PT - JOURNAL ARTICLE AU - Shunsuke Kataoka AU - Priyanka Manandhar AU - Creg J. Workman AU - Hridesh Banerjee AU - Andrea L. Szymczak-Workman AU - Michael Kvorjak AU - Jason Lohmueller AU - Lawrence P. Kane TI - The co-stimulatory activity of Tim-3 requires Akt and MAPK signaling and immune synapse recruitment AID - 10.1101/2019.12.30.878520 DP - 2019 Jan 01 TA - bioRxiv PG - 2019.12.30.878520 4099 - http://biorxiv.org/content/early/2019/12/30/2019.12.30.878520.short 4100 - http://biorxiv.org/content/early/2019/12/30/2019.12.30.878520.full AB - Expression of the transmembrane protein Tim-3 is increased on dysregulated T cells undergoing chronic T cell activation, including in chronic infection and solid tumors. We and others previously reported that Tim-3 exerts apparently paradoxical co-stimulatory activity in T cells (and other cells), including enhancement of ribosomal S6 protein phosphorylation (pS6). Here we examined the upstream signaling pathways that control Tim3-mediated increases in pS6 in T cells. We have also defined the localization of Tim-3 relative to the T cell immune synapse and impacts on downstream signaling. Recruitment of Tim-3 to the immune synapse was regulated exclusively by the transmembrane domain, replacement of which impaired Tim-3 co-stimulation of pS6. Strikingly, enforced localization of the Tim-3 cytoplasmic domain to the immune synapse in the context of a chimeric antigen receptor still allowed for robust T cell activation. Our findings are consistent with a model whereby Tim-3 enhances TCR-proximal signaling under acute conditions.