TRAF family molecules in T cells: Multiple receptors and functions.

The TNFR superfamily of receptors, the major focus of the recent TNFR Superfamily Conference held in June 2019, employ the TNFR-associated factor (TRAF) family of adaptor proteins in key aspects of their signaling pathways. Although many early studies investigated TRAF functions via exogenous overexpression in nonhematopoietic cell lines, it has subsequently become clear that whereas TRAFs share some overlap in function, each also plays unique biologic roles, that can be highly context dependent. This brief review summarizes the current state of knowledge of functions of each of the TRAF molecules that mediate important functions in T lymphocytes: TRAFs 1, 2, 3, 5, and 6. Due to our current appreciation of the contextual nature of TRAF function, our focus is upon findings made specifically in T lymphocytes. Key T cell functions for each TRAF are detailed, as well as future knowledge gaps of interest and importance.