title: Post-weaning increases in the milk-fat globule EGF-factor VIII on fat globules in mouse milk and in the uptake of the fat globules by HC11 mammary epithelial cells.
abstract: Milk fat globules (MFGs) secreted by lactating mammary gland are unique lipid surrounded by a phospholipid bi-layer. We report here post-weaning changes in MFG EGF factor VIII (MFG-E8) and annexin V-accessible phosphatidyl-l-serine on the surface of MFGs. The MFG content in milk markedly decreased to about one-half within 2 days after forced weaning, despite a slight increase in milk protein content. Immunofluorescence-staining of MFGs using anti-MFG-E8 and annexin V indicated that MFG-E8 was present on some, but not all, MFGs before weaning, whereas most of MFGs were MFG-E8-positive and annexin V-negative after weaning. Free MFG-E8 with binding activity to phosphatidyl-l-serine was present abundantly in the post-weaning milk, and indeed exhibited binding to MFGs in pre-weaning milk. MFGs were taken up by HC11 mouse mammary epithelial cells in vitro, and those from post-weaning milk were remarkable for such cellular uptake. Moreover, the uptake of MFGs by the cells was inhibited by an anti-MFG-E8 antibody. Taken together, these findings suggest that MFG-E8 plays a critical role in regulation of MFG dynamics after weaning or during the suckling interval through the control of MFG-epithelial cell interaction in lactating mammary glands.
authors.affiliation: Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Nakatani
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yasueda
authors.forename: Kenzi
authors.initials: K
authors.lastname: Oshima
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Okajima
authors.forename: Daita
authors.initials: D
authors.lastname: Nadano
authors.forename: David J
authors.initials: DJ
authors.lastname: Flint
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Matsuda
mesh_terms: D000042:Absorption; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D000954:Antigens, Surface / Q000737:chemistry / Q000378:metabolism*; D001692:Biological Transport; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D006017:Glycolipids / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D007774:Lactation; D066292:Lipid Droplets; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D008894:Milk Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D010718:Phosphatidylserines / Q000378:metabolism; D012995:Solubility; D013499:Surface Properties; D015854:Up-Regulation; D014886:Weaning
chemical_list: D017304:Annexin A5; D000954:Antigens, Surface; D006017:Glycolipids; D006023:Glycoproteins; C490919:Mfge8 protein, mouse; D008894:Milk Proteins; D010718:Phosphatidylserines; C110367:milk fat globule