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40 developed, we show that application of recombinant PTHrP, Egf-family ligands, or Wnt3A proteins stimulated branching of embryonic mammary glands suggesting that these pathways may cooperatively mediate the effects of Eda. Moreover, we show that in contrast to wild-type male mice, ductal growth proceeded in K14-Eda males similarly to transgenic females. Program/Abstract # 122 Twisted gastrulation, an extracellular BMP binding protein, is required for postnatal mammary gland morphogenesis Forsman, Cynthia, University of Minnesota Genetics, Minneapolis, United States The role bone morphogenetic proteins (BMPs) play and how they are regulated in the postnatal mammary gland (MG) remains virtually unknown. It has been established that BMPs are involved in embryonic MG development and can be dysregulated in breast cancer. This study examines the role of Twisted gastrulation (TWSG1), an extracellular BMP binding protein that can modulate BMP signaling, during postnatal MG development. LacZ staining demonstrates that TWSG1 is expressed in the myoepithelium of the postnantal MG but immunolocalization studies show TWSG1 in both the myoepithelium and the epithelium suggesting a role for TWSG1 in epithelial/stromal communication. Global deletion of Twsg1 leads to a delayin ductal elongation, hyperplastic terminal end buds, occluded lumens and cell shedding. pSMAD1/5/8 level and the expression of BMP target genes (Msx2, Gata-3) are reduced, consistent with a decrease in BMP signaling. Apoptosis of excess body cells is required for lumen formation and in the Twsg1-/- MG apoptosis is reduced which may contribute to occluded lumens seen in these MG. Furthermore, shed cells and some cells within the luminal compartment are K14-positive, while normally K14-positive cells are restricted to the myoepithelial layer suggesting that regulation of BMP signaling by TWSG1 is required for myoepithelial compartmentalization. Altogether, these data show that TWSG1 facilitates BMP signaling and plays a role in ductal morphogenesis in the postnatal MG. Program/Abstract # 123 Planar cell polarity proteins differentially regulate ECM organization during zebrafish gastrulation Jessen, Jason; Williams, Blairanne; Mundell, Nathan, Vanderbilt University Medical Center Medicine, Nashville, United States During zebrafish gastrulation, planar cell polarity (PCP) is defined as the elongation and mediolateral alignment of cells engaged in polarized behaviors including collective migration. A decade ago it was shown that homologs of proteins regulating PCP in fly cuticular structures also control PCP in gastrula cells. Loss of PCP gene function in mutants such as trilobite/vang-like 2 (vangl2) produces a phenotype characterized by shortened and broadened embryonic body axes. While it is thought that disrupted membrane protrusive activity underlies the PCP defect in vangl2 mutants, the establishment of PCP must be coordinated with, and perhaps also regulates, dynamic changes in extracellular matrix (ECM) organization. Previously our lab demonstrated that membrane type-1 matrix metalloproteinase (Mmp14) is required for PCP exhibiting a strong genetic interaction with knypek/glypican4, a Wnt co-receptor necessary for gastrulation cell movements. Subsequently we showed that a fibronectin- and laminin-containing ECM network develops coincidently with the onset of PCP. We have now demonstrated that Vangl2 regulates the endocytosis and cell surface proteolytic activity of Mmp14. Furthermore, our data show that Mmp14 acts as a downstream effector of Vangl2 signaling during gastrulation. Similar to vangl2 mutants, wild-type embryos injected with prickle antisense morpholinos have reduced fibronectin. By contrast, glypican4 and frizzled7a/7b mutant embryos exhibit increased fibronectin fibrillogenesis without an increase in fibronectin protein levels. These data suggest that while Vangl2/Prickle affect proteolysis of ECM substrates, Frizzled/Dishevelled signaling likely influences ECM organization by impacting intercellular adhesion. Program/Abstract # 124 Dynamin is required for the maintenance of EVL integrity and the progression of epiboly Lepage, Stephanie; Bruce, Ashley, Univ of Toronto, Canada Epiboly, the first morphogenetic cell movement that occurs in the zebrafish embryo, is the process by which the blastoderm thins and spreads to engulf the yolk cell. This process requires the concerted actions of the deep cells, which make up the embryo proper, and the two extra-embryonic tissues, the enveloping layer (EVL) and yolk syncytial layer (YSL). One mechanism predicted to contribute to the progression of epiboly is the endocytic removal of yolk cell membrane, just ahead of the advancing blastoderm, in the region of the YSL. Using a drug-based approach, we demonstrate that marginal endocytosis occurs in a Dynamin-dependent and Clathrin-mediated manner and that inhibition of either Dynamin or Clathrin results in a severe epiboly delay. In contrast, localized expression of dominant-negative (DN)-Dynamin 2 in the yolk cell reduced marginal endocytosis, but epiboly still progressed normally. This suggests that endocytic removal of yolk cell membrane is dispensable for the successful progression and completion of epiboly. Instead,
41 these data imply that Dynamin is primarily required in the blastoderm during epiboly. Consistent with this finding, inhibition of Dynamin using the inhibitor dynasore caused profound defects in EVL cell morphology, polarity and tissue integrity. Scattered EVL cells adopted a rounded morphology, lost contact with their neighbours and were occasionally extruded basally from the epithelium. Expression of DN-Rho was able to rescue both the epiboly delay and constricted EVL cell phenotype; however, this occurred independently of Myosin II since the effects of dynasore treatment could not be rescued by the Myosin II inhibitor blebbistatin. Members of the Ezrin/Radixin/Moesin (ERM) protein family are key regulators of cortical tension and epithelial integrity in other systems. EVL cells of dynasore treated embryos had a striking reduction in cortically localized phosphorylated ERM. In addition, morpholino knockdown of a single ERM family member, ezrin, phenocopied the dynasore-induced epiboly delay and EVL defects. Taken together, these data suggest that Dynamin maintains EVL integrity and promotes epiboly progression by maintaining ERM activity at the EVL cell cortex and antagonizing Rho signaling. Program/Abstract # 125 Functional studies of Fam132a/C1qdc2, a secreted molecule downstream of Stat3 signaling, during zebrafish gastrulation Liu, Yinzi; Sepich, Diane; Shin, Jimann; Solnica-Krezel, Lilianna, WUSTL, Saint Louis, United States Convergence and extension (C&E) are evolutionarily conserved vertebrate gastrulation movements, which narrow the germ layers mediolaterally and elongate them anteroposteriorly. Many pathways have been implicated in regulating these processes, including Stat3 signaling in zebrafish. Conserved from Drosophila to mammals, Janus Kinase (JAK)/Signal Transducer and Activator of Transcription (STAT) pathway mediates diverse biological processes through transcriptional regulation of downstream targets in response to cytokines and growth factors. During zebrafish gastrulation, activated Stat3 is required cell-autonomously for the anterior migration of the axialmesodermal cells originating in the gastrula organizer, and also regulates convergence of lateral mesendodermal cells non cell-autonomously. However, the underlying mechanisms remain poorly understood. Here, we identified Fam132a, or family with sequence similarity 132a, C1q domain containing 2 (C1qdc2), a conserved protein of unknown function, as a downstream target of Stat3 signaling by comparing gene expression profiles between stat3-deficient and wild-type gastrulae. We found that zebrafish fam132a is both maternally and zygotically expressed. Fam132a-GFP fusion protein appears to be secreted into the extracellular space and forms puncta during blastula and gastrula stages. Interestingly, over expression of fam132a resulted in not only independent C&E defects, but dorsoventral patterning defects as well. We will report ongoing loss-of-function analysis of fam132a through transcription activator-like effector nuclease(TALEN). Program/Abstract # 126 Gastrulation in high-resolution: New insights into an important process of development. Martik, Megan; McClay, David, Duke University, Durham, United States Gastrulation is a complex orchestration of movements by cells that are specified early in development. Until now, it was thought that lateral rearrangement of endoderm cells by convergent extension was the main contributor to sea urchin archenteron elongation. Our project characterizes, at high-resolution, the repertoire of cellular movements contributing to the length of gut. We have performed cell transplantation to live image and analyze a subset of labeled endoderm cells in the optically clear sea urchin embryo. We have found that the endoderm cells that initially invaginate remain contiguous throughout extension, so that, if convergent extension is present, it is not a major contributor to elongation. We have also found, unexpectedly, that endoderm cells proliferate as they move to elongate the archenteron. Our descriptive studies of the cellular processes during gastrulation have allowed us to begin investigating their molecular control. The sea urchin endomesoderm gene regulatory network (GRN) describes the cell fate specification of the future larval gut; however, the GRN does not describe specific cell biological events driving morphogenesis. We plan to dissect the transcriptional circuitry of the GRN responsible for the cell biological events of gastrulation. Our ability to connect the endomesoderm GRN to the morphogenetic events of gastrulation will provide a framework for characterizing this remarkable sequence of cell movements in the simplest of deuterostome models at an unprecedented scale. Program/Abstract # 127 Functions of p120-catenin in the developing mouse embryo. Hernández-Martínez, Rocío, Sloan-Kettering Institute, United States; Anderson, Kathryn, V., Sloan-Kettering Institute, New York, U.S.A. p120-catenin is an member armadillo family proteins that regulate intercellular junctions. The best-defined role of p120- ctn is to promote the stabilization of cadherins on the cell surface through inhibition of endocytosis. In addition, it is has been observed that p120-ctn also functionally interacts with specific Rho-GTPases family that are important regulators of
Page 1 and 2: 1 Program/Abstract # 1 Role of the
Page 3 and 4: 3 Program/Abstract # 7 Forward gene
Page 5 and 6: 5 Program/Abstract # 13 Evolution a
Page 7 and 8: 7 Program/Abstract # 19 Lethal gian
Page 9 and 10: 9 Program/Abstract # 26 On the comb
Page 11 and 12: 11 Program/Abstract # 32 Imaging in
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Page 15 and 16: 15 paracellular space, and interact
Page 17 and 18: 17 the proximal to distal axis of t
Page 19 and 20: 19 Dominguez-Castellano, Maria; Gar
Page 21 and 22: 21 We are interested in the role of
Page 23 and 24: 23 more likely than students who di
Page 25 and 26: 25 was a significant loss of cells
Page 27 and 28: 27 Fgfr3 expression in the limb cho
Page 29 and 30: 29 division, but rapidly loses its
Page 31 and 32: 31 and migration (ADAM13). They act
Page 33 and 34: 33 Program/Abstract # 101 The influ
Page 35 and 36: 35 Program/Abstract # 107 Shroom3-d
Page 37 and 38: 37 Program/Abstract # 113 Requireme
Page 39: 39 (Queens College, Flushing, Unite
Page 43 and 44: 43 Congenital renal malformations a
Page 45 and 46: 45 Elevated nuclear translocation o
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Page 49 and 50: 49 abnormally dilated capillaries i
Page 51 and 52: 51 malformations in murine limb bud
Page 53 and 54: 53 Yuqing (Mouse Imaging Centre, To
Page 55 and 56: 55 in the villi at E14. At E11, the
Page 57 and 58: 57 Program/Abstract # 173 The role
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Page 61 and 62: 61 examine stem cell-based CNS rege
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Page 69 and 70: 69 Program/Abstract # 209 Drosophil
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Page 73 and 74: 73 experimental analysis. The jerbo
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Page 79 and 80: 79 into the role snx5 playsin the N
Page 81 and 82: 81 Lee, Hu-Hui, National Chiayi ers
Page 83 and 84: 83 understood. Here, we have establ
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91 Program/Abstract # 278 Heterogen
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93 Program/Abstract # 284 Investiga
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95 Program/Abstract # 290 A molecul
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97 dizygotic twin studies have show
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99 Program/Abstract # 301 Dual role
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101 trafficking of cargo proteins a
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103 Sonic Hedgehog (Shh) is a secre
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105 tube was aberrant. Our data ind
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107 degradation of Smad proteins. W
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109 strong affects on organogenesis
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111 that maternally-supplied Lkb1 i
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113 Program/Abstract # 341 Coordina
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115 partners. Our transgenic gain o
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117 delayed and stunted as monitore
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119 Program/Abstract # 359 The meth
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121 Misregulation of molecular path
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123 back to the midbody in cbp-1 RN
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125 versus asymmetric cell division
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127 spinal cord. Iulianella, Angelo
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129 determine cell cycle activity i
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131 in expanded Lmx1a/b+ progenitor
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133 ROS levels. Collectively, our r
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135 limbs. Apoptosis was also pertu
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137 Henkels, Julia; Zamir, Evan, Ge
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139 however, and its role in CSF ma
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141 embryonic precursors to form an
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143 with fork retarding Replication
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145 homeodomain (HD) transcription
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147 fate, potentially acting downst
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149 involved in Drosophila ventral
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151 Program/Abstract # 456 Thoracic
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153 ureteric insertion into the bla
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155 of p16, a known cyclin kinase i
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157 rax mutant was recently found i
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Abstracts - Society for Developmental Biology

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