Monday, July 15, 2024
Mitochondrial Health

Gia Voeltz (CU, HHMI) 1: Factors and Functions of Organelle Membrane Contact Sites

The endoplasmic reticulum (ER) is a dynamic network of tubules that reaches throughout a cell. It interacts with other organelles at membrane contact sites. As Dr. Gia Voeltz explains, these sites are critical for Ca2+ regulation, lipid transport and defining sites of division for endosomes and other organelles.

Many of us are used to seeing cartoons of cells with organelles shown as static, isolated structures. The endoplasmic reticulum is often shown looking like a stack of pancakes pushed up against the nuclear envelope. In her first talk, Dr. Gia Voeltz explains that recent advances in light microscopy have given us a very different view of organelles and their interactions. The ER is, in fact, an expansive, and highly dynamic, network of tubules that spreads throughout the cell. It interacts with other organelles such as the plasma membrane, endosomes, and mitochondria at points called membrane contact sites. Using beautiful fluorescent images and movies, Voeltz shows us that these ER membrane contact sites are important for many functions such as trafficking lipids and Ca2+ and determining where mitochondria divide and endosomes undergo fission. These exciting findings define a new cellular function for the ER.

In her second lecture, Voeltz explains how her lab used a BioID strategy to identify some of the proteins found at membrane contact sites between the ER and endosomes; a difficult task given the transient nature of contact sites. They were able to identify a number of proteins responsible for marking the timing and location of endosome fission and for recruiting the ER to the bud. Depleting these proteins blocked cargo sorting to the Golgi. Voeltz’ lab is now working to determine how much of this machinery is conserved in processes such as the mitochondrial division.

Speaker Biography:
Dr. Gia Voeltz discovered her love for research as an undergraduate student at the University of California Santa Cruz. After graduation, she moved east to Yale University where she was a graduate student with Joan Steitz and studied RNA processing in Xenopus extracts. As a post-doctoral fellow in Tom Rapoport’s lab at Harvard, Voeltz tackled the question of how organelles, and in particular the endoplasmic reticulum, are shaped.

Voeltz started her own lab at the University of Colorado, Boulder in 2006. She became an HHMI Faculty Scholar in 2016 and an HHMI Investigator in 2018. Her lab investigates how the ER interacts with other organelles such as the mitochondria and endosomes via membrane contact sites and how these contact sites may regulate organelle division and function.

Learn more about Voeltz’ research here:


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