Expression of Sox family genes in early lamprey development

Abstract

Members of the Sox (Sry-related high mobility group box) family of transcription factors play a variety of roles during development of both vertebrates and invertebrates. A marked expansion in gene number occurred during emergence of vertebrates, apparently via gene duplication events that are thought to have facilitated new functions. By screening a macroarrayed library as well as the lamprey genome, we have isolated genes of the Sox B, D, E and F subfamilies in the basal jawless vertebrate, lamprey. The expression patterns of all identified Sox genes were examined from gastrulation through early organogenesis (embryonic day 4–14), with particular emphasis on the neural crest, a vertebrate innovation. Coupled with phylogenetic analysis of these Sox genes, the results provide insight into gene duplication and divergence in paralog deployment occurring during early vertebrate evolution.

Characterization of the trunk neural crest in the bamboo shark, Chiloscyllium punctatum

“…Therefore, we conclude that C. punctatum has a full set of osteichthyan Sox8, Sox9, and Sox10 genes. This stands in contrast to earlier vertebrates, such as lampreys, which contain SoxE1-3 (Meulemans and Bronner-Fraser, 2004;Uy et al, 2012).…”

“…However, hagfish trunk neural crest cells appear to express Sox9, although these cells do not enter the somites, as was observed in C. punctatum and osteichthyans (Ota et al, ). Although Sox8 and Sox9 expression has been fully characterized in the lamprey cranial neural crest, little is known about expression in the trunk (Lakiza et al, ; Uy et al, ). Preliminary results indicate that lamprey trunk neural crest migration is segmental, similar to our observations in shark (Dr. Marianne Bronner, personal communication).…”

On the evolutionary relationship between chondrocytes and osteoblasts

“…Runx2 , along with its related family members, Runx1 and 3 , derive from gnathostome duplications of an ancestral Runx , while agnathan Runx genes may have undergone an independent duplication ( Meulemans and Bronner-Fraser, 2007 ; Hecht et al, 2008 ; Cattell et al, 2011 ; Kaneto and Wada, 2011 ; Nah et al, 2014 ). Sox9 , along with its related family members, Sox8 and 10 , derive from duplications to the ancestral SoxE , while agnathan SoxE genes may have undergone an independent duplication ( Meulemans and Bronner-Fraser, 2007 ; Ohtani et al, 2008 ; Yu et al, 2008 ; Cattell et al, 2011 ; Uy et al, 2012 ; Jandzik et al, 2015 ). Runx and SoxE orthologs are expressed in cartilage of amphioxus, lamprey, and hagfish, suggesting that the gene ancestral to Runx2 primitively functioned with the gene ancestral to Sox9 in early cartilage formation ( Hecht et al, 2008 ; Wada, 2010 ; Kaneto and Wada, 2011 ).…”

Evolutionarily conserved role for SoxC genes in neural crest specification and neuronal differentiation

“…Similarly, there is no information regarding the expression or function of SoxCs in development of basal vertebrates, making it difficult to infer the pan-vertebrate role of this gene family. Although the expression pattern of other major Sox gene subfamilies have been described in the sea lamprey (Petromyzon marinus) (Uy et al, 2012), here we expand this analysis to include the SoxC subfamily and characterize the function of the lamprey SoxC orthologs in neural crest formation in a basal vertebrate. To this end, we have cloned and characterized the expression patterns and function of the lamprey SoxC gene family, termed SoxC1–C4, during neural crest development.…”