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

A.L Bryantsev; M.B Chechenova; E.A Shelden

doi:10.1016/j.yexcr.2006.10.004

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

Journal article

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

A.L Bryantsev, M.B Chechenova and E.A Shelden

Experimental cell research, Vol.313(1), pp.195-209

2007

DOI: https://doi.org/10.1016/j.yexcr.2006.10.004

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https://hdl.handle.net/2376/110853

PMCID: PMC1893088

PMID: 17123510

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Abstract

Nucleus

mRNA

Hsp25

Epithelial cells

Hsp27

Heat shock

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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Title: Recruitment of phosphorylated small heat shock protein Hsp27 to nuclear speckles without stress
Creators: A.L Bryantsev - School of Molecular Biosciences, Washington State University, Pullman, WA, USA
M.B Chechenova - School of Molecular Biosciences, Washington State University, Pullman, WA, USA
E.A Shelden - School of Molecular Biosciences, Washington State University, Pullman, WA, USA
Publication Details: Experimental cell research, Vol.313(1), pp.195-209
Academic Unit: Molecular Biosciences, School of
Publisher: Elsevier Inc
Identifiers: 99900547157401842
Language: English
Resource Type: Journal article