Overexpression of Camello, a Member of a Novel Protein Family, Reduces Blastomere Adhesion and Inhibits Gastrulation in Xenopus laevis

Abstract

Vertebrate gastrulation involves complex coordinated movements of cells and cell layers to establish the axial structures and the general body plan. Adhesion molecules and the components of extracellular matrix were shown to be involved in this process. However, other participating molecules and detailed mechanisms of the control of gastrulation movements remain largely unknown. Here, we describe a novel Xenopus gene camello (Xcml) which is expressed in the suprablastoporal zone of gastrulating embryos. Injection of Xcml RNA into dorsovegetal blastomeres retards or inhibits gastrulation movements. Database searches revealed a family of mammalian mRNAs encoding polypeptides highly similar to Xcml protein. Characteristic features of the camello family include the presence of the central hydrophobic domain and the N-acetyltransferase consensus motifs in the C-terminal part, as well as functional similarity to Xcml revealed by overexpression studies in Xenopus embryos. Xcml expression results in the decrease of cell adhesion as demonstrated by the microscopic analysis and the blastomere aggregation assay. Cell fractionation and confocal microscopy data suggest that Xcml protein is localized in the secretory pathway. We propose that Xcml may fine tune the gastrulation movements by modifying the cell surface and possibly extracellular matrix proteins passing through the secretory pathway.

Novel Roles of the Chemorepellent Axon Guidance Molecule RGMa in Cell Migration and Adhesion

“…Our ex vivo analyses indicated that these mutant phenotypes probably arise as a result of aberrant migration. This conclusion is consistent with previous reports that similar phenotypes result from aberrant migration during gastrulation (6,27,30,42,52). For instance, during Xenopus development, loss of Myosin IIb caused defective convergence and extension movements which culminated in abnormal blastopore closure, unfused neural tube, exposed endoderm, and shortened body axis (52).…”

“…9) unilaterally overexpressing FL-RGMa, RGMa-⌬vWF, or RGMa-⌬RGD mRNA (1.15 ng). Most of these embryos exhibited abnormal gross morphology (ϳ95% penetrance), typical of previously described gastrulation-related defects (6,27,30,42,52). Embryos had prominent abnormalities, such as persistently opened blastopore, exposed endoderm, incomplete neural folds, and a reduced body axis (Fig.…”

Distinct Xenopus Nodal ligands sequentially induce mesendoderm and control gastrulation movements in parallel to the Wnt/PCP pathway

“…Antisense riboprobes for sox17 (Hudson et al, 1997), Xbra (Smith et al, 1991), goosecoid (Yasuo and Lemaire, 2001), Xnot-2 (Gont et al, 1993), Xlim-1 (Taira et al, 1994), sox2 (Mizuseki et al, 1998), foxI1e (Mir et al, 2007), Xwnt11 (Tada and Smith, 2000), rnd1 (Wunnenberg-Stapleton et al, 1999), papc (Kim et al, 1998), pdgfr (Ho et al, 1994), has2 (Nardini et al, 2004) and camello (Popsueva et al, 2001) were prepared as described in the respective references.…”

“…In order to test this, we selected several genes from the literature that are known to be involved in various cellular behaviours during gastrulation, including directed migration and adhesion. These genes encode the receptor tyrosine kinase PDGFR (Nagel et al, 2004;Symes and Mercola, 1996), the small GTPase Rnd1 (Wunnenberg-Stapleton et al, 1999), the hyaluronan synthase HAS2 (Nardini et al, 2004), the protocadherin PAPC (Kim et al, 1998) and the putative N-acetyltransferase Camello (Popsueva et al, 2001). All these genes are expressed in invaginating mesendoderm and show dorsal enrichment at the onset of gastrulation (see Fig.…”

Gene Expression Profiling Reveals Complex Changes in the Olfactory Bulbectomy Model of Depression After Chronic Treatment With Antidepressants

“…Camello proteins, which are localized in the Golgi complex, inhibit gastrulation in Xenopus laevis. Camello proteins participate in the acetylation of sugar residues in glycoproteins (54). O-GlcNAc transferase catalyzes the addition of a single N-acetylglucosamine to proteins.…”