Migratory and adhesive properties of Xenopus laevis primordial germ cells in vitro

Abstract

SummaryThe directional migration of primordial germ cells (PGCs) to the site of gonad formation is an advantageous model system to study cell motility. The embryonic development of PGCs has been investigated in different animal species, including mice, zebrafish, Xenopus and Drosophila. In this study we focus on the physical properties of Xenopus laevis PGCs during their transition from the passive to the active migratory state. Pre-migratory PGCs from Xenopus laevis embryos at developmental stages 17–19 to be compared with migratory PGCs from stages 28–30 were isolated and characterized in respect to motility and adhesive properties. Using single-cell force spectroscopy, we observed a decline in adhesiveness of PGCs upon reaching the migratory state, as defined by decreased attachment to extracellular matrix components like fibronectin, and a reduced adhesion to somatic endodermal cells. Data obtained from qPCR analysis with isolated PGCs reveal that down-regulation of E-cadherin might contribute to this weakening of cell-cell adhesion. Interestingly, however, using an in vitro migration assay, we found that movement of X. laevis PGCs can also occur independently of specific interactions with their neighboring cells. The reduction of cellular adhesion during PGC development is accompanied by enhanced cellular motility, as reflected in increased formation of bleb-like protrusions and inferred from electric cell-substrate impedance sensing (ECIS) as well as time-lapse image analysis. Temporal alterations in cell shape, including contraction and expansion of the cellular body, reveal a higher degree of cellular dynamics for the migratory PGCs in vitro.

The Xenopus Maternal-to-Zygotic Transition from the Perspective of the Germline

“…As expected, when the dnd1 3′UTR is fused to GFP, it is competent to direct PGC-specific GFP expression. However, the PGC-specific GFP expression can be observed only when this miR-18-dependent somatic clearance event is complete (Dzementsei, Schneider, Janshoff, & Pieler, 2013; Koebernick et al, 2010). Taken together, these two lines of evidence support the idea that the dramatic decrease in the level of germ-plasm RNAs during gastrulation is a consequence of somatic RNA clearance.…”

“…Six hours later, PGCs are found spread more laterally and express CXCR4 on their surface (Takeuchi, Tanigawa, Minamide, Ikenishi, & Komiya, 2010) while its ligand, SDF-1 is expressed in the dorsal mesentery (Braun et al, 2002). Also around this time, a decreased attachment to ECM components like fibronectin, reduced adhesion to somatic endodermal cells, and downregulation of E-cadherin occurs in isolated PGCs but not in endodermal cells (Dzementsei et al, 2013). …”

Involvement of Membrane Blebbing in Immunological Disorders and Cancer

“…Blebs have been observed in numerous cell types including fibroblasts [ 6 ], endothelial and mesenchymal cells [ 4 ], cancer cells [ 7 , 8 , 9 , 10 , 11 ], immune cells [ 12 , 13 , 14 ], germ cells [ 15 , 16 , 17 ], ameba [ 18 ], parasites [ 19 ] and bacteria [ 20 , 21 , 22 ]. It was originally assumed that blebbing was related solely to pathological conditions in response to nonspecific cellular insults such as lipid peroxidation [ 23 ], anoxia [ 24 ] and energy depletion [ 24 , 25 , 26 ], with motility/invasion [ 11 , 27 ] and multidrug resistance in tumor cells [ 28 ], or as a prerequisite for necrosis.…”

Finding their way: themes in germ cell migration

“…For instance, isolated migrating Xenopus germ cells display less adhesion to Collagen I and fibronectin than isolated pre-migratory germ cells [29]. In contrast, isolated migrating mouse germ cells display more adhesion to fibronectin than germ cells isolated at the end of migration, while adhesion to Collagen IV and laminin remains unchanged [34].…”