Roles for Nkx2–5 and Gata3 in the ontogeny of the murine smooth muscle gastric ligaments

Abstract

The gastric ligaments are superficial cord-like structures, located on the lesser curvature of the stomach, that extend from the pylorus to the esophagus. These ligaments have been documented in a wide variety of mammalian species, including humans, but their composition and ontogeny is unexplored. Here, we demonstrate that, during ontogeny, the gastric ligaments are first visible as extensions from a C-shaped domain of Gata3-expressing cells that surround the future pylorus; this domain will later give rise to the pyloric outer longitudinal muscle (OLM). The open ends of the C are located ventrally, and, beginning at embryonic day (E) 13.5, the ligaments grow anteriorly from these points. Whereas most other ligaments of the stomach are neurovascular in nature, the gastric ligaments are composed of smooth muscle cells that mature between E14.5 and E16.5. The gastric ligaments coexpress the transcription factors Gata3, Nkx2-5, and Sox9, and germline loss of Gata3 or conditional deletion of Nkx2-5 abrogates Sox9 expression and impairs gastric ligament smooth muscle development; similar phenotypes were previously seen in the OLM. In accord with this molecular contiguity between the OLM and gastric ligaments, three-dimensional image reconstruction highlights physical contiguity between these smooth muscle structures, suggesting that they may work together as a unit to control flexure of the pyloric region, a function similar to the ligament of Treitz at the duodenojejunal junction. These findings may have implications for our understanding of normal pyloric sphincter function, as well as the common human congenital pathology idiopathic hypertrophic pyloric stenosis.

Translating Developmental Principles to Generate Human Gastric Organoids

“… 34 Isl1 and Six2 , in particular, have been shown to play a role in the formation of the pyloric sphincter at the same antral-duodenal boundary where Barx1 maintains gastric epithelial identity. 34 , 40 , 45 , 49 , 50 , 51 , 52 , 53 , 54 …”

“… 54 Pyloric abnormalities also are linked to congenital defects, such as the relatively common hypertrophic pyloric stenosis. 50 , 53 , 54 Isl1 and its direct downstream target Gata3 are highly expressed in pyloric smooth muscle, and deficiency in either leads to an almost complete absence of pyloric longitudinal muscle at e18.5 in mice, impairing pyloric smooth muscle formation and sphincter formation. 50 , 54 In addition to Isl1 , Gata3 , and Six2 , several other key genes, including Bmp4 , Nkx2.5 , and Sox9 are known to play a role in pyloric sphincter formation.…”

“… 50 , 53 , 54 Isl1 and its direct downstream target Gata3 are highly expressed in pyloric smooth muscle, and deficiency in either leads to an almost complete absence of pyloric longitudinal muscle at e18.5 in mice, impairing pyloric smooth muscle formation and sphincter formation. 50 , 54 In addition to Isl1 , Gata3 , and Six2 , several other key genes, including Bmp4 , Nkx2.5 , and Sox9 are known to play a role in pyloric sphincter formation. 49 , 50 , 51 Bmp4 up-regulates Nkx2.5 , while Gata3 and Nkx2.5 independently up-regulate Sox9 .…”

Stomach Organ and Cell Lineage Differentiation: From Embryogenesis to Adult Homeostasis

“… 56 , 57 , 58 In the absence of those transcription factors, there is aberrant neuromuscular regulation of the pyloric sphincter, which in human beings can manifest as the relatively common condition known as pyloric stenosis . 58 , 59 …”

Mesenchymal–epithelial interactions during digestive tract development and epithelial stem cell regeneration

“…1). Other transcription factors involved specifically in the pyloric sphincter development, such as GATA3 and the LIM homeodomain transcription factor ISL1, have been recently described and connected with the BMP4/NKX2.5 and SOX9 pathways [78][79][80]. Their requirement or involvement in mesenchymal-epithelial interactions has not been addressed yet.…”