|
Home
About the Center
Investigators
Projects
Seminar Series
Fellowships
Training Directory
Funding Opportunities
Microarray Facility
Mammalian Reproductive Genetics Database
Links
UW and Seattle
About Orchids
|
|
Recent Fellows Supported
on the Reproductive Biology Training Grant
Andrea Coviello (Dr.
William J. Bremner)
Regulation of Spermatogenesis in
Men
Dr. Coviello's research is focused on the
epidemiology of hormones in male aging and the
hypothalamic-pituitary-testicular axis in male reproductive function, with
particular emphasis on male hormonal contraception. She completed a
masters degree in epidemiology in 2003 with the thesis “Androgens and the
Insulin-like Growth Factor System in Normal Middle Age Men: Correlates of
Serum Hormones and Binding Proteins Potentially Related to Prostate Cancer
Risk.” She also works on the relationship between intratesticular
testosterone levels and spermatogenesis. Understanding this may contribute
to the development of more efficacious treatments for male infertility as
well as a male hormonal contraceptive. She recently conducted a pilot
study investigating the dose-response relationship between
human chorionic gonadotropin (hCG)
and intratesticular testosterone levels. Endogenous gonadotropins, LH and
FSH, were suppressed by administration of intramuscular testosterone
enanthate, and testicular production of LH was then stimulated by hCG,
which stimulates production of intratesticular testosterone.
Intratesticular testosterone levels were determined by fine-needle
aspirate of the testes. Knowledge of the response within the testicle to
hCG will allow the design of future studies of spermatogenesis with a
greater focus on the testicular environment. Analysis of data for this
study is under way. Dr. Coviello is currently conducting a clinical study
on the differential rate of gonadotropin suppression by various
combinations of contraceptive agents, such as testosterone enanthate,
levonorgestrel, and a GnRH receptor agonist, acyline.
Wu-Min Deng (Dr. Hanele Ruohola-Baker)
Role of Dystroglycan and other
Genes in Oogenesis
One
of the fundamental questions in sexual reproduction is how maternal
information is stored in oocytes so that proper early embryonic
development is guaranteed prior to the expression of zygotic genes. This
question can be most readily analyzed in a model organism, Drosophila
melanogaster, owing to its easy-to-manipulate genetic system, short
life cycle and relatively low cost. Dr. Deng is interested in
understanding how maternal determinants are localized at different
sub-cellular regions in the oocyte to direct the establishment of
embryonic axes in this model organism. Since the majority of
mammalian genes have homologous sequences and conserved functions in
Drosophila, and the biological complexity of Drosophila is
comparable to that of a mammal, many of the lessons learned in
Drosophila will help us to better understand the mammalian systems.
The Drosophila oocyte is polarized along the anterior-posterior and
dorsal-ventral axes. The establishment of oocyte polarity requires an
intact cytoskeletal network and communication between the germline cells
and overlying somatic follicle cells. Dr. Deng’s previous research led to
the discovery that dystroglycan, a receptor for laminin, is required for
oocyte polarization in Drosophila. Interestingly, it is reported
that altered dystroglycan function causes reduced reproductive fitness in
a mouse model. In the future, he will use genetic techniques in the
Drosophila to investigate in detail the cellular and molecular
function of dystroglycan during oogenesis. In addition, he plans to use a
sensitized dystroglycan mutant background to test in vivo
interactions with genes such as src and Grb2, which are known to interact
biochemically with dystroglycan. He is also screening for novel
dystroglycan-interacting genes using the so-called “modifier screens"
technique. Once the modifiers are identified, their relationship to
dystroglycan and function in ovarian development will be further
investigated.
Ajamete Kaykas (Dr. Randall Moon)
Role of Wnt Signaling in Development
Dr.
Kaykas’s research has focused on understanding the molecular events that
occur in cells after Wnts bind and activate their cognate Frizzled and LRP
receptors. Wnts comprise a family of secreted glycoproteins involved in
specifying axis, cell movements, and cell fate in the developing
vertebrate embryo. Constitutive activation of Wnt signaling in mouse and
man leads to cancer, and Wnt signaling recently has been implicated in the
development of the female reproductive tract. Mice deficient in Wnt7a are
sterile, and their reproductive tracts have developmental defects.
Identifying components of the Wnt-signaling pathway will shed light on
Wnt's role in development and disease. Dr. Kaykas is using both
biochemical and genetic approaches to identify proteins that interact with
Frizzled and LRP6. Multiple yeast 2-hybrid screens have been conducted
with the intracellular tail of LRP6 (another receptor for WNT) and the
intracellular loops and tail of Frizzled. From these screens, he has
identified numerous Frizzled and LPR6 interacting proteins and is
presently characterizing a couple of them. In collaboration with Norbert
Perrimon's lab at Harvard, he is conducting a genome-wide RNAi screen in
Drosophila cell lines to identify novel proteins involved in the Wnt-signaling
pathway. In addition, it has become apparent that Frizzled can form homo-
and hetero-oligomers, and when this oligomerization goes awry it may
contribute to the human disease familial exudative vitreoretinopathy. Dr.
Kaykas is author of three recent papers.
Christiana DelloRusso (Dr.
Mary-Claire King)
Biology of Ovarian Development and
Tumorigenesis in Women
Dr. DelloRusso is studying
the biology of familial ovarian cancer. The evaluation of BRCA1-associated
ovarian cancer is uniquely suited to this study because most cancers occur
in pre-menopausal women, and there is increasing evidence that BRCA1 is
associated with estrogen-dependent processes. Genomic instability is
characteristic of BRCA1-associated breast and ovarian tumors. BRCA1 is
thought to play a major role in the DNA damage response that functions to
maintain genomic stability. Dr. DelloRusso has propagated a novel
BRCA1-null human cancer cell line, UWB1.289, the first such cell line
originating from ovarian tissue. The goals of her project are to
characterize the cell line and to develop it as a model culture system for
testing the pathogenicity of BRCA1 missense mutations. Experiments testing
DNA repair and cell cycle checkpoint regulation in response to induced DNA
damage will be performed. Evaluation of these processes in UWB1.289 cells
may reveal new information about the role of BRCA1 in response to DNA
damage in ovarian epithelial cells. The development of a functional assay
for BRCA1 could demystify the effects of potentially deleterious, but
currently uncharacterized, BRCA1 missense mutations for breast and ovarian
cancer patients (who at present must contemplate severe prophylactic
measures when found to carry these mutations). In addition, a better
understanding of BRCA1 biology within the ovary should lend insight into
the process of ovarian tumorigenesis as well as the role of BRCA1 in
normal ovarian development and aging.
Gregory Fraley (Dr. Robert
Steiner)
Neuropeptides Governing the Integration of Metabolism and Reproduction
Dr. Fraley
has been a fellow in the Steiner lab since March, 2002. He was initially
involved in a collaborative investigation to explore the effects of
centrally administered GALP on feeding, body weight, and other behaviors
in the rat and mouse. He and a graduate student with whom he worked,
Stephanie Krasnow, are coauthors of a paper (Krasnow et al.,
Endocrinology 144:8113-8122, 2003). Next, he studied the effects of
GALP and galanin, delivered centrally (ICV), on the expression of the
immediate early gene product Fos in the hypothalamus of the rat. This
experiment demonstrated that GALP and galanin produced a differential
pattern of Fos expression throughout the forebrain. GALP induced high
levels of Fos expression in hypothalamic areas known to be involved in
feeding and reproductive control, most notably the PVN, caudal POA,
horizontal limb of the diagonal band of Broca, the arcuate nucleus, and
the median eminence. This is an exciting and important finding, suggesting
that certain hypothalamic regions may express GALP-specific receptors.
This work was recently published (Fraley et al., Endocrinology
144:1143-1146, 2003). Dr. Fraley has also studied the effects of metabolic
factors that regulate GALP mRNA expression. The Steiner lab had shown that
leptin induces the expression of GALP mRNA, and Dr. Fraley examined the
effects of other insulin and metabolic fuels (glucose and fatty acids) on
GALP mRNA expression. His experiments demonstrated that insulin regulates
GALP expression independently of leptin and that glucose and fatty acids
may also have a regulatory effect on the expression of GALP mRNA. He has
also discovered that rats with streptozotocin-induced diabetes have
markedly reduced GALP expression in the arcuate nucleus and that insulin
and leptin can both reverse this effect. These results are being prepared
for publication. Dr. Fraley is now taking a two-pronged approach to
determining the physiologic significance of GALP. First, in collaboration
with Jamie Baumgartner at Amgen, Inc., he is exploring the action of
centrally administered GALP to regulate male-specific reproductive
behaviors. Second, he is developing the single-cell microarray technology
in collaboration with Dr. Paul Amieux of the Department of Physiology and
Biophysics (University of Washington) and Dr. Susan Smith of the Oregon
Health and Sciences University. This technology will allow us to analyze
the whole complement of mRNA in only GALP neurons in response to
experimental manipulations. These two collaborative research projects will
greatly extend the current knowledge base for the role of GALP as the
central mediator of the effects of metabolism on reproduction.
Ellen Ward (Dr. Celeste Berg)
Molecular Regulation of Oogenesis in Drosophila
Dorsal
appendage formation during egg development in D. melanogaster
provides an excellent model for understanding the molecular and cellular
interactions necessary to create complex structures from simple
epithelia. The dorsal appendage tubes are formed from an initially flat
somatic follicular epithelium covering the oocyte. As a member of Dr.
Berg’s lab, Dr. Ward proposed studies to examine the mechanism by which
cells interpret positional information and coordinate cell-shape changes
and rearrangements to generate a tube. In studies of wild-type and mutant
egg chambers, Dr. Ward showed that two distinct cell types, the rholacZ
and Broad cells, contribute to the dorsal appendage tubes. Initially, the
rholacZ and Broad cells are in a flat epithelium. They then reorganize to
form an asymmetric tube, with the rholacZ cells forming the ventral floor
of the tube and the Broad cells forming a roof over the rholacZ
cells. Although these cells rearrange to form a dorsal appendage tube,
they never intermingle, suggesting that a boundary exists between them
preventing mixing. Consistent with this hypothesis, the rholacZ and Broad
cells express different levels of Fas3 and Cadherin, two homophilic
adhesion molecules. On the basis of her analysis, Dr. Ward proposed that
signaling across the boundary separating the two types of cells
choreographs the cell-shape changes and rearrangements necessary to make a
tube from an initially flat epithelium. She plans to examine dorsal
appendage formation in the absence of Notch activity, a well-known
signaling molecule that functions at many boundaries during development.
In summary, this work provides the foundation for investigating the link
between the initial patterning events that specify the tube primordium and
the subsequent morphologic changes necessary to generate a tube from a
flat epithelium. Dr. Ward has published one paper (EJ
Ward et al., GAL4 enhancer trap
patterns during Drosophila development. Genesis 34:46-50,
2002) and has another in preparation (EJ Ward and CA Berg, Drosophila
oogenesis as a model for epithelial morphogenesis during development).
|
