Hsp27 suppresses the formation of inclusion bodies induced by expression of R120G alpha B-crystallin, a cause of desmin-related myopathy.
The R120G mutation in the small heat shock protein (sHSP) alpha B-crystallin has been identified in a family suffering from desmin-related myopathy. In this study, we characterized the features of transiently expressed R120G alpha B-crystallin in mammalian cells. In addition, we examined interactions of this mutant alpha B-crystallin with Hsp27, another representative sHSP. In HeLa cells, transiently expressed R120G alpha B-crystallin was mainly fractionated in the insoluble fraction, although wild-type alpha B-crystallin was predominantly found in the soluble fraction. In immunofluorescence studies, we found 15-25% of R120G alpha B-crystallin-expressing cells to contain multiple cytosolic inclusion bodies, in which Hsp27 was also localized. When R120G alpha B-crystallin and Hsp27 were transiently co-expressed in HeLa cells, the amount of R120G alpha B-crystallin in the soluble fraction was greater than with expression of R120G alpha B-crystallin alone. Moreover, co-expression resulted in reduced formation of inclusion bodies, suggesting that Hsp27 acts as a molecular chaperone for R120G alpha B-crystallin.
Ito
H
H
Institute for Developmental Research, Aichi Human Service Center, 713-8 Kamiya, Kasugai, Aichi 480-0392, Japan. itohide@inst-hsc.pref.aichi.jp
Kamei
K
K
Iwamoto
I
I
Inaguma
Y
Y
Tsuzuki
M
M
Kishikawa
M
M
Shimada
A
A
Hosokawa
M
M
Kato
K
K
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003893:Desmin / Q000378:metabolism*; D055551:HSP27 Heat-Shock Proteins; D006367:HeLa Cells; D006360:Heat-Shock Proteins; D006801:Humans; D002479:Inclusion Bodies / Q000378:metabolism / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009135:Muscular Diseases / Q000235:genetics* / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D014162:Transfection; D038203:alpha-Crystallin B Chain / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D003893:Desmin; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; D038203:alpha-Crystallin B Chain