Stacking up insights into the Golgi

Imaging the Golgi complex in a human cell line: Components of the machineries responsible for trafficking and sorting versus modifications and processing appear in red and green, respectively, showing spatially distinct localisation. Credit: Lu Lei.

Similar to the workings of a postal hub, the Golgi apparatus—a large organelle present in all eukaryotic cells—processes, sorts and packages proteins and lipids for transport inside and outside of the cell.

To better understand the Golgi’s complex network of laterally linked stacks, a team of researchers from NTU’s School of Biological Sciences, led by Asst Prof Lu Lei, used super-resolution microscopy to show that the two principal functions of the Golgi—processing and transport—take place in spatially distinct areas of the stacks. Enzymes responsible for processing were predominantly found in the interior, while transport machinery components and cargos with bulky sizes were confined to the cisternal rims.

In a separate study, Asst Prof Lu’s team and his collaborators discovered that amino acids can promote protein trafficking from the endosome—another cellular compartment engaged in molecular sorting—to the Golgi, thereby regulating the cellular localisation of proteins, including receptors that play important roles in cells. By identifying the components of a signalling cascade triggered by amino acid sensing, the findings provide important insights into the effects of nutrients on human physiology and pathology at the molecular and cellular levels.

Functional organisation of the Golgi apparatus is described in “The spatial separation of processing and transport functions to the interior and periphery of the Golgi stack”, published in eLIFE (2018), DOI: 10.7554/eLife.41301. Details of the study into intracellular trafficking can be found in “Amino acids stimulate the endosome-to-Golgi trafficking through Ragulator and small GTPase Arl5”, published in  Nature Communications (2018), DOI: 10.1038/s41467-018-07444-y.

The article appeared first in NTU’s research & innovation magazine Pushing Frontiers (issue #15, June 2019).