title: Variations in site and levels of expression of chondrocyte nucleotide pyrophosphohydrolase with aging.
abstract: The aim of this study was to identify changes in cartilage intermediate layer protein/nucleotide pyrophosphohydrolase (CILP/NTPPH) expression in articular cartilage during aging. Adult (3-4 years old) and young (7-10 days old) porcine articular hyaline cartilage and fibrocartilage were studied by Northern blot analysis, in situ hybridization, and immunohistochemistry using a complementary DNA (cDNA) probe encoding porcine CILP/NTPPH and antibody to a synthetic peptide corresponding to a CILP/NTPPH sequence. Northern blot analysis of chondrocytes showed lower expression of CILP/NTPPH messenger RNA (mRNA) in young cartilage than in adult cartilage. In adult cartilage, extracellular matrix from the surface to the middeep zone was immunoreactive for CILP/NTPPH, especially in the pericellular matrix surrounding the middeep zone chondrocytes. In young cartilage, chondrocytes were moderately immunoreactive for CILP/NTPPH throughout all zones except the calcified zone. The matrix of young cartilage was negative except in the superficial zone. In young cartilage, CILP/NTPPH mRNA expression was undetectable. In adult cartilage, chondrocytes showed strong mRNA expression for CILP/NTPPH throughout middeep zones. Protein and mRNA signals were not detectable below the tidemark. CILP/NTPPH secretion into matrix around chondrocytes increases with aging. In this extracellular site it may generate inorganic pyrophosphate and contribute to age-related calcium pyrophosphate dihydrate crystal deposition disease.
authors.affiliation: Department of Medicine, Medical College of Wisconsin, Milwaukee 53226, USA.
authors.forename: I
authors.initials: I
authors.lastname: Masuda
authors.forename: K I
authors.initials: KI
authors.lastname: Iyama
authors.forename: B D
authors.initials: BD
authors.lastname: Halligan
authors.forename: J T
authors.initials: JT
authors.lastname: Barbieri
authors.forename: A L
authors.initials: AL
authors.lastname: Haas
authors.forename: D J
authors.initials: DJ
authors.lastname: McCarty
authors.forename: L M
authors.initials: LM
authors.lastname: Ryan
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern / Q000379:methods; D002358:Cartilage, Articular / Q000166:cytology / Q000201:enzymology; D019902:Chondrocytes / Q000201:enzymology*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006818:Hyalin; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D013552:Swine
chemical_list: D016326:Extracellular Matrix Proteins; C114607:CILP protein, human; D011755:Pyrophosphatases