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TIMP-2 is required for efficient activation of proMMP-2 in vivo
Z Wang1, R Juttermann, P D Soloway
1Roswell Park Cancer Institute, Department of Molecular and Cellular Biology, Buffalo, New York 16263, USA.
Abstract:
Matrix metalloproteinases (MMPs) are synthesized as latent proenzymes. A proteolytic cleavage event involving processing of the cysteine-rich N-terminal propeptide is required for their full activation. Previous in vitro studies indicated that activation of proMMP-2 can occur through formation of a trimolecular complex between MMP-14, TIMP-2, and proMMP-2 at the cell surface. Using TIMP-2-deficient mice and cells derived from them, TIMP-2 was shown to be required for efficient proMMP-2 activation both in vivo and in vitro. The requirement for TIMP-2 was not cell-autonomous as exogenously added TIMP-2 could restore activation of proMMP-2 to TIMP-2-deficient cells. Mutant mice were overtly normal, viable, and fertile on the C57BL/6 background, indicating that both TIMP-2 and activated proMMP-2 are dispensable for normal development.
Insights
Tissue inhibitor of metalloproteinase-2 (TIMP-2) is essential for the efficient activation of proMMP-2 in vivo and in vitro. However, TIMP-2 and activated proMMP-2 are dispensable for normal mouse development.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Matrix metalloproteinases (MMPs) are synthesized as inactive proenzymes requiring proteolytic processing for activation.
- ProMMP-2 activation is known to involve MMP-14, TIMP-2, and proMMP-2 in a cell-surface complex.
- The precise in vivo role of TIMP-2 in proMMP-2 activation and its developmental significance remain to be fully elucidated.
Purpose of the Study:
- To investigate the essentiality of TIMP-2 for proMMP-2 activation in vivo.
- To determine if TIMP-2-mediated proMMP-2 activation is cell-autonomous.
- To assess the developmental impact of TIMP-2 and proMMP-2 deficiency.
Main Methods:
- Generation and characterization of TIMP-2-deficient mice.
- Analysis of proMMP-2 activation in TIMP-2 deficient cells in vitro.
- Assessment of developmental phenotypes in mutant mice.
Main Results:
- TIMP-2 is strictly required for efficient proMMP-2 activation both in vivo and in vitro.
- The requirement for TIMP-2 in proMMP-2 activation is not cell-autonomous, as exogenous TIMP-2 can rescue the activation defect.
- TIMP-2-deficient mice are viable, fertile, and phenotypically normal, indicating TIMP-2 and activated proMMP-2 are dispensable for normal development.
Conclusions:
- TIMP-2 is a critical regulator of proMMP-2 activation.
- While essential for proMMP-2 activation, TIMP-2 and its downstream product are not required for normal murine development.
- This suggests alternative pathways or compensatory mechanisms may exist for processes normally dependent on MMP-2 activity during development.