title: Deciphering the mechanism of Q145H SFTPC mutation unmasks a splicing defect and explains the severity of the phenotype.
abstract: Mutations in the gene encoding surfactant protein C (SFTPC) have led to a broad range of phenotypes from neonatal respiratory distress syndrome to adult interstitial lung disease. We previously identified the c.435G>C variant in the SFTPC gene associated with fatal neonatal respiratory distress syndrome in an infant girl. Although this variation is predicted to change glutamine (Q) at position 145 to histidine (H), its position at the last base of exon 4 and the severity of the phenotype suggested that it might also induce a splicing defect. To test this hypothesis, we used hybrid minigene, biochemical and immunofluorescence tools to decipher the molecular mechanism of the mutation. Immunoblotting and confocal imaging showed similar maturation and localization of wild-type and Q145H proteins, but hybrid minigene analysis showed complete exon 4 skipping. Since the exon 4 is in frame, a putative truncated protein of 160 amino acids would be produced. We have shown that this truncated protein had an altered intracellular trafficking and maturation. The c.435G>C mutation is deleterious not because of its amino acid substitution but because of its subsequent splicing defect and should be referred to as r.325_435del and p.Leu109_Gln145del. The absence of residual full-length transcripts fully explained the severity of the phenotype we observed in the infant.
authors.affiliation: INSERM, Créteil, France.|Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France.|Université Paris-Est, UPEC, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Delestrain
authors.affiliation: INSERM, Créteil, France.|Université Paris-Est, UPEC, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Simon
authors.affiliation: INSERM, Créteil, France.|Université Paris-Est, UPEC, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.|AP-HP, Hôpital Henri Mondor, Pôle de Biologie-Pathologie, Département de Génétique, Créteil, France.
authors.forename: Abdel
authors.initials: A
authors.lastname: Aissat
authors.affiliation: INSERM, Créteil, France.|AP-HP, Hôpital Henri Mondor, Pôle de Biologie-Pathologie, Département de Génétique, Créteil, France.
authors.forename: Rachel
authors.initials: R
authors.lastname: Medina
authors.affiliation: Université Paris-Est, UPEC, Créteil, France.|INSERM, U955, Plateforme Imagerie, Créteil, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Decrouy
authors.affiliation: INSERM, Créteil, France.|Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Nattes
authors.affiliation: INSERM, Créteil, France.|Université Paris-Est, UPEC, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.
authors.forename: Agathe
authors.initials: A
authors.lastname: Tarze
authors.affiliation: INSERM, Créteil, France.|Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Costes
authors.affiliation: INSERM, Créteil, France.|Université Paris-Est, UPEC, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.|AP-HP, Hôpital Henri Mondor, Pôle de Biologie-Pathologie, Département de Génétique, Créteil, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Fanen
authors.affiliation: INSERM, Créteil, France.|Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France.|Université Paris-Est, UPEC, Créteil, France.|DHU Ageing-Thorax-Vessel-Blood, Créteil, France.
authors.forename: Ralph
authors.initials: R
authors.lastname: Epaud
mesh_terms: D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D007223:Infant; D017563:Lung Diseases, Interstitial / Q000175:diagnosis / Q000235:genetics*; D020125:Mutation, Missense; D010641:Phenotype; D021381:Protein Transport; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis / Q000235:genetics*
chemical_list: D037721:Pulmonary Surfactant-Associated Protein C; C489679:SFTPC protein, human