Papers by Luis Franco Vera
PLOS ONE, 2015
KRAS mutational status is considered a negative predictive marker of the response to anti-EGFR th... more KRAS mutational status is considered a negative predictive marker of the response to anti-EGFR therapies in colorectal cancer (CRC) patients. However, conflicting data exist regarding the variable response to EGFR-targeted therapy. The effects of oncogenic KRAS on downstream targets were studied in cell lines with different KRAS mutations. Cells harboring a single KRAS G13D allele showed the most tumorigenic profile, with constitutive activation of the downstream pathway, rendering them EGF-unresponsive. Conversely, KRAS A146T cells showed a full EGF-response in terms of signal transduction pathways, cell proliferation, migration or adhesion. Moreover, the global acetylome of CRC cells was also dependent on KRAS mutational status. Several hnRNP family members were identified within the 36 acetylated-proteins. Acetylation status is known to be involved in the modulation of EGFresponse. In agreement with results presented herein, hnRNPA1 and L acetylation was induced in response to EGF in KRAS A146T cells, whereas acetyl-hnRNPA1 and L levels remained unchanged after growth factor treatment in KRAS G13D unresponsive cells. Our results showed that hnRNPs induced-acetylation is dependent on KRAS mutational status. Nevertheless hnRNPs acetylation might also be the point where different oncogenic pathways converge.
Journal of Biological Chemistry, 2006
Nuclear events such as chromatin condensation, DNA cleavage at internucleosomal sites, and histon... more Nuclear events such as chromatin condensation, DNA cleavage at internucleosomal sites, and histone release from chromatin are recognized as hallmarks of apoptosis. However, there is no complete understanding of the molecular events underlying these changes. It is likely that epigenetic changes such as DNA methylation and histone modifications that are involved in chromatin dynamics and structure are also involved in the nuclear events described. In this report we have shown that apoptosis is associated with global DNA hypomethylation and histone deacetylation events in leukemia cells. Most importantly, we have observed a particular epigenetic signature for early apoptosis defined by a release of hypoacetylated and trimethylated histone H4 and internucleosomal fragmented DNA that is hypermethylated and originates from perinuclear heterochromatin. These findings provide one of the first links between apoptotic nuclear events and epigenetic markers. Apoptosis is a form of cell death essential for the morphogenesis, development, differentiation, and homeostasis of eukaryotic multicellular organisms. The activation of a genetically controlled cell death program leading to apoptosis results in characteristic biochemical and morphological features that take place both outside and inside the nucleus (1). The biochemical mechanisms responsible for key nuclear events, such as chromatin condensation, DNA fragmentation, and release of nuclear proteins, although commonly used as markers for apoptosis, are not fully understood (2). The regulated nature of apoptosis makes it likely that nuclear changes experienced by apoptotic cells are mediated by epigenetic markers. This epigenetic information is basically stored as DNA methylation and post-translational histone modifications. These two groups of modifications play an active role in organizing, compartmentalizing, and regulating genetic information encoded in DNA by defining nuclear architecture, and gene expression (3). With regard to gene regulation, the major functional consequence of DNA methylation is the repression of transcription (4). In the case of
Journal of Biological Chemistry, 2003
FEBS Letters, 1993
Core histones can be modified by reversible, posttranslational acetylation of specific lysine res... more Core histones can be modified by reversible, posttranslational acetylation of specific lysine residues within the N‐terminal protein domains. The dynamic equilibrium of acetylation is maintained by two enzyme activities, histone acetyltransferase and histone deacetylase. Recent data on histone deacetylases and on anionic motifs in chromatin‐ or DNA‐binding regulatory proteins (e.g. transcription factors, nuclear proto‐oncogenes) are summarized and united into a hypothesis which attributes a key function to histone deacetylation for the binding of regulatory proteins to chromatin by a transient, specific local increase of the positive charge in the N‐terminal domains of nucleosomal core histones. According to our model, the rapid deacetylation of distinct lysines in especially H2A and H2B would facilitate the association of anionic protein domains of regulatory proteins to specific nucleosomes. Therefore histone deacetylation (histone deacetylases) may represent a unique regulatory m...
FEBS Letters, 1985
Histone acetyltransferase B activity has been found in pea (Pisun sativum) seedlings. The enzyme ... more Histone acetyltransferase B activity has been found in pea (Pisun sativum) seedlings. The enzyme has been partially purified and it has been found that it is highly specific for H4. The results confirm that histone acetyltransferase B occurs in 3 eukaryotic kingdoms.
FEBS Letters, 1986
A method, termed ‘sliding‐end‐labelling’, has been devised to avoid a frequent artifact in nucleo... more A method, termed ‘sliding‐end‐labelling’, has been devised to avoid a frequent artifact in nucleosome positioning by indirect end labelling, namely the appearing of DNA fragments originated by two nuclease cuts, one of them lying within the region covered by the probe. The method is applied to the nucleosome positioning in the yeast SUC2 gene for invertase.
High mobility group non-histone chromosomal proteins from chicken erythrocytes
Biochemical and Biophysical Research Communications, 1978
ABSTRACT
Journal of Biological Chemistry, 1983
Prrnted m U S.A.
Epigenetic Transcriptional Regulation of the Growth Arrest-Specific gene 1 (Gas1) in Hepatic Cell Proliferation at Mononucleosomal Resolution
PLoS ONE, 2011
Nucleic Acids Research, 1978
A method for large scale isolation of a native deoxyribonucleohistone complex from yeast is descr... more A method for large scale isolation of a native deoxyribonucleohistone complex from yeast is described. Crude chromatin, obtained after disrupting yeast cells at low ionic strength, contains a large amount of lipids, partially due to contaminating membranes. Most of them are removed by a Triton X-100 treatment, followed by step-gradient centrifugation. About 90% of the pellet may be solubilized by mild procedures, the composition of the soluble material being: hlstone/DNA = 1.0; nonhistone proteins/DNA = 0.55; RNA/DNA = 0.18. Histones can be obtained with high purity. Micrococcal nuclease digests DNA to yield a series of oligomeric fragments, with an average repeat length of about 160 base pairs. Circular dichroism spectra show that (3)270 is reduced by about 30% when compared to pure DNA and that chromosomal proteins are not denatured. These results indicate that the components of the complex conserve the native state.
Nucleic Acids Research, 1987
Fine analysis of the chromatin structure of the yeast SUC2 gene and of its changes upon Fine anal... more Fine analysis of the chromatin structure of the yeast SUC2 gene and of its changes upon Fine analysis of the chromatin structure of the yeast SUC2 gene and of its changes upon derepression. Comparison between the chromosomal and plasmid-inserted genes
The International Journal of Biochemistry & Cell Biology, 2000
Methionine adenosyltransferase (MAT) catalyzes the biosynthesis of S-adenosylmethionine (AdoMet).... more Methionine adenosyltransferase (MAT) catalyzes the biosynthesis of S-adenosylmethionine (AdoMet). In mammals MAT activity derives from two separate genes which display a tissue-speci®c pattern of expression. While MAT1A is expressed only in the adult liver, MAT2A is expressed in non-hepatic tissues. The mechanisms behind the selective expression of these two genes are not fully understood. In the present report we have evaluated MAT1A and MAT2A methylation in liver and in other tissues, such as kidney, by methylationsensitive restriction enzyme digestion of genomic DNA. Our data indicate that MAT1A is hypomethylated in liver and hypermethylated in non-expressing tissues. The opposite situation is found for MAT2A. Additionally, histones associated to MAT1A and MAT2A genes showed enhanced levels of acetylation in expressing tissues (two-fold for MAT1A and 3.5-fold for MAT2A liver and kidney respectively). These observations support a role for chromatin structure and its modi®cation in the tissue-speci®c expression of both MAT genes.
Glutamate cysteine ligase up-regulation fails in necrotizing pancreatitis
Free Radical Biology and Medicine, 2008
Glutathione depletion is a key factor in the development of acute pancreatitis. Our aim was to st... more Glutathione depletion is a key factor in the development of acute pancreatitis. Our aim was to study the regulation of glutamate cysteine ligase, the rate-limiting enzyme in glutathione synthesis, in edematous or necrotizing pancreatitis in rats. Glutathione levels were kept low in necrotizing pancreatitis for several hours, with no increase in protein or mRNA levels of glutamate cysteine ligase subunits, despite binding of RNA polymerase II to their promoters and coding regions. The survival signal pathway mediated by ERK and c-MYC was activated, and c-MYC was recruited to the promoters. The failure in gene up-regulation seems to be due to a marked increase in cytosolic ribonuclease activity. In contrast, in edematous pancreatitis glutathione levels were depleted and rapidly restored, and protein and mRNA expression of glutamate cysteine ligase increased markedly due to enhanced transcription mediated by recruitment of c-MYC, NF-kappaB, and SP-1 to the promoters. No increase in cytosolic ribonuclease activity was found in this case. We propose a novel pathophysiological mechanism to differentiate necrotizing from edematous pancreatitis, which is the inefficient up-regulation of glutamate cysteine ligase caused by increased cytosolic ribonuclease activity in the severe form of the disease. This mechanism would abrogate a rapid recovery of glutathione levels.
Biochemistry, 1980
A peptide containing the globular region of the histone H1 from the fruit fly Ceratitis capitata ... more A peptide containing the globular region of the histone H1 from the fruit fly Ceratitis capitata has been isolated after limited tryptic digestion of insect H1. The composition of this trypsin-resistant core resembles that of the homologous peptide from calf thymus H1, although the insect H I core possesses one cysteine, two tyrosines, one histidine, and more isoleucine and less glycine and leucine than the calf thymus H 1 core. Circular dichroism measurements indicate that all the fragments that possess an ordered secondary
Nucleic Acids Research, 2004
We describe a procedure, RNAPol-ChIP, to measure actual transcriptional rate. It consists of the ... more We describe a procedure, RNAPol-ChIP, to measure actual transcriptional rate. It consists of the detection, by chromatin immunoprecipitation (ChIP), of RNA polymerase II within the coding region of genes. To do this, the DNA immunoprecipitated with polymerase antibodies is analysed by PCR, using an amplicon well within the coding region of the desired genes to avoid interferences with polymerase paused at the promoter. To validate RNAPol-ChIP, we compare our results to those obtained by classical methods in several genes induced during either liver regeneration or acute pancreatitis. When short half-life mRNA genes are studied (e.g. c-fos and egr1), RNAPol-ChIP gives results similar to those of other procedures. However, in genes whose mRNA is more stable (e.g. the hemopexin, hpx, gene) RNAPol-ChIP informs on real-time transcription with results comparable to those of methods such as nuclear run-on or runoff , which require the isolation of highly purified nuclei. Moreover, RNAPol-ChIP advantageously compares with methods based on the analysis of steady-state mRNA (northern blot or RT-PCR). Additional advantages of RNAPol-ChIP, such as the possibility of combining it with classical ChIP analysis to study transcriptionassociated changes in chromatin are discussed.
Estética, creatividad y ciencia
ha lle v a d o a cabo en lo s l a b o r a t o r i e s d e l D ep artam en to de B loquxm ica de l... more ha lle v a d o a cabo en lo s l a b o r a t o r i e s d e l D ep artam en to de B loquxm ica de l a F a c u lta d de C ie n c ia s de l a U n iv e rs id a d de M ad rid , b a jo l a d i r e cc io n d e l P r o f . D r. D. A ngel M a rtin M u n icio . A e l v a d i r ^ g id o , en p rim e r l u g a r , mi a g ra d e c im ie n to p o r s u s v a l io s o s c o n s e jo s y e n s e n a n z a s , que b an s u p u e s to mucho mas que l a s im p le r e a l i z a c i o n de e s t e t r a b a j o . Deseo ta m b ien m a n if e s ta r mi g r a t i t u d a to d o s m is com paneros d e l D ep artam en to de B io q u im ica p o r e l apoyo que sie m p re h e e n c o n tra d o en e l l o s . F in a lm e n te , me e s muy g r a to h a c e r c o n s ta r mi agradja c im ie n to a l P a tr o n a to J u a n de l a C ie rv a d e l C .S .I .C . y a l a F u n d acio n J u a n March p o r l a ayuda econom ica p r e s t a d a . M ad rid , Enero de 1971 1 . 4 .1 1 .1 . Genes r e g u la d o r e s .
Aislamiento y caracterización parcial de una proteína específica de embriones asociada a la cromatina de guisante
La historia sobre la organizacion del material genetico de eucariotas comienza a finales del sigl... more La historia sobre la organizacion del material genetico de eucariotas comienza a finales del siglo XIX. La investigacion se realizo en dos frentes separados que solo llegaron a reunirse a mediados del siglo XX. Esos dos frentes se podrian denominar como la “linea celular”, consecuencia fundamentalmente de observaciones microscopicas, y la “linea molecular”, en la que quimicos y fisiologos se esforzaron por conocer la naturaleza quimica de los materiales implicados en la herencia biologica.
¿La Epigenética? ¡Pero si también es química!
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Papers by Luis Franco Vera