Apoptosis and Surivivin gene expression during Holothuria glaberrima intestinal regeneration

Abstract

The sea cucumber (Holothuria glaberrima) is an excellent model to study regeneration processes in deuterostomes. H.glaberrima has the ability to regenerate most of its viscera after the process of evisceration, where most of the viscera are expelled from the body. We have showed that apoptosis takes place during intestinal regeneration. Apoptosis, is the result of DNA internucleosomal cleavage, the morphological characteristics are: cell contraction, nuclear pyknosis, chromatin condensation and cell fragmentation. By using the TUNEL assay, where the TdT enzyme catalyzes the addition of Br‐dUTP, labelling the 3′‐OH terminal groups exposed during the internucleosomal cleavage; we identified apoptotic cells by fluorescence microscopy. We showed a peak in the number of apoptotic cells throughout the first week of regeneration and the distribution of apoptotic cells in the different layers of the large intestine (serosa, sub‐mucosa, mucosa and mesentery). Moreover we have now identified the holothurian homologue of the Survivin gene that in vertebrates functions as an inhibitor of apoptosis. Preliminary results have shown a differential expression of this gene during regeneration. Molecular experiments, PCR and In‐situ hybridization are under way to asses the temporal and spatial expression of apoptosis and survivin expression. Our results prove that similar to embryonic development, apoptosis plays an important role during intestinal regeneration. These studies provide a deeper understanding of the process of intestinal regeneration in the sea cucumber and the applications to studies in other animals, including humans.

The constructive function of apoptosis: More than a dead-end job

“…It appears that this mechanism results from the ability of apoptotic cells to induce an upregulation of mitogen factors such as decapentaplegic and wingless mitogens (Pérez-Garijo et al, 2004;Ryoo et al, 2004). Apoptotic-dependent proliferation has also been reported or suggested in several organisms after injuries (Tseng et al, 2007;Donato-Santana et al, 2008;Mashanov et al, 2010;Pellettieri et al, 2010;Fok et al, 2020). After bisection of the cnidarian Hydra vulgaris, the apoptotic Frontiers in Cell and Developmental Biology frontiersin.org cells from the site of injury induce Wnt3 signaling in a caspasedependent manner, leading to the proliferation of adjacent stem cells, allowing tissue regeneration (Chera et al, 2009).…”