Gia Voeltz: Cellular Cartographer

Associate Professor, Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder. Age: 43

By | December 1, 2015

© REBECCA STUMPFAfter a childhood spent moving about the U.S., Gia Voeltz left her teenage home of Binghamton, New York, for the West Coast to start her undergraduate studies. Three years later, as a senior at the University of California (UC), Santa Cruz in 1993, she discovered her passion for lab research while studying RNA splicing under Manuel Ares.

In 1995, Voeltz moved to Yale University for a PhD in Joan Steitz’s lab. Using Xenopus egg extracts, she was able to show that posttranslational RNA decay was turned on in sequential steps during early frog development. Voeltz also discovered a new poly(A) binding protein, called ePAB, which regulates translation.1

As a PhD student, Voeltz attended a talk at Yale by cell biologist Tom Rapoport of Harvard University. At the end of the talk, Rapoport mentioned a new project to study how organelles form. “How can a protein even know how to wrap up the membrane bilayer into a structure that’s really defined and that only does its given set of functions?” Voeltz says. “I didn’t even know it was a question.”

Rapoport took her on as a postdoc in 2001 to work on endoplasmic reticulum (ER) formation. After a few false starts—“I basically purified salt for three years”—Voeltz discovered the key role of a reticulon protein in shaping the structure of the tubular ER.2 She induced membrane vesicles from Xenopus egg extracts to form a tubular ER network, and while looking for the underlying molecular mechanism, she found a nonspecific inhibitor that could stop the reaction at low concentrations. When Voeltz tagged the inhibitor, she observed it binding to a reticulon. The study redefined the role of the protein family, which was previously thought to regulate axon formation in neurons.

Voeltz moved to the University of Colorado, Boulder, in 2006, planning to continue studying how reticulons dictated ER shape. She quickly deviated, however, after observing the 3-D structure of ER in yeast cells extending like a spiderweb throughout the cell. “It’s all over the place,” says Voeltz. “We pretty much had to solve the structure of all of the other organelles around it to figure out what was ER and what was something else.”3

When her team imaged multiple organelles at the same time, Voeltz saw ER tubules constricting mitochondria like lassoes. “It was literally a picture that got us thinking that might be where the mitochondrial division assembles,” she says. Voeltz’s team, working with researchers from UC Davis, demonstrated that the ER regulates the position of mitochondrial division.4 “Some people, you start a collaboration and there can be some tension with them,” says Jodi Nunnari, a UC Davis cell biologist who’s worked with Voeltz. “That never happened with Gia. It’s pretty amazing.”

Voeltz’s lab then showed that the ER also plays a role in endosome fission.5 “Gia’s really involved. Her door is always open,” says Ashley Rowland, Voeltz’s recently graduated PhD student who led the endosome project. “She always gave me opportunities to grow.”

Now, Voeltz is focusing on the functional aspects of contact sites between the ER, mitochondria, and endosomes, as well as exploring the ways viruses might interact with the ER. “Organelles have been studied for years and all of a sudden you have these contact sites. For a cell biologist, that’s exciting,” says Voeltz. “You can take machinery from the ER and the mitochondria, and now you can do something that neither organelle can do by itself. That’s what we’re trying to uncover.” 

References

  1. G.K. Voeltz et al., “A novel embryonic poly(A) binding protein, ePAB, regulates mRNA deadenylation in Xenopus egg extracts,” Genes Dev, 15:774-88, 2001. (Cited 109 times)
  2. G.K. Voeltz et al., “A class of membrane proteins shaping the tubular endoplasmic reticulum,” Cell, 124:573-86, 2006. (Cited 564 times)
  3. M. West et al., “A 3-D analysis of yeast ER structure reveals how ER domains are organized by membrane curvature,” J Cell Biol, 193:333-46, 2011. (Cited 111 times)
  4. J.R. Friedman et al., “ER tubules mark sites of mitochondrial division,” Science, 334:358-62, 2011. (Cited 357 times)
  5. A.A. Rowland et al., “ER contact sites define the position and timing of endosome fission,” Cell, 159:1027-41, 2014. (Cited 15 times)

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