Ya-Lin Chiu
By Gary Howard
Ya-Lin Chiu, PhD, a research scientist at the Gladstone Institute of Virology and Immunology (GIVI), was selected as the recipient of the 2007 Dean's Postdoctoral Prize.
The prize recognizes the outstanding creative and independent research efforts of a postdoctoral scholar. Chiu will receive a cash prize of $1,000. She will present her research to the UCSF community on Tuesday, Feb. 20, at 4 p.m. in Byers Auditorium in Genentech Hall on the Mission Bay campus. The lecture will be simulast to the Parnassus campus in the School of Nursing room N 217.
"Gladstone and UCSF have a lot of postdocs, but only one is recognized by this prestigious award each year, and I am thrilled that it is Ya-Lin," said Warner Greene, MD, PhD, director of the Gladstone Institute of Virology and Immunology, the Nick and Sue Hellmann Endowed Professor of Translational Medicine, and a professor of medicine and of microbiology and immunology at UCSF. "It is a singular honor for her."
Chiu, who works in Greene's laboratory at the GIVI, was honored for her work on APOBEC3G (A3G). A3G is a potent inhibitor of HIV found normally in cells and incorporated into new virus particles, or virions, as they are made. When the virus tries to replicate itself in the next infected cell, A3G massively mutates the nascent viral DNA, rendering the virus nonviable and ending the infection.
However, HIV uses its Vif protein to partially block the production of new A3G and to greatly accelerate the intracellular degradation of existing A3G in the proteasome. Thus, there is no A3G left in the cell for incorporation into virions, and the potent antiviral action of A3G is forfeited.
Chiu found that the cytoplasmic A3G is sequestered in very large RNA-protein complexes that are enzymatically inactive. She has since characterized the large complexes, and found that they contain approximately 95 different proteins and multiple RNAs.
Surprisingly, the RNAs are known to be mobile genetic elements that can jump from one place to another in human chromosomes. Such jumping, termed retrotransposition, involves a reverse transcription step similar to that used by HIV. "Jumping genes" have been linked to various genetic mutations and cancer. Chiu showed that recruitment of retrotransposon RNAs into the large A3G complexes blocked the ability of these RNAs to undergo reverse transcription, and thus limited their retrotransposition.
So A3G has been controlling the retrotransposition of these elements over millions of years, and has been helping to protect the integrity of the human genome. The hope is that this ancient protector can now be harnessed to protect against HIV too.
Chiu earned a BS degree in biology and an MS degree in virology from the National Taiwan University in Taipei and a PhD degree in biochemistry and molecular pharmacology from the University of Massachusetts Medical School. Her other awards include an amfAR Fellowship Award and the Dean's Award for Outstanding Academic Achievement at University of Massachusetts. She is the author of 19 peer-reviewed papers (11 as first author) and two patents.
Related Links:
Office of Postdoctoral Education
Gladstone Institute of Virology and Immunology
