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

Abstract

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.

Ubiquitination-Deubiquitination by the TRIM27-USP7 Complex Regulates Tumor Necrosis Factor Alpha-Induced Apoptosis

“…A recent study that used Trim27-deficient mice, which were generated independently from ours, showed that TRIM27 catalyzes the K48-linked ubiquitination of the class II phosphatidylinositol 3 kinase C2␤ (PI3KC2␤), promoting inhibition of its enzymatic activity, and negatively regulates CD4 T cells by inhibiting TCR-stimulated Ca 2ϩ influx and cytokine production (48). TRIM27 also negatively regulates IgE receptor activation and downstream signaling by the same mechanism (49).…”

TRIM27 (tripartite motif containing 27)

“…TRIM27 has a critical role in regulating PTEN phosphatase activity through ubiquitination which inhibits PTEN increasing AKT signalling (Lee et al, 2013). TRIM27 functions as an E3 ligase to ubiquitinate and inhibit PI3K-C2beta's kinase activity and negatively regulates CD4 T cells (Cai et al, 2011). TRIM27 also negatively regulates IgE receptor activation and downstream signalling by the same mechanism (Srivastava et al, 2012).…”

Phosphatidylinositol-3-Kinase C2β and TRIM27 Function To Positively and Negatively Regulate IgE Receptor Activation of Mast Cells

“…TRIM27 Ϫ/Ϫ mice were generated from the embryonic stem (ES) cell line 345D11(The Center for Disease Modeling at The University of Toronto), which contained the exon-trapping plasmid pUPA, located between exons 1 and 2 of TRIM27 on mouse chromosome 13, and has been previously described (6). Bone marrow cells were cultured for 6 to 8 weeks in RPMI supplemented with interleukin 3 (IL-3) (20 ng/ml), stem cell factor (100 ng/ml), and 10% fetal calf serum (FCS).…”

“…We have recently found that the tripartite motif containing protein TRIM27 functions as an E3 ligase to ubiquitinate and inhibit PI3KC2␤'s kinase activity and, via this effect, functions to negatively regulate KCa3.1 channel activity and TCR-stimulated Ca 2ϩ influx and cytokine production in activated CD4 T cells (6). We now show that PI3KC2␤ is also essential for FcεRI activation of KCa3.1 and Ca 2ϩ influx in mast cells and that TRIM27 plays a similar role to negatively regulate KCa3.1 channel activity and FcεRI activation of mast cells in vitro and in vivo.…”