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Delestrain C, Aissat A, Nattes E, Gibertini I, Lacroze V, Simon S, Decrouy X, de Becdelièvre A, Fanen P, Epaud R. Deciphering an isolated lung phenotype of NKX2-1 frameshift pathogenic variant. Front Pediatr 2022; 10:978598. [PMID: 36733766 PMCID: PMC9888430 DOI: 10.3389/fped.2022.978598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 12/20/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND to perform a functional analysis of a new NK2 homeobox 1 (NKX2-1) variant (c.85_86del denominated NKX2-1DEL) identified in a family presenting with isolated respiratory disease, in comparison to another frameshift variant (c.254dup denominated NKX2-1DUP) identified in a subject with classical brain-lung-thyroid syndrome. METHODS pathogenic variants were introduced into the pcDNA3-1(+)-wt-TTF1 plasmid. The proteins obtained were analyzed by western blot assay. Subcellular localization was assessed by confocal microscopy in A549 and Nthy cells. Transactivation of SFTPA, SFTPB, SFTPC, and ABCA3 promoters was assessed in A549 cells. Thyroglobulin promoter activity was measured with the paired box gene 8 (PAX8) cofactor in Nthy cells. RESULTS The two sequence variants were predicted to produce aberrant proteins identical from the 86th amino acid, with deletion of their functional homeodomain, including the nuclear localization signal. However, 3D conformation prediction of the conformation prediction of the mutant protein assumed the presence of a nuclear localization signal, a bipartite sequence, confirmed by confocal microscopy showing both mutant proteins localized in the nucleus and cytoplasm. Transcriptional activity with SFTPA, SFTPB, SFTPC, ABCA3 and thyroglobulin promoters was significantly decreased with both variants. However, with NKX2-1DEL, thyroglobulin transcriptional activity was maintained with the addition of PAX8. CONCLUSION These results provide novel insights into understanding the molecular mechanism of phenotypes associated with NKX2-1 pathogenic variants.
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Affiliation(s)
- Céline Delestrain
- Univ Paris Est Creteil, INSERM, IMRB, Creteil, France.,Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France
| | - Abdel Aissat
- Univ Paris Est Creteil, INSERM, IMRB, Creteil, France.,Département de Génétique, AP-HP, Hopital Henri Mondor, DMU de Biologie-Pathologie, Créteil, France
| | - Elodie Nattes
- Univ Paris Est Creteil, INSERM, IMRB, Creteil, France.,Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France.,Département de Génétique, AP-HP, Hopital Henri Mondor, DMU de Biologie-Pathologie, Créteil, France
| | - Isabelle Gibertini
- Département de Pédiatrie, Centre Hospitalier Universitaire de Tours, Tours, France
| | - Valérie Lacroze
- AP-HM, Hôpital de la Conception, Service de Médecine Néonatale, Marseille, France
| | | | | | - Alix de Becdelièvre
- Univ Paris Est Creteil, INSERM, IMRB, Creteil, France.,Département de Génétique, AP-HP, Hopital Henri Mondor, DMU de Biologie-Pathologie, Créteil, France
| | - Pascale Fanen
- Univ Paris Est Creteil, INSERM, IMRB, Creteil, France.,Département de Génétique, AP-HP, Hopital Henri Mondor, DMU de Biologie-Pathologie, Créteil, France
| | - Ralph Epaud
- Univ Paris Est Creteil, INSERM, IMRB, Creteil, France.,Centre Hospitalier Intercommunal de Créteil, Service de Pédiatrie Générale, Créteil, France
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Attarian SJ, Leibel SL, Yang P, Alfano DN, Hackett BP, Cole FS, Hamvas A. Mutations in the thyroid transcription factor gene NKX2-1 result in decreased expression of SFTPB and SFTPC. Pediatr Res 2018; 84. [PMID: 29538355 PMCID: PMC6599453 DOI: 10.1038/pr.2018.30] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Mutations in the NK2 homeobox 1 (NKX2-1) gene are associated with lung disease in infants and children. We hypothesize that disruption of normal surfactant gene expression with these mutations contributes to the respiratory phenotypes observed. METHODS To assess transactivational activity, cotransfection of luciferase reporter vectors containing surfactant protein B or C (SFTPB or SFTPC) promoters with NKX2-1 plasmids was performed and luciferase activity was measured. To assess the binding of mutated proteins to target DNA, electrophoretic mobility shift assays (EMSA) were performed using nuclear protein labeled with oligonucleotide probes representing NKX2-1 consensus binding sequences followed by gel electrophoresis. The effect of overexpression of wild-type (WT) and mutant NKX2-1 on SFTPB and SFTPC was evaluated with quantitative real-time PCR. RESULTS Decreased transactivation of the SFTPB promoter by both mutants and decreased transactivation of the SFTPC promoter by the L197P mutation was observed. EMSA demonstrated decreased DNA binding of both mutations to NKX2-1 consensus binding sequences. Transfection of A549 cells with NKX2-1 expression vectors demonstrated decreased stimulation of SFTPB and SFTPC expression by mutant proteins compared with that of WT. CONCLUSION Disruption of transcriptional activation of surfactant protein genes by these DNA-binding domain mutations is a plausible biological mechanism for disruption of surfactant function and subsequent respiratory distress.
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Affiliation(s)
- Stephanie J Attarian
- Edward Mallinckrodt Department of Pediatrics, Division of Newborn Medicine, Washington University School of Medicine and St Louis Children's Hospital, St Louis, Missouri, USA.
| | - Sandra L Leibel
- Department of Pediatrics, University of California San Diego School of Medicine, San Diego, California
| | - Ping Yang
- Edward Mallinckrodt Department of Pediatrics, Division of Newborn Medicine, Washington University School of Medicine and St Louis Children’s Hospital, St Louis, Missouri
| | - Danielle N Alfano
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Brian P Hackett
- Edward Mallinckrodt Department of Pediatrics, Division of Newborn Medicine, Washington University School of Medicine and St Louis Children’s Hospital, St Louis, Missouri
| | - F Sessions Cole
- Edward Mallinckrodt Department of Pediatrics, Division of Newborn Medicine, Washington University School of Medicine and St Louis Children’s Hospital, St Louis, Missouri
| | - Aaron Hamvas
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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