16 May 2017 Shape matters at the intracellular post-office

The shape and function of Golgi cisterna is controlled by lipid homeostasis from flat (left) to curled (right) morphology

New insights on how lipids control the shape and function of the Golgi complex reported in eLife. The Golgi complex is the central hub inside the cells for the transport of many so-called cargo proteins, very alike to a post-office. The structure and function of the Golgi complex are intimately linked, although the role of lipids and proteins in keeping its peculiar shape has remained enigmatic. A research performed by Dr. Felix Campelo at the Single Molecule Biophotonics group led by ICREA Professor at ICFO Maria Garcia-Parajo and in collaboration with ICREA Professor Vivek Malhotra at CRG, now demonstrate a clear role for lipid homeostasis regulating the shape of the Golgi complex and its function. The work has been recently published in eLife.

The Golgi complex receives freshly made proteins, processes them, and finally sends them to different places inside or outside the cell, where these proteins need to perform their functions. The Golgi complex is formed by a stack of flat membranes, named cisternae, which enclose a very small volume inside. These membranes, just like any other membranes inside the cell, are made of lipids and proteins. What are these lipids and proteins doing to keep the peculiar shape of the Golgi cisternae? Is this shape important for the Golgi complex to perform its functions efficiently?

Dr. Felix Campelo and colleagues used physical concepts, such as elasticity or entropy, to mathematically describe how a Golgi cisterna can retain or change its shape. The theory predicts that some proteins keep the cisternae flat by holding the membrane rim that connects the two faces of a cisterna. To test this prediction, the researchers did experiments in human cells and found that when the Golgi lipid composition changes, certain proteins jump from the rim causing the cisternae to curl. Remarkably, these proteins are also needed to export cargo proteins, demonstrating that there is a connection between Golgi shape and function.

The shape of the Golgi complex is affected in many neurodegenerative diseases, such as in Alzheimer’s disease. The results obtained during this research will contribute to further our understanding on how the shape of the Golgi is affected in these diseases, what are the consequences for the cell, and if this effect can be somehow prevented.