Organization and dynamics of the Aspergillus nidulans Golgi during apical extension and mitosis

• Published in: Molecular biology of the cell 2009-10, Vol.20 (20), p.4335-4347
• Main Authors: Pantazopoulou, Areti, Peñalva, Miguel A
• Format: Article
• Language: English
• Subjects: Animals; Aspergillus nidulans - drug effects; Aspergillus nidulans - growth & development; Aspergillus nidulans - ultrastructure; Brefeldin A - pharmacology; Bridged Bicyclo Compounds, Heterocyclic - pharmacology; Cell Polarity; Cell Shape - drug effects; Fungal Proteins - genetics; Fungal Proteins - physiology; Genes, Reporter; Genes, Synthetic; Golgi Apparatus - ultrastructure; Humans; Hyphae - drug effects; Hyphae - growth & development; Hyphae - ultrastructure; Image Processing, Computer-Assisted; Intracellular Membranes - ultrastructure; Microscopy, Fluorescence; Mitosis; Organelles - chemistry; Organelles - ultrastructure; Phosphatidylinositol Phosphates - analysis; Phosphatidylinositol Phosphates - physiology; Protein Structure, Tertiary; Rats; Receptors, Steroid - analysis; Receptors, Steroid - chemistry; Receptors, Steroid - genetics; Recombinant Fusion Proteins - analysis; Recombinant Fusion Proteins - chemistry; Thiazolidines - pharmacology; Type C Phospholipases - analysis; Type C Phospholipases - chemistry; Type C Phospholipases - genetics
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.E09-03-0254

Aspergillus nidulans hyphae grow exclusively by apical extension. Golgi equivalents (GEs) labeled with mRFP-tagged PH(OSBP) domain form a markedly polarized, dynamic network of ring-shaped and fenestrated cisternae that remains intact during "closed" mitosis. mRFP-PH(OSBP) GEs advance associated with the growing apex where secretion predominates but do not undergo long-distance movement toward the tip that could account for their polarization. mRFP-PH(OSBP) GEs overlap with the trans-Golgi resident Sec7 but do not colocalize with also polarized accretions of the early Golgi marker GrhA(Grh1)-GFP, indicating that early and late Golgi membranes segregate spatially. AnSec23-GFP ER exit sites (ERES) are numerous, relatively static foci localizing across the entire cell. However, their density is greatest near the tip, correlating with predominance of early and trans-Golgi elements in this region. Whereas GrhA-GFP structures and ERES reach the apical dome, mRFP-PH(OSBP) GEs are excluded from this region, which contains the endosome dynein loading zone. After latrunculin-mediated F-actin disruption, mRFP-PH(OSBP) GEs fragment and, like AnSec23-GFP ERES, depolarize. Brefeldin A transiently collapses late and early GEs into distinct aggregates containing Sec7/mRFP-PH(OSBP) and GrhA-GFP, respectively, temporarily arresting apical extension. Rapid growth reinitiates after washout, correlating with reacquisition of the normal Golgi organization that, we conclude, is required for apical extension.