HSPB7 is a SC35 speckle resident small heat shock protein

Biochim Biophys Acta. 2009 Aug;1793(8):1343-53. doi: 10.1016/j.bbamcr.2009.05.005. Epub 2009 May 21.


Background: The HSPB family is one of the more diverse families within the group of HSP families. Some members have chaperone-like activities and/or play a role in cytoskeletal stabilization. Some members also show a dynamic, stress-induced translocation to SC35 splicing speckles. If and how these features are interrelated and if they are shared by all members are yet unknown.

Methods: Tissue expression data and interaction and co-regulated gene expression data of the human HSPB members was analyzed using bioinformatics. Using a gene expression library, sub-cellular distribution of the diverse members was analyzed by confocal microscopy. Chaperone activity was measured using a cellular luciferase refolding assay.

Results: Online databases did not accurately predict the sub-cellular distribution of all the HSPB members. A novel and non-predicted finding was that HSPB7 constitutively localized to SC35 splicing speckles, driven by its N-terminus. Unlike HSPB1 and HSPB5, that chaperoned heat unfolded substrates and kept them folding competent, HSPB7 did not support refolding.

Conclusion: Our data suggest a non-chaperone-like role of HSPB7 at SC35 speckles.

General significance: The functional divergence between HSPB members seems larger than previously expected and also includes non-canonical members lacking classical chaperone-like functions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Coiled Bodies / metabolism
  • Female
  • HSP27 Heat-Shock Proteins / chemistry
  • HSP27 Heat-Shock Proteins / genetics
  • HSP27 Heat-Shock Proteins / metabolism
  • HeLa Cells
  • Heat-Shock Proteins
  • Heat-Shock Proteins, Small / chemistry*
  • Heat-Shock Proteins, Small / genetics
  • Heat-Shock Proteins, Small / metabolism*
  • Humans
  • Male
  • Molecular Chaperones
  • Pregnancy
  • Protein Denaturation
  • Protein Folding
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • RNA Splicing
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Subcellular Fractions / metabolism
  • Tissue Distribution
  • Transcriptional Activation


  • HSP27 Heat-Shock Proteins
  • HSPB1 protein, human
  • Heat-Shock Proteins
  • Heat-Shock Proteins, Small
  • Molecular Chaperones
  • RNA, Messenger
  • Recombinant Proteins