Faculty Collaboration Database

Extrahepatic synthesis of plasminogen in the human cornea is up-regulated by interleukins-1alpha and -1beta. Biochem J 1999 May 01;339 ( Pt 3)(Pt 3):705-12

Date

04/24/1999

Pubmed ID

10215610

Pubmed Central ID

PMC1220207

DOI

10.1042/0264-6021:3390705

Scopus ID

2-s2.0-0033136583 (requires institutional sign-in at Scopus site)   54 Citations

Abstract

The avascular cornea has limited access to plasma proteins, including plasminogen, a protein that is synthesized by the liver and supplied to most tissues via the blood. Recent experiments by others using plasminogen-deficient mice revealed the importance of plasmin, the active form of plasminogen, for the maintenance of the normal cornea and for corneal wound healing [Kao, Kao, Bugge, Kaufman, Kombrinck, Converse, Good and Degan (1998) Invest. Ophthalmol. Vis. Sci. 39, 502-508; Drew, Kaufman, Kombrinck, Danton, Daugherty, Degen and Bugge (1998) Blood 91, 1616-1624]. In the present experiments, plasmin was identified as a major serine proteinase in the human cornea. The major plasminogen and plasmin forms on non-reducing zymograms and Western blots had Mr values of 76x10(3) and 85x10(3), with minor forms of Mr 200x10(3), 135x10(3), 68x10(3) and 45x10(3). Angiostatin-like peptides with Mrs of 48x10(3), 45x10(3) and 38x10(3) were observed which bound to lysine-Sepharose and reacted with anti-plasminogen monoclonal antibodies directed towards kringle domains 1-3 of plasminogen. The cornea contained 1.1+/-0.15 microgram of plasminogen+plasmin/cornea, or 0.54+/-0.05 microgram of plasminogen+plasmin/mg of protein. Cornea conditioned medium contained nine times the amount of plasminogen+plasmin that could be extracted from the cornea. These data suggested that corneal cells, unlike most extrahepatic cells, synthesize plasminogen. The synthesis of plasminogen by the cornea was confirmed by immunoprecipitation of metabolically labelled plasminogen, sequencing of its cDNA obtained by reverse transcriptase-PCR and inhibition of protein synthesis. Interleukins-1alpha and -1beta stimulated corneal plasminogen synthesis 2-3-fold; however, interleukin-6 decreased corneal plasminogen synthesis by approx. 40% at early times after addition of the cytokine. By 24 h of culture, no differences were noted in the presence and absence of interleukin-6. Thus the cornea can synthesize plasminogen and regulate its synthesis in response to its environment, including cytokines induced in the cornea by injury and inflammation. Therefore the cornea can control the amount of plasminogen, the precursor of both plasmin and angiostatin.

Author List

Twining SS, Wilson PM, Ngamkitidechakul C

Author

Sally S. Twining PhD Assistant Dean, Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

ADP Ribose Transferases
Bacterial Toxins
Blotting, Western
Caseins
Cornea
Culture Media, Conditioned
Enzyme Activation
Exotoxins
Fibrinolysin
Gelatinases
Humans
Interleukin-1
Interleukin-6
Molecular Weight
Organ Culture Techniques
Plasminogen
Reverse Transcriptase Polymerase Chain Reaction
Serine Proteinase Inhibitors
Up-Regulation
Urokinase-Type Plasminogen Activator
Virulence Factors