Testican-3: a brain-specific proteoglycan member of the BM-40/SPARC/osteonectin family

J Neurochem. 2013 May;125(3):399-409. doi: 10.1111/jnc.12212. Epub 2013 Mar 13.

Abstract

The testicans are a three-member family of secreted proteoglycans structurally related to the BM-40/secreted protein acidic and rich in cystein (SPARC) osteonectin family of extracellular calcium-binding proteins. In vitro studies have indicated that testicans are involved in the regulation of extracellular protease cascades and in neuronal function. Here, we describe the biochemical characterization and tissue distribution of mouse testican-3 as well as the inactivation of the corresponding gene. The expression of testican-3 in adult mice is restricted to the brain, where it is located diffusely within the extracellular matrix, as well as associated with cells. Brain-derived testican-3 is a heparan sulphate proteoglycan. In cell culture, the core protein is detected in the supernatant and the extracellular matrix, whereas the proteoglycan form is restricted to the supernatant. This indicates possible interactions of the testican-3 core protein with components of the extracellular matrix which are blocked by addition of the glycosaminoglycan chains. Mice deficient in testican-3 are viable and fertile and do not show an obvious phenotype. This points to a functional redundancy among the different members of the testican family or between testican-3 and other brain heparan sulphate proteoglycans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain / anatomy & histology
  • Brain / metabolism
  • Cell Line, Tumor
  • Cloning, Molecular
  • Extracellular Matrix / metabolism
  • Fibrosarcoma / pathology
  • Gene Expression Regulation, Developmental / genetics
  • Humans
  • Immunoprecipitation
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Osteonectin / metabolism*
  • Proteoglycans / deficiency
  • Proteoglycans / genetics*
  • Proteoglycans / metabolism*
  • Transfection

Substances

  • Osteonectin
  • Proteoglycans
  • Spock1 protein, mouse
  • Spock3 protein, mouse