Regulation of membrane phospholipid asymmetry by Notch-mediated flippase expression controls the number of intraepithelial TCRαβ+CD8αα+ T cells

PLoS Biol. 2019 May 9;17(5):e3000262. doi: 10.1371/journal.pbio.3000262. eCollection 2019 May.

Abstract

Intestinal intraepithelial lymphocytes (IELs) expressing CD8αα on αβ T cells (TCRαβ+CD8αα+ IELs) have suppressive capabilities in enterocolitis, but the mechanism that maintains homeostasis and cell number is not fully understood. Here, we demonstrated that the number of TCRαβ+CD8αα+ IELs was severely reduced in mice lacking recombination signal binding protein for immunoglobulin kappa J region (Rbpj) or Notch1 and Notch2 in T cells. Rbpj-deficient TCRαβ+CD8αα+ IELs expressed low levels of Atp8a2, which encodes a protein with flippase activity that regulates phospholipid asymmetry of plasma membrane such as flipping phosphatidylserine in the inner leaflet of plasma membrane. Rbpj-deficient TCRαβ+CD8αα+ IELs cannot maintain phosphatidylserine in the inner leaflet of the plasma membrane. Furthermore, depletion of intestinal macrophages restored TCRαβ+CD8αα+ IELs in Rbpj-deficient mice, suggesting that exposure of phosphatidylserine on the plasma membrane in Rbpj-deficient TCRαβ+CD8αα+ IELs acts as an "eat-me" signal. Together, these results revealed that Notch-Atp8a2 is a fundamental regulator for IELs and highlighted that membrane phospholipid asymmetry controlled by Notch-mediated flippase expression is a critical determinant in setting or balancing the number of TCRαβ+CD8αα+ IELs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Animals
  • CD8-Positive T-Lymphocytes / metabolism*
  • Immunoglobulin J Recombination Signal Sequence-Binding Protein / metabolism
  • Intraepithelial Lymphocytes / metabolism*
  • Macrophages / metabolism
  • Male
  • Mice, Inbred C57BL
  • Phospholipid Transfer Proteins / metabolism
  • Phospholipids / metabolism*
  • Receptors, Antigen, T-Cell, alpha-beta / metabolism*
  • Receptors, Notch / metabolism*

Substances

  • Immunoglobulin J Recombination Signal Sequence-Binding Protein
  • Phospholipid Transfer Proteins
  • Phospholipids
  • Rbpj protein, mouse
  • Receptors, Antigen, T-Cell, alpha-beta
  • Receptors, Notch
  • ATP8a2 protein, mouse
  • Adenosine Triphosphatases

Grant support

This work was supported by MEXT KAKENHI grant number JP26110008 to KY, JSPS KAKENHI grant numbers JP 18K15191 to CI, and the Research Clusters program of Tokushima University to KY. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.