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Biomedical subjects

C Chaperon

Publications and source records attributed to C Chaperon.

10 recordsLinked to original sources
PubMed2000

Syntaxin 13 is a developmentally regulated SNARE involved in neurite outgrowth and endosomal trafficking.

In addition to its role in exocytosis, SNAP-25 is essential for axonal outgrowth. In order to identify SNARE proteins involved in neurite growth we have used SNAP-25 antibodies to affinity-purify protein complexes enriched in developing rat brain membrane extracts. We have identified a complex between SNAP-25 and syntaxin 13 predominantly present in brain at embryonic or early postnatal stages. We show that syntaxin 13 is developmentally regulated with a decrease in adult brain. In differentiated neuroendocrine PC12 cells as well as primary cortical neurons the protein is localized to a punctated and tubular staining in the perinuclear region and along processes with high levels in the central region of growth cones. Carboxy-terminally tagged syntaxin 13 was also detected on the plasma membrane by in vivo surface-labelling where it colocalized with SNAP-25. Syntaxin 13 has recently been shown to be implicated in early endosomal trafficking. In our study, colocalization with internalized transferrin in the cell body and along neurites confirmed endosomal location in both compartments. Finally, overexpression of full-length syntaxin 13 enhanced neurite outgrowth in NGF-stimulated PC12 cells, whilst it had no effect on regulated secretion. The data suggest that a syntaxin 13-dependent endocytic trafficking step plays a limiting role in membrane expansion during neuronal development.

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PubMed1998

Inhibition of the cAMP-dependent protein kinase by synthetic A-helix peptides.

The catalytic subunit of the cAMP-dependent protein kinase from Dictyostelium discoideum, PkaC, displays the same properties as its mammalian counterpart, except for being about twice as large in size. Sequence comparisons indicated the presence of a conserved alpha-helix (A-helix) within the N-terminal region of PkaC which could potentially establish close contacts with the catalytic core [Véron, M., et al. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 10618-10622]. We show in this report that a synthetic peptide with the A-helix sequence inhibits PKA activity, whereas unrelated peptides display no inhibitory activity. The inhibition seems competitive with respect to the kemptide substrate rather than due to binding to a secondary site. We further show by amino acid replacements that the last lysine of the A-helix sequence is involved in this specific inhibition. A model is proposed for the possible role of the A-helix.

Amino Acid Sequence↗
PubMed1983

[Results of 10 years of deafness screening and diagnosis in children and its implications. Early education of the young deaf child].

In ten years, we have tested more than 1 200 children of 0 to 4 years in this way: at birth, within the maternity hospital, and then at 2, 6 and 9 months-old, doubtful cases with the Veit-Bizaguet audiometer and also Mrs Borel-Maisonny's sound toys: we have thus obtained the child's hearing test. Later on, according to age, we use R.O.C.--Peep-Show, tonal audiometry, and vocal audiometry with pictures. We also resort to objective means: systematically, tympanometry and Stape Reflex, and in difficult, doubtful cases, psychomotor retardation and autistic behaviour, we make B.E.R.A. We also search for hereditary, iatrogen and meningitic deafness. Such screening methods, at an early stage, to trace down severe and profound deafness enabled a demutization and early education of deaf children who will be equipped with stereophonic hearing aids; we use only an oral method with some cued speech. The children will thus be given a good school and social integration within the world of normal people. Then the children are in possession of a more structural language, of a voice of better quality and can develop all their abilities.

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