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Tripartite motif containing protein 27 negatively regulates CD4 T cells by ubiquitinating and inhibiting the class II PI3K-C2β.

The K(+) channel KCa3.1 is required for Ca(2+) influx and the subsequent activation of CD4 T cells. The class II phosphatidylinositol 3 kinase C2β (PI3KC2β) is activated by the T-cell receptor (TCR) and is critical for KCa3.1 channel activation. Tripartite motif containing protein 27 (TRIM27) is a member of a large family of proteins that function as Really Interesting New Gene (RING) E3 ubiquitin ligases. We now show that TRIM27 functions as an E3 ligase and mediates lysine 48 polyubiquitination of PI3KC2β, leading to a decrease in PI3K enzyme activity. By inhibiting PI3KC2β, TRIM27 also functions to negatively regulate CD4 T cells by inhibiting KCa3.1 channel activity and TCR-stimulated Ca(2+) influx and cytokine production in Jurkat, primary human CD4 T cells, and Th0, Th1, and Th2 CD4 T cells generated from TRIM27(-/-) mice. These findings provide a unique mechanism for regulating class II PI3Ks, and identify TRIM27 as a previously undescribed negative regulator of CD4 T cells.

Pubmed ID: 22128329


  • Cai X
  • Srivastava S
  • Sun Y
  • Li Z
  • Wu H
  • Zuvela-Jelaska L
  • Li J
  • Salamon RS
  • Backer JM
  • Skolnik EY


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

December 13, 2011

Associated Grants

  • Agency: NIDDK NIH HHS, Id: P60 DK020541
  • Agency: NIGMS NIH HHS, Id: R01 GM099873
  • Agency: NIAID NIH HHS, Id: R01AI052459
  • Agency: NIGMS NIH HHS, Id: R01GM084195

Mesh Terms

  • Animals
  • CD4-Positive T-Lymphocytes
  • Calcium
  • Cytokines
  • DNA-Binding Proteins
  • Humans
  • Intermediate-Conductance Calcium-Activated Potassium Channels
  • Ion Channel Gating
  • Jurkat Cells
  • Mice
  • Mucoproteins
  • Nuclear Proteins
  • Phosphatidylinositol 3-Kinases
  • Polyubiquitin
  • Protein Binding
  • Proteolysis
  • Receptors, Antigen, T-Cell
  • Signal Transduction
  • Th1 Cells
  • Th2 Cells
  • Two-Hybrid System Techniques
  • Ubiquitination