The role of the small GTPase Arf6 during morphogenesis in sea urchin early development

Date
2016
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University of Delaware
Abstract
ADP ribosylation factor 6 (Arf6) is a small GTPase that acts as a molecular switch, which regulates endocytosis by mediating membrane trafficking between the plasma membrane and endosomal compartments, as well as cell motility by remodeling the actin cytoskeleton. This protein is evolutionarily highly conserved and has been identified in organisms ranging from yeast to human. Although in vitro studies have revealed the cellular functions of Arf6, relatively little is known about its physiological role in development. In this study we examined the function of Arf6 in early development using the purple sea urchin as a model organism. We found that perturbation of Arf6 with loss-of-function morpholino antisense oligonucleotide (MASO), the constitutively active GTPase defective Arf6 mutant Arf6 Q67L, and the dominant negative Arf6 mutant Arf6 T27N led to embryonic defects in gut development, skeletal structures, PMC patterning, and pigment cell motility and pseudopodial projections. The cells types that we focus on are those that undergo cellular morphogenesis during gastrulation: 1) endodermal cells which undergo morphogenesis in order to form the larval gut, 2) primary mesenchyme cells (PMCs) which undergo migration and give rise to the larval skeleton, and 3) pigment cells which are immune cells that are highly motile. Results indicate that Arf6 perturbed embryos led to a range of dose-dependent developmental defects, including a delay in development, exogastrulation, defective larval gut, aberrant PMC development, and pigment cell morphological changes. These results support the hypothesis that Arf6 is essential for proper morphogenesis and cell movements during early development; hence, this study provides insights into the functional role of Arf6 during early development.
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