title: Mutations in TrkA Causing Congenital Insensitivity to Pain with Anhidrosis (CIPA) Induce Misfolding, Aggregation, and Mutation-dependent Neurodegeneration by Dysfunction of the Autophagic Flux.
abstract: Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disorder characterized by insensitivity to noxious stimuli and variable intellectual disability (ID) due to mutations in the NTRK1 gene encoding the NGF receptor TrkA. To get an insight in the effect of NTRK1 mutations in the cognitive phenotype we biochemically characterized three TrkA mutations identified in children diagnosed of CIPA with variable ID. These mutations are located in different domains of the protein; L213P in the extracellular domain, Δ736 in the kinase domain, and C300stop in the extracellular domain, a new mutation causing CIPA diagnosed in a Spanish teenager. We found that TrkA mutations induce misfolding, retention in the endoplasmic reticulum (ER), and aggregation in a mutation-dependent manner. The distinct mutations are degraded with a different kinetics by different ER quality control mechanisms; although C300stop is rapidly disposed by autophagy, Δ736 degradation is sensitive to the proteasome and to autophagy inhibitors, and L213P is a long-lived protein refractory to degradation. In addition L213P enhances the formation of autophagic vesicles triggering an increase in the autophagic flux with deleterious consequences. Mouse cortical neurons expressing L213P showed the accumulation of LC3-GFP positive puncta and dystrophic neurites. Our data suggest that TrkA misfolding and aggregation induced by some CIPA mutations disrupt the autophagy homeostasis causing neurodegeneration. We propose that distinct disease-causing mutations of TrkA generate different levels of cell toxicity, which may provide an explanation of the variable intellectual disability observed in CIPA patients.
authors.affiliation: From the Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València, IBV-CSIC, c/o Jaume Roig 11, 46010 València,.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Franco
authors.affiliation: From the Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València, IBV-CSIC, c/o Jaume Roig 11, 46010 València,.
authors.forename: Cristina
authors.initials: C
authors.lastname: Melero
authors.affiliation: the Department of Genetics, Basurto University Hospital (osakidetza/Servicio Vasco de Salud), Bilbao, and.
authors.forename: Esther
authors.initials: E
authors.lastname: Sarasola
authors.affiliation: the Chronic and.
authors.forename: Paloma
authors.initials: P
authors.lastname: Acebo
authors.affiliation: Rare Disease Centers, ISCIII, Crta. Majadahonda a Pozuelo km.2 Majadahonda, Madrid 28220, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Luque
authors.affiliation: From the Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València, IBV-CSIC, c/o Jaume Roig 11, 46010 València,.
authors.forename: Isabel
authors.initials: I
authors.lastname: Calatayud-Baselga
authors.affiliation: the Department of Genetics, Basurto University Hospital (osakidetza/Servicio Vasco de Salud), Bilbao, and.
authors.forename: María
authors.initials: M
authors.lastname: García-Barcina
authors.affiliation: From the Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València, IBV-CSIC, c/o Jaume Roig 11, 46010 València,, mvilar@ibv.csic.es.
authors.forename: Marçal
authors.identifier: http://orcid.org/0000-0002-9376-6544
authors.initials: M
authors.lastname: Vilar
mesh_terms: D000293:Adolescent; D019943:Amino Acid Substitution; D000818:Animals; D001343:Autophagy; D002540:Cerebral Cortex / Q000201:enzymology; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007007:Hypohidrosis / Q000201:enzymology* / Q000235:genetics; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D020125:Mutation, Missense; D019636:Neurodegenerative Diseases / Q000201:enzymology* / Q000235:genetics; D009619:Nociceptors / Q000201:enzymology; D000699:Pain Insensitivity, Congenital / Q000201:enzymology* / Q000235:genetics; D066263:Protein Aggregation, Pathological / Q000201:enzymology* / Q000235:genetics; D057165:Proteostasis Deficiencies / Q000201:enzymology* / Q000235:genetics; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism*
chemical_list: C000611485:NTRK1 protein, human; D020917:Receptor, trkA
keywords: ER quality control; TRK1-transforming tyrosine kinase protein (Trk-A); autophagic flux; autophagy; congenital insensitivity to pain with anhidrosis; neurodegeneration; protein aggregation