Dynamic localization of αB-crystallin at the microtubule cytoskeleton network in beating heart cells

αB-crystallin is highly expressed in the heart and slow skeletal muscle; however, the roles of αB-crystallin in the muscle are obscure. Previously, we showed that αB-crystallin localizes at the sarcomere Z-bands, corresponding to the focal adhesions of cultured cells. In myoblast cells, αB-crystalli...

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Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 2020-08, Vol.168 (2), p.125-137
Main Authors: Ohto-Fujita, Eri, Hayasaki, Saaya, Atomi, Aya, Fujiki, Soichiro, Watanabe, Toshiyuki, Boelens, Wilbert C, Shimizu, Miho, Atomi, Yoriko
Format: Article
Language:English
Subjects:
alpha-Crystallin B Chain - metabolism
Animals
Cells, Cultured
Cytoskeleton - metabolism
Female
Mice
Mice, Mutant Strains
Microtubules - metabolism
Myocytes, Cardiac - cytology
Myocytes, Cardiac - metabolism
Rats
Rats, Wistar
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Summary:αB-crystallin is highly expressed in the heart and slow skeletal muscle; however, the roles of αB-crystallin in the muscle are obscure. Previously, we showed that αB-crystallin localizes at the sarcomere Z-bands, corresponding to the focal adhesions of cultured cells. In myoblast cells, αB-crystallin completely colocalizes with microtubules and maintains cell shape and adhesion. In this study, we show that in beating cardiomyocytes α-tubulin and αB-crystallin colocalize at the I- and Z-bands of the myocardium, where it may function as a molecular chaperone for tubulin/microtubules. Fluorescence recovery after photobleaching (FRAP) analysis revealed that the striated patterns of GFP-αB-crystallin fluorescence recovered quickly at 37°C. FRAP mobility assay also showed αB-crystallin to be associated with nocodazole-treated free tubulin dimers but not with taxol-treated microtubules. The interaction of αB-crystallin and free tubulin was further confirmed by immunoprecipitation and microtubule sedimentation assay in the presence of 1-100 μM calcium, which destabilizes microtubules. Förster resonance energy transfer analysis showed that αB-crystallin and tubulin were at 1-10 nm apart from each other in the presence of colchicine. These results suggested that αB-crystallin may play an essential role in microtubule dynamics by maintaining free tubulin in striated muscles, such as the soleus or cardiac muscles.
ISSN:0021-924X
1756-2651
DOI:10.1093/jb/mvaa025