ER-to-Golgi trafficking of procollagen in the absence of large carriers

Secretion and assembly of collagen is fundamental to the function of the extracellular matrix. Defects in the assembly of a collagen matrix lead to pathologies including fibrosis and osteogenesis imperfecta. Owing to the size of fibril-forming procollagen molecules it is assumed that they are transp...

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Bibliographic Details
Published inbioRxiv
Main Authors Mccaughey, Janine, Stevenson, Nicola, Cross, Stephen, Stephens, David
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 05.06.2018
Subjects
Collagen
Endoplasmic reticulum
Extracellular matrix
Fibrosis
Golgi apparatus
Osteogenesis
Osteogenesis imperfecta
Procollagen
Secretion
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Summary:Secretion and assembly of collagen is fundamental to the function of the extracellular matrix. Defects in the assembly of a collagen matrix lead to pathologies including fibrosis and osteogenesis imperfecta. Owing to the size of fibril-forming procollagen molecules it is assumed that they are transported from the endoplasmic reticulum to the Golgi in specialised large COPII-dependent carriers. Here, analysing endogenous procollagen and a new engineered GFP-tagged form, we show that transport to the Golgi occurs in the absence of large carriers. Large GFP-positive structures are observed occasionally but these are non-dynamic, are not COPII-positive, and label with markers of the ER. We propose a short-loop model of ER-to-Golgi traffic that, while consistent with models of ERGIC-dependent expansion of COPII carriers, does not invoke long-range trafficking of large vesicular structures. Our findings provide an important insight into the process of procollagen trafficking and reveal a short-loop pathway from the ER to the Golgi, without the use of large carriers.
DOI:10.1101/339804