STUDENT RESEaRch SympoSiUm 2010 - Graduate and Research ...

AbstrActs
hCD34+ cells using immunofluorescence. To date, one of three
livers analyzed has been found to contain engrafted hCD45+
cells. However, engrafted hCD45+ cells were hCD34-, suggesting
that they underwent continued differentiation along the hematopoietic
lineage following transplantation. Screening of mouse
bone marrow, liver, and spleen samples is ongoing.
#172 11:30–1:00
Use of Human Embryonic Stem Cells to Study Mechanisms
of Mitochondrial Clearance in a Human Neuronal Model of
Niemann Pick Type C
Chelsea Kidwell, Biology (U)
Lawrence S. B. Goldstein, UCSD CME
Niemann Pick Type C (NPC) is a progressive genetic childhood
neurodegenerative disease caused by mutations of the transmembrane
protein NPC1 that result in lysosomal accumulation
of cholesterol. Although rare, NPC is lethal and affected children
die in their childhood or early adolescence. Our knowledge of
the disease is very limited and therefore no cure or treatment is
available. With the use of human embryonic stem cells (hESC)
and gene silencing technology, my lab has created the first human
neuronal model of NPC. By studying hESC derived wild type
and NPC neurons my lab is starting to describe known and new
phenotypes of NPC that have never been probed in live human
neurons. An interesting such phenotype we have observed is
mitochondrial accumulation. My initial observations suggest that
this accumulation is due to abnormal clearance of mitochondria
by the autophagic pathway. I am currently exploring the mechanisms
of this newly described phenotype in human fibroblasts and
hESC derived neurons with decreased function of NPC1, and the
contribution it may have on the neuronal failure seen in patients
with NPC. I believe analysis of human NPC neurons will expand
our knowledge of the role of NPC-1 in neurodegeneration and has
the potential to generate new therapies for children affected with
NPC.
#173 11:30–1:00
Complementation of the Disrupted TRPC6 and VPRBP Genes
in an Autistic Patient Using a Stem Cell Approach
Yanelli Nunez, biology (U)
Ralph Feuer, Biology
Autism spectrum disorders (ASD) have a strong genetic component,
and several chromosomal loci and genes associated to ASD
vulnerability indicate that these disorders are genetically heterogeneous.
However, a large number of genes implicated in the
development of ASD may be part of common molecular pathways.
For example, genes involved in calcium signaling have been
strongly related to ASD. Mutations in different voltage-gated Ca 2+
channels have been identified in ASD patients, in addition, Ca 2+
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regulated signaling molecules have also been associated to these
disorders. Our group has recently identified a clear-diagnosed
autistic patient with a translocation that disrupts the TRPC6 gene
in chromosome 11, causing a drastic reduction in the levels of
its expression. Recent studies indicate that TRPC6 promotes
dendritic formation and growth through CaMKIV and CREB
phosphorylation, dependent on Ca 2+ influx. These evidences suggest
that alterations in the function of TRPC6, and maybe others
genes in this pathway, can lead to neuronal alterations that may
be causally involved in the etiology of ASDs. With the purpose of
studying the possible association between TRPC6 and autism,
we will realize a set of complementation studies using induced
pluripotent stem cells, reprogrammed from the autistic patient’s
dental pulp with the identified mutation. We will complement
the disturbed gene using a lentivirus carrying the TRPC6 cDNA,
and would then analyze the resulting phenotypes looking for an
improvement in dentritic growth or cell proliferation. Simultaneously
we will down regulate the expression of TRPC6 in control
cells using short hairpin RNA interference. Such a gain/loss of
function approach can place TRPC6 as a novel candidate gene in
ASDs, and also provide a proof-of-principle of functional recovery
via gene therapy.
#174 11:30–1:00
Characterization of White Matter Architecture in Subjects
with APOE2 and APOE4 Genotypes
Michael Valdez, Biology (U)
Usha Sinha, Physics
Apolipoprotein E (APOE) genotype is the best indicator for
Alzheimer’s disease (AD) risk factor. Allele APOE4 reduces this
risk while allele APOE2 increases it. Patients with AD experience
a loss of integrity of the white matter in their brains. Magnetic
Resonance based diffusion tensor imaging (DTI) and indices
derived from it such as apparent diffusion coefficient, fractional
anisotropy, and relative anisotropy provide important information
on the microarchitecture of brain tissue. As water diffuses more
readily along fibers rather than perpendicular to the fibers, diffusion
anisotropy is a sensitive indicator of the structural integrity
of white matter fibers. Normal subjects with the two alleles were
imaged with diffusion tensor imaging and the diffusion indices
were analyzed in regions of interest selected manually. Regional
comparisons of the diffusion indices showed that there was a
difference (P < .05) between the subjects with the APOE4 and
APOE2 alleles, indicating the potential for DTI to identify differences
in white matter micro-architecture in the two populations.
STUDENT RESEARCH SYMPOSIUM 2010