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Expression of a progelatinase activator (MT1-MMP) in human fetal membranes
S J Fortunato1, R Menon, S J Lombardi
1Maternal-Fetal Group, Women's Hospital, Centennial Medical Center, Nashville Tennessee 37203, USA.
Problem:
The finding of MMP-2 (which degrades type IV collagen) and TIMP-2 (the tissue inhibitor of MMP) in fetal membranes suggests the possibility of membrane self-destruction as an etiology of premature rupture of fetal membranes. MMP-2 is activated by a membrane-bound MMP (MT1-MMP). This study was undertaken to detect the presence of MT1-MMP in human fetal membranes.
Method Of Study:
Fetal membranes were placed in an organ explant system and stimulated with lipopolysaccaride (LPS). MT1-MMP expression was studied in frozen tissues by reverse transcriptase (RT)-polymerase chain reaction (PCR) using primers designed in our laboratory. DNA sequence analysis was performed to verify the specificity of PCR products. In situ hybridization and immunocytochemistry were used to localize MT1-MMP mRNA and peptide, respectively.
Results:
RT-PCR data indicated the presence of mRNA for MT1-MMP in fetal membranes. Although PCR is not quantitative, no differences in mRNA band intensities were noticed after LPS stimulation. MT1-MMP expression was constitutive throughout the culture period. In situ hybridization demonstrated amnion, chorionic laeve, cytotrophoblast cells, and the cells in the reticular and spongy layer of the extracellular matrix as the origin of MT1-MMP mRNA and peptide.
Conclusions:
This is the first study documenting the amniochorionic membrane as a source of MT1-MMP mRNA and peptide. Activation of progelatinase A requires the presence of this membrane-associated MMP. The finding of MT1-MMP in a tissue already known to produce MMP-2 and TIMP-2 documents the full system for activation and inhibition of this gelatinase. During infection, an imbalance in the expression of MT1-MMP, MMP-2 and TIMP-2 may constitute an endogenous pathway of membrane degradation.
Insights
Matrix metalloproteinase-1 (MT1-MMP) is present in fetal membranes, suggesting a role in premature rupture. This enzyme, along with MMP-2 and TIMP-2, may contribute to membrane degradation during infection.
Area of Science:
- Reproductive biology
- Biochemistry
- Cell biology
Background:
- Fetal membranes contain MMP-2 and TIMP-2, suggesting a role in self-degradation and premature rupture.
- MMP-2 activation involves membrane-bound MMP (MT1-MMP).
Purpose of the Study:
- To detect the presence of MT1-MMP in human fetal membranes.
- To investigate the role of MT1-MMP in fetal membrane integrity.
Main Methods:
- Human fetal membranes were cultured and stimulated with lipopolysaccharide (LPS).
- MT1-MMP expression was analyzed using RT-PCR, DNA sequencing, in situ hybridization, and immunocytochemistry.
Main Results:
- MT1-MMP mRNA and peptide were detected in fetal membranes.
- Expression was constitutive and not significantly altered by LPS stimulation.
- MT1-MMP originates from amnion, chorionic laeve, cytotrophoblast, and extracellular matrix cells.
Conclusions:
- This study first documents amniochorionic membranes as a source of MT1-MMP.
- The presence of MT1-MMP, MMP-2, and TIMP-2 establishes a complete system for gelatinase activation and inhibition.
- Imbalances in these factors during infection may lead to endogenous membrane degradation.