Small heat shock protein αB-crystallin is part of cell cycle-dependent golgi reorganization

Abstract

αB-Crystallin is a developmentally regulated small heat shock protein known for its binding to a variety of denatured polypeptides and suppression of protein aggregation in vitro. Elevated levels of αB-crystallin are known to be associated with a number of neurodegenerative pathologies such as Alzheimer disease and multiple sclerosis. Mutations in αB-crystallin gene have been linked to desmin-related cardiomyopathy and cataractogenesis. The physiological function of this protein, however, is unknown. Using discontinuous sucrose density gradient fractionation of post-nuclear supernatants, prepared from rat tissues and human glioblastoma cell line U373MG, we have identified discrete membrane-bound fractions of αB-crystallin, which co-sediment with the Golgi matrix protein, GM130. Confocal microscopy reveals co-localization of αB-crystallin with BODIPY TR ceramide and the Golgi matrix protein, GM130, in the perinuclear Golgi in human glioblastoma U373MG cells. Examination of synchronized cultures indicated that αB-crystallin follows disassembly of the Golgi at prometaphase and its reassembly at the completion of cytokinesis, suggesting that this small heat shock protein, with its chaperone-like activity, may have an important role in the Golgi reorganization during cell division.