SCPP Gene Evolution and the Dental Mineralization Continuum

Abstract

Many genes critical to vertebrate skeletal mineralization are members of the secretory calcium-binding phosphoprotein (SCPP) gene family, which has evolved by gene duplication from a single ancestral gene. In humans, mutations in some of these SCPP genes have been associated with various diseases related to dentin or enamel hypoplasia. Recently, systematic searches for SCPP genes of various species have allowed us to investigate the history of phylogenetically variable dental tissues as a whole. One important conclusion is that not all disease-associated SCPP genes are present in tetrapods, and teleost fish probably have none, even in toothed species, having acquired their complement of SCPP genes through an independent duplication history. Here, we review comparative analyses of mineralized dental tissues, with particular emphasis on the use of SCPPs, within and between tetrapods and teleosts. Current knowledge suggests a close relationship among bone, dentin, teleost fish enameloid (enamel-like hard tissue), and tetrapod enamel. These tissues thus form a mineralized-tissue continuum. Contemporary dental tissues have evolved from an ancestral continuum through lineage-specific modifications.

DMP1 and DSPP: Evidence for Duplication and Convergent Evolution of Two SIBLING Proteins

“…Our analysis of the SIBLINGs in the chicken genome ( fig. 1 a) agreed with 2 previous publications [Kawasaki and Weiss, 2008;Sire et al, 2008] in that this toothless animal has 4 of the SIBLING genes but lacks a DSPP gene. Furthermore, like Kawasaki and Weiss [2008], we found that the order and relative transcriptional directions of the SIB-LING genes and SPARCL1 (plus we note PDK2) had the same orientation as in mammals.…”

Evidence for a single loss of mineralized teeth in the common avian ancestor

“…S7). Similar to other vertebrate genomes, including human and crocodile, we found that AMBN is located between AMTN and ENAM in the secretory calciumbinding phosphoprotein (SCPP) gene cluster (24) (Fig. 2), AMELX is found within the ARHGAP6 gene (Fig.…”

Expression and Function of Enamel-related Gene Products in Calvarial Development

“…Five of the ERP genes studied here, Ambn, Enam, Amtn, Odam, and Amel, are members of the secretory calcium-binding phosphoprotein (SCPP) gene cluster of evolutionarily related skeletal mineralization molecules (Kawasaki and Weiss, 2008). According to our analysis, individual ERPs displayed 20% to 40% similarity with other SCPP family members, and bone proteins such as IBSP and OPN had more negatively charged amino acid residues than ERPs, suggesting that bone proteins may play a greater role in the regulation of crystal growth regulation (nucleation and/or inhibition) than ERPs.…”