title: Novel mutations at RET ligand genes preventing receptor activation are associated to Hirschsprung's disease.
abstract: Hirschsprung disease (HSCR) is a developmental disorder characterized by the absence of ganglion cells along variable lengths of the distal gastrointestinal tract. The major susceptibility gene for the disease is the RET proto-oncogene, which encodes a receptor tyrosine kinase activated by the glial cell-derived neurotrophic factor (GDNF) family ligands. We analyzed the coding sequence of GDNF, NTRN, and, for the first time, ARTN and PSPN in HSCR patients and detected several novel variants potentially involved in the pathogenesis of HSCR. In vitro functional analysis revealed that the variant R91C in PSPN would avoid the correct expression and secretion of the mature protein. Moreover, this study also highlighted the role of both this variant and F127L in NRTN in altering RET activation by a significant reduction in phosphorylation. To support the role of PSPN R91C in HSCR phenotype, enteric nervous system (ENS) progenitors were isolated from human postnatal gut tissues and expression of GFRα4, the main co-receptor for PSPN, was demonstrated. This suggests that not only GDNF and NRTN but also PSPN might promote survival of precursor cells during ENS development. In summary, we report for the first time the association of PSPN gene with HSCR and confirm the involvement of NRTN in the disease, with the identification of novel variants in those genes. Our results suggest that the biological consequence of the mutations NTRN F127L and PSPN R91C would be a reduction in the activation of RET-dependent signaling pathways, leading to a defect in the proliferation, migration, and/or differentiation process of neural crest cells within the developing gut and thus to the typical aganglionosis of the HSCR phenotype.
authors.affiliation: Unidad de Gestión Clínica de Genética, Reproducción y Medicina Fetal, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Avda. Manuel Siurot s/n, Seville, Spain.
authors.forename: Macarena
authors.initials: M
authors.lastname: Ruiz-Ferrer
authors.forename: Ana
authors.initials: A
authors.lastname: Torroglosa
authors.forename: Berta
authors.initials: B
authors.lastname: Luzón-Toro
authors.forename: Raquel M
authors.initials: RM
authors.lastname: Fernández
authors.forename: Guillermo
authors.initials: G
authors.lastname: Antiñolo
authors.forename: Lois M
authors.initials: LM
authors.lastname: Mulligan
authors.forename: Salud
authors.initials: S
authors.lastname: Borrego
mesh_terms: D002460:Cell Line; D017615:Enteric Nervous System / Q000378:metabolism; D005260:Female; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D006627:Hirschsprung Disease / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009432:Neural Crest / Q000166:cytology; D051101:Neurturin / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D000090063:Proto-Oncogene Mas; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C490886:ARTN protein, human; D051100:Glial Cell Line-Derived Neurotrophic Factor; C000715470:MAS1 protein, human; C495053:NRTN protein, human; D009419:Nerve Tissue Proteins; D051101:Neurturin; D000090063:Proto-Oncogene Mas; C110758:persephin; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human