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Biomedical subjects

Luciana Dente

Publications and source records attributed to Luciana Dente.

6 recordsLinked to original sources
PubMed2006

Dystroglycan is required for proper retinal layering.

Dystroglycan (DG) is a transmembrane receptor linking the extracellular matrix to the internal cytoskeleton. Its structural function has been mainly characterized in muscle fibers, but DG plays signaling and developmental roles also in different tissues and cell types. We have investigated the effects of dystroglycan depletion during eye development of Xenopus laevis. We have injected a specific morpholino (Mo) antisense oligonucleotide in the animal pole of one dorsal blastomere of embryos at four cells stage. Mo-mediated loss of DG function caused disruption of the basal lamina layers, increased apoptosis and reduction of the expression domains of specific retinal markers, at early stages. Later in development, morphants displayed unilateral ocular malformations, such as microphtalmia and retinal delayering with photoreceptors and ganglion cells scattered throughout the retina or aggregated in rosette-like structures. These results recall the phenotypes observed in specific human diseases and suggest that DG presence is crucial at early stages for the organization of retinal architecture.

Animals↗
PubMed2005

Redox-regulated affinity of the third PDZ domain in the phosphotyrosine phosphatase PTP-BL for cysteine-containing target peptides.

PDZ domains are protein-protein interaction modules that are crucial for the assembly of structural and signalling complexes. They specifically bind to short C-terminal peptides and occasionally to internal sequences that structurally resemble such peptide termini. The binding of PDZ domains is dominated by the residues at the P(0) and P(-2) position within these C-terminal targets, but other residues are also important in determining specificity. In this study, we analysed the binding specificity of the third PDZ domain of protein tyrosine phosphatase BAS-like (PTP-BL) using a C-terminal combinatorial peptide phage library. Binding of PDZ3 to C-termini is preferentially governed by two cysteine residues at the P(-1) and P(-4) position and a valine residue at the P(0) position. Interestingly, we found that this binding is lost upon addition of the reducing agent dithiothrietol, indicating that the interaction is disulfide-bridge-dependent. Site-directed mutagenesis of the single cysteine residue in PDZ3 revealed that this bridge formation does not occur intermolecularly, between peptide and PDZ3 domain, but rather is intramolecular. These data point to a preference of PTP-BL PDZ3 for cyclic C-terminal targets, which may suggest a redox state-sensing role at the cell cortex.

Amino Acid Motifs↗
PubMed2002

In vitro evolution of recognition specificity mediated by SH3 domains reveals target recognition rules.

We have designed a repertoire of 10(7) different SH3 domains by grafting the residues that are represented in the binding surfaces of natural SH3 domains onto the scaffold of the human Abl-SH3 domain. This phage-displayed library was screened by affinity selection for SH3 domains that bind to the synthetic peptides, APTYPPPLPP and LSSRPLPTLPSP, which are peptide ligands for the human Abl or Src SH3 domains, respectively. By characterizing the isolates, we have observed that as few as two or three amino acid substitutions lead to dramatic changes in recognition specificity. We propose that the ability to shift recognition specificity with a small number of amino acid replacements is an important evolutionary characteristic of protein binding modules. Furthermore, we have used the information obtained by these in vitro evolution experiments to generate a scoring matrix that evaluates the probability that any SH3 domain binds to the peptide ligands for the Abl and Src SH3 domains. A table of predictions for the 28 SH3 domains of baker's yeast is presented.

Algorithms↗
PubMed2002

Molecular cloning and expression analysis of dystroglycan during Xenopus laevis embryogenesis.

Dystroglycan is a transmembrane receptor protein that provides a structural linkage between extracellular matrix components and cytoskeletal proteins. It was originally characterized as a member of dystrophin associated protein complex in muscle but, unlike other proteins of this complex, mutations in the dystroglycan gene have not been implicated as a cause of muscular dystrophies. Indeed, dystroglycan is an essential gene, expressed early in development that, if removed in knockout mice, provokes lethal defects before the onset of myogenesis. Dystroglycan is synthesized as a precursor propeptide that is post-translationally cleaved and glycosylated to yield alpha and beta subunits. We have cloned and characterized a cDNA clone, containing the complete coding region of the dystroglycan precursor, from a Xenopus laevis cDNA library. We have performed a spatial and temporal analysis of its expression in X. laevis embryos, using whole-mount in situ hybridization and reverse transcription-polymerase chain reaction analysis. Early expression of dystroglycan in a variety of tissues of different embryological derivation suggests a crucial role in morphogenetic events, especially during central nervous system differentiation.

Amino Acid Sequence↗
PubMed2002

Molecular cloning and expression analysis of dystroglycan during Xenopus laevis embryogenesis.

Dystroglycan is a transmembrane receptor protein that provides a structural linkage between extracellular matrix components and cytoskeletal proteins. It was originally characterized as a member of dystrophin associated protein complex in muscle but, unlike other proteins of this complex, mutations in the dystroglycan gene have not been implicated as a cause of muscular dystrophies. Indeed, dystroglycan is an essential gene, expressed early in development that, if removed in knockout mice, provokes lethal defects before the onset of myogenesis. Dystroglycan is synthesized as a precursor propeptide that is post-translationally cleaved and glycosylated to yield alpha and beta subunits. We have cloned and characterized a cDNA clone, containing the complete coding region of the dystroglycan precursor, from a Xenopus laevis cDNA library. We have performed a spatial and temporal analysis of its expression in X. laevis embryos, using whole-mount in situ hybridization and reverse transcription-polymerase chain reaction analysis. Early expression of dystroglycan in a variety of tissues of different embryological derivation suggests a crucial role in morphogenetic events, especially during central nervous system differentiation.

Animals↗