Dynamic interactions of RNA binding proteins to human cytokine mRNA govern T cell responses

Effective T cell responses against infections and tumors depend on the production of effector molecules, including the key pro-inflammatory cytokines IFN-γ, TNF-α and IL-2. Recent studies revealed that post-transcriptional events determine the magnitude and duration of cytokine production in T cells, a feature that is largely defined by RNA-binding proteins (RBPs). However, to date the interplay of RBPs with cytokine mRNA, and their mode of action are ill-defined. Here we employed an RNA-aptamer-based capture assay from human T cell lysates to map RBP interactions with the full length 3’untranslated regions of IFNG, TNF and IL2. We found that RBPs binding can be both promiscuous and cytokine-specific. Furthermore, the RBP binding landscape rapidly alters upon T cell activation. Genetic deletion of confirmed mRNA interactors uncovered RBP-specific activity in primary T cells in response to target cells. Thus, RBPs are critical determinants of fast but tightly controlled cytokine production in T cells.