The keratan sulphate proteoglycan lumican regulates collagen fibrillogenesis to maintain the integrity and function of connective tissues such as cornea. We examined the role of a highly conserved cysteine-containing domain proximal to the N-terminus of lumican in collagen fibrillogenesis using site-specific mutagenesis to prepare plasmid DNA encoding wild-type murine lumican (Cys37-Xaa3-Cys41-Xaa-Cys-Xaa9-Cys) and a Cys→Ser (C/S) mutant (Cys37-Xaa3-Ser41-Xaa-Cys-Xaa9-Cys). cDNAs were cloned into the pSecTag2A vector, and cultures of MK/T-1 cells (an immortalized cell line from mouse keratocytes) were transfected with the cDNAs. Stable transformants were selected and cloned in the presence of Zeocin. All stable transformants maintained a dendritic morphology and growth rate similar to those of parental MK/T-1 cells. Western blot analysis with anti-lumican antibody detected a 42kDa lumican protein secreted into the culture medium of both wild-type and C/S mutant lumican cell lines. Ultrastructural analyses by transmission electron microscopy showed both cell lines to form a multi-layered stroma ex vivo, but the matrix assembled by the two cell lines differed. Compared with the mutant cell line, the wild-type cells assembled a more organized matrix with regions containing orthogonal collagen fibrils. In addition, the fibrils in the extracellular matrix formed by the mutant cell line exhibited alterations in fibril packing and structure. Immunostaining analysed by confocal microscopy showed a further difference in this matrix, with the marked occurrence of lumican and collagen I co-localization in the lumican wild-type cells, but a lack thereof in the lumican C/S mutant cells. The results indicate that the cysteine-rich domain of lumican is important in collagen fibrillogenesis and stromal matrix assembly.
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February 2003
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Research Article|
February 01 2003
Role of Cys41 in the N-terminal domain of lumican in ex vivo collagen fibrillogenesis by cultured corneal stromal cells
Eric C. CARLSON;
Eric C. CARLSON
∗Department of Ophthalmology, University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267, U.S.A.
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Kazuhisa MAMIYA;
Kazuhisa MAMIYA
∗Department of Ophthalmology, University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267, U.S.A.
†Department of Ophthalmology, Hirosaki University, Hirosaki, Aomori, Japan
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Chia-Yang LIU;
Chia-Yang LIU
∗Department of Ophthalmology, University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267, U.S.A.
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Robert L. GENDRON;
Robert L. GENDRON
‡Division of Basic Medical Sciences, Memorial University of Newfoundland, St. Johns, Newfoundland, Canada A1B 3V6
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David E. BIRK;
David E. BIRK
§Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, U.S.A.
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James L. FUNDERBURGH;
James L. FUNDERBURGH
∥Department of Ophthalmology, University of Pittsburgh, PA 15213, U.S.A.
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Winston W.-Y. KAO
Winston W.-Y. KAO
1
∗Department of Ophthalmology, University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267, U.S.A.
1To whom correspondence should be addressed (e-mail Winston.Kao@uc.edu).
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Publisher: Portland Press Ltd
Received:
April 15 2002
Revision Received:
September 20 2002
Accepted:
October 16 2002
Accepted Manuscript online:
October 16 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2003
2003
Biochem J (2003) 369 (3): 461–468.
Article history
Received:
April 15 2002
Revision Received:
September 20 2002
Accepted:
October 16 2002
Accepted Manuscript online:
October 16 2002
Citation
Eric C. CARLSON, Kazuhisa MAMIYA, Chia-Yang LIU, Robert L. GENDRON, David E. BIRK, James L. FUNDERBURGH, Winston W.-Y. KAO; Role of Cys41 in the N-terminal domain of lumican in ex vivo collagen fibrillogenesis by cultured corneal stromal cells. Biochem J 1 February 2003; 369 (3): 461–468. doi: https://doi.org/10.1042/bj20020593
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