Cellular distribution of alpha B-crystallin in non-lenticular tissues.

Iwaki, Toru; Kume-Iwaki, A.; Goldman, J. E.

doi:10.1177/38.1.2294148

Cited by 272 publications

(151 citation statements)

References 22 publications

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“…Other than muscle, they are also seen in prostate, ovary, intestine, and colon. As shown previously, ␣B-crystallin mRNA is also expressed in kidney and brain (37). Compared with these sHSPs, the expression of HSPB3 mRNA is unusual in its exclusive expression in striated muscles; it is also unique in its preferential expression in heart.…”

Section: Identification Of a Novel Shsp With A Molecular Mass Of 17 Kdamentioning

confidence: 80%

“…Although there have been several studies in which the tissue distributions of three sHSPs, HSP27, ␣B-crystallin, and p20, were examined individually (18,19,26,(37)(38)(39), this is the first study that examines on the same basis all known members other than lens-specific ␣A-crystallin. Fig.…”

Section: Identification Of a Novel Shsp With A Molecular Mass Of 17 Kdamentioning

confidence: 99%

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Muscle Develops a Specific Form of Small Heat Shock Protein Complex Composed of MKBP/HSPB2 and HSPB3 during Myogenic Differentiation

Sugiyama

Suzuki

Kishikawa

et al. 2000

Journal of Biological Chemistry

279

255

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Previously, we identified a new mammalian sHSP, MKBP, as a myotonic dystrophy protein kinase-binding protein, and suggested its important role in muscle maintenance (Suzuki, A., Sugiyama, Y., Hayashi, Y., Nyu-i, N., Yoshida, M., Nonaka, I., Ishiura, S., Arahata, K., and Ohno, S. (1998) J. Cell Biol. 140, 1113-1124). In this paper, we develop the former work by performing extensive characterization of five of the six sHSPs so far identified, that is, HSP27, ␣B-crystallin, p20, MKBP/ HSPB2, and HSPB3, omitting lens-specific ␣A-crystallin. Tissue distribution analysis revealed that although each sHSP shows differential constitutive expression in restricted tissues, tissues that express all five sHSPs are only muscle-related tissues. Especially, the expressions of HSPB3, identified for the first time as a 17-kDa protein in this paper, and MKBP/HSPB2 are distinctly specific to muscles. Moreover, these sHSPs form an oligomeric complex with an apparent molecular mass of 150 kDa that is completely independent of the oligomers formed by HSP27, ␣B-crystallin, and p20. The expressions of MKBP/HSPB2 and HSPB3 are induced during muscle differentiation under the control of MyoD, suggesting that the sHSP oligomer comprising MKBP/ HSPB2 and HSPB3 represents an additional system closely related to muscle function. The functional divergence among sHSPs in different oligomers is also demonstrated in several ways: 1) an interaction with myotonic dystrophy protein kinase, which has been suggested to be important for the maintenance of myofibril integrity, was observed only for MKBP/HSPB2; 2) a myotube-specific association with actin bundles was observed for HSP27 and ␣B-crystallin, but not for MKBP/ HSPB2; and 3) sHSPs whose mRNAs are induced by heat shock are ␣B-crystallin and HSP27. Taken together, the results suggest that muscle cells develop two kinds of stress response systems composed of diverged sHSP members, and that these systems work independently in muscle maintenance and differentiation.Heat shock and numerous other stress conditions lead to the rapid induction of several genes whose protein products, collectively called heat shock proteins (HSPs), 1 play protective roles in cell survival (1). Considering that muscles are frequently subjected to severe conditions caused by heat, oxidative, and mechanical stresses, especially during exercise (2), these HSPs may be especially important in this particular tissue. In fact, several HSPs, including HSP60, 70, and 90, have been shown to be induced after exhaustive exercise (3). In addition, the inducible isoform of HSP70 has been shown to be constitutively expressed in a certain type of skeletal muscle fiber (4), suggesting that muscle cells are chronically ready to respond to frequent stresses. However, there have been limited numbers of studies that focus on HSPs in muscle cells.HSPs with low molecular masses of 15-30 kDa are called small heat shock proteins (sHSPs); they commonly share a homologous sequence of about 80 amino acids called the "␣-crystallin domain" (5). Among ...

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Section: Identification Of a Novel Shsp With A Molecular Mass Of 17 Kdamentioning

confidence: 80%

Section: Identification Of a Novel Shsp With A Molecular Mass Of 17 Kdamentioning

confidence: 99%

Muscle Develops a Specific Form of Small Heat Shock Protein Complex Composed of MKBP/HSPB2 and HSPB3 during Myogenic Differentiation

Sugiyama

Suzuki

Kishikawa

et al. 2000

Journal of Biological Chemistry

279

255

View full text Add to dashboard Cite

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“…Of the two constituents of α-crystallin, αB-crystallin is the more widespread chaperone with versatile functions: Besides the eye lens, it is abundantly expressed in other tissues (7) and upregulated by various stresses (8). There is growing evidence for its implications in several neuropathological diseases (9) including Parkinson disease, Alzheimer's disease, and multiple sclerosis (10,11) as well as in cancer (12).…”

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confidence: 99%

Multiple molecular architectures of the eye lens chaperone αB-crystallin elucidated by a triple hybrid approach

Braun

Zacharias²,

Peschek³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

150

177

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The molecular chaperone αB-crystallin, the major player in maintaining the transparency of the eye lens, prevents stress-damaged and aging lens proteins from aggregation. In nonlenticular cells, it is involved in various neurological diseases, diabetes, and cancer. Given its structural plasticity and dynamics, structure analysis of αB-crystallin presented hitherto a formidable challenge. Here we present a pseudoatomic model of a 24-meric αB-crystallin assembly obtained by a triple hybrid approach combining data from cryoelectron microscopy, NMR spectroscopy, and structural modeling. The model, confirmed by cross-linking and mass spectrometry, shows that the subunits interact within the oligomer in different, defined conformations. We further present the molecular architectures of additional well-defined αB-crystallin assemblies with larger or smaller numbers of subunits, provide the mechanism how "heterogeneity" is achieved by a small set of defined structural variations, and analyze the factors modulating the oligomer equilibrium of αB-crystallin and thus its chaperone activity.T he most prominent member of the small heat-shock protein (sHsp) family, α-crystallin, is expressed at high concentrations in the vertebrate eye lens (1) where it plays a major role in maintaining lens transparency (2). Moreover, it protects lens epithelial cells from environmental stress by preventing aggregation of stress-damaged proteins (3). In the low protein turnover milieu of the eye lens, proteins gradually deteriorate throughout the lifespan due to posttranslational modifications and become increasingly prone to aggregation leading to opacity. Thus, the chaperone action of α-crystallin is vital for maintaining the eye lens transparency. Lenticular α-crystallin is composed of two homologous polypeptides, αA-and αB-crystallin, which comprise 173 and 175 amino acid residues, respectively (1, 4). Both proteins possess a three-domain organization consisting of the α-crystallin domain (ACD), a consensus sequence of approximately 90 amino acids common to all sHsps, flanked by a diverse N-terminal region and a moderately conserved C-terminal extension (5, 6).Of the two constituents of α-crystallin, αB-crystallin is the more widespread chaperone with versatile functions: Besides the eye lens, it is abundantly expressed in other tissues (7) and upregulated by various stresses (8). There is growing evidence for its implications in several neuropathological diseases (9) including Parkinson disease, Alzheimer's disease, and multiple sclerosis (10, 11) as well as in cancer (12). In vitro, αB-crystallin prevents the stress-induced aggregation of partially folded polypeptides (3, 13).The αB-crystallin assembles into homooligomers with a variable number of subunits, primarily 24-32 (14-16), and the subunits exchange between homooligomers (17). These properties have hampered high-resolution structural studies on the functionally assembled, full-length protein. An earlier cryoelectron microscopy (cryo-EM) study (18) presented at low resolution (3...

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“…The hetero-oligomeric mixtures of the 2 isoforms cannot be separated under native conditions (12). Whereas ␣A-crystallin expression is mainly limited to the lens and only trace amounts are found in few other tissues (13), ␣B-crystallin is ubiquitously expressed and is abundant in brain, heart, and muscle (14). The importance of ␣-crystallins as molecular chaperones was demonstrated by knock-out mice, in which the deletion of ␣A-crystallin led to young onset cataract formation (15).…”

mentioning

confidence: 99%

The eye lens chaperone α-crystallin forms defined globular assemblies

Peschek

Braun

Franzmann

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

131

121

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␣-Crystallins are molecular chaperones that protect vertebrate eye lens proteins from detrimental protein aggregation. ␣B-Crystallin, 1 of the 2 ␣-crystallin isoforms, is also associated with myopathies and neuropathological diseases. Despite the importance of ␣-crystallins in protein homeostasis, only little is known about their quaternary structures because of their seemingly polydisperse nature. Here, we analyzed the structures of recombinant ␣-crystallins using biophysical methods. In contrast to previous reports, we show that ␣B-crystallin assembles into defined oligomers consisting of 24 subunits. The 3-dimensional (3D) reconstruction of ␣B-crystallin by electron microscopy reveals a spherelike structure with large openings to the interior of the protein.␣A-Crystallin forms, in addition to complexes of 24 subunits, also smaller oligomers and large clusters consisting of individual oligomers. This propensity might explain the previously reported polydisperse nature of ␣-crystallin.electron microscopy ͉ molecular chaperone ͉ protein aggregation ͉ small heat shock protein ͉ stress response

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Cellular distribution of alpha B-crystallin in non-lenticular tissues.

Cited by 272 publications

References 22 publications

Muscle Develops a Specific Form of Small Heat Shock Protein Complex Composed of MKBP/HSPB2 and HSPB3 during Myogenic Differentiation

Muscle Develops a Specific Form of Small Heat Shock Protein Complex Composed of MKBP/HSPB2 and HSPB3 during Myogenic Differentiation

Multiple molecular architectures of the eye lens chaperone αB-crystallin elucidated by a triple hybrid approach

The eye lens chaperone α-crystallin forms defined globular assemblies

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