Alternative titles; symbols
HGNC Approved Gene Symbol: MMP28
Cytogenetic location: 17q12 Genomic coordinates (GRCh38): 17:35,756,249-35,795,641 (from NCBI)
Matrix metalloproteinases, including MMP28, constitute a family of enzymes that function both in the turnover and degradation of extracellular matrix proteins and in the processing, activation, or deactivation of a variety of soluble factors (Lohi et al., 2001).
By searching a database for sequences similar to the MMP catalytic domain, followed by PCR of a fibrosarcoma cell line cDNA library and screening foreskin keratinocyte and pooled testis cDNA libraries, Lohi et al. (2001) cloned MMP28, which they called epilysin. The deduced 520-amino acid protein has a calculated molecular mass of 59 kD. MMP28 contains an N-terminal signal sequence, followed by a prototypic MMP prodomain with a conserved cysteine switch; a furin (136950) recognition sequence; a catalytic center with 3 conserved histidine residues; a hinge region; and a typical hemopexin (142290)-like domain. Unlike other MMPs, MMP28 contains a threonine within its catalytic center. The active, furin-processed enzyme was estimated to be 45 kD. Northern blot analysis detected transcripts of 2.6, 2.0, and 1.2 kb in several tissues. The 2.6-kb transcript was most abundant and showed highest expression in testis, followed by lung, heart, colon, intestine, and brain. RNase protection analysis of several cell lines found epilysin expressed only in keratinocytes. Western blot analysis of endogenous epilysin secreted by HaCaT keratinocytes showed a protein with an apparent molecular mass of about 58 kD. Immunohistochemical staining showed expression of epilysin protein in the basal and suprabasal epidermis of intact skin. In injured skin, prominent staining for epilysin was seen in basal keratinocytes both at and some distance from the wound edge, a pattern distinct from those of other MMPs expressed during tissue repair.
By subtraction for known MMP genes, followed by PCR and 3-prime and 5-prime RACE of kidney, lung, and testis cDNA libraries, Marchenko and Strongin (2001) cloned MMP28. MMP28 shares 40% amino acid identity with MMP19 (601807). PCR analysis detected highest expression in adult lung, followed by fetal lung, brain, skeletal muscle, and kidney, and adult kidney and pancreas. No expression was detected in placenta and liver.
By zymogram analysis, Lohi et al. (2001) confirmed that recombinant epilysin expressed by E. coli showed caseinolytic activity, which was completely inhibited by exclusion of calcium and zinc and by the addition of EDTA or a specific MMP inhibitor.
Using a reporter gene assay with the MMP28 promoter region, Illman et al. (2001) found that deletion or mutation of the GT box, which shows homology to the consensus binding site for Sp transcription factors, reduced the transcriptional activity of MMP28 in keratinocytes and spermatogonia. Supershift assays identified Sp1 (189906) and Sp3 (601804) as likely regulators of the MMP28 promoter.
Lohi et al. (2001) and Marchenko and Strongin (2001) determined that the MMP28 gene contains 8 exons. Illman et al. (2001) determined that the MMP28 promoter region contains a GT box, but it contains no typical TATA boxes or CCAAT sequences.
By genomic sequence analysis, Lohi et al. (2001) mapped the MMP28 gene to chromosome 17. By somatic cell hybrid analysis, Marchenko and Strongin (2001) mapped the MMP28 gene to chromosome 17q11.2.
Manicone et al. (2009) found that mice lacking Mmp28 were healthy and fertile with histologically normal airways. Using a mouse model of Pseudomonas aeruginosa pneumonia, they found that Mmp28 -/- mice had an early increase in macrophage recruitment to the lung, enhanced bacterial clearance, and reduced pulmonary neutrophilia. Depletion of macrophages in wildtype and Mmp28 -/- mice confirmed a role for macrophages in bacterial clearance and regulating neutrophil recruitment. Immunofluorescence microscopy revealed expression of Mmp28 in mouse bronchial epithelial (club) cells. Chemotaxis assays showed that Mmp28 -/- macrophages migrated faster than wildtype cells to bronchoalveolar lavage fluid from P. aeruginosa-infected mice of either genotype. Manicone et al. (2009) concluded that MMP28 functions as an intrinsic negative regulator of macrophage recruitment by retarding the chemotaxis of these cells.
Illman, S. A., Keski-Oja, J., Lohi, J. Promoter characterization of the human and mouse epilysin (MMP-28) genes. Gene 275: 185-194, 2001. [PubMed: 11574168] [Full Text: https://doi.org/10.1016/s0378-1119(01)00664-3]
Lohi, J., Wilson, C. L., Roby, J. D., Parks, W. C. Epilysin, a novel human matrix metalloproteinase (MMP-28) expressed in testis and keratinocytes and in response to injury. J. Biol. Chem. 276: 10134-10144, 2001. [PubMed: 11121398] [Full Text: https://doi.org/10.1074/jbc.M001599200]
Manicone, A. M., Birkland, T. P., Lin, M., Betsuyaku, T., van Rooijen, N., Lohi, J., Keski-Oja, J., Wang, Y., Skerrett, S. J., Parks, W. C. Epilysin (MMP-28) restrains early macrophage recruitment in Pseudomonas aeruginosa pneumonia. J. Immun. 182: 3866-3876, 2009. [PubMed: 19265166] [Full Text: https://doi.org/10.4049/jimmunol.0713949]
Marchenko, G. N., Strongin, A. Y. MMP-28, a new human matrix metalloproteinase with an unusual cysteine-switch sequence is widely expressed in tumors. Gene 265: 87-93, 2001. [PubMed: 11255011] [Full Text: https://doi.org/10.1016/s0378-1119(01)00360-2]