Molecular chaperones participate in folding of many
proteins and several families are known to exist in mammalian cells including the
small heat shock protein (sHSP) family. sHSPs have a molecular mass of 15-30 kDa and are known to be induced and phosphorylated in response to various stimuli. There are several reports describing the correlation between sHSPs and degenerative diseases. We have been reported that Hsp27 and
alpha B-crystallin were recruited to aggresome when cells were treated with
proteasome inhibitors. Expression of Hsp27 suppresses the cell death induced by expression of expanded
polyglutamine via down regulation of the oxidative stress pathway. Recently, a missense mutation in
alpha B-crystallin, R120G, has been found in a French family suffering from
desmin-related myopathy. Moreover, transgenic mice expressing R120G
alpha B-crystallin exhibit symptoms similar to
desmin-related myopathy. We recently examined the interaction of R120G
alpha B-crystallin and Hsp27 in mammalian cells and found that expression of R120G
alpha B-crystallin caused formation of inclusion bodies and co-expression of Hsp27 inhibited this formation of inclusion bodies. Clarification of physiological roles of sHSPs in degenerative diseases may lead to the development of new
therapy.