Molecular characterization and partial cDNA cloning of facilitative glucose transporters expressed in human articular chondrocytes; stimulation of 2-deoxyglucose uptake by IGF-I and elevated MMP-2 secretion by glucose deprivation

Osteoarthritis Cartilage. 2003 Feb;11(2):92-101. doi: 10.1053/joca.2002.0858.

Abstract

Objective: Recent evidence suggests that human chondrocytes express several facilitative glucose transporter (GLUT) isoforms and also that 2-deoxyglucose transport is accelerated by cytokine stimulation. The aim of the present investigation was to determine if human articular chondrocytes express any of the recently identified members of the GLUT/SLC2A gene family and to examine the effects of endocrine factors, such as insulin and IGF-I on the capacity of human chondrocytes for transporting 2-deoxyglucose.

Design/methods: PCR, cloning and immunohistochemistry were employed to study the expression of GLUT/SLC2A transporters in normal human articular cartilage. The uptake of 2-deoxyglucose was examined in monolayer cultured immortalized human chondrocytes following stimulation with TNF-alpha, insulin and IGF-I. Levels of MMP-2 were assessed by gelatin zymography following glucose deprivation of alginate cultures.

Results: Using PCR we detected transcripts for eight glucose transporter isoforms (GLUTs 1, 3, 6, 8, 9, 10, 11 and 12) and for a fructose transporter (GLUT5) in human articular cartilage. Expression of GLUT1, GLUT3 and GLUT9 proteins in normal human articular cartilage was confirmed by immunohistochemistry. The uptake of 2-deoxyglucose was dependent on time and temperature, inhibited by cytochalasin B and phloretin, and significantly accelerated in chondrocyte cultures stimulated with IGF-I. However, 2-deoxyglucose uptake was unaffected by short and long-term insulin treatment, which ruled out a functional role for insulin-sensitive GLUT4-mediated glucose transport. Furthermore, secretion of MMP-2 was increased in alginate cultures deprived of glucose.

Conclusions: The data supports a critical role for glucose transport and metabolism in the synthesis and degradation of cartilage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western / methods
  • Cartilage, Articular / metabolism
  • Cell Line
  • Chondrocytes / drug effects
  • Chondrocytes / metabolism*
  • Cytochalasin B / pharmacology
  • DNA, Circular / genetics*
  • Deoxyglucose / pharmacokinetics*
  • Glucose / pharmacokinetics
  • Growth Substances / metabolism*
  • Hot Temperature
  • Humans
  • Immunohistochemistry / methods
  • Insulin / pharmacology
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Matrix Metalloproteinase 2 / metabolism*
  • Monosaccharide Transport Proteins / genetics*
  • Monosaccharide Transport Proteins / metabolism
  • Phloretin / pharmacology
  • Polymerase Chain Reaction / methods
  • Protein Isoforms
  • Time Factors
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • DNA, Circular
  • Growth Substances
  • Insulin
  • Intercellular Signaling Peptides and Proteins
  • Monosaccharide Transport Proteins
  • Protein Isoforms
  • Tumor Necrosis Factor-alpha
  • myotrophin
  • Cytochalasin B
  • Deoxyglucose
  • Matrix Metalloproteinase 2
  • Glucose
  • Phloretin