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Matrix metalloproteinase expression and activity following prostaglandin F(2 alpha)-induced luteolysis
William A Ricke1, George W Smith, Michael F Smith
1Department of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA.
Abstract:
Luteal tissue contains matrix metalloproteinases (MMPs) that cleave specific components of the extracellular matrix (ECM) and are inhibited by tissue inhibitors of metalloproteinases (TIMPs). We previously reported a decrease in luteal TIMP-1 within 15 min of prostaglandin F(2 alpha) (PGF(2 alpha))-induced luteolysis. An increase in the MMP:TIMP ratio may promote ECM degradation and apoptosis, as observed in other tissues that undergo involution. The objectives of these experiments were to determine whether 1) PGF(2 alpha) affects expression of mRNA encoding fibrillar collagenases (MMP-1 and -13), gelatinases A and B (MMP-2 and -9), membrane type (mt)-1 MMP (MMP-14), stromelysin (MMP-3), and matrilysin (MMP-7), and 2) PGF(2 alpha) increases MMP activity during PGF(2 alpha)-induced luteolysis in sheep. Corpora lutea (n = 3-10/time point) were collected at 0, 15, and 30 min and 1, 2, 4, 6, 12, 24, and 48 h after PGF(2 alpha) administration. Northern blot analysis confirmed the presence of all MMPs except MMP-9. Expression of mRNA for the above MMPs (except MMP-2) increased significantly (P < 0.05) by 30 min, and all MMPs increased significantly (P < 0.05) by 6 h after PGF(2 alpha) administration. Expression of MMP-14 mRNA increased significantly (P < 0.05) by 15 min post-PGF(2 alpha) and remained elevated through 48 h. MMP activity in luteal homogenates (following proenzyme activation and inactivation of inhibitors) was increased significantly (P < 0.05) by 15 min and remained elevated through 48 h post-PGF(2 alpha). MMP activity was localized (in situ zymography) to the pericellular area of various cell types in the 0-h group and was markedly increased by 30 min post-PGF(2 alpha). MMP mRNA expression and activity were significantly increased following PGF(2 alpha) treatment. Increased MMP activity may promote ECM degradation during luteolysis.
Insights
Prostaglandin F(2 alpha) significantly increases matrix metalloproteinase (MMP) mRNA expression and activity in sheep corpora lutea, promoting extracellular matrix degradation during luteolysis.
Area of Science:
- Reproductive biology
- Biochemistry
- Cellular signaling
Background:
- Luteal tissue relies on matrix metalloproteinases (MMPs) to degrade extracellular matrix (ECM), balanced by tissue inhibitors of metalloproteinases (TIMPs).
- Previous studies indicated a rapid decrease in TIMP-1 following prostaglandin F(2 alpha) (PGF(2 alpha)) administration, suggesting a potential shift in the MMP:TIMP ratio.
Purpose of the Study:
- To investigate the effect of PGF(2 alpha) on the expression of various MMPs (MMP-1, -13, -2, -9, -14, -3, -7) mRNA in sheep corpora lutea.
- To determine if PGF(2 alpha) enhances MMP activity during induced luteolysis in sheep.
Main Methods:
- Northern blot analysis was used to assess MMP mRNA expression levels in corpora lutea collected at various time points after PGF(2 alpha) administration.
- MMP activity was measured in luteal homogenates, and its localization was examined using in situ zymography.
Main Results:
- Northern blot confirmed the presence of most targeted MMPs, with significant increases in mRNA expression observed for MMP-1, -13, -14, -3, and -7 by 30 minutes post-PGF(2 alpha).
- MMP activity in luteal homogenates significantly increased by 15 minutes and remained elevated throughout the 48-hour experimental period.
- In situ zymography revealed a marked increase in pericellular MMP activity by 30 minutes after PGF(2 alpha) treatment.
Conclusions:
- PGF(2 alpha) administration leads to a significant upregulation of MMP mRNA expression and activity in the ovine corpus luteum.
- The observed increase in MMP activity likely contributes to extracellular matrix degradation, playing a crucial role in the process of luteolysis.