Browsing by Author "Quiñones, V"

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    Identification of the RPS10 polypeptide encoded by the mitochondrial genome in Solanum tuberosum
    (2000) Zanlungo, S; Quiñones, V; Holuigue, L; Jordana, X
    We have previously reported the identification of a gene encoding ribosomal protein S10 (rps10) in the Solanum tuberosum mitochondrial genome and shown that its transcripts undergo processing in the form of splicing and editing. Specific antibodies were raised against recombinant potato RPS10 obtained in Escherichia call from the corresponding cDNA. Protein blot analysis revealed that the RPS10 polypeptide is present in potato mitochondria and is assembled into the mitochondrial ribosome. Potato rps10 mRNA translation may initiate at a genomic-encoded AUG codon, or at a downstream in-frame AUG codon which is created by RNA editing and coincides with liverwort and pea initiation codons. A peptide corresponding to the 19 amino acid sequence between both putative initiation codons was used to raise antibodies specific for the potato RPS10 N-terminal extension. These antibodies were able to recognise a polypeptide of 16 kDa in a potato mitochondrial fraction enriched in ribosomes. This molecular mass corresponds to that of the polypeptide detected with antibodies against recombinant RPS10 and is in agreement with the molecular weight calculated from the cDNA sequence. These results shelved that potato mitochondrial rps10 gene is expressed at the protein level and that translation initiates at the first genomic-encoded AUG codon. Potato RPS10 has an N-terminal extension of unknown function when compared to RPS10 from other organisms.
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    Peroxisome proliferator-activated receptor γ is a novel target of the nerve growth factor signaling pathway in PC12 cells
    (2005) Fuenzalida, KM; Aguilera, MC; Piderit, DG; Ramos, PC; Contador, D; Quiñones, V; Rigotti, A; Bronfman, FC; Bronfman, M
    Peroxisome proliferator- activated receptor gamma ( PPARgamma), a member of the nuclear receptor superfamily, is subject to considerable interest because of its role in adipocyte differentiation, metabolic control, and anti- inflammatory action. PPARgamma research in brain cells is presently focused on glial PPARgamma because of its potential as a pharmacological target in the treatment of neurodegenerative diseases with an inflammatory component. In neurons PPARgamma function is far from clear, and PPARgamma agonist-dependent and -independent effects on cell survival or differentiation have been reported. We used PC12 cells, widely used to study neuronal signaling, such as nerve growth factor (NGF)-induced differentiation and survival or epidermal growth factor-dependent cell proliferation to dissect the possible involvement of PPARgamma in these pathways. We show that NGF but not epidermal growth factor increases the transcriptional activity of PPARgamma, and modulates the expression of this transcription factor. Because NGF signals through the tyrosine kinase (TrkA) NGF receptor and/ or the p75(NTR) receptor, we used rescue experiments with a PC12 cell mutant lacking TrkA to show that NGF- induced PPARgamma activation is dependent on TrkA activation. Our results point out PPARgamma as a novel target of the TrkA-mediated neuronal cell survival and differentiating pathway and suggest a potential new inflammatory-independent therapeutic approach for pharmacological intervention in neurological disorders.