Libin
studies lipids, or fat molecules (cholesterol, vitamin A and vitamin E are
examples), and their oxidation, a chemical reaction that generates free
radicals that can damage DNA and body tissues. Having too many free radicals leads
to oxidative stress, but this process can be prevented by antioxidants made in
our own body or absorbed from diet. The Xu Lab studies how certain lipids are
oxidized and metabolized, and how oxidation during lipid metabolism might be
involved in human diseases.
The
Xu lab is studying a rare disease called Smith-Lemli-Opitz syndrome or SLOS. SLOS
is a cholesterol disorder that causes problems in the development of the central
nervous system starting at embryonic stages. People who have SLOS have birth
defects, intellectual disability and behavior problems such as autism.
SLOS
is caused by a mutation in a gene (DHCR7) that makes an enzyme (3β-hydroxysterole-Δ7-reductase) that turns one lipid
molecule (7-DHC) into another (cholesterol). The mutation means that SLOS
patients have a lot of 7-DHC and not enough cholesterol. And it turns out that 7-DHC
is extremely reactive toward oxidation, leading to the formation of free
radicals and toxic oxidation products called oxysterols. In addition, some oxidative
enzymes (cytochrome P450) can also turn 7-DHC into toxic oxysterols. This may
be the problem underlying SLOS.
The goal of the work in Dr.
Xu’s lab is to figure out the exact biochemical processes that lead to the
broad phenotype of SLOS, and to find therapies to improve SLOS and other
diseases caused by disrupted lipids. This research also will help scientists understand other
intellectual and developmental disabilities that are associated with lipid metabolism
problems and affect the function of the brain.
The research tools being
developed in Dr. Xu’s lab to study lipids, based on advanced mass spectrometry,
can also be used to study the side effects that common drugs might have on the
metabolism of lipid molecules.
Working with the CEEH
Community Outreach and Engagement Core (COEC), Libin Xu and Andrew Dinh in the
Xu Lab have created a handout of interest to the general public: Fast Facts about Fat-Soluble Vitamins. Libin has also agreed to talk about lipid
oxidation and his research at a Public Health Café next year.
Dr. Xu graduated with a B.Sc.
in Chemistry from Nankai University, Tianjin, China. He earned his PhD in
Organic Chemistry from the University of Illinois at Chicago, and did a
post-doc at Vanderbilt where he became interested in lipid peroxidation and its
role in human diseases. He received the
Young Investigator Award from the Society for Free Radical Biology and Medicine
in 2011 and the NIH Pathway to Independence Award from the National Institute
of Child Health and Human Development in 2012. We welcome Libin Xu to the CEEH.
--Marilyn
Hair
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