ER to Golgi transport during apoptosis
The Golgi complex, a single -copy organelle, is composed of a ribbon of flattened stacks of cisternae during interphase. However, during apoptosis the Golgi is shown to fragment and disperse throughout the cytoplasm. Immunoelectron microscopy identified these fragments as vesicular-tubular structures that contained the Golgi marker n-acetyl-glucosaminyl-transferase-1. Newly-synthesised proteins translocated to the endoplasmic reticulum also failed to exit from this organelle and reach the Golgi in apoptotic cells.Induction of apoptosis by Fas receptor ligation led to the caspase-dependent cleavage of GM130, a key Golgi-localised protein involved in tethering incoming secretory vesicles to the cis -Golgi. Cleavage of GM130 was prevented by the broad-range protein kinase inhibitor staurosporine, suggesting that phosphorylation played a role in the regulation of GM130 activity during apoptosis. These morphological and functional changes to the early secretory pathway during apoptosis could explain the down-regulation of the exocytic pathway in apoptotic neutrophils, which may prevent the inappropriate release of proinflammatory agents during resolution of inflammation.