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Expression, purification and characterization of recombinant mouse MT5-MMP protein products
Abstract:
We have recently identified the fifth member of the membrane-type matrix metalloproteinase subfamily, MT5-MMP/MMP24, which is expressed in a brain specific manner (Duanqing Pei (1999) J. Biol. Chem. 274, 8925-8932). To further characterize its enzymic properties, an expression construct was engineered to produce MT5-MMP as a soluble and active form by truncating its transmembrane domain. Stable expression cell lines were subsequently established from MDCK cells transfected with this construct. Unfortunately, purification of MT5-MMP from the culture media in large quantity proves to be difficult initially due to its rapid turnover via a mechanism which can be inhibited by a broad spectrum metalloproteinase inhibitor, BB94. Thus, BB94 was included in the cell culture medium and throughout the purification process except the final step of chromatography to protect MT5-MMP from destruction. Purified to homogeneity and free of the synthetic inhibitor, MT5-MMP can activate progelatinase A efficiently in a TIMP2 sensitive fashion. A preliminary screen for its potential substrates among extracellular matrix components identified the proteoglycans as the preferred substrates for MT5-MMP. Furthermore, it is determined that the stability of purified MT5-MMP is temperature dependent with rapid destruction at 37 degrees C, but being relatively stable at temperatures 4 degrees C or lower. These observations establish MT5-MMP as a proteoglycanase with a short half-life at body temperature, which may be critical for tightly controlled turnover of ECM components such as those in the brain.
Insights
Matrix metalloproteinase-24 (MT5-MMP) is a brain-specific enzyme that efficiently degrades proteoglycans. Its instability at body temperature suggests a role in regulating extracellular matrix turnover in the brain.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- The membrane-type matrix metalloproteinase (MT5-MMP/MMP24) is a newly identified enzyme specifically expressed in the brain.
- Understanding its enzymatic properties is crucial for elucidating its biological functions.
Purpose of the Study:
- To characterize the enzymatic properties of soluble, active MT5-MMP.
- To identify its substrates and assess its stability under different conditions.
Main Methods:
- Engineered an expression construct to produce soluble MT5-MMP by truncating its transmembrane domain.
- Established stable expression cell lines using MDCK cells.
- Utilized BB94, a metalloproteinase inhibitor, to prevent MT5-MMP degradation during purification.
- Purified MT5-MMP to homogeneity and assessed its activity and substrate specificity.
Main Results:
- Purified MT5-MMP efficiently activated progelatinase A in a TIMP2-sensitive manner.
- Proteoglycans were identified as preferred substrates for MT5-MMP.
- MT5-MMP exhibited temperature-dependent stability, with rapid degradation at 37°C but stability at 4°C or lower.
Conclusions:
- MT5-MMP functions as a proteoglycanase.
- Its short half-life at body temperature is critical for the controlled turnover of extracellular matrix components, particularly in the brain.