| First Author | Thien CB | Year | 2003 |
| Journal | J Exp Med | Volume | 197 |
| Issue | 4 | Pages | 503-13 |
| PubMed ID | 12591907 | Mgi Jnum | J:81965 |
| Mgi Id | MGI:2450459 | Doi | 10.1084/jem.20021498 |
| Citation | Thien CB, et al. (2003) A mouse with a loss-of-function mutation in the c-Cbl TKB domain shows perturbed thymocyte signaling without enhancing the activity of the ZAP-70 tyrosine kinase. J Exp Med 197(4):503-13 |
| abstractText | The unique tyrosine kinase binding (TKB) domain of Cbl targets phosphorylated tyrosines on activated protein tyrosine kinases (PTKs); this targeting is considered essential for Cbl proteins to negatively regulate PTKs. Here, a loss-of-function mutation (G304E) in the c-Cbl TKB domain, first identified in Caenorhabditis elegans, was introduced into a mouse and its effects in thymocytes and T cells were studied. In marked contrast to the c-Cbl knockout mouse, we found no evidence of enhanced activity of the ZAP-70 PTK in thymocytes from the TKB domain mutant mouse. This finding contradicts the accepted mechanism of c-Cbl-mediated negative regulation, which requires TKB domain targeting of phosphotyrosine 292 in ZAP-70. However, the TKB domain mutant mouse does show aspects of enhanced signaling that parallel those of the c-Cbl knockout mouse, but these involve the constitutive activation of Rac and not enhanced PTK activity. Furthermore, the enhanced signaling in CD4(+)CD8(+) double positive thymocytes appears to be compensated by the selective down-regulation of CD3 on mature thymocytes and peripheral T cells from both strains of mutant c-Cbl mice. |
