title: Role of CCN2 in Amino Acid Metabolism of Chondrocytes.
abstract: CCN2/connective tissue growth factor (CTGF) is a multi-functional molecule that promotes harmonized development and regeneration of cartilage through its matricellular interaction with a variety of extracellular biomolecules. Thus, deficiency in CCN2 supply profoundly affects a variety of cellular activities including basic metabolism. A previous study showed that the expression of a number of ribosomal protein genes was markedly enhanced in Ccn2-null chondrocytes. Therefore, in this study, we analyzed the impact of CCN2 on amino acid and protein metabolism in chondrocytes. Comparative metabolome analysis of the amino acids in Ccn2-null and wild-type mouse chondrocytes revealed stable decreases in the cellular levels of all of the essential amino acids. Unexpectedly, uptake of such amino acids was rather enhanced in Ccn2-null chondrocytes, and the addition of exogenous CCN2 to human chondrocytic cells resulted in decreased amino acid uptake. However, as expected, amino acid consumption by protein synthesis was also accelerated in Ccn2-null chondrocytes. Furthermore, we newly found that expression of two genes encoding two glycolytic enzymes, as well as the previously reported Eno1 gene, was repressed in those cells. Considering the impaired glycolysis and retained mitochondrial membrane potential in Ccn2-null chondrocytes, these findings suggest that Ccn2 deficiency induces amino acid shortage in chondrocytes by accelerated amino acid consumption through protein synthesis and acquisition of aerobic energy. Interestingly, CCN2 was found to capture such free amino acids in vitro. Under physiological conditions, CCN2 may be regulating the levels of free amino acids in the extracellular matrix of cartilage.
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.|Department of Oral and Maxillofacial Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Yurika
authors.initials: Y
authors.lastname: Murase
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Hattori
authors.affiliation: Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Aoyama
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishida
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Maeda-Uematsu
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Kawaki
authors.affiliation: Department of Orthopaedic Surgery, UCLA School of Medicine, Los Angeles, California.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Lyons
authors.affiliation: Department of Oral and Maxillofacial Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.|Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takigawa
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.|Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kubota
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002356:Cartilage / Q000166:cytology / Q000378:metabolism*; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D055513:Connective Tissue Growth Factor / Q000235:genetics* / Q000378:metabolism; D004622:Embryo, Mammalian; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D055442:Metabolome; D051379:Mice; D018345:Mice, Knockout; D046228:Microarray Analysis; D010751:Phosphopyruvate Hydratase / Q000235:genetics / Q000378:metabolism; D061251:Primary Cell Culture; D014176:Protein Biosynthesis; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000596:Amino Acids; C526318:CCN2 protein, mouse; D012269:Ribosomal Proteins; D055513:Connective Tissue Growth Factor; C457379:Eno1 protein, mouse; D010751:Phosphopyruvate Hydratase
keywords: CARTILAGE; CCN2; CHONDROCYTES; CTGF; METABOLISM