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Matrix metalloproteinase (2, 9, and 14) expression, localization, and activity in ovine corpora lutea throughout the
William A Ricke1, George W Smith, Lawrence P Reynolds
1Department of Animal Science, 160 Animal Sciences Center, University of Missouri, Columbia, MO 65211, USA.
Abstract:
Members of the matrix metalloproteinase (MMP) family collectively degrade extracellular matrix (ECM) and help regulate luteal function. The objectives of these experiments were to characterize the mRNA expression, localization, and activity of MMPs 2, 9, and 14 in ovine corpora lutea (CL). Ovine CL were collected on Days 2, 4, 10, and 15 of the estrous cycle (Day 0 = estrus). Messenger RNA transcripts for MMPs 2 and 14 were detected using Northern analysis; however, expression of MMP-9 was undetectable. Expression of MMP-14 mRNA (membrane type-1 MMP) was increased (P < 0.05) on Day 4; whereas, expression of MMP-2 mRNA was highest (P < 0.05) on Day 10, which corresponded to the observed increases in gelatinolytic activity in luteal homogenates as measured by a fluroscein-labeled gelatin substrate assay. MMP 2 and 9 proteins were localized predominantly to large luteal cells (LLCs), whereas MMP-14 was localized primarily to cells other than LLCs as demonstrated by immunohistochemistry. Immunolocalization of MMP-2 to putative endothelial cells was also observed on Day 15. Localization of MMP activity was determined using in situ zymography. Luteal tissues contained gelatinolytic activity primarily localized pericellularly to various cell types, including LLCs. These results support the hypothesis that ECM remodeling occurs throughout the luteal phase and may help potentiate cellular migration, differentiation, angiogenesis, and growth factor bioavailability.
Insights
Matrix metalloproteinases (MMPs) remodel the extracellular matrix during the luteal phase. MMP-2 and MMP-14 expression and activity in ovine corpora lutea (CL) suggest their role in CL function.
Area of Science:
- Reproductive biology
- Biochemistry
- Cell biology
Background:
- Matrix metalloproteinases (MMPs) are enzymes crucial for extracellular matrix (ECM) degradation.
- These enzymes play a significant role in regulating reproductive processes, including luteal function.
- Understanding MMP roles in the corpus luteum (CL) is key to comprehending reproductive cycles.
Purpose of the Study:
- To investigate the messenger RNA (mRNA) expression patterns of MMP-2, MMP-9, and MMP-14 in ovine corpora lutea (CL).
- To determine the cellular localization of MMP-2, MMP-9, and MMP-14 proteins within the CL.
- To assess the activity and localization of MMPs during the estrous cycle in sheep.
Main Methods:
- Ovine CL were collected at specific stages of the estrous cycle (Days 2, 4, 10, 15).
- Northern analysis was used to detect MMP mRNA expression.
- Immunohistochemistry and in situ zymography were employed to localize MMP proteins and activity.
Main Results:
- MMP-14 mRNA expression peaked on Day 4, while MMP-2 mRNA expression was highest on Day 10.
- Gelatinolytic activity in luteal homogenates increased, correlating with MMP-2 mRNA levels.
- MMP-2 and MMP-9 proteins were found in large luteal cells, MMP-14 in other cell types, and MMP activity was pericellular.
Conclusions:
- Extracellular matrix remodeling occurs throughout the luteal phase in sheep CL.
- MMPs, particularly MMP-2 and MMP-14, are dynamically regulated during the luteal phase.
- These MMPs likely contribute to cellular migration, differentiation, angiogenesis, and growth factor availability within the CL.