Time-dependent regulation of cytokine production by RNA binding proteins defines T cell effector function

Abstract

SummaryEffective T cell responses against target cells require controlled production of the key pro-inflammatory cytokines IFN-γ, TNF and IL-2. Post-transcriptional events determine the magnitude and duration of cytokine production in T cells, a process that is largely regulated by RNA binding proteins (RBPs). Here we studied the identity and mode of action of RBPs interacting with cytokine mRNAs. With an RNA aptamer-based capture assay from human T cell lysates, we identified >130 RBPs interacting with the full length 3’untranslated regions of IFNG, TNF and IL2. The RBP landscape altered upon T cell activation. Furthermore, RBPs display temporal activity profiles to control cytokine production. Whereas HuR promotes early cytokine production, the peak production levels and response duration is controlled by ZFP36L1, ATXN2L and ZC3HAV1. Importantly, ZFP36L1 deletion boosts T cell responses against tumors in vivo, revealing the potential of the RBP map to identify critical modulators of T cell responses.

Regulation of IFNγ production by ZFP36L2 in T cells is context-dependent

“…5A ). As previously reported (47) and in line with the cytokine production kinetics of T cells (34, 43), the production of TNF and IL-2 dropped to undetectable levels at 24h and 48h of activation. Only the production of IFNγ was sustained ( Fig.…”

“…3B ). In contrast, at 24h of reactivation with αCD3/αCD28, at a time point when the IL-2 production is undetectable and TNF production is low (34, 43), the percentage and magnitude of IFNγ production was significantly increased (1.25 fold) in CD8 + ZFP36L2 CKO VM cells ( Fig. 3C ).…”

“…and Granzyme B were unaffected in ZFP36L2 CKO TILs, and such broader alterations may be required when the increase of IFNγ is limited (34,(61)(62)(63). Additionally, the antitumour effects of IFNγ may be outcompeted by the pro-tumourigenic function of IFNγ, including the induction of PDL1 and IDO1 (64).…”

“…However, because ZFP36L2 is expressed throughout, we argue that other RBPs may outcompete, or control its RNA binding activity and regulatory function at early T cell activation. Recently, several RBPs that regulate cytokine production during early T cell activation were identified, including ZFP36 and ZFP36L1 (23, 34). It is therefore conceivable that ZFP36L1 or other ARE-binding RBPs outcompete ZFP36L2 binding during the early phase of T cell activation.…”

“…ZFP36-deficient murine CD4 + T cells produce more IFNγ,TNF, IL-17, and IL-2 (23,25,(31)(32)(33). Likewise, human effector T cells devoid of ZFP36L1 show increased and prolonged production of IL-2, TNF, and IFNγ (34). Conversely, ZFP36L2 prevents the premature translation of pre-formed cytokine mRNA in quiescent memory T cells (35).…”