HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Data Buy All Versions of this Article: fj.08-116814v1 23/6/1728    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lanner, J. T. Articles by Westerblad, H. Search for Related Content PubMed PubMed Citation Articles by Lanner, J. T. Articles by Westerblad, H.

Knockdown of TRPC3 with siRNA coupled to carbon nanotubes results in decreased insulin-mediated glucose uptake in adult skeletal muscle cells

Johanna T. Lanner^*, Joseph D. Bruton^*, Yohannes Assefaw-Redda, Zoita Andronache, Shi-Jin Zhang^*, Denise Severa^*, Zhi-Bin Zhang, Werner Melzer, Shi-Li Zhang, Abram Katz^* and Håkan Westerblad^*

^* Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden;

School of Information and Communication Technology, Royal Institute of Technology, Stockholm, Sweden; and

Institut für Angewandte Physiologie, Universität Ulm, Ulm, Germany

¹Correspondence: Karolinska Institutet, Department of Physiology and Pharmacology, 171 77 Stockholm, Sweden. E-mail: lanner{at}bcm.tmc.edu

The involvement of Ca²⁺ in the insulin-mediated signaling cascade, resulting in glucose uptake in skeletal muscle, is uncertain. Here, we test the hypothesis that Ca²⁺ influx through canonical transient receptor potential 3 (TRPC3) channels modulates insulin-mediated glucose uptake in adult skeletal muscle. Experiments were performed on adult skeletal muscle cells of wild-type (WT) and obese, insulin-resistant ob/ob mice. Application of the diacylglycerol analog 1-oleyl-2-acetyl-sn-glycerol (OAG) induced a nonselective cation current, which was inhibited by the addition of anti-TRPC3 antibody in the patch pipette and smaller in ob/ob than in WT cells. Knockdown of TRPC3, using a novel technique based on small interfering RNA (siRNA) coupled to functionalized carbon nanotubes, resulted in pronounced (70%) decreases in OAG-induced Ca²⁺ influx and insulin-mediated glucose uptake. TRPC3 and the insulin-sensitive glucose transporter 4 (GLUT4) coimmunoprecipitated, and immunofluorescence staining showed that they were colocalized in the proximity of the transverse tubular system, which is the predominant site of insulin-mediated glucose transport in skeletal muscle. In conclusion, our results indicate that TRPC3 interacts functionally and physically with GLUT4, and Ca²⁺ influx through TRPC3 modulates insulin-mediated glucose uptake. Thus, TRPC3 is a potential target for treatment of insulin-resistant conditions.—Lanner, J. T., Bruton, J. D., Assefaw-Redda, Y., Andronache, Z., Zhang, S.-J., Severa, D., Zhang, Z.-B., Melzer, W., Zhang, S.-L., Katz, A., Westerblad, H. Knockdown of TRPC3 with siRNA coupled to carbon nanotubes results in decreased insulin-mediated glucose uptake in adult skeletal muscle cells.

Key Words: Ca²⁺ • sarcolemma • transverse tubules • near-membrane Ca²⁺ • colocalization