Expression Pattern of .ALPHA.v.BETA.3 and .ALPHA.v.BETA.5 Integrin mRNA in Mouse Fetal Gonads

Abstract

Abstract. The αvβ3 and αvβ5 integrins are known as transmembrane receptors capable of binding to the RGD amino acid peptide sequence. In mouse early gonadogenesis, some proteins containing the RGD sequence are deposited into extracellular space and participate in morphogenesis. We analyzed the expression patterns of the αvβ3 and αvβ5 integrins in mouse developing gonads (10.5-13.5 days post coitum) using whole-mount in situ hybridization. The αv integrin mRNA was homogenously expressed in developing gonadal regions. On the other hand, the β3 integrin mRNA was found only in large and round cells (presumptive germ cells), whereas β5 integrin was localized in gonadal somatic cells, with the exception of coelomic epithelial cells. The β3 integrin-expressed cells were determined to be primordial germ cells because the number of these cells was drastically reduced in busulfan-treated gonads. In this study, we demonstrated that the αvβ3 and αvβ5 integrins are widely localized in the mouse developing gonads and discussed their presumptive functions on mouse gonadogenesis. Key words: αvβ3 integrin, αvβ5 integrin, Gonadogenesis, Mouse, RGD sequence (J. Reprod. Dev. 52: [461][462][463][464][465][466][467][468] 2006) ntegrins, heterodimeric transmembrane receptors, consist of α-and β-subunits. They mediate cell-cell and cell-matrix bindings, and transmit intracellular signals that induce cellular d i f f e r e n t i a t i o n , m i g r a t i o n , p r o l i f e r a t i o n , morphogenesis, and cell death. Integrins bind to various ligands containing fibronectin, vitronectin, collagen, and laminin. Some of these ligands have a three amino acid peptide sequence, RGD (ArgGly-Asp), which can be recognized by integrins [1][2][3][4]. It has been reported that the αvβ3 and αvβ5 integrins are RGD-dependent [5][6][7]. The αvβ3integrin is a member of the β3 integrin family, and is commonly noted as a vitronectin receptor expressed in a variety of cell types [8]. The αvβ3 integrin also has a wide variety of ligands, including fibronectin, fibrinogen, osteopontin, and von Willebrand factor. On the other hand, αvβ5 integrin is known to preferentially bind to vitronectin [9] and to be the only member of the β5 integrin subfamily. Recently, integrin-binding p r o t e i n s o t h e r t h a n t h e a b o v e -m e n t i o n e d extracellular matrix molecules have been found that have the RGD sequence. Milk fat globule-EGF factor 8 (MFG-E8) is one such integrin-binding protein, and it is capable of binding to the αvβ3 and αvβ5 integrins via the RGD sequence of its EGF domain [10]. In previous studies, we demonstrated that MFG-E8 was expressed in the interstitial stromal cells of developing gonads at 11.5-12.5 days post coitum (dpc) [11] and that it had a stage-

Prion Protein Expression Regulates Embryonic Stem Cell Pluripotency and Differentiation

“…Integrins are essential for PGC functionality [40], [41] and it has been reported that the absence of Prnp may be compensated by these proteins [42], [43]. Since integrin signalling is crucial in promoting mouse ESC self-renewal [44], we speculated that Prnp expression might also be related to this integrin expression during ESC differentiation.…”

“…8A). Interestingly, mRNA for Itgb5 , described to be a gonadal tissue marker [41], appeared in higher amounts in the WT ESC than in the KO ESC; however, expression was higher in the PGC-like KO EBs at all the differentiation times (Fig. 8A).…”

“…Here, we analysed the expression of three integrins during PRNP-null stem cell differentiation to investigate if these integrins play some sort of role in maintaining the stemness of these ESC. Integrin αvβ3 (ITGB3) and integrin αvβ5 (ITGB5) are expressed in mouse foetal developing gonads (from Days 10.5 to 13.5); ITGB3 is specific to primordial germ cells [41] and ITGB5 plays important roles in maintaining stemness in undifferentiated mouse ESC [56]. The observation of Itgb3 transcription only on Day 5 in the KO EB population indicated primordial germ cell transcription activity at this stage.…”

Identification and Expression of Integrins during Testicular Fusion in Spodoptera litura

“…We previously reported [19] that the ECM remodeling of enzymes matrix metalloproteinases (mmp2 and mmp3) and ECM proteins, including collagens, proteoglycans, and glycoproteins, were highly expressed in testicular ECM when testicular fusion occurred. During gonadal morphogenesis, integrin plays a variety of critical roles in cell migration, differentiation, and connection between the germ and somatic or somatic and somatic cells [16]. It is yet unknown how interactions and cellular signaling between these glycoproteins and integrins control gonadal morphogenesis.…”

“…For example, the integrin β6 subunit is specifically expressed in epithelial cells [12,13] and plays key roles in regulating cell adhesion and the migration of cancer disease [14,15]. During the early gonadogenesis of mice, the primordial germ cells specifically expressed integrin beta3 [16] and played roles in cell adhesion during the theca cell layer formation in mouse ovarian follicles [17]. In the mouse ovary, integrin beta5 mRNA was primarily expressed in the granulosa cells of follicles [18,19], which suggested that integrin could play a function in granulosa cell proliferation.…”