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

J. Biol. Chem., Vol. 283, Issue 26, 18086-18098, June 27, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/26/18086    most recent M801821200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map 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 Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Stumpf, T. Articles by Fecher-Trost, C. Search for Related Content PubMed PubMed Citation Articles by Stumpf, T. Articles by Fecher-Trost, C. Social Bookmarking                      What's this?

The Human TRPV6 Channel Protein Is Associated with Cyclophilin B in Human Placenta^*

Tobias Stumpf, Qi Zhang, Daniela Hirnet, Urs Lewandrowski, Albert Sickmann, Ulrich Wissenbach^¶, Janka Dörr, Christian Lohr^||, Joachim W. Deitmer^||, and Claudia Fecher-Trost¹

From the Abteilungen Proteinfunktion/Proteomics and Allgemeine Zoologie des Fachbereichs Biologie, Technische Universität Kaiserslautern, P. O. Box 3049, D-67663 Kaiserslautern, Germany, ^¶Experimentelle und Klinische Pharmakologie und Toxikologie, Universitaet des Saarlandes, Geb 46, D-66421 Homburg, Germany, and ^||Rudolf-Virchow-Center, Deutsche Forschungsgemeinschaft Research Center for Experimental Biomedicine, University of Wuerzburg, Versbacher Strasse 9, D-9707 Würzburg, Germany

Transcellular calcium transport in the kidney, pancreas, small intestine, and placenta is partly mediated by transient receptor potential (TRP) channels. The highly selective TRPV6 calcium channel protein is most likely important for the calcium transfer in different specialized epithelial cells. In the human placenta the protein is expressed in trophoblast tissue, where it is implicated in the transepithelial calcium transfer from mother to the fetus. We enriched the TRPV6 channel protein endogenously expressed in placenta together with annexin A2 and cyclophilin B (CypB), which is a member of the huge immunophilin family. In the human placenta TRPV6 and CypB are mainly located intracellularly in the syncytiotrophoblast layer, but a small amount of the mature glycosylated TRPV6 channel protein and CypB is also expressed in microvilli apical membranes, the fetomaternal barrier. To understand the role of CypB on the TRPV6 channel function, we evaluated the effect of CypB co-expression on TRPV6-mediated calcium uptake into Xenopus laevis oocytes expressing TRPV6. A significant increase of TRPV6-mediated calcium uptake was observed after CypB/TRPV6 co-expression. This stimulatory effect of CypB was reversed by the immunosuppressive drug cyclosporin A, which inhibits the enzymatic activity of CypB. Cyclosporin A had no significant effect on TRPV6 and CypB protein expression levels in the oocytes. In summary, our results establish CypB as a new TRPV6 accessory protein with potential involvement in TRPV6 channel activation through its peptidyl-prolyl cis/trans isomerase activity.

Received for publication, March 6, 2008 , and in revised form, April 25, 2008.

^* This work was supported by Deutsche Forschungsgemeinschaft Grants Fe 629/1-2 and FZT-82, Graduiertenkolleg Grant 845/1, and by the Stiftung Rheinland Pfalz für Innovation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed. Tel.: 49-631-2054838; Fax: 49-631-2053251; E-mail: fecher{at}biologie.uni-kl.de.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?