Nuclear staining for the small heat shock protein αB-crystallin colocalizes with splicing factor SC35

Rijk, Anke F. van; Stege, G. J. J.; Bennink, Erik; May, Christian Albrecht; Bloemendal, H.

doi:10.1078/0171-9335-00321

Cited by 40 publications

(20 citation statements)

References 48 publications

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“…Both Hsp27 and alpha-B crystallin have been shown to interact with nuclear granules in nuclei of injured cells. Additionally, alpha-B crystallin interacts with nuclear speckles in the absence of stress, and in a phosphorylation dependent manner [21,25,53]. Here, we have shown a highly similar pattern of interactions for Hsp27.…”

Section: Discussionsupporting

confidence: 56%

Recruitment of phosphorylated small heat shock protein Hsp27 to nuclear speckles without stress

Bryantsev

Chechenova

Shelden

2007

Experimental Cell Research

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During stress, the mammalian small heat shock protein Hsp27 enters cell nuclei. The present study examines the requirements for entry of Hsp27 into nuclei of normal rat kidney (NRK) renal epithelial cells, and for its interactions with specific nuclear structures. We find that phosphorylation of Hsp27 is necessary for the efficient entry into nuclei during heat shock but not sufficient for efficient nuclear entry under control conditions. We further report that Hsp27 is recruited to an RNAse sensitive fraction of SC35 positive nuclear speckles, but not other intranuclear structures, in response to heat shock. Intriguingly, Hsp27 phosphorylation, in the absence of stress, is sufficient for recruitment to speckles found in post-anaphase stage mitotic cells. Additionally, pseudophosphorylated Hsp27 fused to a nuclear localization peptide (NLS) is recruited to nuclear speckles in unstressed interphase cells, but wildtype and nonphosphorylatable Hsp27 NLS fusion proteins are not. The expression of NLS-Hsp27 mutants does not enhance colony forming abilities of cells subjected to severe heat shock, but does regulate nuclear speckle morphology. These data demonstrate that phosphorylation, but not stress, mediates Hsp27 recruitment to an RNAse soluble fraction of nuclear speckles and support a site-specific role for Hsp27 within the nucleus.

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Section: Discussionsupporting

confidence: 56%

Recruitment of phosphorylated small heat shock protein Hsp27 to nuclear speckles without stress

Bryantsev

Chechenova

Shelden

2007

Experimental Cell Research

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“…Thus, several sHSPs enter, and presumably function, in nuclei. Hsp27, Hsp25 and aB-crystallin bind nucleoli and speckles, intranuclear structures populated by splicing factors, possibly regulating molecular processes or protecting proteins [77][78][79][80]. Immunofl uorescent staining of cultured C2C12 myoblasts and myotubes discloses the intranuclear position of aB-crystallin and Hsp25, showing that interaction with speckles varies as cells differentiate [78].…”

Section: Membranes Interact With Shspsmentioning

confidence: 95%

Small heat shock proteins: molecular structure and chaperone function

Sun

MacRae

2005

Cell. Mol. Life Sci.

437

352

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Small heat shock proteins (sHSPs) associate with nuclei, cytoskeleton and membranes, and as molecular chaperones they bind partially denatured proteins, thereby preventing irreversible protein aggregation during stress. sHSP monomers consist of a conserved alpha-crystallin domain of approximately 90 amino acid residues, bordered by variable amino- and carboxy-terminal extensions. The sHSPs undergo dynamic assembly into mono- and poly-disperse oligomers where the rate of disassembly affects chaperoning. The alpha-crystallin domain contains several beta-strands organized into two beta-sheets responsible for dimer formation, the basic building block of most sHSPS. The amino-terminal extension modulates oligomerization, subunit dynamics and substrate binding, whereas the flexible carboxy-terminal extension promotes solubility, chaperoning and oligomerization, the latter by inter-subunit linkage. Crystallization studies have revealed sHSP structure and function. Additionally, site-directed mutagenesis, biophysical investigations, functional studies and the discovery of relationships between mutated sHSPs and diseases have illuminated the role of sHSP within cells.

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“…45,46 It is also present in the nucleus and mitochondria. [47][48][49] In the cytoplasm it is associated with cytoskeletal proteins including actin, vimentin, and desmin. 50 Moreover, ␣Bc has together with other small heat shock proteins (HSP25 and HSP27) been shown to associate with GFAP and protect astrocytes against stress by proteasomal inhibition.…”

Section: Discussionmentioning

confidence: 99%

αB-Crystallin Is Elevated in Highly Infiltrative Apoptosis-Resistant Glioblastoma Cells

Goplen

Bougnaud

Rajčević

et al. 2010

The American Journal of Pathology

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We have previously established two distinct glioma phenotypes by serial xenotransplantation of human glioblastoma (GBM) biopsies in nude rats. These tumors undergo a gradual transition from a highly invasive nonangiogenic to a less-invasive angiogenic phenotype. In a protein screen to identify molecular markers associated with the infiltrative phenotype, we identified ␣-basic-crystallin (␣Bc) , a small heatshock protein with cytoprotective properties. Its increased expression in the infiltrative phenotype was validated by immunohistochemistry and Western blots , confirming its identity to be tumor-derived and not from the host. Stereotactic human GBM biopsies taken from MRI-defined areas verified stronger ␣Bc expression in the infiltrative edge compared to the tumor core. Cell migration assays and immunofluorescence staining showed ␣Bc to be expressed by migrating cells in vitro. To determine ␣Bc function, we altered its expression levels. ␣Bc siRNA depletion caused a loss of migrating tumor cells from biopsy spheroids and delayed monolayer wound closure. In contrast, glioma cell migration in a Boyden chamber assay was unaffected by either ␣Bc knockdown or overexpression, indicating that ␣Bc is not functionally linked to the cell migration machinery. However, after siRNA ␣Bc depletion, a significant sensitization of cells to various apoptotic inducers was observed (actinomycin, tumor necrosis factor ␣, and TNF-related apoptosisinducing ligand [TRAIL]). In conclusion, ␣Bc is overexpressed by highly migratory glioma cells where it plays a functional role in apoptosis resistance. (Am J Pathol

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Nuclear staining for the small heat shock protein αB-crystallin colocalizes with splicing factor SC35

Cited by 40 publications

References 48 publications

Recruitment of phosphorylated small heat shock protein Hsp27 to nuclear speckles without stress

Recruitment of phosphorylated small heat shock protein Hsp27 to nuclear speckles without stress

Small heat shock proteins: molecular structure and chaperone function

αB-Crystallin Is Elevated in Highly Infiltrative Apoptosis-Resistant Glioblastoma Cells

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