July 1994
Volume 35, Issue 8
Free
Articles  |   July 1994
Alpha 2-macroglobulin is present in and synthesized by the cornea.
Author Affiliations
  • S S Twining
    Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
  • T Fukuchi
    Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
  • B Y Yue
    Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
  • P M Wilson
    Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
  • X Zhou
    Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
  • G Loushin
    Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
Investigative Ophthalmology & Visual Science July 1994, Vol.35, 3226-3233. doi:
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    • Get Citation

      S S Twining, T Fukuchi, B Y Yue, P M Wilson, X Zhou, G Loushin; Alpha 2-macroglobulin is present in and synthesized by the cornea.. Invest. Ophthalmol. Vis. Sci. 1994;35(8):3226-3233.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

PURPOSE: The purposes of this study were to determine whether the proteinase inhibitor alpha 2-macroglobulin is present in the cornea, and, if so, where it is located, and whether it is synthesized by the cornea, and, if so, where it is being synthesized. METHODS: alpha 2-Macroglobulin was immunolocalized using a double antibody technique and quantified by immunodot blot assays, and its identity was confirmed by Western blot analysis. Corneal synthesis of this inhibitor was determined by immunoprecipitation of extracts from corneas incubated in organ culture with 35S-methionine. mRNA was localized by in situ hybridization of 3H-labeled cDNA to the inhibitor. RESULTS: alpha 2-Macroglobulin was localized in the epithelial, endothelial, and stromal cells. It was also found in the stromal extracellular matrix. When extracts of the epithelium, stroma, and Descemet's membrane-endothelium were analyzed by Western blot, an immunoreactive band for this inhibitor was detected in all extracts. This band comigrated with the alpha 2-macroglobulin form isolated from plasma. Metabolically labeled inhibitor was immunoprecipitated from the stromal layer but not from the epithelial or endothelial layer. However, when examined by in situ hybridization, mRNA was localized to epithelial and endothelial cells in addition to stromal keratocytes. CONCLUSIONS: Because alpha 2-macroglobulin has the ability to inhibit a wide range of proteinases, it is probable that this inhibitor plays an important role in protecting the cornea from damage caused by proteinases. This includes proteinases synthesized by the cornea and those released from inflammatory cells and invading organisms.

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