Isolation and characterization of five Fox (Forkhead) genes from the sponge Suberites domuncula

Fox or Forkhead genes constitute a subgroup of the helix-turn-helix class of transcription factors with a characteristic and highly conserved DNA binding domain. To date, around 100 different Fox genes have been reported ranging from yeast to humans; these have been classified into 18 subclasses (A to P). Fox proteins are responsible for a wide range of functions and key roles in early developmental processes, during organogenesis and also for the function of the major organs and tissues in the adult. Here, we report the isolation and phylogenetic characterization of five members of the Fox family from the sponge Suberites domuncula. Four of them (Sd-FoxL2, Sd-FoxP, Sd-FoxD and Sd-FoxF) fall in the root of four of the already established families of vertebrates Fox, suggesting that in sponges, the basal group of metazoans, the main groups of Fox proteins were already established. We also demonstrate that they are differentially regulated during the culture of sponge cells.