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This Article Full Text Full Text (PDF) All Versions of this Article: jimmunol.0900613v1 183/10/6296    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Google Scholar Articles by Nicolaou, S. A. Articles by Conforti, L. PubMed PubMed Citation Articles by Nicolaou, S. A. Articles by Conforti, L.

Localization of Kv1.3 Channels in the Immunological Synapse Modulates the Calcium Response to Antigen Stimulation in T Lymphocytes¹

Stella A. Nicolaou,^2* Lisa Neumeier,^2* Ashleigh Steckly,^* Vladimir Kucher,^* Koichi Takimoto, and Laura Conforti^3*

^*Department of Internal Medicine and Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, OH 45267; and Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan

The immunological synapse (IS), a highly organized structure that forms at the point of contact between a T cell and an APC, is essential for the proper development of signaling events, including the Ca²⁺ response. Kv1.3 channels control Ca²⁺ homeostasis in human T cells and move into the IS upon Ag presentation. However, the process involved in channel accumulation in the IS and the functional implications of this localization are not yet known. Here we define the movement of Kv1.3 into the IS and study whether Kv1.3 localization into the IS influences Ca²⁺ signaling in Jurkat T cells. Crosslinking of the channel protein with an extracellular Ab limits Kv1.3 mobility and accumulation at the IS. Moreover, Kv1.3 recruitment to the IS does not involve the transport of newly synthesized channels and it does not occur through recycling of membrane channels. Kv1.3 localization in the IS modulates the Ca²⁺ response. Blockade of Kv1.3 movement into the IS by crosslinking significantly increases the amplitude of the Ca²⁺ response triggered by anti-CD3/anti-CD28-coated beads, which induce the formation of the IS. On the contrary, the Ca²⁺ response induced by TCR stimulation without the formation of the IS with soluble anti-CD3/anti-CD28 Abs is unaltered. The results presented herein indicate that, upon Ag presentation, membrane-incorporated Kv1.3 channels move along the plasma membrane to localize in the IS. This localization is important to control the amplitude of the Ca²⁺ response, and disruption of this process can account for alterations of downstream Ca²⁺-dependent signaling events.

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 This work was supported by National Institutes of Health Grants CA95286 and AI083076 and American Heart Association Ohio Affiliate Grant-in-Aid 0855457D to L.C. S.A.N. was supported by a American Heart Association Ohio Affiliate Fellowship 0615213B and A.S. by a Fellowship of the National Science Foundation Research Experiences for Undergraduates Program (no. 0647677).

² S.A.N. and L.N. contributed equally to this work.

³ Address correspondence and reprint requests to Dr. Laura Conforti, Department of Internal Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267. E-mail address: Laura.Conforti{at}uc.edu

⁴ Abbreviations used in this paper: [Ca²⁺]_i, intracellular Ca²⁺ concentration; CHX, cycloheximide; CRAC, Ca²⁺ release-activated Ca²⁺ channel; DIP, dynamin inhibitor peptide; IS, immunological synapse; SLE, systemic lupus erythematosus.