Expression Pattern of Dab1, Reelin, PGP9.5 and Sox2 in the Stomach of Yotari (Dab1−/−) Mice

<b>Background/Objectives</b>: The Reelin-Dab1 signaling pathway, known for its crucial role in neurodevelopment, particularly in neuronal migration and the formation of cortical layers, has been a subject of extensive research. However, its involvement in gastrointestinal organogenesis is a relatively unexplored area. Our study investigates the expression patterns of Dab1, Reelin, PGP9.5, and Sox2 during stomach development in <i>yotari</i> (<i>Dab1^-/-</i>) mice and aims to shed light on how <i>Dab1</i> inactivation affects epithelial-mesenchymal signaling dynamics, thereby contributing to a deeper understanding of this pathway's non-neural functions. <b>Methods</b>: Embryonic stomach tissues from <i>yotari</i> and wild-type mice, collected at developmental stages E13.5 and E15.5, were examined by immunofluorescenceto evaluate the difference in expression of Dab1, Reelin, PGP9.5, and Sox2. Semi-quantitative scoring and quantitative image analysis were used to assess protein localization and intensity within epithelial and mesenchymal compartments. <b>Results</b>: Dab1 expression was significantly increased in both the epithelium and mesenchyme of <i>yotari</i> mice at E13.5 and E15.5. Reelin expression in the epithelium showed a visible but statistically non-significant decrease in <i>yotari</i> at E15.5, while mesenchymal expression remained low and significantly lower than controls. PGP9.5 expression was significantly reduced in <i>yotari</i> epithelium at E13.5, then strongly upregulated at E15.5. Mesenchymal PGP9.5 remained consistently high. Sox2 showed no statistically significant changes but increased semi-quantitatively in <i>yotari</i> epithelium and mesenchyme at E15.5. These findings highlight compartment-specific disruptions and potential compensatory mechanisms following <i>Dab1</i> inactivation. <b>Conclusions</b>: Our findings indicate that <i>Dab1</i> deficiency leads to distinct molecular changes in epithelial and mesenchymal compartments of the developing stomach. The Reelin-Dab1 axis appears critical for epithelial-mesenchymal coordination, while PGP9.5 and Sox2 upregulation in <i>yotari</i> mice may represent potential compensatory responses that could support epithelial integrity, although this remains speculative without functional validation.