Liqun Luo
Title
Assistant Professor
Department
Biological Sciences
Research Interests
Molecular mechanisms of neuronal morphogensis.
Email
lluo@stanford.edu
Phone
723-6645
Fax
723-0589
Address
Herrin Lab Rm 144B
Mail Code: 5020
Faculty Research Description
We use molecular genetics in the fruit fly Drosophila melanogaster and
rodents to study how neurons elaborate their dendrites and guide their
axons, and how neural circuits are formed during development.
One of our major focuses has been on the intracellular signal transduction
mechanisms that allow extracellular guidance cues to instruct the reorganization
the actin cytoskeleton in neuronal growth cone. Our previous studies have
suggested that small GTPases of the Rho subfamily and their signaling
partners play important functions in different aspects of neuronal morphogenesis.
To study the function of these pleiotropic genes using loss-of-function
mutants, we have developed the MARCM system in Drosophila (for Mosaic
Analysis with a Repressible Cell Marker), which enables us to remove the
functions of these genes in a very small population of neurons, down to
single neurons. At the same time we can selectively visualize the entire
axon and dendrite projections of only these mutant neurons with high resolution.
We use the neurons of the mushroom bodies, a structure important for insect
learning and memory, as our experimental paradigm to study the functions
of candidate genes in neuronal morphogenesis. We are in the process of
connection Rho GTPases upstream with guidance receptors, and downstream
with the regulation of the actin cytoskeleton. The MARCM system has also
allowed us to perform genetic screens to identify new genes essential
for elaboration of dendrites, branching of axons, and establishment of
neuronal polarity. Once we have identified genes important for neuronal
morphogenesis in flies, we also study the functions of their mammalian
homologs in the morphogenesis of more complex neurons of the mammalian
brain using gene gun transfection of brain slices and mouse genetics.
We have recently started two new research projects in developmental neurobiology.
The first is to understand the molecular basis of neuronal reorganization:
how neurons prune existing axons and dendrites that allow them to form
new connections. We use again the Drosophila mushroom body neurons as
a model system. The second is to investigate the mechanisms of neural
network formation: how one group of neurons make one-to-one connection
with another group of neurons. We use the Drosophila olfactory system
to attack this general problem.
Scott, E. and Luo, L. (2001) How do dendrites take their shape? Nature
Neurosci.4, 359-365.
Winter, C.G., Wang, B., Ballew, A., Royou, A., Karess, R., Axelrod, J.D., and Luo, L. (2001) Drosophila Rho-associated kinase (Drok) links Frizzled-mediated planar cell polarity signaling to the actin cytoskeleton. Cell 105, 81-91.
Luo, L. (2000) Rho GTPases in neuronal morphogenesis. Nature Reviews
Neurosci. 1, 173-180.
Lee, T., Marticke, S., Sung, C., Robinow, S. and Luo, L. (2000). Cell
autonomous requirement of the USP/EcR-B ecdysone receptor for mushroom
body neuronal remodeling in Drosophila. Neuron 28, 807-818.
Liu, Z., Steward, R., and Luo, L. (2000). Drosophila Lis1 is required
for neuroblast proliferation, dendritic elaboration and axonal transport.
Nature Cell Biology 2, 776-783.
Nakayama, A. Y., Harms, M.B., and Luo, L. (2000) Small GTPases Rac and
Rho in the maintenance of dendritic spines and branches in hippocampal
pyramidal neurons. J. Neurosci. 20, 5329-5338.
Lee, T., and Luo, L. (1999). Mosaic analysis with a repressible cell marker
for studies of gene function in neuronal morphogenesis. Neuron 22, 451-461.
Areas of Study
Cellular Neurobiology
Molecular Neurobiology
Developmental Neuroscience
SBRC
Ph.D.