Journal Article

A candidate enhancer element responsible for high-level expression of the aggrecan gene in chondrocytes

Yuichi Ikeda, Kazuo Ito, Yuichi Izumi and Tamayuki Shinomura

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 156, issue 1, pages 21-28
Published in print July 2014 | ISSN: 0021-924X
Published online February 2014 | e-ISSN: 1756-2651 | DOI: https://dx.doi.org/10.1093/jb/mvu014

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Aggrecan is the most abundant proteoglycan in cartilage. It contains a lot of negatively charged glycosaminoglycan chains along the core protein, providing a large osmotic swelling pressure within the cartilage. Therefore, the biomechanical properties of cartilage, such as its compressive load-bearing capacity, are highly dependent on the presence of abundant aggrecan in the cartilage matrix. To elucidate the transcriptional mechanism that leads to abundant expression of aggrecan by chondrocytes, we screened for enhancer elements in 130 kb of the aggrecan gene, Agc1, using a reporter assay system that we previously developed. The system is based on co-transfection of candidate enhancer elements and reporter constructs into Swarm rat chondrosarcoma chondrocytes that retain a high level of aggrecan expression. We found an element that might be involved in high-level expression of Agc1 gene in chondrocytes in vivo. The element is located 30 kb upstream of the Agc1 transcription start site.

Keywords: Aggrecan; cartilage; extracellular matrix; transcriptional enhancer; type II collagen

Journal Article.  4768 words.  Illustrated.

Subjects: Biochemistry