Biomedical subjects

David Depoil

Publications and source records attributed to David Depoil.

3 recordsLinked to original sources

PubMed2007

CD2 and TCR synergize for the activation of phospholipase Cgamma1/calcium pathway at the immunological synapse.

Upon conjugation with cognate antigen-presenting cells (APCs), T lymphocytes undergo a sustained [Ca(2+)](i) increase resulting from the engagement of TCR and of accessory molecules with ligands expressed on the surface of APCs. We investigated the contribution of the accessory molecule CD2 to the activation of phospholipase Cgamma1 (PLCgamma1)/calcium pathway in antigen-stimulated T cells. We show that CD2 binding with its ligand CD58 expressed on the surface of APCs augments and sustains antigen-induced [Ca(2+)](i) increase in individual T cells interacting with APCs. We also show that in conditions in which CD2-CD58 interaction is impeded, the recruitment of PLCgamma1 to the immunological synapse (IS) is reduced. Interestingly, in these conditions PLCgamma1 phosphorylation in the regulatory tyrosine 783 is also defective. Our results indicate that TCR- and CD2-derived signals converge for the recruitment and activation of PLCgamma1 at the IS and shed new light on the accessory function of CD2 in T cell activation by specific antigen.

Antigen-Presenting Cells↗

PubMed2006

Cytotoxic T lymphocytes kill multiple targets simultaneously via spatiotemporal uncoupling of lytic and stimulatory synapses.

A longstanding paradox in the activation of cytotoxic T lymphocytes (CTL) arises from the observation that CTL recognize and rapidly destroy target cells with exquisite sensitivity despite the fact that cytokine production requires sustained signaling at the immunological synapse. Here we solve this paradox by showing that CTL establish sustained synapses with targets offering strong antigenic stimuli and that these synapses persist after target cell death. Simultaneously, CTL polarize lytic granules toward different cells without discrimination regarding antigenic potential. Our results show that spatiotemporal uncoupling of immunological synapse and lytic granule secretion allows multiple killing and sustained signaling by individual CTL. This unique mechanism of responding to multiple contacts provides remarkable efficiency to CTL function.

Apoptosis↗

PubMed2005

Immunological synapses are versatile structures enabling selective T cell polarization.

Helper T cells discriminate among different antigen-presenting cells to provide their help in a selective fashion. The molecular mechanisms leading to this exquisite selectivity are still elusive. Here, we demonstrate that immunological synapses are dynamic and adaptable structures allowing T cells to communicate with multiple cells. We show that T cells can form simultaneous immunological synapses with cells presenting different levels of antigenic ligands but eventually polarize toward the strongest stimulus. Remarkably, living T cells form discrete foci of signal transduction of different intensities during the interaction with different antigen-presenting cells and rapidly relocate TCR and Golgi apparatus toward the cell providing the strongest stimulus. Our results illustrate that, although T cell activation requires sustained signaling, T cells are capable of rapid synapse remodeling and swift polarization responses. The combination of sustained signaling with preferential and rapid polarization provides a mechanism for the high sensitivity and selectivity of T cell responses.

Animals↗