Expression of the (V+C)- fibronectin isoform is tightly linked to the presence of a cartilaginous matrix

Nancy Burton-Wurster, Caroline Borden, George Lust, James N. Macleod

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22 Scopus citations


Fibronectin is encoded by a single gene, but heterogeneity is introduced by alternative splicing of the pre-mRNA. An unique splice variant, designated (V+C)-, which deletes nucleotides encoding the V, III-15 and I-10 segments, has been identified in articular cartilage. In this study, a ribonuclease protection assay was used to quantitate expression of the (V+C)- isoform in eight canine cartilaginous tissues and in chondrocytes cultured as monolayers or in alginate beads. The (V+C)- fibronectin isoform was detected in all cartilaginous tissues examined, ranging from a low of 11% of steady-state fibronectin mRNA in the nucleus pulposus to 71% in the rib. An age dependent increase, from 18% in the epiphyseal cartilage of a newborn to 54% in the articular cartilage of dogs over 10 months of age, was observed. The ubiquitous presence of this isoform in cartilaginous tissues and its absence in all non-cartilaginous tissues examined to date is consistent with a very strong association of the (V+C)- fibronectin isoform with the cartilaginous phenotype. Results from a ribonuclease protection assay using a probe extending into the V region from III-14 were combined with the quantitative information about (V+C)- fibronection expression to develop an over-all profile of splicing within the V region in cartilage. Monolayer culture of articular chondrocytes altered fibronectin splicing patterns. The (V+C)- isoform was rapidly lost and ED-A(+) fibronectin was induced. Three-dimensional culture in alginate beads prevented induction of ED-A(+) fibronection, but failed to sustain expression of the (V+C)- isoform. Thus, some matrix component or structure, lost in cell culture, may be essential to maintain expression of the (V+C)- isoform. The possible relationship of changing patterns of fibronectin isoforms in cultured chondrocytes to maintenance of the differentiated phenotype is discussed.

Original languageEnglish
Pages (from-to)193-203
Number of pages11
JournalMatrix Biology
Issue number3
StatePublished - Jul 1998

Bibliographical note

Funding Information:
This work was supportedb y NationalI nstituteso f Health grantN o. AR 35664;N ationaIln stituteos f Healthg rantN o. AR44340;t he ArthritisF oundationa; nd a grant-in-aidfr om NovartisP harmaceutica(flos rmerlyC iba-GeigyC orporation). We thankA lma Jo Williamsf or technicaal ssistancaen d DorothyS corellef or assistancwe ith the preparatioonf the manuscript.


  • Alternative splicing
  • Cartilaginous tissues
  • Chondrocytes
  • Fibronectin isoforms

ASJC Scopus subject areas

  • Molecular Biology


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