Subject(s)
Brain Neoplasms/diagnosis , Brain Neoplasms/secondary , Delusions/etiology , Neurosyphilis/diagnosis , Parietal Lobe/pathology , Psychomotor Agitation/etiology , Salivary Gland Neoplasms/diagnosis , Submandibular Gland/pathology , Temporal Lobe/pathology , Biopsy , Brain Neoplasms/pathology , Diagnosis, Differential , Dominance, Cerebral , Female , Humans , Magnetic Resonance Imaging , Middle Aged , Salivary Gland Neoplasms/pathology , Syphilis SerodiagnosisABSTRACT
Integrin-binding sialoprotein (IBSP) is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family; and the whole SIBLING family is further included in a larger secretory calcium-binding phosphoprotein (SCPP) family. SIBLING proteins are known to construct a part of the non-collagenous extracellular matrices of calcified tissues, and considered to have arisen by duplication and subsequent divergent evolution of a single ancient gene. To understand the alterations of SIBLING molecules associated with the evolution of calcified tissues in vertebrates, we initiated a search for lower vertebrate orthologs of SIBLING genes. In the present study, an IBSP ortholog from a reptile (caiman) and two distinct orthologs from an amphibian (African clawed toad) were identified and characterized. As expected, the toad IBSP genes were transcribed only in calcified tissue (jaw and tibia), as also seen in mammals. The caiman, toad, avian, and mammalian IBSPs share several unique features specific for IBSP and apparently have similar properties. Furthermore, analysis of the sequences suggested that the IBSP molecule might have gradually intensified its functions related to calcification during its evolutionary process through tetrapods.
Subject(s)
Alligators and Crocodiles/genetics , DNA/genetics , Peptide Initiation Factors/genetics , Sialoglycoproteins/genetics , Xenopus laevis/genetics , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , DNA Primers , DNA, Complementary/genetics , Humans , Integrin-Binding Sialoprotein , Mammals/genetics , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction , Protein Biosynthesis , RNA/geneticsABSTRACT
Matrix metalloproteinase-20 (MMP20; enamelysin) is important for proteolytic processing of extracellular matrix (ECM) proteins during the formation of enamel and plays a critical role in proteolytic processing of amelogenin (AMEL), the most abundant enamel ECM protein. MMP20 might have played a role in the emergence of teeth, because jawless vertebrates with primordial teeth on their external skeletons may have possessed the MMP20 gene, and MMP20 and enamel ECM proteins are thought to have evolved together in a special relationship over time. Thus, an understanding of the molecular evolution of the MMP20 gene is important for elucidating the evolution of enamel and it is necessary to identify the orthologs of the MMP20 gene in non-mammals, as it has been identified in mammals. In the present study, orthologs of the MMP20 genes from a reptile (caiman) and an amphibian (African clawed toad) were cloned and characterized. Comparisons of the orthologs revealed that the MMP20 proteins were highly conserved throughout the evolution of tetrapods. Further, the caiman, toad, and mammalian MMP20 shared several unique features specific for MMP20, but not for other matrix metalloproteinases. In addition, the toad MMP20 gene was transcribed only in the upper jaw, presumably in teeth. These results suggest that MMP20 in a common ancestor of tetrapods might have been recruited for the processing of AMEL and conserved over 350 million years of evolution.
