CARMA1 coiled-coil domain is involved in the oligomerization and subcellular localization of CARMA1 and is required for T cell receptor-induced NF-κB activation

T lymphocyte (T cell) activation and proliferation is induced by the activation of multiple signal transduction pathways. Earlier studies indicate that CARMA1, a Caspase Recruitment Domain (CARD) and Membrane-associated GUanylate Kinase domain (MAGUK)-containing scaffold protein, plays an essential role in NF-kappa B activation induced by the costimulation of T cell receptor (TCR) and CD28 molecules. However, the molecular mechanism by which CARMA1 mediates TCR-CD28 costimulation-induced NF-kappa B activation is not fully understood. Here we show that CARMA1 is constitutively oligomerized. This oligomerization of CARMA1 is through its Coiled-coil domain. Disruption of the predicted structure of the Coiled-coil domain of CARMA1 impaired its oligomerization and, importantly, abrogated CARMA1-mediated NF-kappa B activation. Interestingly, disruption of the CC1 domain abrogates CARMA1 localization, whereas disruption of the CC2 domain seems to inhibit CARMA1 self-association. Together, our results demonstrate that the oligomerization of CARMA1 is required for TCR-induced NF-kappa B activation.