title: Cellular expression of the monocarboxylate transporter (MCT) family in the placenta of mice.
abstract: Lactate plays an important role as an alternative energy substrate, especially in conditions with a decreased utility of glucose. Proton-coupled monocarboxylate transporters (MCTs) are essential for the transport of lactate, ketone bodies, and other monocarboxylates through the plasma membrane and may contribute to the net transport of lactate through the placental barrier. The present study examined the expression profile and subcellular localization of MCTs in the mouse placenta. An in situ hybridization survey of all MCT subtypes detected intense mRNA expressions of MCT1, MCT4, and MCT9 as well as GLUT1 in the placenta from gestational day 11.5. The expression of MCT mRNAs decreased in the intensity at the end of gestation in contrast to a consistently intense expression of GLUT1 mRNA. Immunohistochemically, MCT1 and MCT4 showed a polarized localization on the maternal side and fetal side of the two cell-layered syncytiotrophoblast, respectively. The membrane-oriented localization of MCTs was supported by the coexistence of CD147 which recruits MCT to the plasma membrane. However, the subcellular arrangement of MCT1 and MCT4 along the trophoblastic cell membrane was completely opposite of that in the human placenta. Although we cannot exactly explain the reversed localization of MCTs between human and murine placentas, it may be related to differences between humans and mice in the origin of lactate and its utilization by fetuses.
authors.affiliation: Laboratory of Histology and Cytology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Nagai
authors.forename: K
authors.initials: K
authors.lastname: Takebe
authors.forename: J
authors.initials: J
authors.lastname: Nio-Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Takahashi-Iwanaga
authors.forename: T
authors.initials: T
authors.lastname: Iwanaga
mesh_terms: D000818:Animals; D051926:Basigin / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D005260:Female; D005865:Gestational Age; D051246:Glucose Transport Proteins, Facilitative / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D027501:Monocarboxylic Acid Transporters / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D010920:Placenta / Q000378:metabolism* / Q000648:ultrastructure; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013045:Species Specificity; D027981:Symporters / Q000235:genetics / Q000378:metabolism; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D051926:Basigin; D051246:Glucose Transport Proteins, Facilitative; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D011257:Pregnancy Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1; C406962:SLC16A4 protein, human; C549233:SLC16A9 protein, human; C498648:Slc16a4 protein, mouse