High impact information on fibronectin

• Pattern formation and temporal control of gene expression in Xenopus development were investigated using fibronectin as a biochemical marker [1].
• This in vivo pathway is rich in fibronectin, a glycoprotein that promotes cell adhesion and migration in vitro [2].
• Isolated PGCs are associated with cells from the mesentery and with fibronectin [2].
• In contrast, cultured adult mesentery epithelial cells synthesize large amounts of fibronectin and lay it down in subcellular fibrils that align with intracellular microfilament bundles [2].
• Primordial germ cells of Xenopus embryos: the role of fibronectin in their adhesion during migration [2].

Biological context of fibronectin

• A comparison of V-region alternative splicing between embryonic and adult liver RNAs indicates a segment of 345 nucleotides that can be either completely excluded or included in mature FN transcripts but there is no evidence for additional V-region variants [3].
• The cellular forms of the FN protein predominate in the early embryo with the EIIIA and EIIIB exons included in most mRNAs at this time [3].
• By comparing the activities of different fibronectin gene reporter constructs in fibroblasts and cadherin transfectants, the LEF-TCF site at position -368 was identified as a Wnt/Wg response element [4].
• This may indicate that fibronectin-mediated cell migration is not required for convergent extension [5].
• Lack of fibronectin fibrils in vivo is correlated with blastocoel roof thickening and a loss of deep cell polarity [6].

Anatomical context of fibronectin

• Maternal mRNAs encoding alternatively spliced forms of FN can be specifically eliminated from Xenopus oocytes following the injection of antisense oligodeoxynucleotides into the cytoplasm, thereby making it possible to analyze the structure, composition, and function of FN mRNAs in early embryos [3].
• In Xenopus laevis gastrulae, a fibronectin-rich extracellular matrix is deposited on the basal surface of ectoderm cells over which cardiac and visceral primordia move during development [7].
• Our results suggest that the ability of xSyn4 to translocate xDsh is regulated by fibronectin, a component of the extracellular matrix required for proper convergent extension movements [8].
• In the embryo of this frog, dorsal mesoderm involution can be diverted from its normal course by injection of peptides that inhibit interaction of fibronectin with its receptor [9].
• This behavior is similar to that of migrating mesoderm cells in vivo that spread and form lamellipodia and filipodia on contact with fibronectin-rich extracellular matrix [10].

Associations of fibronectin with chemical compounds

• Sequence analysis of cDNA clones encoding fibronectin (FN) from Xenopus laevis reveals extensive amino acid identities with other vertebrate FNs, including the presence of the Arg-Gly-Asp (RGD) cell attachment site in type III-10 and of a second, cell-binding site (EILDV) in the alternative spliced V region of the protein [3].
• To further investigate this, we made use of GRGDSP, a peptide which inhibits binding of integrins to vitronectin and fibronectin [11].
• We have investigated the molecular basis of XTC-MIF-induced gastrulation-like movements by measuring rates of synthesis of fibronectin and of the integrin beta 1 chain in induced and control explants [5].
• The extracellular portion of the macrophage mannose receptor is composed of several cysteine-rich domains, including a fibronectin type II repeat and eight segments related in sequence to Ca(2+)-dependent carbohydrate-recognition domains (CRDs) of animal lectins [12].
• While these two sites are sufficient for cranial neural crest cell migration, we find that the second Heparin-binding domain of fibronectin can provide additional support for cranial neural crest cell migration in vitro [13].

Regulatory relationships of fibronectin

• The Wnt/Wg signal transducer beta-catenin controls fibronectin expression [4].
• In addition, Xbra appears to inhibit cell migration by inhibiting adhesion to fibronectin [14].

Other interactions of fibronectin

• The distribution of fibronectin and tenascin along migratory pathways of the neural crest in the trunk of amphibian embryos [15].
• In Xenopus, aggregates of mesodermal cells derived from embryos microinjected with alphaPIX significantly increased the peripheral spreading on fibronectin substrate in response to PDGF through PI3-kinase [16].
• Our results suggest that the activation of PKC and tyrosine kinase but not actin reorganization plays a role in the SSC potentiating action of fibronectin [17].
• The SSC frequency increased markedly right after a train stimulation, which was defined as post-train potentiation (PTrP), when the cultures were plated onto fibronectin substratum and chronically treated with brain-derived neurotrophic factor (BDNF) [17].
• The cDNA clone is 4179 bp long and encodes a putative transmembrane glycoprotein of 718 amino acids, containing 12 leucine-rich repeats followed by one C2-type immunoglobulin-like domain and one fibronectin type-III repeat [18].

Analytical, diagnostic and therapeutic context of fibronectin

• Multiple sequence alignment reveals that differences in the size of tenascin-W from various vertebrate classes can be explained by duplications of specific fibronectin type III domains [19].
• We determined the spatial localization of fibronectin in the embryo by immunofluorescence and the temporal program of its expression by biosynthesis studies and Western blotting techniques [1].
• Modulation of protein kinase A activation by fibronectin matrix proteins at developing neuromuscular synapses in Xenopus laevis cell cultures [20].
• Use of a colloidal gold probe for SEM immunocytochemistry has shown that fibrils observed by SEM contain fibronectin, probably as a major component [21].
• To find what bead action is responsible for this mimicry, we compared the effects of active and inert microbeads on Xenopus muscle cells developing in culture and on glass-adsorbed films of laminin or fibronectin [22].

References