Phylogenetic Analysis, Expression And Function Of DjSparc-like Gene Of Dujesia Japonica

Dugesia japonica, (Platyhelminthes, Tricladida) an invertebrate group, is well known for its extraordinary regenerative ability, which firstly appears bilateral symmetry and mesoderm. Platyhelminthes are excellent models for the study of stem cell biology, regeneration, evolutionary and development. SPARC (secreted protein acidic and rich in cysteine,) also known as osteonectin, is revealed distribution in the different species widely. It is an extracellular matrix and is expressed spatially and temporally during embryogenesis, tissue remodeling and repair. Therefore, the aims of our study were to characterize DjSparc-like gene from the Dugesia japonica, then examines its localizations and functions in the embryos, intact and regenerating animals. Research on the gene of DjSparc-like will contribute to the molecular mechanism of regeneration and establishment of body plan.The cDNA clone encoding a planarian SPARC (DjSPARC-like) protein was isolated from a cDNA library of Dugesia japonica. It contained a 783 bp open reading frame corresponding to a deduced protein of 261 amino acids. Bioinformatics ananlysis suggested that DjSparc—like has two conserved domains typical of Sparc including FS-like and EC domain. Phylogenetic analysis showed that vertebrate and invertebrate SPARC proteins are each grouped together, with DjSparc—like falling at the base of clade, suggesting that SPARC are conserved proteins in almost all species.Whole mount in situ hybridization result revaled that DjSparc-like exhibits a tissue and stage-specific expression pattern during early embryonic development. And its expression seems persistent along the body margin of dorsal epithelium and especially at the head and tail, which seems important in the pattern of dosal and A-P axis. In regeneration worms the result of hybridization was similar to the intact ones. RT-PCR analyses showed that the expression level of DjSparc-like gene was changed by cutting, suggesting a relationship between the DjSparc-like gene and regeneration. RNAi analysis confirmed that DjSparc-like gene play role of regeneration.