title: A Novel Zebrafish ret Heterozygous Model of Hirschsprung Disease Identifies a Functional Role for mapk10 as a Modifier of Enteric Nervous System Phenotype Severity.
abstract: Hirschsprung disease (HSCR) is characterized by absence of enteric neurons from the distal colon and severe intestinal dysmotility. To understand the pathophysiology and genetics of HSCR we developed a unique zebrafish model that allows combined genetic, developmental and in vivo physiological studies. We show that ret mutant zebrafish exhibit cellular, physiological and genetic features of HSCR, including absence of intestinal neurons, reduced peristalsis, and varying phenotype expressivity in the heterozygous state. We perform live imaging experiments using a UAS-GAL4 binary genetic system to drive fluorescent protein expression in ENS progenitors. We demonstrate that ENS progenitors migrate at reduced speed in ret heterozygous embryos, without changes in proliferation or survival, establishing this as a principal pathogenic mechanism for distal aganglionosis. We show, using live imaging of actual intestinal movements, that intestinal motility is severely compromised in ret mutants, and partially impaired in ret heterozygous larvae, and establish a clear correlation between neuron position and organised intestinal motility. We exploited the partially penetrant ret heterozygous phenotype as a sensitised background to test the influence of a candidate modifier gene. We generated mapk10 loss-of-function mutants, which show reduced numbers of enteric neurons. Significantly, we show that introduction of mapk10 mutations into ret heterozygotes enhanced the ENS deficit, supporting MAPK10 as a HSCR susceptibility locus. Our studies demonstrate that ret heterozygous zebrafish is a sensitized model, with many significant advantages over existing murine models, to explore the pathophysiology and complex genetics of HSCR.
authors.affiliation: Development and Homeostasis of the Nervous System Lab, The Francis Crick Institute, London, United Kingdom.
authors.forename: Tiffany A
authors.identifier: http://orcid.org/0000-0002-6678-8246
authors.initials: TA
authors.lastname: Heanue
authors.affiliation: Laboratory for Enteric Neuroscience, TARGID, KU Leuven, Leuven, Belgium.
authors.forename: Werend
authors.identifier: http://orcid.org/0000-0002-2426-0451
authors.initials: W
authors.lastname: Boesmans
authors.affiliation: Crick Advanced Light Microscopy, The Francis Crick Institute, London, United Kingdom.
authors.forename: Donald M
authors.identifier: http://orcid.org/0000-0002-3788-1580
authors.initials: DM
authors.lastname: Bell
authors.affiliation: Division of Molecular and Developmental Biology, National Institute of Genetic and Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, Shizuoka, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kawakami
authors.affiliation: Laboratory for Enteric Neuroscience, TARGID, KU Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.identifier: http://orcid.org/0000-0002-0009-2094
authors.initials: P
authors.lastname: Vanden Berghe
authors.affiliation: Development and Homeostasis of the Nervous System Lab, The Francis Crick Institute, London, United Kingdom.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Pachnis
mesh_terms: D000818:Animals; D003106:Colon / Q000294:innervation / Q000473:pathology; D004195:Disease Models, Animal; D017615:Enteric Nervous System / Q000378:metabolism* / Q000473:pathology; D006627:Hirschsprung Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D048057:Mitogen-Activated Protein Kinase 10 / Q000235:genetics*; D009154:Mutation; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics* / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics*
chemical_list: D048057:Mitogen-Activated Protein Kinase 10; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human