Classification and evolutionary analysis of the basic helix-loop-helix gene family in the Japanese lamprey (Lethenteron japonicum)

Abstract

Basic helix-loop-helix (bHLH) transcription factors are widely distributed in eukaryotic organisms ranging from yeast to mammals and are thought to be one of the largest families of regulatory proteins. They possess crucial functions in the control of a variety of developmental processes, such as cell proliferation and differentiation, cell lineage determination, myogenesis, neurogenesis, hematopoiesis, sex determination, gut development, as well as other essential processes. Lampreys are representatives of an ancient jawless vertebrates that diverged from our own ~500 million years ago and therefore are important for the study of vertebrate evolution. In this study, we conducted a genome-wide survey using the Japanese lamprey genomic database and identified 102 putative bHLH genes. Based on phylogenetic analysis, these Japanese lamprey genes were classified into 43 families, the identified LjbHLH genes were classified into 40 bHLH families with 42, 24, 18, 2, 13, and 0 member(s) in group A, B, C, D, E and F respectively, and 3 members categorized as “orphans”.