The Mechanism of Milk Lipid Secretion

乳脂分泌的机制

• 批准号: 7576149
• 负责人: IAN HEYWOOD MATHER
• 金额: $ 26.44万
• 依托单位: UNIV OF MARYLAND, COLLEGE PARK
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2010-08-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7576149
• 关键词: Ablation; Adenovirus Vector; Affinity Chromatography; Apical; Binding; Biochemical Genetics; Biological; Biological Assay; Breast Feeding; Cell membrane; Cells; Chimeric Proteins; Column Chromatography; Confocal Microscopy; Cytoplasm; Cytoplasmic Tail; Data; Defect; Dominant-Negative Mutation; Epithelial Cells; Fatty acid glycerol esters; Filtration; Fluorescence Microscopy; Gel; Genes; Gland; Green Fluorescent Proteins; Human; Human Milk; In Vitro; Knock-out; Knockout Mice; Label; Lactation; Language; Length; Life; Link; Lipid Bilayers; Lipids; Location; Mammalian Cell; Mammary gland; Membrane; Milk; Milk Proteins; Molecular; Mothers; Mus; Mutant Strains Mice; Oxidases; Phenotype; Proteins; Research Personnel; Role; Rupture; Screening procedure; Surface; Survivors; Testing; Tissues; Transgenes; Triglycerides; Weaning; Weight; Wild Type Mouse; Work; Xanthine Dehydrogenase; Xanthine Oxidase; apical membrane; butyrophilin; cellular imaging; in vitro Assay; in vivo; monomer; neonate; nutrition; programs; promoter; protein complex; pup; stoichiometry

The long-term objective is to determine the mechanism of milk-lipid secretion from mammary epithelial cells during lactation. Despite the importance of breast milk for the survival and nutrition of the suckling neonate, molecular and cellular mechanisms underlying secretion of the principal components of milk including lipid and protein remain unknown. Lactation fails in about 5% of breast-feeding mothers for unknown reasons. In this proposed work, the potential role of the milk proteins, butyrophilin (Btnlat) and xanthine dehydrogenase/ oxidase (Xdh), in the secretion of milk-lipid droplets will be studied. Btn1a1 and Xdh are the first proteins to be genetically linked to milk-lipid secretion because ablation of the respective genes severely disrupts the regulated secretion of milk lipid. We will test the hypothesis that Btn1a1 is transported to the apical plasma membrane and binds to Xdh on the surface of intracellular lipid droplets forming a linker protein complex essential for the budding and release of lipid from the cell. Interactive domain(s) in the cytoplasmic tail of Btn1a1 and in Xdh will be identified by assaying for binding between truncated forms of the proteins by GST pull-down assays and column chromatography. Interactive domains of Btn1a1 and Xdh, identified in vitro, will be screened for function in vivo by expressing wild-type or truncated functional forms of either protein from transgenes driven by a mammary-specific promoter. Wild-type Btn1a1 or its functional domain should restore the wild-type phenotype in Btn1aT'~ mice but the functional domain of Xdh should inhibit lipid secretion in wild-type mice by acting in a dominant negative manner. The intracellular distribution and targeting dynamics of Btn1a1 and Xdh will be determined by confocal microscopy of mammaryexplants prepared from glands transduced with adenoviral vectors encoding fluorescently labeled fusion proteins of either protein. The working hypothesis will be supported if Btn1a1 is transported to the apical membrane and becomes less mobile in the lipid bilayer as it is incorporated into budding lipid droplets. Xdh should bind to lipid droplets in the cytoplasm and colocalize with Btn1a1 at the apical surface. Lay language: Lactation fails in about 5% of breast-feeding mothers. This project will test the hypothesis that the milk proteins, butyrophilin and xanthine oxidase, are essential for the secretion of milk lipid and thus enhance our understanding of, and potential ability to treat lactation deficiencies in humans.

长期目标是确定乳腺上皮细胞分泌乳脂的机制

项目成果

Kinetics of milk lipid droplet transport, growth, and secretion revealed by intravital imaging: lipid droplet release is intermittently stimulated by oxytocin.

• DOI: 10.1091/mbc.e16-11-0776
• 发表时间: 2017-04-01
• 期刊: Molecular biology of the cell
• 影响因子: 3.3
• 作者: Masedunskas A;Chen Y;Stussman R;Weigert R;Mather IH
• 通讯作者: Mather IH

A test of current models for the mechanism of milk-lipid droplet secretion.

• DOI: 10.1111/tra.12087
• 发表时间: 2013-09
• 期刊: Traffic (Copenhagen, Denmark)
• 作者: Jeong J;Lisinski I;Kadegowda AK;Shin H;Wooding FB;Daniels BR;Schaack J;Mather IH
• 通讯作者: Mather IH