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Developmental expression of MMP-9 (gelatinase B) mRNA in mouse embryos
R Cañete-Soler1, Y H Gui, K K Linask
1Department of Pathology and Laboratory Medicine, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
Abstract:
Considerable remodeling of the extracellular matrix as well as cellular migration takes place during embryogenesis. Since the metalloproteinase MMP-9 is implicated in these functions in cancer cells, we studied the patterns of expression of MMP-9 mRNA during the development of post-implantation mouse embryos. MMP-9 mRNA was detected using the ribonuclease protection assay in poly A+RNA from 13 to 17 day embryos, but not at 11 days. In order to localize these transcripts, in situ hybridization was performed on sections of murine embryos from 7.5 to 15 days of gestation. At the time of implantation, MMP-9 mRNA was localized to the invading trophoblast cells. Strong signals were also seen in the yolk sac. No signal for MMP-9 mRNA was seen by in situ hybridization in the embryo until day 11 when detectable reaction was seen in the central nervous system. By day 15 strong signals were seen in the liver, in the developing bronchial epithelium of the lungs and in the primordial alveoli, in the epithelium of the thyroid gland, in the thymus, in the endochondrial plates of the bone, and in neural cells. The liver from day 15 embryos contained gelatinase activity at 105 kDa consistent with MMP-9. Thus, MMP-9 expression appears to be expressed in specific organs in a precise temporal sequence during development.
Insights
Matrix metalloproteinase-9 (MMP-9) mRNA expression is detected in specific mouse embryonic organs, appearing in a precise temporal sequence during development. This study maps MMP-9 mRNA localization from implantation through day 15 of gestation.
Area of Science:
- Developmental Biology
- Molecular Biology
- Biochemistry
Background:
- Embryogenesis involves significant extracellular matrix remodeling and cellular migration.
- Matrix metalloproteinase-9 (MMP-9) plays a role in these processes in cancer cells.
Purpose of the Study:
- To investigate the temporal and spatial expression patterns of MMP-9 mRNA during mouse embryonic development.
- To understand the role of MMP-9 in embryonic development.
Main Methods:
- Ribonuclease protection assay to detect MMP-9 mRNA in poly A+ RNA from mouse embryos (days 11-17).
- In situ hybridization to localize MMP-9 mRNA transcripts in murine embryo sections (days 7.5-15).
- Gelatinase activity assay on day 15 embryonic liver tissue.
Main Results:
- MMP-9 mRNA was detected from day 13 to 17, but not at day 11.
- Early expression (implantation) localized to invading trophoblast cells and yolk sac.
- Post-implantation, MMP-9 mRNA appeared in the central nervous system (day 11), liver, lungs, thyroid, thymus, bone, and neural cells (day 15).
- Gelatinase activity consistent with MMP-9 was found in day 15 embryonic liver.
Conclusions:
- MMP-9 is expressed in specific organs during mouse embryonic development.
- The expression follows a precise temporal sequence, suggesting a role in organogenesis.
- MMP-9 is involved in key developmental processes beyond cancer cell functions.