Store-operated cation entry mediated by CD20 in membrane rafts

J Biol Chem. 2003 Oct 24;278(43):42427-34. doi: 10.1074/jbc.M308802200. Epub 2003 Aug 14.

Abstract

B cell activation requires sustained elevation of cytoplasmic free calcium, achieved by influx through store-operated calcium (SOC) channels. The molecular identity of these channels is not known. Ectopic expression of the raft-associated tetraspan protein CD20 in Chinese hamster ovary cells introduced a novel SOC entry pathway that was permeable to strontium as well as to calcium. The activity of this SOC pathway was abolished by deletion of a cytoplasmic sequence in CD20 essential for its efficient raft localization. Strontium-permeable SOC channels were detected in B cells, and B cell receptor-stimulated influx was significantly reduced by downregulation of CD20 expression using short interfering RNA and also by cholesterol depletion. This is the first evidence that raft-associated CD20 constitutes a component of a SOC entry pathway activated by the B cell receptor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD20 / physiology*
  • B-Lymphocytes / metabolism
  • COS Cells
  • Calcium / metabolism*
  • Calcium Channels / metabolism
  • Cell Membrane Permeability
  • Cholesterol / pharmacology
  • Cricetinae
  • Down-Regulation / drug effects
  • Humans
  • Ion Transport
  • Membrane Microdomains / metabolism*
  • RNA, Small Interfering / pharmacology
  • Strontium / metabolism

Substances

  • Antigens, CD20
  • Calcium Channels
  • RNA, Small Interfering
  • Cholesterol
  • Calcium
  • Strontium