*E. J. AVILES-RIOS, M. GROSSO-GARCIA, J. E. GARCÍA-ARRARÁS;
Biol., Univ. de Puerto Rico, Rio Piedras, San Juan, Puerto Rico

INTRODUCTION: Insulin and insulin-related peptides such as Insulin-like Growth Factors (IGFs) are crucial in different biological processes including growth, cell differentiation and metabolism. Other important genes associated with the IGF system are the IGF-binding protein (IGFBP), the Acid Labile Subunit (IGFBP-ALS) and the IGF receptor (IGFR). The first two form a trimeric complex with the IGF and are involved in the regulation, transportation and stability of the peptide. Despite their significance, the understanding of the IGF system and its involvement in regeneration remains limited.

METHODS: In the present study, we have characterized the components of the IGF system in the echinoderm Holothuria glaberrima ( sea cucumber), a marine organism known for its ability to regenerate lost body parts. We have then determined their expression profile during the process of intestinal regeneration. Bioinformatic analyses identified orthologs of IGF, IGFBP, IGFBP-ALS and IGFR in the H.glaberrima transcriptome,revealing that these genes are present in the holothurian digestive tract.

RESULTS: HgIGF, HgIGFBP and HgIGFR show 46%, 53% and 63% similarity, respectively, when compared to the orthologs found in the sea urchin Strongylocentrotus purpuratus. We have also determined their expression profiles during intestinal regeneration. Surprisingly, each gene exhibited a distinct expression pattern. While IGF was upregulated during the first three weeks of regeneration, IGFBP-ALS was downregulated and IGFBP showed initial downregulation followed by over-expression in more advanced stages. Interestingly, the expression of the IGFR remained unchanged during the initial stages of the regeneration process.

CONCLUSION: This study provides valuable insight into the presence and dynamics of the IGF system’s molecular mechanisms in echinoderms and paves the way for future studies on its role in the regenerative process.

Acknowledgements:  We gratefully acknowledge support from the Neurograd program from the University of Puerto Rico- Rio Piedras Campus (1R25NS127776-01), and from the National institutes of health ( NIH), NIH-R15 1R15GM124595.

Keywords: insulin-like Growth Factor, Regeneration.