparent in the constitutive level of hsp90 in various body tissues of the unstressed rabbit. Western blotting with monoclonal antibody 29A revealed very low levels in muscle and highest levels in neural regions (cerebellum, cerebral hemispheres, and retina) and in testes and thymus. Intermediate levels were apparent in other tissues such as liver, kidney, heart, and small intestine. Following hyperthermia, induction of hsp90 was not detected with 1-D Western blotting in tissues which demonstrated high constitutive levels; however, elevations were noted in tissues which showed lower constitutive amounts of the protein, such as kidney, heart, and muscle. Immunocytochemical studies revealed that hsp90 is preferentially localized to neuronal cell populations in the rabbit brain and that this pattern does not alter following hyperthermic conditions which result in glial induction of hsp70. In kidney, where constitutive levels of hsp90 are lower than in brain, an induction of hsp90 was noted in renal tubules following hyperthermia.

EXPOSURE TO 2.45 GHz MICROWAVE RADIATION PROVOKES CEREBRAL CHANGES IN INDUCTION OF HSP-90 α/β HEAT SHOCK PROTEIN IN RAT.

“…To our knowledge no in vivo studies have described changes in the levels and distribution of the heat shock protein HSP-90 in several rat brain regions analyzed after acute controlled exposure of the animals to 2.45 GHz at non thermal SAR in a GTEM cell (see Tables 2, 3). In this study, we found that at 90 minutes post-irradiation, there was an increase in cellular HSP-90 and the same regional pattern of distribution was observed as in the cerebral cortex of non-irradiated rats [12] as also observed with other stimuli such as hyperthermia [39,40] anoxia [41] and alcohol [42]. As the cortex is the uppermost part of the brain structure, it may initially be the most strongly affected [43] in relation to the energy of non-ionizing radiation that the tissue absorbs -expressed as the specific absorption rate (SAR).…”

Retinal toxicity induced by small-molecule Hsp90 inhibitors in beagle dogs

“…Hsp90 is a protein that is widely distributed in the retina in various animals (Quraishi and Brown, 1995;Song and Sokolov, 2009) and is involved in maintaining stability of the junction between Müller cells and photoreceptor cells in the retina (Dean and Tytell, 2001). Furthermore, Hsp90 regulates proliferation and death of retinal cells (Arruda-Carvalho et al, 2007).…”

Time-dependent expression of heat shock proteins 70 and 90 in tissues of the anoxic western painted turtle

“…Interestingly, there was an upregulation in expression of five specific proteins in turtle hepatocytes under anoxia or heat shock but these proteins were not rigorously identified (Land and Hochachka, 1995). Heat shock proteins (Hsps) have been considered as possible candidates, since their expression is induced by various stresses such as hyperthermia, radiation, heavy metals, ischemia, anoxia and reoxygenation in anoxia-sensitive models (Airaksinen et al, 1998;Manzerra et al, 1997;Quraishi and Brown, 1995). Chang et al (2000) provided the first evidence of increased Hsp70 expression in painted turtle myocardium subjected to a 12·h forced dive, but the antibody they used did not distinguish between the constitutive (Hsp73) and inducible (Hsp72) isoform.…”

“…Similarly to Hsp70, Hsp90 expression is induced in the stressed cell (Kawagoe et al, 2001;Quraishi and Brown, 1995), where it binds to partially unfolded proteins, holding them in a folding-competent state until other chaperones, such as Hsp70, are recruited to help restore the original structure of the protein.…”