Three-dimensional reconstruction of the golgi complex and trans-golgi network: A HVEM tomographic study

The Golgi complex is the central organelle in the secretory pathway of eukaryotic cells. It is composed of multiple cisternae that contain various enzymes involved in posttranslational modification of newly synthesized proteins. The cisternae are connected to a reticular lattice, the trans-Golgi Network (TGN), which is responsible for sorting and targeting proteins and lipids to other cellular locations. Transport between the Golgi cisternae is thought to occur largely via carrier vesicles, but recent studies suggest that some transport may be via tubules which link the cisternae and TGN. Although the Golgi complex has been well characterized biochemically, only a few studies have addressed its 3-D fine structure. Specific staining, high voltage electron microscopy (HVEM), and computer axial tomography were used to visualize the structure of the Golgi cisternae and the TGN in 3-D. A technique developed by R. E. Pagano was used to facilitate the visualization of the TGN and trans-most cisternae: Normal rat kidney (NRK) cells are treated with a fluorescent analog of ceramide (BODIPY-cer) which is internalized and metabolized in the Golgi complex (Fig. 1a).