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

J Cell Biol. 2019 Mar 4;218(3):929-948. doi: 10.1083/jcb.201806035. Epub 2018 Dec 26.

Abstract

Secretion and assembly of collagen are 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 specialized large COPII-dependent carriers. Here, analyzing endogenous procollagen and a new engineered GFP-tagged form, we show that transport to the Golgi occurs in the absence of large (>350 nm) carriers. Large GFP-positive structures were observed occasionally, but these were nondynamic, are not COPII positive, and are labeled with markers of the ER. We propose a short-loop model of COPII-dependent 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport, Active / physiology
  • COP-Coated Vesicles / metabolism*
  • Cell Line, Transformed
  • Endoplasmic Reticulum / metabolism*
  • Golgi Apparatus / metabolism*
  • Humans
  • Models, Biological*

Associated data

  • GENBANK/KP202880.1
  • GENBANK/NM_000088.3