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

J. Biol. Chem., Vol. 279, Issue 50, 52414-52424, December 10, 2004

This Article Full Text Full Text (PDF) All Versions of this Article: 279/50/52414    most recent M408872200v1 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Solís-Garrido, L. M. Articles by Montiel, C. Search for Related Content PubMed PubMed Citation Articles by Solís-Garrido, L. M. Articles by Montiel, C. Social Bookmarking                      What's this?

Cross-talk between Native Plasmalemmal Na⁺/Ca²⁺ Exchanger and Inositol 1,4,5-Trisphosphate-sensitive Ca²⁺ Internal Store in Xenopus Oocytes^*

Luisa M. Solís-Garrido, Antonio J. Pintado, Eva Andrés-Mateos, María Figueroa, Carlos Matute¶, and Carmen Montiel||

From the Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain and the ^¶Departamento de Neurociencias, Facultad de Medicina, Universidad del País Vasco, 48940 Leioa, Spain

Because the presence of a native plasmalemmal Na⁺/Ca²⁺ exchange (NCX) activity in Xenopus laevis oocytes remains controversial, its possible functional role in these cells is poorly understood. Here, in experiments on control oocytes and oocytes overexpressing a cloned NCX1 cardiac protein, confocal microscopy combined with electrophysiological techniques reveal that these cells express an endogenous NCX protein forming a functional microdomain with inositol 1,4,5-trisphosphate receptors (InsP₃R) that controls intracellular Ca²⁺ in a restricted subplasmalemmal space. The following data obtained in control denuded oocytes are consistent with this view: (i) reverse transcription-PCR revealed that the oocyte expresses two transcripts for the NCX1 and NCX3 isoforms; (ii) immunofluorescence experiments showed that native NCX1 and InsP₃Rs are largely codistributed in discrete areas of the plasma membrane in close apposition to the cortical endoplasmic reticulum shell; (iii) when stimulated by rabbit serum, which elevates intracellular Ca²⁺ mediated by InsP₃, voltage-clamped oocytes display a large and transient inward Ca²⁺-activated chloride current, I_Cl(Ca), as a result of the Ca²⁺ rise at the inner surface membrane; (iv) this current is significantly enhanced by KB-R7943 and by an extracellular sodium-depleted medium, two maneuvers that prevent "Ca²⁺ extrusion" via NCX; and (v) blocking NCX enhanced the I_Cl(Ca) elicited by InsP₃ but not by Ca²⁺ photolysis in oocytes injected with the respective caged compounds. Moreover, overexpression of cardiac NCX1, confirmed by confocal microscopy, has functional consequences for the "Ca²⁺ influx" but not for the serum-elicited "Ca²⁺ efflux" mode of basal exchange activity and does not alter the number of endogenous NCX/InsP₃Rs colocalization sites. Our results suggest that native NCX, because of its strategic position, may regulate InsP₃-mediated Ca²⁺ signaling during the early phases of oocyte maturation and/or fertilization, and furthermore foreign cardiac protein is excluded from the Ca²⁺ microdomains surrounding the native NCX/InsP₃Rs complex in the oocyte.

Received for publication, August 4, 2004

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank^TM/EBI Data Bank with accession number(s) AY753310

^* This work was supported by Grant SAF2002-01851 from the Ministerio de Ciencia y Tecnología, Spain (to C. Montiel). 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.

Both authors contributed equally to this work.

^|| To whom correspondence should be addressed: Dept. de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo 4, 28029 Madrid, Spain. Tel.: 34-91-4975390; Fax: 34-91-4975353; E-mail: carmen.montiel{at}uam.es.

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

This article has been cited by other articles:

				P. Eder, D. Probst, C. Rosker, M. Poteser, H. Wolinski, S.D. Kohlwein, C. Romanin, and K. Groschner Phospholipase C-dependent control of cardiac calcium homeostasis involves a TRPC3-NCX1 signaling complex Cardiovasc Res, January 1, 2007; 73(1): 111 - 119. [Abstract] [Full Text] [PDF]

				R. Serantes, F. Arnalich, M. Figueroa, M. Salinas, E. Andres-Mateos, R. Codoceo, J. Renart, C. Matute, C. Cavada, A. Cuadrado, et al. Interleukin-1beta Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway: RELEVANCE TO SEPSIS-ASSOCIATED ENCEPHALOPATHY J. Biol. Chem., May 26, 2006; 281(21): 14632 - 14643. [Abstract] [Full Text] [PDF]