Desmin interacts with STIM1 and coordinates Ca2+ signaling in skeletal muscle
Hengtao Zhang, Victoria Graham Bryson, Chaojian Wang, TianYu Li, Jaclyn P. Kerr, Rebecca Wilson, Deborah M. Muoio, Robert J. Bloch, Christopher Ward, Paul B. Rosenberg
Hengtao Zhang, Victoria Graham Bryson, Chaojian Wang, TianYu Li, Jaclyn P. Kerr, Rebecca Wilson, Deborah M. Muoio, Robert J. Bloch, Christopher Ward, Paul B. Rosenberg
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Research Article Muscle biology

Desmin interacts with STIM1 and coordinates Ca2+ signaling in skeletal muscle

Abstract

Stromal interaction molecule 1 (STIM1), the sarcoplasmic reticulum (SR) transmembrane protein, activates store-operated Ca2+ entry (SOCE) in skeletal muscle and, thereby, coordinates Ca2+ homeostasis, Ca2+-dependent gene expression, and contractility. STIM1 occupies space in the junctional SR membrane of the triads and the longitudinal SR at the Z-line. How STIM1 is organized and is retained in these specific subdomains of the SR is unclear. Here, we identified desmin, the major type III intermediate filament protein in muscle, as a binding partner for STIM1 based on a yeast 2-hybrid screen. Validation of the desmin-STIM1 interaction by immunoprecipitation and immunolocalization confirmed that the CC1-SOAR domains of STIM1 interact with desmin to enhance STIM1 oligomerization yet limit SOCE. Based on our studies of desmin-KO mice, we developed a model wherein desmin connected STIM1 at the Z-line in order to regulate the efficiency of Ca2+ refilling of the SR. Taken together, these studies showed that desmin-STIM1 assembles a cytoskeletal-SR connection that is important for Ca2+ signaling in skeletal muscle.

Authors

Hengtao Zhang, Victoria Graham Bryson, Chaojian Wang, TianYu Li, Jaclyn P. Kerr, Rebecca Wilson, Deborah M. Muoio, Robert J. Bloch, Christopher Ward, Paul B. Rosenberg

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Figure 2

Interaction between STIM1 and desmin in the skeletal muscle.

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Interaction between STIM1 and desmin in the skeletal muscle. (A) C2C12 c...
(A) C2C12 cells expressed STIM1 and desmin during differentiation. Expression levels of STIM1 and desmin in C2C12 cell lysates collected from day 0 to day 5 differentiation were analyzed by immunoblotting using antibodies against STIM1 and desmin, respectively. Coomassie-stained membrane was used for loading control. (B) Desmin and STIM1 readily cross-linked to macromolecular complexes by DTBP. Lysates from C2C12 cells were treated with DTBP or DTBP and DTT. Immunoblotting for STIM1 and desmin identified 130 kD complexes in the DTBP-treated cell lysate that were lost after DTT treatment. Arrow indicates 130 kD complex. (C) Verification of STIM1 and desmin interaction by GST pulldown assay. Resins that bind to GST-STIM1 were used to incubate with skeletal muscle lysates prepared from WT mice. Anti-GST antibody was used to detect fusion proteins. Desmin was detected by specific antibody only in elutes from STIM1-GST beads. Experiments were performed in triplicate. (D) Co-IP of endogenous STIM1 and desmin in skeletal muscle. Anti-desmin and anti-STIM1 antibodies were incubated with skeletal muscle lysate (labeled on the top). Immunoblotting with a STIM1 antibody detected endogenous STIM1 protein in the desmin IP and STIM1 IP but not the control IP with IgG. WL, whole lysate. (E) Immunofluorescence staining and colocalization of STIM1 and desmin from WT FDB muscle fibers. (F) Expression profiles for STIM1 and desmin. The profile color matches image color for each protein. Scale bars: 5 μm for high-magnification images.