Distribution, phosphorylation, and activities of Hsp25 in heat-stressed H9c2 myoblasts: a functional link to cytoprotection

AL Bryantsev*, SA Loktionova, OP Ilyinskaya, EM Tararak, HH Kampinga, AE Kabakov

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    57 Citations (Scopus)

    Abstract

    The behavior of the endogenous heat shock protein 25 (Hsp25) in heat-stressed rat H9c2 myoblasts was studied. After mild or severe heating, this protein became less extractable with Triton X-100 and displayed characteristic immunofluorescence patterns, namely (1) granules in the nucleus, and (2) association with F-actin bundles in the cytoplasm. The intranuclear granulation of Hsp25 and its association with F-actin were sensitive to drugs affecting Hsp25 phosphorylation (cantharidin, sodium orthovanadate, SB203580, SB202190). Isoform analysis of Hsp25 translocated to the nucleus-free cytoskeletal fraction revealed only mono- and biphosphorylated Hsp25 and no unphosphorylated Hsp25. Transfected luciferase with initial localization in the nucleosol became colocalized with the Hsp25-containing granules after a heat shock treatment that denatured the enzyme in the cells. The association of Hsp25 with actin filaments after a mild heat stress conferred protection from subsequent F-actin-damaging treatments with cytochalasins (D and B) or severe heat stress. We hypothesize that (1) the binding of heat-denatured nucleosolic proteins to the Hsp25 contained in specific granular structures may serve for the subsequent chaperoning or degradation of the bound proteins, and (2) the actin cytoskeleton is stabilized by the direct targeting of phosphorylated Hsp25 to microfilament bundles.

    Original languageEnglish
    Pages (from-to)146-155
    Number of pages10
    JournalCell stress & chaperones
    Volume7
    Issue number2
    Publication statusPublished - Apr-2002

    Keywords

    • ALPHA-B-CRYSTALLIN
    • C-DEPENDENT ACTIVATION
    • P38 MAP KINASE
    • SHOCK-PROTEIN
    • OXIDATIVE STRESS
    • CYTOCHROME-C
    • IN-VIVO
    • ACTIN POLYMERIZATION
    • CONFERS RESISTANCE
    • MAMMALIAN-CELLS

    Cite this