Integrins functioning in uterine endometrial stromal and epithelial cells in estrus

Here, as a basic study in the construction of a non-cellular niche that supports artificial organization of three-dimensional endometrial tissue, we defined the types of integrin heterodimers that are expressed transcriptionally, translationally and functionally in endometrial stromal (ES) and endometrial epithelial (EE) cells isolated from the mouse uterus in estrus. Gene and protein expression of integrin subunits were analyzed at the transcriptional and translational level by real-time PCR and fluorescent immunoassay, respectively. Moreover, the functionality of integrin heterodimers was confirmed by attachment and antibody inhibition assays. Itga2, Itga5, Itga6, Itga9, Itgav, Itgb1, Itgb3 and Itgb5 in ES cells, and Itga2, Itga5, Itga6, Itga7, Itga9, Itgav, Itgb1, Itgb3, Itgb4, Itgb5 and Itga6 and in EE cells showed significantly higher transcriptional levels than the other integrin subunits. Furthermore, translational expression of the total integrin α and β subunit genes that showed increased transcription was determined in ES and EE cells. ES cells showed significantly increased adhesion to collagen I, fibronectin and vitronectin, and functional blocking of integrin α₂, α₅ or α_V significantly inhibited adhesion to these molecules. Moreover, EE cells showed significantly increased adhesion to collagen I, fibronectin, laminin and vitronectin, and functional blocking of integrin α₂, α₅, α₆ or α_V significantly inhibited adhesion to these molecules. Accordingly, we confirmed that integrin α₂β₁, α₅β₁, α_Vβ₁, α_Vβ₃ and/or α_Vβ₅, and integrin α₂β₁, α₅β₁, α₆β₁ and/or α₆β₄, α_Vβ₁, α_Vβ₃ and/or α_Vβ₅, actively function on the surface of ES and EE cells from mouse uterus in estrus phase, respectively.