title: P-glycoprotein is expressed in the mineralizing regions of the skeleton.
abstract: Using oligonucleotide primers specific for the human MDR 1 gene, we were able to identify a specific amplicon using RT-PCR from total bovine growth plate chondrocyte RNA. The identification of MDR mRNA in growth plate chondrocytes led us to examine the precise distribution of MDR P-glycoprotein in bone and cartilage. We applied two monoclonal antibodies (C219 and C494) to human fetal, neonatal, and childhood growth plates and bone. In growth plates, P-glycoprotein was detected at high levels in a perilacunar distribution in the calcifying zone and at lower levels in hypertrophic, but not proliferative or reserve zone, chondrocytes. P-glycoprotein was also observed in perichondrial chondrocytes, in perivascular chondrocytes and matrix in the fetal cartilage anlage, and in osteoblasts and the surface osteoid matrix of newly formed bone trabeculae in the primary spongiosa. The recently described chloride channel of P-glycoprotein suggests a potential role of P-glycoprotein in growth plate chondrocyte hypertrophy.
authors.affiliation: Orthopaedic Research Laboratories, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Mangham
authors.forename: A
authors.initials: A
authors.lastname: Cannon
authors.forename: S
authors.initials: S
authors.lastname: Komiya
authors.forename: R L
authors.initials: RL
authors.lastname: Gendron
authors.forename: K
authors.initials: K
authors.lastname: Dunussi
authors.forename: M C
authors.initials: MC
authors.lastname: Gebhardt
authors.forename: H J
authors.initials: HJ
authors.lastname: Mankin
authors.forename: R J
authors.initials: RJ
authors.lastname: Arceci
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000293:Adolescent; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D015139:Blotting, Southern; D001842:Bone and Bones / Q000196:embryology / Q000378:metabolism*; D002113:Calcification, Physiologic / Q000502:physiology*; D002417:Cattle; D002648:Child; D002675:Child, Preschool; D005260:Female; D005333:Fetus / Q000737:chemistry; D006132:Growth Plate / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D012333:RNA, Messenger