title: Menaquinone-4 (vitamin K2) up-regulates expression of human intestinal alkaline phosphatase in Caco-2 cells.
abstract: Alkaline phosphatase (ALP) hydrolyzes several monophosphate esters into inorganic acid and alcohol. In humans, 4 kinds of ALP isozymes have been identified: tissue-nonspecific ALP, intestinal ALP, placental ALP, and germ cell ALP. Intestinal ALP is expressed at a high concentration in the brush border membrane of intestinal epithelial cells and is known to be affected by several kinds of nutrients, such as lipids, but the physiological function of intestinal ALP has remained elusive. Vitamin K is an essential cofactor for the posttranslational carboxylation of glutamate residues into γ-carboxy glutamate. Menaquinone-4 (MK-4) with 4 isoprene units, vitamin K2, has been shown to induce bone-type ALP activity and osteoblastogenesis in human bone marrow cells. In this study, we investigated the effects of MK-4 on the level of ALP activity and expression of ALP messenger RNA in the human colon carcinoma cell line Caco-2, which is known to differentiate into small intestinal epithelial cells in vitro. After treatment with MK-4, there were significant increases in the ALP activities of Caco-2 cells. Inhibitor and thermal inactivation experiments demonstrated that the increased ALP had properties of intestinal-type ALP. Semiquantitative reverse transcription-polymerase chain reaction analysis revealed that expressions of human intestinal ALP and sucrase-isomaltase, which are intestinal differentiation markers, were highly enhanced in Caco-2 cells by MK-4. This is the first report concerning ALP messenger RNA expression induced by vitamin K2in Caco-2 cells. Further studies on the physiological functions of human intestinal ALP will provide useful data on the novel effects of vitamin K.
authors.affiliation: Department of Food and Nutrition, Faculty of Human Sciences and Design, Japan Women's University, Tokyo, Japan.
authors.forename: Seiko
authors.initials: S
authors.lastname: Noda
authors.affiliation: Department of Food and Nutrition, Faculty of Human Sciences and Design, Japan Women's University, Tokyo, Japan.
authors.forename: Asako
authors.initials: A
authors.lastname: Yamada
authors.affiliation: Department of Food and Nutrition, Faculty of Human Sciences and Design, Japan Women's University, Tokyo, Japan.
authors.forename: Rieko
authors.initials: R
authors.lastname: Tanabe
authors.affiliation: Department of Food and Nutrition, Faculty of Human Sciences and Design, Japan Women's University, Tokyo, Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Nakaoka
authors.affiliation: Kenkoin Clinic, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hosoi
authors.affiliation: Department of Food and Nutrition, Faculty of Human Sciences and Design, Japan Women's University, Tokyo, Japan. Electronic address: goseki@fc.jwu.ac.jp.
authors.forename: Masae
authors.initials: M
authors.lastname: Goseki-Sone
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism*; D018938:Caco-2 Cells; D002454:Cell Differentiation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D058851:GPI-Linked Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007421:Intestine, Small / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007422:Intestines / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D024482:Vitamin K 2 / Q000494:pharmacology*
chemical_list: D058851:GPI-Linked Proteins; D012333:RNA, Messenger; D024482:Vitamin K 2; C063088:ALPI protein, human; D000469:Alkaline Phosphatase
keywords: Caco-2 cells; Differentiation; Intestinal alkaline phosphatase; Menaquinone-4; Vitamin K(2)