| First Author | Manicassamy S | Year | 2006 |
| Journal | J Immunol | Volume | 176 |
| Issue | 11 | Pages | 6709-16 |
| PubMed ID | 16709830 | Mgi Jnum | J:131799 |
| Mgi Id | MGI:3774483 | Doi | 10.4049/jimmunol.176.11.6709 |
| Citation | Manicassamy S, et al. (2006) Protein kinase C-theta-mediated signals enhance CD4+ T cell survival by up-regulating Bcl-xL. J Immunol 176(11):6709-16 |
| abstractText | Productive engagement of TCR results in delivering signals required for T cell proliferation as well as T cell survival. Blocking TCR-mediated survival signals, T cells undergo apoptosis instead of proliferation upon TCR stimulation. During the activation process, T cells produce IL-2, which acts as an extrinsic survival factor. In addition, TCR stimulation results in up-regulation of Bcl-xL to enhance T cell survival intrinsically. We show in this study that protein kinase C (PKC)-theta is required for enhancing the survival of activated CD4+ T cells by up-regulating Bcl-xL. In response to TCR stimulation, CD4+ PKC-theta-/- T cells failed to up-regulate Bcl-xL, and underwent accelerated apoptosis via a caspase- and mitochondria-dependent pathway. Similar to PKC-theta-deficient primary CD4+ T cells, small interfering RNA-mediated knockdown of PKC-theta in Jurkat cells also resulted in apoptosis upon TCR stimulation. Forced expression of Bcl-xL was sufficient to inhibit apoptosis observed in PKC-theta knockdown cells. Furthermore, ectopic expression of PKC-theta stimulated a reporter gene driven by a mouse Bcl-xL promoter. Whereas an inactive form of PKC-theta or knockdown of endogenous PKC-theta led to inhibition of Bcl-xL reporter. PKC-theta-mediated activation of Bcl-xL reporter was inhibited by dominant-negative IkappaB kinase beta or dominant-negative AP-1. Thus, the PKC-theta-mediated signals may function not only in the initial activation of naive CD4+ T cells, but also in their survival during T cell activation by regulating Bcl-xL levels through NF-kappaB and AP-1 pathways. |
