Egr gene in visceral organ regeneration in the holothurian eupentacta fraudatrix.

Holothurians represent a convenient model system for studying the cellular and molecular mechanisms of regeneration of visceral organs. In holothurians, it involves remodeling of the extracellular matrix (ECM) and dedifferentiation, migration, proliferation, and redifferentiation of diverse cell types. The molecular mechanisms regulating these processes remain poorly understood. In the present study, the spatial and temporal expression and functional role of the egr (early growth response) gene during regeneration of the aquapharyngeal complex (AC) and gut were investigated in the holothurian Eupentacta fraudatrix. In regeneration, egr is expressed in tissues undergoing dedifferentiation, migration, and proliferation. Knockdown of egr during regeneration leads to abnormalities in gut development, including thickening of the intestinal tube, improper lumen formation, excessive loosening of the extracellular matrix, and delayed differentiation of coelomic and luminal epithelial cells. Taken together, these findings indicate that during gut regeneration, egr is associated with the regulation of extracellular matrix remodeling and epithelial cell plasticity, thereby ensuring proper morphogenesis.