Targeting the chromatin binding of exportin-1 disrupts NFAT and T cell activation

Abstract

Exportin-1 (XPO1/CRM1) plays a central role in the nuclear-to-cytoplasmic transport of hundreds of proteins and contributes to other cellular processes, such as centrosome duplication. Small molecules targeting XPO1 induce cytotoxicity, and selinexor was approved by the Food and Drug Administration in 2019 as a cancer chemotherapy for relapsed multiple myeloma. Here, we describe a cell-type-dependent chromatin-binding function for XPO1 that is essential for the chromatin occupancy of NFAT transcription factors and thus the appropriate activation of T cells. Additionally, we establish a class of XPO1-targeting small molecules capable of disrupting the chromatin binding of XPO1 without perturbing nuclear export or inducing cytotoxicity. This work defines a broad transcription regulatory role for XPO1 that is essential for T cell activation as well as a new class of XPO1 modulators to enable therapeutic targeting of XPO1 beyond oncology including in T cell-driven autoimmune disorders. Exportin-1 (XPO1) was identified as the target of small molecules suppressing T cell activation. Selective disruption of the chromatin scaffolding function of XPO1 without blocking nuclear export implicates XPO1 as a target in autoimmunity.