Title

Mature Vldl Triggers The Biogenesis Of A Distinct Vesicle From The Trans-Golgi Network For Its Export To The Plasma Membrane

Keywords

Apolipoprotein B; Endoplasmic reticulum; Post-Golgi vldl transport vesicle (PG-VTV); Trans-Golgi network (TGN); Triacylglycerol; Very low-density lipoprotein (VLDL)

Abstract

Post-Golgi trafficking of mature VLDL (very-low-density lipoprotein) is crucial in maintaining normal TAG (triacylglycerol) homoeostasis of hepatocytes; however, the mechanism that regulates the exit of mature VLDL from the TGN (trans-Golgi network) is not known. We developed an in vitro TGN-budding assay that allowed us to examine the formation of secretory vesicles from the TGN in primary rat hepatocytes. We isolated TAG-rich PG-VTVs (post-TGN VLDL transport vesicles) using a continuous sucrose density gradient. PG-VTVs were distributed in low-density fractions, whereas protein transport vesicles were present in relatively higher-density fractions of the same sucrose gradient. EM revealed large intact PG-VTVs ranging 300-350 nm in size. The biogenesis of PG-VTVs from the TGN required cytosol, ATP, GTP hydrolysis and incubation at 37°C. PG-VTVs concentrated the VLDL proteins: apolipoproteins apoB100, apoAIV, apoAI and apoE, but did not contain either albumin or transferrin. Proteinase K treatment did not degrade VLDL core proteins, suggesting that PG-VTVs were sealed. PG-VTVs were able to fuse with and deliver VLDL to the PM (plasma membrane) in a vectorial manner. We conclude that we have identified a new TGN-derived vesicle, the PG-VTV, which specifically transports mature VLDL from the TGN to the PM. © The Authors Journal compilation © 2014 Biochemical Society.

Publication Date

4-1-2014

Publication Title

Biochemical Journal

Volume

459

Issue

1

Number of Pages

47-58

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1042/BJ20131215

Socpus ID

84896141430 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84896141430

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