Journal article

FcRn mediates fast recycling of endocytosed albumin and IgG from early macropinosomes in primary macrophages

Wei Hong Toh, Jade Louber, Ismail S Mahmoud, Jenny Chia, Greg T Bass, Steve K Dower, Anne M Verhagen, Paul A Gleeson

JOURNAL OF CELL SCIENCE | COMPANY BIOLOGISTS LTD | Published : 2020

Abstract

The neonatal Fc receptor (FcRn) rescues albumin and IgG from degradation following endocytosis and thereby extends the half-life of these plasma proteins. However, the pathways for the uptake of these soluble FcRn ligands, and the recycling itinerary of the FcRn-ligand complexes, have not been identified in primary cells. Here, we have defined the recycling of human albumin and IgG in primary mouse macrophages selectively expressing the human FcRn. Albumin is internalised by macropinocytosis; in the absence of FcRn, internalised albumin is rapidly degraded, while in the presence of FcRn albumin colocalises to SNX5-positive membrane domains and is partitioned into tubules emanating from early..

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