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Article
Homology of lubricin and superficial zone protein (SZP): products of megakaryocyte stimulating factor (MSF) gene expression by human synovial fibroblasts and articular chondrocytes localized to chromosome 1q25
Faculty Publications
  • Deborah E Britt, Rhode Island College
  • Gregory D. Jay, Department of Medicine, Rhode Island Hospital
  • Umadevi Tantravahi, Department of Pathology, Brown University School of Medicine
Document Type
Article
Date of Original Version
1-1-2001
Abstract

We have previously identified megakaryocyte stimulating factor (MSF) gene expression by synovial fibroblasts as the origin of lubricin in the synovial cavity. Lubricin is a mucinous glycoprotein responsible for the boundary lubrication of articular cartilage. MSF has a significant homology to vitronectin and is composed of 12 exons. RNA was purified from human synovial fibroblasts and articular chondrocytes grown in vitro from tiessue explants obtained from subjects without degenerative joint disease. RT-PCR was used with multiple complimentary primer pairs spanning the central mucin expressing exon 6 of the MSF gene and individual exons on both the N- and C-terminal sides of exon 6. Exons 2, 4 and 5 appear to be variably expressed by synovial fibroblasts and articular chondrocytes. Lubricating mucin, in the form of MSF, is expressed by both chondrocytes and synovial fibroblasts in vitro. Both lubricin and superficial zone protein (SZP), a related proteogylcan, share a similar primary structure but could differ in post-translational modifications with O-link oligosaccharides which are predominant in lubricin and with limited amounts chondroitin and keratan sulfate found in SZP. Since most of the MSF exons are involved in the expression of lubricating mucin, a strong, homology to vitronectin persists. It is therefore appropriate to consider that both SZP and lubricin occupy a new class of bio-molecules termed tribonectins. Screening of a human genome bacterial artificial chromosome (BAC) library with a cDNA primer pair complimentary for exon 6 identified two clones. Both clones were complimentary for chromosome 1q25 by in situ hybridization. This same locus was previously implicated in camptodacty-arthropathy-pericarditis syndrome (CAP) by genetic mapping. It is hypothesized that CAP, a large joint arthropathy, may be associated with ineffective boundary lubrication provided by synovial fluid.

Citation Information
Deborah E Britt, Gregory D. Jay and Umadevi Tantravahi. "Homology of lubricin and superficial zone protein (SZP): products of megakaryocyte stimulating factor (MSF) gene expression by human synovial fibroblasts and articular chondrocytes localized to chromosome 1q25" (2001)
Available at: http://works.bepress.com/deborah_britt/4/