Tracheal separation is driven by NKX2-1-mediated repression of Efnb2 and regulation of endodermal cell sorting

• Published in: Cell reports (Cambridge) Vol. 38; no. 11; p. 110510
• Main Authors: Lewis, Ace E., Kuwahara, Akela, Franzosi, Jacqueline, Bush, Jeffrey O.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.03.2022
• Subjects: cell sorting; Digestive System - metabolism; endoderm; Endoderm - metabolism; Eph/ephrin; ephrin-B2; Ephrin-B2 - metabolism; esophagus; Esophagus - metabolism; foregut; Nkx2-1; Sox2; trachea; Trachea - metabolism; tracheoesophageal fistula; foregut; Sox2; Eph/ephrin; endoderm; trachea; cell sorting; tracheoesophageal fistula; esophagus; ephrin-B2; Nkx2-1
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2022.110510

The mechanisms coupling fate specification of distinct tissues to their physical separation remain to be understood. The trachea and esophagus differentiate from a single tube of definitive endoderm, requiring the transcription factors SOX2 and NKX2-1, but how the dorsoventral site of tissue separation is defined to allocate tracheal and esophageal cell types is unknown. Here, we show that the EPH/EPHRIN signaling gene Efnb2 regulates tracheoesophageal separation by controlling the dorsoventral allocation of tracheal-fated cells. Ventral loss of NKX2-1 results in disruption of separation and expansion of Efnb2 expression in the trachea independent of SOX2. Through chromatin immunoprecipitation and reporter assays, we find that NKX2-1 likely represses Efnb2 directly. Lineage tracing shows that loss of NKX2-1 results in misallocation of ventral foregut cells into the esophagus, while mosaicism for Nkx2-1 generates ectopic NKX2-1/EPHRIN-B2 boundaries that organize ectopic tracheal separation. Together, these data demonstrate that NKX2-1 coordinates tracheal specification with tissue separation through the regulation of EPHRIN-B2 and tracheoesophageal cell sorting. [Display omitted] •EPHRIN-B2 regulates trachea and esophagus separation, but not patterning•Loss of EPHRIN-B2 permits aberrant intermixing of tracheal and esophageal cells•NKX2-1 directly represses Efnb2 to establish a dorsoventral separation boundary•NKX2-1 regulates tracheoesophageal separation and tracheal cell allocation Lewis et al. show that, in the development of the mammalian trachea and esophagus, cell fate specification is coupled with morphogenesis by NKX2-1-mediated repression of Efnb2. This establishes an EPH/EPHRIN boundary that drives cell allocation and physical separation of the trachea and esophagus.