Theranostics 2021; 11(9):4316-4334. doi:10.7150/thno.51745

Research Paper

Trio cooperates with Myh9 to regulate neural crest-derived craniofacial development

Shuyu Guo1*, Li Meng1*, Haojie Liu1*, Lichan Yuan1, Na Zhao1, Jieli Ni1, Yang Zhang1, Jingjing Ben2, Yi-Ping Li3, Junqing Ma1✉

1. Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, China.
2. Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, China.
3. Department of Pathology, University of Alabama at Birmingham, SHEL 810, 1825 University Boulevard, Birmingham, Alabama 35294-2182, USA.
* These authors contributed equally to this work.

This is an open access article distributed under the terms of the Creative Commons Attribution License ( See for full terms and conditions.
Guo S, Meng L, Liu H, Yuan L, Zhao N, Ni J, Zhang Y, Ben J, Li YP, Ma J. Trio cooperates with Myh9 to regulate neural crest-derived craniofacial development. Theranostics 2021; 11(9):4316-4334. doi:10.7150/thno.51745. Available from

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Trio is a unique member of the Rho-GEF family that has three catalytic domains and is vital for various cellular processes in both physiological and developmental settings. TRIO mutations in humans are involved in craniofacial abnormalities, in which patients present with mandibular retrusion. However, little is known about the molecular mechanisms of Trio in neural crest cell (NCC)-derived craniofacial development, and there is still a lack of direct evidence to assign a functional role to Trio in NCC-induced craniofacial abnormalities.

Methods: In vivo, we used zebrafish and NCC-specific knockout mouse models to investigate the phenotype and dynamics of NCC development in Trio morphants. In vitro, iTRAQ, GST pull-down assays, and proximity ligation assay (PLA) were used to explore the role of Trio and its potential downstream mediators in NCC migration and differentiation.

Results: In zebrafish and mouse models, disruption of Trio elicited a migration deficit and impaired the differentiation of NCC derivatives, leading to craniofacial growth deficiency and mandibular retrusion. Moreover, Trio positively regulated Myh9 expression and directly interacted with Myh9 to coregulate downstream cellular signaling in NCCs. We further demonstrated that disruption of Trio or Myh9 inhibited Rac1 and Cdc42 activity, specifically affecting the nuclear export of β-catenin and NCC polarization. Remarkably, craniofacial abnormalities caused by trio deficiency in zebrafish could be partially rescued by the injection of mRNA encoding myh9, ca-Rac1, or ca-Cdc42.

Conclusions: Here, we identified that Trio, interacting mostly with Myh9, acts as a key regulator of NCC migration and differentiation during craniofacial development. Our results indicate that trio morphant zebrafish and Wnt1-cre;Triofl/fl mice offer potential model systems to facilitate the study of the pathogenic mechanisms of Trio mutations causing craniofacial abnormalities.

Keywords: Neural crest cells, craniofacial deformity, Trio, Myh9, cell migration.