Page 73 - Mouse Molecular Genetics

Full Abstracts
Program number is above title. Author in bold is the presenter.
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interconnected, particularly since the latter stages of both pathways require fusion with lysosomes. It is tempting to speculate that
perturbation of normal phagocytosis and/or autophagy may be a factor in AMD, because A3/A1-crystallin has been reported to
be present in human drusen, and a possible role of lysosomes in AMD has recently been suggested.
111
Conditional-invertible genetic strategy to understand the role of NIPBL deficiency in the etiology of developmental
defects in Cornelia de Lange Syndrome.
Rosaysela Santos
1,3
,
Xu Wang
1,3
,
Shimako Kawauchi
1,3
,
Russell Jacobs
4
,
Martha
Lopez-Burks
2,3
,
Akihiko Muto
2,3
,
Mona Yazdi
1
,
Salvador Deniz
1
,
Samir Qurashi
1
,
Scott Fraser
4
,
Thomas Schilling
2,3
,
Arthur
Lander
2,3
,
Anne Calof
1,2,3
. 1)
Dept. of Anatomy & Neurobiology, University of California, Irvine, Irvine, CA; 2) Dept. of
Developmental & Cell Biology, University of California, Irvine, Irvine, CA; 3) Center for Complex Biological System,
University of California, Irvine, Irvine, CA; 4) Beckman Insititute, California Institute of Technology, Pasadena, CA.
Cornelia de Lange Syndrome (CdLS) is a multi-systems birth defects disorder caused, in most cases, by haploinsufficiency for
Nipped-B-like (NIPBL), a highly-conserved protein with roles in cohesin loading and transcriptional regulation. Data from
multiple systems suggest that developmental defects in CdLS result from the collective action of many otherwise innocuous,
small changes in gene expression. To investigate these developmental defects, we have developed mouse and zebrafish models of
Nipbl deficiency (Kawauchi et al., 2009; Muto et al., 2011). Both Nipbl+/- mice and nipbl morphants exhibit a spectrum of
developmental defects with strong parallels to those observed in human CdLS, and initial studies indicate that many structural
defects - such as heart defects - originate during early stages of development. Nipbl-deficient embryos in both systems also show
alterations in expression of genes with known roles in L-R patterning and other aspects of heart development. To understand the
stage(s) and tissue(s) in which Nipbl deficiency is critical for development of heart defects in CdLS, we have used the
EUCE313f02 ES cell line, containing a FLEX (conditional-invertible) gene-trap vector in intron 1 of Nipbl, to develop a line of
NipblFLEX/+ mice. We will discuss data showing that this allele can be toggled successfully between mutant and wildtype
conformations; and that NipblFLEX/+ mice exhibit cardiac defects at a frequency similar to Nipbl+/- mice. Currently our studies
are focused on analyzing hearts of mouse embryos in which Nipbl has been inactivated (or rescued) in cardiogenic mesoderm
and/or endoderm, using 3D magnetic resonance microscopy (MRM) to analyze heart morphology. Results of these studies, and
their implications for understanding the origins of structural birth defects in CdLS, will be discussed. Supported by NIH grant
P01-HD052860.
112
Production and Characterization of Transgenic Mice Systemically Expressing Endo-b-galactosidase. Satoshi Watanabe
1
,
Takayuki Sakurai
2
,
Masako Misawa
3
,
Takashi Matsuzaki
3
,
Takashi Muramatsu
4
,
Masahiro Sato
5
. 1)
Animal Genome Reseach
Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan; 2) Department of Cardiovascular Research Graduate
school of Medicine, Shinshu University, Matsumoto, Nagano, Japan; 3) Department of Biological Science, Faculty of life and
Environmental Science, Shimane University, Matsue, Shimane, Japan; 4) Department of Health Science, Faculty of
Psychological and Physical Sciences, Aichi Gakuin University, Nisshin, Aich, Japan; 5) Frontier Science Research Center,
Kagoshima University, Kagoshima, Japan.
TheGal epitope (Gal1-3Gal) is a sugar structure expressed on the cell surface of almost all organisms except humans and old-
world-monkeys, which express natural anti-Gal antibodies. The presence of these antibodies elicits a hyper acute rejection (HAR)
upon xenotransplantation of cellular materials, such as from pigs to human beings. Endo--galactosidase C (EndoGalC), an
enzyme isolated from Clostridium perfringens, removes the Gal epitope by cleaving the Gal1-4GlcNAc linkage in the Gal1-
3
Gal1-4GlcNAc sequence. To explore the possibility that cells or organs from transgenic pigs systemically expressing EndoGalC
might be suitable for xenotransplantation, we first introduced the EndoGalC transgene into the mouse genome via pronuclear
injection. The progeny of the resulting transgenics expressed EndoGalC mRNA and protein. Flow cytometry and histochemical
analyses revealed a dramatic reduction in the expression of the Gal epitope in these mice. They also exhibited abnormal
phenotypes such as occasional death immediately after birth, growth retardation and transient skin lesions. Interestingly, the
phenotypic abnormalities seen in these transgenics were similar to those observed in 1,4-galactosyltransferase 1 (4GalT-1)
knockout mice. Most probably, these phenotypes were caused by exposure of the internal N-acetylglucosamine residue at the end
of the sugar chain on the cell surface. The present findings also provide some basis for evaluating possible application of the
transgenic approach for xenotranplantation.
113
Studies of cell behaviors regulated by HH-GLI2 signaling during medulloblastomas tumor progression. Alexandre
Wojcinski
,
Alexandra Joyner. developmental biology, Memorial Sloan-Kettering Cancer Center, new york, NY.
The quality of life for survivors of Medulloblastoma (MB), the most common developmental brain tumor, is greatly
compromised due to treatment. MBs are divided into subtypes based on expression of key developmental genes. Tumors arise
from at least two embryonic cell types (cells of origin), and hedgehog (HH) signaling is elevated in ~25% of tumors that arise
from cerebellar granule cell progenitors (GCPs). Sonic HH (SHH) functions through GLI2 to stimulate expansion of GCPs in
mice (Corrales, 2006). As inhibition of HH signaling can not be used to treat children due to severe developmental defects, a
more detailed understanding of the GCP behaviors and critical genes regulated by HH signaling are needed to improve survival
of MB patients. Several mouse genetic models of the HH subtype of MB have been generated and have been critical tools for
identifying the cell of origin of MBs. However, the induction of mutations in most GCPs in the highly penetrant murine models