13-P118 Wnt/β-catenin pathway activation and myogenic differentiation are induced by cholesterol depletion

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13-P118 Wnt/β-catenin pathway activation and myogenic differentiation are induced by cholesterol depletion
  spatio-temporally altered gene expression profiles during the contactand subsequent fusion of mouse palatal shelves. A total of 882 geneswere identified as candidates that were differentiallyexpressed at themedial portion of palatal shelves. The KEGG pathwayanalysis showedthat Wnt (Canonical, Ca 2+ , PCP), Tgfb (Tgfb, Bmp, Activin), Notch andRetinol signalings were involved in palatal fusion. The results of GOanalysis in BiNGO underlined the functional categories (i.e., JNKactivity, integrin-mediated signaling, cellcell adhesion and apoptosis)specifically related to the MEE contact and fusion. The present resultsalso proved that a significant number of the documented cleft palateresponsegenesdisplayeddistinctspatio-temporalexpressionpatterns.doi:10.1016/j.ydbio.2009.05.364 Program/Abstract # 336Numb differentially regulates the function of Notch1 and Notch3  Jeanne Wilson-Rawls a , Brian J. Beres a , Eric J. Lougher a ,Michael Barton a , Brian C. Verrelli a,b , Jane McGlade d,e , Alan Rawls c a School of Life Sciences, Arizona State Univ., Tempe, AZ, USA b Center for Evolutionary and Functional Genomics, The BioDesignInstitute, ASU, Tempe, AZ, USA c  Univ. of Arizona College of Medicine-Phoenix in partnership with ASU,Phoenix, AZ, USA d  Arthur and Sonia LabattBrain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada e Medical Biophysics, University of Toronto, Toronto, ON, Canada Numb, a cytosolic adaptor protein, is a negative regulator of Notchsignaling. In thevertebrate embryo, skeletal muscle is derived from themyotome of the somites. Notch13 demonstrate overlapping expressionin mouse somites. Numb is limited in expression to dividing cells of the dorsal medial and ventral lateral lips and the myotome. Notch1and Notch2 have been shown to inhibit skeletal myogenesis and wedemonstrate that Notch3 is an effective inhibitor as well. The focus of these studies was to determine if there was Notch receptor specificitydemonstrated by the four Numb protein isoforms during myogenesis.In transcription and myogenesis assays, Notch1 was consistentlynegatively regulated by all four Numb isoforms. Notch2 was variablyaffected and Notch3 was not a target for Numb. Subsequent analysesshowed that unlike Notch1, that Notch3 was not polyubiquitinated,nor degraded when co-expressed in cells with Numb. These dataprovide the first observation that Notch receptors are variably affectedby Numb and will be important for the interpretation of the functionof Notch and Numb interactions during development. This work wasfunded by the American Heart Association.doi:10.1016/j.ydbio.2009.05.365 Program/Abstract # 337 Wnt/  β - catenin pathway activation and myogenic differentiationare induced by cholesterol depletion Debora M. Portilho, Fabio Mendes, Manoel Costa, Jose Garcia, Claudia Mermelstein Institute of Biomedical Science, Federal University of Rio de Janeiro,Rio de Janeiro, Brazil Skeletal muscle differentiation is a multi-step process that beginswith the commitment of mononucleated precursors that withdrawfromcell cycle.Thesemyoblastselongatewhilealigningtoeachother,guided by the recognition between their membranes. This step isfollowed by cell fusion and the formation of striated multinucleatedmyotubes. Myogenic differentiation is influenced by a number of growth factors and determination factors, such as the proteins of theWnt family, that are required for the induction of embryonicmyogenesis. The main interest of the present work was to study theeffects of cholesterol depletion in the Wnt/ β -catenin signalingpathway during muscle differentiation. We used primary culturesprepared from breast muscles of 11-day-old chick embryos, andtreated them with MCD after 24h. We analyzed the expression anddistribution of beta-catenin as a downstream component of the Wntpathway. Cholesterol depletion increased the expression of beta-catenin,its translocationtothenuclei,and activation of Wntpathway.Moreover, we show an enhancement in the expression of theTroponin-T and Sarcomeric-actin in MCD-treated cells. Frizzled, thereceptorofWntproteins,wasco-localizedwiththeGM1gangliosideinmembrane micro-domains. Taken together, the data here presentedprovide evidence that cholesterol depletion from myoblasts mem-branes induces the activation of Wnt signaling pathway, the enhance-mentof  β -cateninexpressionanditsnucleartranslocation,resultinginmyoblast recognition and fusion into multinucleated myotubes.doi:10.1016/j.ydbio.2009.05.366 Program/Abstract # 338 WID, a novel negative regulator of the WNT signaling pathway, isimportant for kidney development Myong Shin Kim, Jirouta Kitagaki, Frank Bollig,Christoph Englert, Alan O. Perantoni, Sean B. Lee Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USACancerand Developmental Biology Laboratory, National Cancer Institute,NCI-Frederick, Frederick, MD, USALeibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany Mammalian kidney development is regulated by distinct activitiesof the Wilms tumor gene, WT1, and the WNT/ β -catenin pathway, buthow these two pathways converge on renal development is not wellunderstood. Here we identified a novel gene WID (WT1-inducedInhibitor of Dishevelled) as a WT1 transcriptional target that is bothcritical for kidney development and negatively regulates WNT/ β -catenin signaling. WID interacts with Dishevelled via its C-terminalCXXC zinc finger and Dishevelled Binding domains and potentlyinhibitsWNT/ β -cateninsignalinginvitroandinvivo.Inthedevelopingmouse kidney, Wid and Wt1 expression overlap closelyand Wid − / − mice exhibit glomerular defects with proteinurea and early postnatallethality. In addition, a subset of Wid+/ −  and Wid − / −  micedisplayed duplicated kidneys and ureter hydronephrosis. Remarkably,knockdown of wid expression in zebrafish also interferes withdevelopment of the embryonic kidney. Taken together, our resultsdemonstrate that the WT1 target gene WID playsan importantrole inkidney development, and implicate WT1 in the negative regulation of WNTsignaling during nephrogenesis, via WID.doi:10.1016/j.ydbio.2009.05.367 Program/Abstract # 339ERK1/2-signaling is required for cell differentiation during ocular lens development Lixing W. Reneker Department of Ophthalmology, Univ. of Missouri, Columbia, MO, USA The ocularlens is a simple andpolarizedtissue thatis madeof twocell types, epithelial and fiber cells. Duringlens development, the lensepithelial cells at the periphery are induced to proliferate and thendifferentiate into the lens fiber cells. Growth factor signaling has been  Abstracts / Developmental Biology 331 (2009) 481 – 486  484
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