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DTSTART:20190331T030000
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DTSTART:20191027T020000
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DTSTAMP:20260404T083516Z
UID:5c332682b11eb804946577@ist.ac.at
DTSTART:20190827T111500
DTEND:20190827T133000
DESCRIPTION:Speaker: Sonya Widen\nhosted by Carl-Philipp Heisenberg\nAbstra
 ct: Proper development of vertebrate embryos requires fusion of epithelial
  cell sheets\, resulting in closure of the developing neural tube\, palate
  and retina. Within the eye\, failure of the ocular fissure to close resul
 ts in ocular coloboma\, one of the leading causes of pediatric blindness w
 orldwide. Our understanding of causative genetic lesions represents only a
  fraction of cases\, highlighting the need for continued study of genes in
 volved in regulating eye development. Previous work from our lab and other
 s has defined key roles for TGF?/BMP and Wnt signaling pathways in regulat
 ing vertebrate ocular fissure closure\, though our understanding remains l
 imited. Here\, I discuss work identifying novel mutations that implicate t
 wo genes in causality of ocular coloboma and microphthalmia\, Frizzled-5 (
 FZD5) and Bone morphogenetic protein-3 (BMP3). The FZD5 mutation results i
 n a truncated protein that retains the ligand-binding domain but lacks all
  transmembrane domains. In vitro assays suggest truncated FZD5 is a secret
 ed dominant negative receptor that can antagonize both canonical and non-c
 anonical Wnt signaling. We show in vivo that depletion of Fzd5 in zebrafis
 h not only causes microphthalmia and coloboma\, but also tissue-dependent 
 effects on Wnt signaling\, consistent with roles for Fzd5 on more than one
  Wnt pathway. Furthermore\, ectopic expression of human truncated FZD5 hig
 hlights altered biological activity of the mutant transcript. This represe
 nts the first Wnt pathway member implicated in human structural ocular dis
 ease. In a separate study\, we identified a novel missense mutation in BMP
 3 in a family with coloboma\, and two additional missense mutations in an 
 unrelated coloboma patient cohort. Consistent with a role for bmp3 in eye 
 morphogenesis\, zebrafish bmp3 mutants display fissure closure defects. Bm
 p3 is a known TGF? ligand and is expressed directly adjacent to the develo
 ping fissure. We therefore hypothesize that Bmp3 is a novel factor governi
 ng retinal TGF? signaling to control fissure closure. In summary\, my work
  has contributed to our understanding of vertebrate ocular development and
  genetic lesions leading to ocular coloboma.
LOCATION:Meeting room 2nd floor / Bertalanffy Bldg. (I04.2OG - LAB)\, ISTA
ORGANIZER:lalesch@ist.ac.at
SUMMARY:Sonya Widen: 'Closing the gap' in understanding vertebrate choroid 
 fissure closure and ocular coloboma
URL:https://talks-calendar.ista.ac.at/events/2069
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