RT Journal Article
SR Electronic
T1 Differential sorting behavior for soluble and transmembrane cargoes at the trans-Golgi network in endocrine cells
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 797134
DO 10.1101/797134
A1 Blake H. Hummer
A1 Drew Maslar
A1 Margarita Soltero Gutierrez
A1 Noah F. de Leeuw
A1 Cedric S. Asensio
YR 2019
UL http://biorxiv.org/content/early/2019/10/08/797134.abstract
AB Regulated secretion of neuropeptides and peptide hormones by secretory granules (SGs) is central to physiology. Formation of SGs occurs at the trans-Golgi network (TGN) where their soluble cargo aggregates to form a dense core, but the mechanisms controlling the sorting of regulated secretory cargoes (soluble and transmembrane) away from constitutively secreted proteins remain unclear. Optimizing the use of the retention using selective hooks (RUSH) method in (neuro-)endocrine cells, we now quantify TGN budding kinetics of constitutive and regulated secretory cargoes. We further show that, by monitoring two cargoes simultaneously, it becomes possible to visualize sorting to the constitutive and regulated secretory pathways in real-time. Further analysis of the localization of SG cargoes immediately after budding from the TGN revealed that, surprisingly, the bulk of two studied transmembrane SG cargoes (phogrin and VMAT2) does not sort directly onto SGs during budding, but rather exit the TGN into non-regulated vesicles to get incorporated to SGs at a later step. This differential behavior of soluble and transmembrane cargoes suggests a more complex model of SG biogenesis than anticipated.