Identification and characterization of matrix metalloproteinase-20 (MMP20; enamelysin) genes in reptile and amphibian

Shintani, Seikou; Kobata, Mitsuhiko; Kamakura, Naofumi; Toyosawa, Satoru; Ooshima, Takashi

doi:10.1016/j.gene.2006.11.014

Cited by 12 publications

(8 citation statements)

References 31 publications

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“…However, exon 2 of MMP20 encodes the carboxyl-terminal region of the propeptide, as well as 18 amino-terminal residues of the catalytic (Zn 2þ , Ca 2þ ) subdomain, and removal of this exon from the mRNA would presumably render MMP20 non-functional. Indeed, the homologous 18-amino acid region of the catalytic (Zn 2þ , Ca 2þ ) subdomain encoded by exon 2 is completely conserved in human, cow, pig and spectacled caiman, and shows only one amino acid difference in mouse [24]. This pattern of evolutionary conservation validates the critical importance of the catalytic subdomain that is partially encoded by exon 2.…”

Section: Resultsmentioning

confidence: 60%

Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

et al. 2010

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Whales in the suborder Mysticeti are filter feeders that use baleen to sift zooplankton and small fish from ocean waters. Adult mysticetes lack teeth, although tooth buds are present in foetal stages. Cladistic analyses suggest that functional teeth were lost in the common ancestor of crown-group Mysticeti. DNA sequences for the tooth-specific genes, ameloblastin (AMBN), enamelin (ENAM) and amelogenin (AMEL), have frameshift mutations and/or stop codons in this taxon, but none of these molecular cavities are shared by all extant mysticetes. Here, we provide the first evidence for pseudogenization of a tooth gene, enamelysin (MMP20), in the common ancestor of living baleen whales. Specifically, pseudogenization resulted from the insertion of a CHR-2 SINE retroposon in exon 2 of MMP20. Genomic and palaeontological data now provide congruent support for the loss of enamel-capped teeth on the common ancestral branch of crown-group mysticetes. The new data for MMP20 also document a polymorphic stop codon in exon 2 of the pygmy sperm whale (Kogia breviceps), which has enamel-less teeth. These results, in conjunction with the evidence for pseudogenization of MMP20 in Hoffmann's two-toed sloth (Choloepus hoffmanni), another enamel-less species, support the hypothesis that the only unique, non-overlapping function of the MMP20 gene is in enamel formation.

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Section: Resultsmentioning

confidence: 60%

Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

et al. 2010

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“…In enamel proteinases, KLK4 appears to have originated in a mammalian lineage (28), whereas MMP20 has been identified in the caiman and frog but not confirmed in teleosts (29). Searching for a further evolutionary link between tetrapod enamel and teleost enameloid, here we explored the presence or absence of MMP20 in teleosts.…”

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confidence: 99%

Molecular evolution of matrix metalloproteinase 20

Kawasaki

Suzuki

2011

European J Oral Sciences

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Dental enamel is a hypermineralized tissue, containing only trace amounts of organic components. During enamel formation, matrix metalloproteinase 20 (MMP20) processes proteins comprising enamel matrix and facilitates hypermineralization. In the human genome, 24 distinct MMP genes have been identified. Among these genes, MMP20 is clustered with eight other genes, including MMP13, and all these clustered genes show phylogenetically close relationships. In this study, we investigated MMP20 and closely related MMP genes in various tetrapods and in a teleost fish, fugu. In the genome of the chicken, a toothless tetrapod, we identified degraded exons of MMP20, which supports the previous proposition that MMP20 is important specifically for enamel formation. Nevertheless, for unknown reasons, we failed to identify MMP20 in the platypus genome. In the opossum, lizard, and frog genomes, MMP20 was found clustered with MMP13. Furthermore, in the fugu genome, we identified an MMP20-like gene located adjacent to MMP13, suggesting that MMP20 arose before the divergence of ray-finned fish and lobe-finned fish. The teleost tooth surface is covered with enameloid, a hypermineralized tissue different from enamel. Thus, we hypothesize that MMP20 could have been used in an ancient hypermineralized tissue, which evolved into enameloid in teleosts and into enamel in tetrapods.

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“…In a series of earlier studies on the evolution of molecules, we identified and characterized a number of orthologs in X. laevis involved in the formation of hard tissues (Toyosawa et al, '98;Shintani et al, 2003Shintani et al, , 2007Shintani et al, , 2008. X. laevis was chosen as it is commonly used for studies of developmental biology and genetics.…”

Section: Discussionmentioning

confidence: 99%

Identification, characterization, and expression of dentin matrix protein 1 gene in Xenopus laevis

et al. 2013

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Dentin matrix protein 1 (DMP1) is an acidic extracellular matrix protein expressed mainly in bone and dentin, and is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family. The DMP1 gene, however, appears to evolve rapidly in comparison with other SIBLING genes, even though such functionally important molecules usually evolve more slowly than less important ones. The purpose of this study was to identify and characterize an ortholog of the DMP1 gene in an amphibian (Xenopus laevis; X. laevis) to clarify molecular evolutionary alterations in DMP1 associated with calcified tissues in tetrapods. Furthermore, we analyzed the mRNA expression of this gene to elucidate its functional change in bone and developing tooth germ in comparison with amniote DMP1s. The similarities of the deduced amino acid sequence of X. laevis DMP1 to that of the corresponding amniote proteins were low, although they did share several unique features specific to DMP1 and have similar properties. Expression of X. laevis DMP1 mRNA was predominant in osteocytes and odontoblasts, but only transiently observed in ameloblasts, as in amniotes. These results suggest that DMP1 has conserved several functions during tetrapod evolution. This indicates that continuity of biochemical properties has been more important in maintaining DMP1 functionality than that of the sequence of amino acid residues, which has undergone change over the course of molecular evolution.

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Identification and characterization of matrix metalloproteinase-20 (MMP20; enamelysin) genes in reptile and amphibian

Cited by 12 publications

References 31 publications

Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

Molecular evolution of matrix metalloproteinase 20

Identification, characterization, and expression of dentin matrix protein 1 gene in Xenopus laevis

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