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Gene Expr Patterns
2010 Jun 01;104-5:207-13. doi: 10.1016/j.gep.2010.03.002.
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Cell adhesion glycoprotein vitronectin during Xenopus laevis embryogenesis.
Luque ME
,
Serrano MA
,
Honoré SM
,
Mónaco ME
,
Sánchez SS
.
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Vitronectin (vn) is a cell-adhesive glycoprotein present in blood and extracellular matrix of all vertebrates. In the present study we reported the cDNA cloning of Xenopus laevisvitronectin and its spatial and temporal expression pattern during the embryonic development of this important model organism. The deduced amino acid sequence of Xenopus laevis vn showed 49%, 47% and 43% identity with human, chicken and zebrafish orthologs, respectively, whereas the comparison with Xenopus tropicalis vn presented 85% identity. The structural organization consisting of a somatomedin B domain and two hemopexin-like domains was similar to higher vertebrate vitronectins. The vn transcripts were detected from stage 28 onward. At tadpole stages, vn is expressed in heart, gut derivatives and in the notochord. The protein was detected in heart, liver, foregut, pronephros and notochord at stages 43 and 47 of Xenopus embryos. Our results suggest that vitronectin is developmentally regulated and could participate in embryo organogenesis.
Fig. 4. Whole-mount in situ hybridization analysis of Xenopus vitronectin mRNA expression. Developmental stages (Nieuwkoop and Faber, 1967) shown are (A) stages 37–38, (B) stage 39, (C) stage 40, (D) stage 43 and (E) stage 44. The vitronectin transcripts were first detected at embryonic stages 37–38 in the outline of the heart and gastrointestinal tract. At later stages, the expression in these embryonic regions was increased and at stage 43 it starts to be detected in the notochord. he, heart; li, liver; asterisk, gastrointestinal area; arrows, notochord.
Fig. 6. Immunolocalization of glycoprotein vitronectin in tissue sections of Xenopus laevis embryos. (A–D, E, M) Stage 42. (F–N) Stage 47. (A, F, K) Histological sections (100×). (B, G, L) Immunofluorescence micrographs of embryos sections treated with anti-vitronectin antibody and visualized with FITC (400×). (D and I) Immunofluorescence of X. laevis embryos sections treated with anti-vitronectin antibody and visualized with Alexa 546 (400×). (B and D) Note the heart strongly labeled. (G and I) Notochord (arrowhead) show a weak staining. (C, E, H, J) Controls performed omitting the first antibody (400×). (M and N) Schematic diagram showing the respective level of each embryo section, 1: (A–E); 2: (K and L); 3: (F–J). ve, ventricle; ey, eye; ph, pharynx; he, heart; sc, spinal cord; no, notochord; in, intestine; pa, pancreas; li, liver; pr, pronephro; so, somite.
Fig. 1.Xenopus laevis vitronectin structure. (A) Domain structural organization of Xenopus laevis vitronectin. The predicted amino acid sequence of X. laevis vitronectin was analyzed with SMART software. Abbreviations correspond to the conserved somatomedin B (SO) and hemopexin-like (HX) domains. RGD tripeptides are signed. Hexagonalsymbols designate Asn residues that are potential N-glycosylation sites. Numbers indicate the first/last residues. (B) Phylogenetic tree of vitronectin proteins composed from various species: HVN (human vitronectin, AAH05046), OVN (orangutan vitronectin, CAI29588), GVN (goat vitronectin, ABA27428), PVN (pig vitronectin, NP_999269), MVN(mouse vitronectin, AAA40558), CVN (chicken vitronectin, NP_990392), XlVN (African clawed frog vitronectin, ACI29973), XtVN (Xenopus vitronectin, AAH89081), TVN (tetraodon vitronectin, CAG08847), ZVN (zebrafish vitronectin, AAH55570), and TVN (trout vitronectin, CAJ57657). The relationships among the various orthologs were analyzed by the neighbour-joining algorithm within MEGA version 4. Branch points were validated by 1000 bootstrap replications.
Fig. 5. Western blot analysis of human and Xenopus laevis vitronectin. Lane 1: molecular mass markers. Lane 2: X. laevis liver. Lane 3: X. laevis serum. Lane 4: human serum. These results show that X. laevis vnt is immunologically cross-reactive with anti-human vitronectin antibody.
