Role of the Conserved Oligomeric Golgi Complex in the Abnormalities of Glycoprotein Processing in Breast Cancer Cells
Annual summary 1 May 2004-30 Apr 2005
ARKANSAS UNIV FOR MEDICAL SCIENCES LITTLE ROCK
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The conserved oligomeric Golgi COG complex composed of eight subunits was identified as one of the evolutionary conserved protein complexes that regulates a cis-Golgi step in intracellular vesicular transport. Available mutants with the mutations in COG complex subunits exhibit defects in basic Golgi functions glycosylation of secretory proteins. protein sorting and retention of Golgi resident proteins. For analysis of COG complex function we utilized RNA interference assay to knockdown COG3p subunit of COG complex in normal and breast cancer cells and other tumor cell lines. SiRNA dependent Cog3 depletion causes rapid Golgi fragmentation and possibly accumulation of Golgi resident proteins in transport vesicles. Furthermore acute knock-down KD of the COG3 was accompanied by reduction in Cog1, 2 and 4 protein levels and by accumulation of COG complex independent CCD vesicles carrying Golgi v-SNARE molecules and cis-Golgi glycoprotein GPPi3O. Some of these CCD vesicles appeared to be vesicular coat complex I COPI coated. Prolonged knock-down of COG3p affects glycosylation in secretory pathway. Altered level of expression of COG3p or COG complex could be a common feature of cancer cells defective in protein trafficking and Golgi modifications. The importance of the COG complex for both function and architecture of the Golgi apparatus does not depend on type of cells. Partial malfunction of the COG complex may play a role in establishing of cancer phenotype.
- Medicine and Medical Research