Abstract
We are investigating the molecular pathway(s) involved in phenotypic and functional changes accompanying in vitro TCR ligation of CD48double positive (DP) thymocytes. H-Y transgenic mice express an aβTCR that is specific for the HY antigen in the context of H-2Db class IMHC molecules. In vitro incubation of HY thymocytes in the presence of plale-bound antibody to the transgenic TCR a-chain or to CD3e down-regulates CD4 and CDS coreceptors and up-regulates the early activation antigen CD69 in the DP subset. However, assessment of DNA fragmentation using the TUNEL assay demonstrates that TCR cross-linking does not result in appreciable apoptosis in DP thymocytes. Interestingly, addition of the immunosuppressant cyclosporin A (CsA) which inhibits calcineurin activation to TCR cross-linked cultures specifically depletes the DP thymocyte subset. CsA induced apoptosis of DP cells cultured with plate-bound anti-TCR is blocked by the addition of the protein synthesis inhibitor cyclohexamide (CHX). However, if the addition of CHX is delayed for 6-9 hours it fails to prevent CsA induced death of activated DP cells indicating that the factor(s) involved in the apoptotic pathway is synthesized within this time frame. In addition, the inhibitor H7 but not HA1004 prevents CsA induced death suggesting toe involvement of PKC but not PKA. Studies are underway to further characterize the molecular mechanism(s) of CsA induced death of activated DP thymocytes. Our working hypothesis is that calcineurin mediated events rexulate the outcomes of TCR stimulation in DP thymocytes.
Original language | English (US) |
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Pages (from-to) | A1446 |
Journal | FASEB Journal |
Volume | 10 |
Issue number | 6 |
State | Published - 1996 |
ASJC Scopus subject areas
- Biotechnology
- Biochemistry
- Molecular Biology
- Genetics