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Principal Investigator: AMIN S GHABRIAL
Organization: COLUMBIA UNIVERSITY HEALTH SCIENCES
Fiscal Year: 2019
Award: $335,807
Funding agency: National Institute of General Medical Sciences
Ghabrial – Project Summary
To build a functional vascular system, a network of endothelial tubes must be generated through a combination
of vasculogenesis and angiogenesis. During sprouting angiogenesis, endothelial tip cells lead the outgrowth of
new branches. Tip cells anastomose with other tip cells or with pre-existing tubes. At the same time, tip cells
must also lumenize so that the tubes become patent. Studies in zebrafish indicate tip cells lumenize by a
process that an intracellular tube that, in cross section, lacks junctional seams (seamless tube). Even tip cells
that later remodel to contribute to multicellular tubes, pass through a seamless tube intermediate stage.
Likewise, during primary branching of the Drosophila respiratory system, tracheal tip cells lead the outgrowth of
new branches. To form a network, some tracheal tip cells anastomose (fusion cells) while others (terminal
cells) branch extensively to produce dozens of blind ended tubes that ramify on target tissues and act as the
sites of gas exchange. Like endothelial tip cells, tracheal tip cells form seamless tubes. Cell biological studies
have led to the current model of seamless tube formation by inverse membrane blebbing; however, very little is
known about the genetic and molecular pathways that are required. We have been exploiting the powerful
forward genetic approaches possible in Drosophila to meet our long-term objective of pioneering an
understanding of the genetic and molecular framework required to make, shape and maintain seamless tubes.
The rationale of our approach is that the fundamental rules and genetic pathways operative in Drosophila are
likely to be conserved throughout the animal kingdom. As we build our understanding by identifying novel
genes required for seamless tube morphogenesis (AIM 1: Determine the molecular identity and function of
the cystic lumens gene.), we also go deeper – using molecular genetic, cellular, and proteomic approaches –
to identify additional components and mechanisms of action for genetic pathways we have previously
identified, and extending our findings to endothelial seamless tubes (AIM 2: Elucidate the cellular and
molecular mechanisms of TBC1D10 and Rab35 action in seamless tube growth). Additionally, one
seamless tubulogenesis pathway (the Cerebral Cavernous Malformations 3-Germinal Center Kinase III
pathway) we identified, is known to be critical in endothelial cells, as mutations in orthologous human genes
lead to familial vascular disease. Using Drosophila genetic and proteomic approaches, we have identified
factors required both upstream and downstream in the CCM3-GCKIII pathway, and now propose to more
clearly define the biological consequences of perturbing the pathway and to identify the downstream targets of
the signaling pathway. Given the conserved role of CCM3 in tubulogenesis, we also seek to extend our results
to the vertebrate endothelial system, making use of zebrafish, whose unique properties will allow both genetic
manipulation and live imaging in vivo of vascular lesion formation (AIM 3: To characterize the role of the
NDR kinase, Tricornered, in regulating seamless tube shape.).
Terms: <3-D><3-Dimensional><3D><Adherens Junction><Adhering Junction><Adhesive Junction><Affect><Anchoring Junction><Animals><Apical><Basic Research><Basic Science><Biological><Biological Testing><Blood Vessels><Body Tissues><Brachydanio rerio><CAP43><CMT4D><Caliber><Cardiovascular><Cardiovascular Body System><Cardiovascular Organ System><Cardiovascular system><Cavernoma><Cavernous Angioma><Cavernous Hemangioma><Cell Body><Cell Communication and Signaling><Cell Signaling><Cell fusion><Cells><Cerebral Infarction><Characteristics><Chemoattractants><Chemotactic Factors><Chemotaxins><Cues><DRG1><Danio rerio><Defect><Diameter><Distal><Drosophila><Drosophila genus><Endothelial Cells><Endothelium><Follow-Up Studies><Followup Studies><Gases><Generalized Growth><Generations><Genes><Genetic><Genetic Alteration><Genetic Change><Genetic Screening><Genetic analyses><Genetic defect><Goals><Growth><Growth Agents><Growth Factor><Growth Substances><HMSNL><Health><Heart Vascular><Human><Intracellular Communication and Signaling><Kinases><Kruppel-like transcription factors><Lead><Legal patent><Length><Lesion><Life><Maintenance><Mediating><Membrane><Modeling><Modern Man><Molecular><Molecular Genetics><Morphogenesis><Mutation><NDR1><NDRG1><NDRG1 gene><NMSL><Organ><Organ System><Ortholog><Orthologous Gene><PROXY1><Patents><Pathway interactions><Pb element><Phenotype><Phosphotransferase Gene><Phosphotransferases><Position><Positioning Attribute><Process><Property><Proteins Growth Factors><Proteomics><Pulmonary Body System><Pulmonary Organ System><Respiratory System><Respiratory Tracts><Respiratory tract structure><Role><Septate><Shapes><Side><Signal Pathway><Signal Transduction><Signal Transduction Systems><Signaling><Site><Stereotyping><System><TDD5><Testing><Time><Tissue Growth><Tissues><Transphosphorylases><Tube><Tubular><Tubular formation><Vascular Diseases><Vascular Disorder><Vascular System><Vertebrate Animals><Vertebrates><Vesicle><Work><Zebra Danio><Zebra Fish><Zebrafish><angiogenesis><apical membrane><base><biological signal transduction><blind><blood vessel disorder><body system><cerebral cavernous malformations><cerebral infarct><circulatory system><cofilin><complement chemotactic factor><fruit fly><genetic analysis><genetic approach><genetic manipulation><genome mutation><germinal center kinase family><germinal center kinases><heavy metal Pb><heavy metal lead><imaging in vivo><in vivo imaging><loss of function><membrane structure><membrane-organizing extension spike protein><migration><moesin><mutant><notch><notch protein><notch receptors><novel><off-patent><ontogeny><pathway><recruit><repair><repaired><respiratory><response><social role><trafficking><vascular><vascular bed><vascular dysfunction><vasculogenesis><vasculopathy><vertebrata>