In recent years, extensive research has been conducted into the functions of specific chaperones known as Heat-shock Proteins (Hsp), and the responses they mediate. Heat-shock proteins are a form of cellular defense employed by an organism when faced with harsh environmental conditions and deleterious genetic mutation. Massimo Pigliucci revealed the effects of inhibiting or altering the expression of a particular Heat-shock protein (Hsp90) gene within two small organisms; the fruit fly and Arabidopsis thaliana plant. The results revealed hidden genetic mutations that had previously been buffered by the chaperone, proving that heat-shock proteins play an important role in maintaining a balance between stability and change. What about other stresses such as physiological changes? Does Hsp90 provide some means of protection against normal abnormalities induced by the organism’s own body? A study conducted by Gordon P. Meares and colleagues, tested this theory by measuring the effect of Hsp90 inhibition on the activation of Akt, an important signaling molecule needed for glucose transport. After inhibiting Hsp90 with geldanamycin, amplified Akt phosphorylation, induced by insulin, was observed. Upon removal of the inhibitor, Hsp90 began to regulate Akt signaling by facilitating phosphatase-mediated dephosphorylation of Akt. These observations indicate that Hsp90 normally plays an important role in buffering these signals.
Thus, Hsp90 not only buffers the cellular effects brought upon by mutations and environmental stresses, but also buffers physiological activities of the body necessary for survival.
Daniel Tang
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Primary Source
Gordon P. Meares, Anna A. Zmijewska and Richard S. Jope, (2004), Heat shock protein-90 dampens and directs signaling stimulated by insulin-like growth factor-1 and insulin, FEBS Letters, Vol. 574 Issues 1-3, pp 181-186
Secondary Source
Pigliucci, M. (2002). Developmental genetics: Buffer zone. Nature, Vol. 417, pp 598-599
