Adhesion activity of fetal gonadal cells to EGF and discoidin domains of milk fat globule-EGF factor 8 (MFG-E8), a secreted integrin-binding protein which is transiently expressed in mouse early gonadogenesis.
MFG-E8, a secreted integrin-binding protein, consists of two EGF domains containing a RGD motif and two discoidin domains. In mouse embryogenesis, MFG-E8 is highly expressed in gonadal stromal cells near mesonephros at 11.5-12.5 dpc, but its function in gonadogenesis has not been characterized. To clarify a possible role of MFG-E8 in developing gonads, we analyzed the adhesion activity of 10.5-15.5 dpc gonadal cells to recombinant proteins of EGF or discoidin domains of MFG-E8. In EGF-coated wells, the gonadal cells at 11.5-12.5 dpc revealed a significantly higher adhesion activity as compared to those at 10.5 and 15.5 dpc, while discoidin domains showed a constant number of the adhered cells throughout these stages. To identify the adhesive cells of 11.5-dpc gonads, immunohistochemistry with anti-SF1/Ad4Bp antibody (a specific marker for supporting, steroidogenic, and coelomic epithelial cells) and staining for alkaline phosphatase (a germ cell marker) were carried out. As a result, EGF domains, as well as discoidin domains, were capable of binding to all three groups of SF1/Ad4Bp-positive and negative somatic cells, and germ cells of 11.5-dpc gonads. These findings therefore suggest that MFG-E8 mediates the cell-to-cell interaction among several somatic cell types and germ cells in mouse early gonadogenesis.
Ishii
Maki
M
Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Kanai
Yoshiakira
Y
Kanai-Azuma
Masami
M
Tajima
Youichi
Y
Wei
Tay Tat
TT
Kidokoro
Tomohide
T
Sanai
Yutaka
Y
Kurohmaru
Masamichi
M
Hayashi
Yoshihiro
Y
D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D000070818:Discoidin Domain Receptors; D004815:Epidermal Growth Factor / Q000378:metabolism*; D006066:Gonads / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D006801:Humans; D051379:Mice; D008894:Milk Proteins / Q000378:metabolism*; D038081:Organogenesis; D017434:Protein Structure, Tertiary / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011975:Receptors, Mitogen / Q000378:metabolism*
D000954:Antigens, Surface; D015415:Biomarkers; C490919:Mfge8 protein, mouse; D008894:Milk Proteins; D011975:Receptors, Mitogen; D004815:Epidermal Growth Factor; D000070818:Discoidin Domain Receptors; D020794:Receptor Protein-Tyrosine Kinases