The Role of Sdf‐1α signaling in Xenopus laevis somite morphogenesis

Abstract

Background Stromal derived factor-1α (sdf-1α), a chemoattractant chemokine, plays a major role in tumor growth, angiogenesis, metastasis and in embryogenesis. The sdf-1α signaling pathway has also been shown to be important for somite rotation in zebrafish (Hollway, et al 2007). Given the known similarities and differences between zebrafish and Xenopus laevis somitogenesis, we sought to determine whether the role of sdf-1α is conserved in Xenopus laevis. Results Using a morpholino approach, we demonstrate that knockdown of sdf-1α or its receptor, cxcr4, leads to a significant disruption in somite rotation and myotome alignment. We further show that depletion of sdf-1α or cxcr4 leads to the near absence of β-dystroglycan and laminin expression at the intersomitic boundaries. Finally, knockdown of sdf-1α decreases the level of activated RhoA, a small GTPase known to regulate cell shape and movement. Conclusion Our results show that sdf-1α signaling regulates somite cell migration, rotation and myotome alignment by directly or indirectly regulating dystroglycan expression and RhoA activation. These findings support the conservation of sdf-1α signaling in vertebrate somite morphogenesis; however, the precise mechanism by which this signaling pathway influences somite morphogenesis is different between the fish and the frog.

Roles of Xenopus chemokine ligand CXCLh (XCXCLh) in early embryogenesis

“…However, recent studies have shown that chemokine molecules play a role in early morphogenesis before the immune system is established. The chemokine ligand xSDF‐1α and its receptor xCXCR4 contribute to the directional migration of mesendodermal cells towards the blastocoel roof during Xenopus gastrulation (Fukui, Goto, Kitamoto, Homma, & Asashima, ), and both knockdown of xSDF‐1α and xCXCR4 affect somite morphogenesis (Leal et al., ). The expression of XCXCLC in the midline region during gastrulation and neurulation promotes lateral–medial directional tissue convergence (Goto & Asashima, ).…”

RARβ2 is required for vertebrate somitogenesis

“…Lampreys lack a myoseptum and adaxial cells (Hammond et al, 2009) despite possessing chevron-shaped somites (Rost et al, 2014). Differences in Xenopus and zebrafish have already been recognized with regard to somite rotation, intersomitic boundary formation and other early morphogenic movements in somitogenesis (Afonin et al, 2006;Henry et al, 2005;Leal et al, 2014). This could contribute to the difficulty in making direct comparisons between zebrafish and Xenopus with regard to myosepta, adaxial cells and chevron morphology.…”

Making muscle: Morphogenetic movements and molecular mechanisms of myogenesis in Xenopus laevis

“…This signaling pathway was also shown to play a role in regulating somite cell rotation in X. laevis . However, the morphogenetic processes underlying somite rotation are quite distinct between X. laevis and zebrafish [14]. …”