Ce. Heegard et al., PRODUCTION OF VARIOUS FORMS OF PLASMINOGEN-ACTIVATOR AND PLASMINOGEN-ACTIVATOR INHIBITOR BY CULTURED MAMMARY EPITHELIAL-CELLS, Journal of dairy science, 77(10), 1994, pp. 2949-2958
We examined amounts and types of plasminogen activator and plasminogen
activator inhibitor produced by cultured bovine mammary epithelial ce
lls. The MAC-T and two other mammary epithelial cell lines, MACT-UV1 a
nd MACT-UV2 derived from the parental MAC-T cells by subcloning, were
used as model systems. Cells were cultured in a medium free of serum a
nd protein. Data showed that MACT-UV2 cells produced 6.2 and 17.2% mor
e plasminogen activator than MACT-UV1 and parental MAC-T cells, respec
tively. Addition of amiloride, a specific urokinase-plasminogen activa
tor inhibitor, dramatically decreased the activity in the culture medi
um of parental and subclonal lines, indicating that urokinase-plasmino
gen activator was present. Zymography revealed the presence of urokina
se-plasminogen activator with an approximate molecular mass of 50,000
kDa in the culture medium of parental MAC-T cells. The culture medium
of the subclonal lines contained urokinase-plasminogen activator and t
issue-plasminogen activator with approximate molecular masses of 50,00
0 and 75,000 kDa, respectively. Complexes of both types of plasminogen
activators with plasminogen activator-inhibitor-1 were detected in th
e culture medium of subclonal lines.