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A.J. Williams, D.J. Rhee; Survey of Matrix Metalloproteinase mRNA Expression in the Human Trabecular Meshwork and Ciliary Body . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1174.
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Purpose: Remodeling of extracellular matrix (ECM) by matrix metalloproteinases (MMP's) is thought to be an important regulatory mechanism of aqueous humor outflow resistance. We wished to determine which matrix metalloproteinases are present in human trabecular meshwork (TM) and ciliary body (CB). Methods: Human TM and CB were dissected from donor eyes. Total mRNA was isolated and RT-PCR was performed using previously published matrix metalloproteinase oligonucleotide primer sequences. RT-PCR products were analyzed using agarose gel electrophoresis. Results: Bands corresponding to mRNA for MMP-14, MMP-15, MMP-16, MMP-18, MMP-25 and MMP-28 were present in both HTM and CB tissue. Bands for MMP-13, MMP-17 were present in the TM but not in the CB. Bands for MMP-20, MMP-23, and MMP-26 were not found in either tissue. Conclusions: It has been reported that MMP's degrade ECM and reduce the resistance to aqueous humor outflow, but the full complement of MMPs present in the TM and CB critical to ECM degradation has not yet fully been described. Our results indicate that the trans-membrane-bound MMP's (14,15,16,25) are present in both in the HTM and CB, and may play an important role in cell signaling and processing of biologically important proteins on these cell surfaces. We have also shown the presence of MMP-18, which may play a role in basement membrane degradation and angiogenesis, and MMP-28 whose substrate is yet unknown in both HTM and CB tissue. TM tissue contains MMP-13 and MMP-17, which were not found in CB tissue. These endopeptidases may play an important role in ECM turnover and reduction of resistance to aqueous outflow in the conventional pathway but not in the uveoscleral outflow tract.
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