ALX1‐related frontonasal dysplasia results from defective neural crest cell development and migration

• Published in: EMBO molecular medicine Vol. 12; no. 10; pp. e12013 - n/a
• Main Authors: Pini, Jonathan, Kueper, Janina, Hu, Yiyuan David, Kawasaki, Kenta, Yeung, Pan, Tsimbal, Casey, Yoon, Baul, Carmichael, Nikkola, Maas, Richard L, Cotney, Justin, Grinblat, Yevgenya, Liao, Eric C
• Format: Journal Article
• Language: English
• Published: England EMBO Press 07.10.2020; John Wiley and Sons Inc; Springer Nature
• Subjects: ALX1; Animals; Apoptosis; Bone morphogenetic protein 2; Bone morphogenetic protein 9; Bone morphogenetic proteins; Cell culture; Cell differentiation; Cell Movement; Cloning; Congenital diseases; Craniofacial Abnormalities - genetics; Culture media; Face - abnormalities; frontonasal dysplasia; Gene expression; Genomes; Homeobox; Humans; iPSC; Mutation; Neural Crest; neural crest cells; Parents & parenting; Phenotypes; Pluripotency; Stem cells; Zebrafish; neural crest cells; ALX1; zebrafish; frontonasal dysplasia; iPSC
• ISSN: 1757-4676; 1757-4684
• DOI: 10.15252/emmm.202012013

A pedigree of subjects presented with frontonasal dysplasia (FND). Genome sequencing and analysis identified a p.L165F missense variant in the homeodomain of the transcription factor ALX1 which was imputed to be pathogenic. Induced pluripotent stem cells (iPSC) were derived from the subjects and differentiated to neural crest cells (NCC). NCC derived from ALX1L165F/L165F iPSC were more sensitive to apoptosis, showed an elevated expression of several neural crest progenitor state markers, and exhibited impaired migration compared to wild‐type controls. NCC migration was evaluated in vivo using lineage tracing in a zebrafish model, which revealed defective migration of the anterior NCC stream that contributes to the median portion of the anterior neurocranium, phenocopying the clinical presentation. Analysis of human NCC culture media revealed a change in the level of bone morphogenic proteins (BMP), with a low level of BMP2 and a high level of BMP9. Soluble BMP2 and BMP9 antagonist treatments were able to rescue the defective migration phenotype. Taken together, these results demonstrate a mechanistic requirement of ALX1 in NCC development and migration. Synopsis Variants of the transcription factor ALX1 are implicated in the development of Frontonasal Dysplasia. This study explores the role of ALX1 in neural crest cell development and migration in patient‐derived induced pluripotent stem cells and zebrafish. A novel missense mutation of ALX1 was associated with familial Frontonasal Dysplasia in a pedigree of four children born with bilateral oblique clefts and ocular malformations. Neural Crest Cells harboring the L165F variant within ALX1 showed transcriptomic differences of marker genes indicative of a prolonged progenitor state, dysbalance of BMPs, increased rate of apoptosis, and delayed migration. Disruption of alx1 in zebrafish resulted in perturbed Neural Crest Cell migration and increased expression of other alx family members. Variants of the transcription factor ALX1 are implicated in the development of Frontonasal Dysplasia. This study explores the role of ALX1 in neural crest cell development and migration in patient‐derived induced pluripotent stem cells and zebrafish.