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Cog3p depletion blocks vesicle-mediated Golgi retrograde trafficking in HeLa cells.

Zolov SN, Lupashin VV - J. Cell Biol. (2005)

Bottom Line: In this work we used short interfering RNA strategy to achieve an efficient knockdown (KD) of Cog3p in HeLa cells.Fragmented Golgi membranes maintained their juxtanuclear localization, cisternal organization and are competent for the anterograde trafficking of vesicular stomatitis virus G protein to the plasma membrane.In a contrast, Cog3p KD resulted in inhibition of retrograde trafficking of the Shiga toxin.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.

ABSTRACT
The conserved oligomeric Golgi (COG) complex is an evolutionarily conserved multi-subunit protein complex that regulates membrane trafficking in eukaryotic cells. In this work we used short interfering RNA strategy to achieve an efficient knockdown (KD) of Cog3p in HeLa cells. For the first time, we have demonstrated that Cog3p depletion is accompanied by reduction in Cog1, 2, and 4 protein levels and by accumulation of COG complex-dependent (CCD) vesicles carrying v-SNAREs GS15 and GS28 and cis-Golgi glycoprotein GPP130. Some of these CCD vesicles appeared to be vesicular coat complex I (COPI) coated. A prolonged block in CCD vesicles tethering is accompanied by extensive fragmentation of the Golgi ribbon. Fragmented Golgi membranes maintained their juxtanuclear localization, cisternal organization and are competent for the anterograde trafficking of vesicular stomatitis virus G protein to the plasma membrane. In a contrast, Cog3p KD resulted in inhibition of retrograde trafficking of the Shiga toxin. Furthermore, the mammalian COG complex physically interacts with GS28 and COPI and specifically binds to isolated CCD vesicles.

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Model for the COG complex function in membrane trafficking. Cis-Golgi localized COG complex acts a tether for retrograde COPI-coated CCD vesicles that originate from the trans-Golgi/endosomal compartment(s). The COG3 KD abolishes vesicle tethering to the cis-Golgi. As a result multiple nontethered vesicles are transiently accumulated in cell cytoplasm and the membrane-depleted Golgi ribbon is fragmented into multiple Golgi mini-stacks.
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fig10: Model for the COG complex function in membrane trafficking. Cis-Golgi localized COG complex acts a tether for retrograde COPI-coated CCD vesicles that originate from the trans-Golgi/endosomal compartment(s). The COG3 KD abolishes vesicle tethering to the cis-Golgi. As a result multiple nontethered vesicles are transiently accumulated in cell cytoplasm and the membrane-depleted Golgi ribbon is fragmented into multiple Golgi mini-stacks.

Mentions: In conclusion we propose a model (Fig. 10) in which the cis-Golgi localized COG complex acts as a tether for retrograde COPI coated CCD vesicles that originate from distal trans-Golgi/endosomal compartments. The acute COG3 KD and corresponding defects in the Lobe A of the COG complex discontinue normal vesicle recycling. Non-tethered vesicles are transiently accumulated in cell cytoplasm as membrane-depleted Golgi ribbon is fragmented in multiple Golgi mini-stacks. Detailed biochemical analysis of CCD vesicles and the elucidation of exact roles of both lobes of the COG complex should help in our understanding of mechanisms of Golgi maintenance and function.


Cog3p depletion blocks vesicle-mediated Golgi retrograde trafficking in HeLa cells.

Zolov SN, Lupashin VV - J. Cell Biol. (2005)

Model for the COG complex function in membrane trafficking. Cis-Golgi localized COG complex acts a tether for retrograde COPI-coated CCD vesicles that originate from the trans-Golgi/endosomal compartment(s). The COG3 KD abolishes vesicle tethering to the cis-Golgi. As a result multiple nontethered vesicles are transiently accumulated in cell cytoplasm and the membrane-depleted Golgi ribbon is fragmented into multiple Golgi mini-stacks.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171815&req=5

fig10: Model for the COG complex function in membrane trafficking. Cis-Golgi localized COG complex acts a tether for retrograde COPI-coated CCD vesicles that originate from the trans-Golgi/endosomal compartment(s). The COG3 KD abolishes vesicle tethering to the cis-Golgi. As a result multiple nontethered vesicles are transiently accumulated in cell cytoplasm and the membrane-depleted Golgi ribbon is fragmented into multiple Golgi mini-stacks.
Mentions: In conclusion we propose a model (Fig. 10) in which the cis-Golgi localized COG complex acts as a tether for retrograde COPI coated CCD vesicles that originate from distal trans-Golgi/endosomal compartments. The acute COG3 KD and corresponding defects in the Lobe A of the COG complex discontinue normal vesicle recycling. Non-tethered vesicles are transiently accumulated in cell cytoplasm as membrane-depleted Golgi ribbon is fragmented in multiple Golgi mini-stacks. Detailed biochemical analysis of CCD vesicles and the elucidation of exact roles of both lobes of the COG complex should help in our understanding of mechanisms of Golgi maintenance and function.

Bottom Line: In this work we used short interfering RNA strategy to achieve an efficient knockdown (KD) of Cog3p in HeLa cells.Fragmented Golgi membranes maintained their juxtanuclear localization, cisternal organization and are competent for the anterograde trafficking of vesicular stomatitis virus G protein to the plasma membrane.In a contrast, Cog3p KD resulted in inhibition of retrograde trafficking of the Shiga toxin.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.

ABSTRACT
The conserved oligomeric Golgi (COG) complex is an evolutionarily conserved multi-subunit protein complex that regulates membrane trafficking in eukaryotic cells. In this work we used short interfering RNA strategy to achieve an efficient knockdown (KD) of Cog3p in HeLa cells. For the first time, we have demonstrated that Cog3p depletion is accompanied by reduction in Cog1, 2, and 4 protein levels and by accumulation of COG complex-dependent (CCD) vesicles carrying v-SNAREs GS15 and GS28 and cis-Golgi glycoprotein GPP130. Some of these CCD vesicles appeared to be vesicular coat complex I (COPI) coated. A prolonged block in CCD vesicles tethering is accompanied by extensive fragmentation of the Golgi ribbon. Fragmented Golgi membranes maintained their juxtanuclear localization, cisternal organization and are competent for the anterograde trafficking of vesicular stomatitis virus G protein to the plasma membrane. In a contrast, Cog3p KD resulted in inhibition of retrograde trafficking of the Shiga toxin. Furthermore, the mammalian COG complex physically interacts with GS28 and COPI and specifically binds to isolated CCD vesicles.

Show MeSH
Related in: MedlinePlus