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Mature VLDL Particles Exit the Golgi in Distinct Post‐Golgi VLDL Vesicles
Author(s) -
Siddiqi Shadab A,
Hossain Tanvir,
Siddiqi Shaila
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.588.5
Subject(s) - golgi apparatus , vesicle , very low density lipoprotein , copi , microbiology and biotechnology , chemistry , biochemistry , golgi membrane , biology , secretory pathway , cholesterol , membrane , endoplasmic reticulum , lipoprotein
Post‐Golgi transport of VLDL is crucial for maintaining normal triacylglycerol (TAG) homeostasis of hepatocytes, however, nothing is known about the exit of VLDLs from the Golgi. To study this important process, we established an in vitro Golgi‐budding assay to examine the formation of Golgi‐derived VLDL vesicles using hepatic Golgi containing [3H]TAG as a marker for VLDL. Post‐Golgi vesicles (PGV) containing TAG‐rich VLDL were distributed in the low‐density portion of sucrose density gradient. Consistent with the biogenesis of ER‐derived VLDL transport vesicle (VTV), the generation of PGV required cytosolic proteins, ATP and incubation at 37 OC. PGVs were found to concentrate ApoB100, Apo‐AIV and Apo‐AI. The presence of Apo‐AI in PGVs, which is not present in the VTVs, suggested the differences in protein composition of two vesicles. Proteinase K treatment did not affect the PGV‐cargo proteins, apoB100, Apo‐AIV and Apo‐AI, indicating that PGVs were sealed. PGVs were able to fuse with plasma membrane as determined by in vitro PGV‐plasma membrane fusion assay. Electron microscopy revealed that PGVs were larger (~280–340 nm) than VTVs (~100–120 nm). Further biochemical and morphological characterization revealed that PGVs are different than VTVs and facilitate the transport of VLDL to the plasma membrane. This study was supported by NIDDK, NIH R01 DK081413 to SAS.