MmuEX6099746 @ mm10

Activation-induced alternative splicing of Sec16a (inclusion/exclusion of HsaEX0056828 and/or HsaEX0056829) controls adaptation of COPII transport to increased secretory cargo upon T-cell activation. Using splice-site blocking morpholinos and CRISPR/Cas9-mediated genome engineering, the authors show that the number of ER exit sites, COPII dynamics and transport efficiency depend on Sec16 alternative splicing. As the mechanistic basis, the authors suggest the C-terminal Sec16 domain to be a splicing-controlled protein interaction platform, with individual isoforms showing differential abilities to recruit COPII components. These work connects the COPII pathway with alternative splicing, adding a new regulatory layer to protein secretion and its adaptation to changing cellular environments.