Secretion of 92 kDa gelatinase (MMP-9) by bovine neutrophils.
To understand the process of neutrophil migration into mammary glands during mastitis, secretion of MMP-9 by bovine neutrophils was investigated. The methods of zymograms and RT-PCR were used to measure the secretory MMP-9 activity and its gene transcription, respectively. Both MMP-9 protein and mRNA were found to be expressed constitutively and greatly enhanced by PMA. However, the significant increase in the enzyme activity was found after 1 ng/ml PMA treatment for 1 h, while increasing MMP-9 mRNA transcription was only obvious after 1 ng/ml PMA treatment for 3 h. Moreover, secretion of MMP-9 protein was not inhibited by actinomycin D and cycloheximide. These results suggest that quick MMP-9 protein release from bovine neutrophils by the stimulation of PMA was due to the degranulation. As MMP-9 is an important proteinase in breakdown of the extracellular matrix and can be rapidly secreted by neutrophils through degranulation, it should play a critical role in the recruitment of neutrophils into mammary glands in bovine mastitis.
Li
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Department of Animal Science, McGill University, Ste. Anne de Bellevue, Que., Canada.
Zhao
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Ma
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D000818:Animals; D002417:Cattle / Q000097:blood*; D017364:Collagenases / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D020780:Matrix Metalloproteinase 9; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic
D017364:Collagenases; D020780:Matrix Metalloproteinase 9; D013755:Tetradecanoylphorbol Acetate