DRAK2, a lymphoid-enriched DAP kinase, regulates the TCR activation threshold during thymocyte selection.
DAP kinases are a family of serine/threonine kinases known to regulate intrinsic apoptotic processes. DAP-related apoptotic kinase-2 (DRAK2) is highly expressed in lymphoid organs, with differential expression during thymocyte development. Low levels of transcript were observed in CD4/CD8 double-positive (DP) and double-negative populations, whereas single-positive thymocytes possessed elevated levels. Ex vivo stimulation of DP thymocytes with phorbol myristate acetate or antibodies that activate the TCR complex led to the accumulation of DRAK2 in a protein kinase C- and MAP Kinase-dependent fashion. Although DAP kinase family members are thought to potentiate apoptosis, ectopic expression of DRAK2 using retroviral transduction of primary T cells and NIH3T3 fibroblasts failed to decrease rates of survival, suggesting that DRAK2 expression is not sufficient to promote apoptosis. Rather, our results demonstrate that DRAK2 is a primary response gene activated by TCR stimulation in DP thymocytes. Further, we observed that DRAK2 controlled the threshold for calcium signaling in the thymus since positively selected Drak2-deficient thymocytes displayed a reduced requirement for TCR cross-linking. These findings are consistent with a role for DRAK2 in thymocyte selection and lymphoid maturation, and demonstrate that DRAK2 transduces non-apoptotic signals during thymocyte differentiation.[1]References
- DRAK2, a lymphoid-enriched DAP kinase, regulates the TCR activation threshold during thymocyte selection. Friedrich, M.L., Wen, B.G., Bain, G., Kee, B.L., Katayama, C., Murre, C., Hedrick, S.M., Walsh, C.M. Int. Immunol. (2005) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
