Biomedical subjects

Cecilia Saccone

Publications and source records attributed to Cecilia Saccone.

At least 19 recordsLinked to original sources

PubMed2006

The fatty acid synthase gene is a conserved p53 family target from worm to human.

The discovery that the p53 family consists of three members (p53, p63 and p73) in vertebrates and of a single homolog in invertebrates has raised the challenge of understanding the functions of the ancestor and how they have evolved and differentiated within the duplicated genes in vertebrates. Here, we report that the fatty acid synthase (FAS) gene, encoding for a key enzyme involved in the biogenesis of membrane lipids in rapidly proliferating cells, is a conserved target of the p53 family throughout the evolution. We show that CEP-1, the C. elegans p53 homolog, is able to bind the two p53 family responsive elements (REs) identified in the worm fasn-1 gene. Moreover, we demonstrate that fasn-1 expression is modulated by CEP-1 in vivo, by comparing wild-type and CEP-1 knockout worms. In human, luciferase and chromatin immunoprecipitation assays demonstrate that TAp73alpha and DeltaNp63alpha, but not p53, TAp73beta and TAp63alpha bind the two p53 REs of the human FASN gene. We show that the ectopic expression of TAp73alpha and DeltaNp63alpha leads to an increase of FASN mRNA levels, while their silencing produces a decrease of FASN expression. Furthermore, we present data showing a correlation between DeltaNp63alpha and FASN expression in cellular proliferation. Of relevant importance is that fasn-1 is the first CEP-1 direct target gene identified so far in C. elegans and our results suggest a new CEP-1 role in cellular proliferation and development, besides the one already described in apoptosis of germ cells. These data confirm the hypothesis that the ancestral functions of the single invertebrate gene may have been spread out among the three vertebrate members, each of them have acquired specific role in cell cycle regulation.

Animals↗

PubMed2006

Evolution of ATP synthase subunit c and cytochrome c gene families in selected Metazoan classes.

To investigate the integrated evolution of mitochondrial and nuclear genomes in the eukaryotic cell, we have focused our attention on OXPHOS (oxidative phosphorylation) gene families which encode proteins involved in the main mitochondrial function. The present study reports the phylogenetic analysis of two OXPHOS gene families: ATP synthase subunit c (or lipid binding protein, LBP) and Cytochrome c (Cytc). Both gene families possess a higher expansion trend than the typically low duplication rate of OXPHOS genes in Metazoa, but follow a completely different evolutionary history, especially in mammals. LBP is represented by three well conserved isoforms in all mammals (P1, P2, P3): only P3 possesses a clearly conserved isoform in all Vertebrates, P1 and P2 were already present before the bird-mammal divergence and there are preliminary evidence from the in silico analysis that P1, the most evolutionary divergent isoform, is poorly expressed and not regulated by NRF1. In contrast, Cytc family presents at least two duplicated genes in all the analysed Vertebrates, is subject to a high expansion trend, especially of processed pseudogenes in mammals, and some events of gain and loss of function can be supposed.

Animals↗

PubMed2006

MitoRes: a resource of nuclear-encoded mitochondrial genes and their products in Metazoa.

BACKGROUND: Mitochondria are sub-cellular organelles that have a central role in energy production and in other metabolic pathways of all eukaryotic respiring cells. In the last few years, with more and more genomes being sequenced, a huge amount of data has been generated providing an unprecedented opportunity to use the comparative analysis approach in studies of evolution and functional genomics with the aim of shedding light on molecular mechanisms regulating mitochondrial biogenesis and metabolism. In this context, the problem of the optimal extraction of representative datasets of genomic and proteomic data assumes a crucial importance. Specialised resources for nuclear-encoded mitochondria-related proteins already exist; however, no mitochondrial database is currently available with the same features of MitoRes, which is an update of the MitoNuc database extensively modified in its structure, data sources and graphical interface. It contains data on nuclear-encoded mitochondria-related products for any metazoan species for which this type of data is available and also provides comprehensive sequence datasets (gene, transcript and protein) as well as useful tools for their extraction and export. DESCRIPTION: MitoRes http://www2.ba.itb.cnr.it/MitoRes/ consolidates information from publicly external sources and automatically annotates them into a relational database. Additionally, it also clusters proteins on the basis of their sequence similarity and interconnects them with genomic data. The search engine and sequence management tools allow the query/retrieval of the database content and the extraction and export of sequences (gene, transcript, protein) and related sub-sequences (intron, exon, UTR, CDS, signal peptide and gene flanking regions) ready to be used for in silico analysis. CONCLUSION: The tool we describe here has been developed to support lab scientists and bioinformaticians alike in the characterization of molecular features and evolution of mitochondrial targeting sequences. The way it provides for the retrieval and extraction of sequences allows the user to overcome the obstacles encountered in the integrative use of different bioinformatic resources and the completeness of the sequence collection allows intra- and interspecies comparison at different biological levels (gene, transcript and protein).

Animals↗

PubMed2005

Evolution of nuclearly encoded mitochondrial genes in Metazoa.

All Metazoan nuclear genomes underwent a continuous process of both complete and partial genetic material gain and loss. The forces modulating these events are also subject to the strict interaction between nuclear and mitochondrial (mt) genome. In this context we investigate the evolution of nuclear genes encoding proteins which target the mitochondrion, with a particular attention to genes involved in oxidative phosphorylation (OXPHOS), one of the most ancient and conserved functions. To examine thoroughly the evolutionary strategies that preserve OXPHOS and coordinate the two cellular genomes, a comparative analysis has been carried out for 78 OXPHOS gene families in several Metazoa (insects, tunicates, fishes and mammals). We demonstrate that the duplication rate of OXPHOS genes increases passing from invertebrates to vertebrates consistently with the total increase in genome size, but all species are prone to negatively select OXPHOS duplicates compared to the general trend of nuclear gene families. These results are consistent with the 'balance hypothesis' and, at least in insects, the expression of duplicate genes is low and strongly testis-biased.

Animals↗

PubMed2005

UTRdb and UTRsite: a collection of sequences and regulatory motifs of the untranslated regions of eukaryotic mRNAs.

The 5' and 3' untranslated regions of eukaryotic mRNAs play crucial roles in the post-transcriptional regulation of gene expression through the modulation of nucleo-cytoplasmic mRNA transport, translation efficiency, subcellular localization and message stability. UTRdb is a curated database of 5' and 3' untranslated sequences of eukaryotic mRNAs, derived from several sources of primary data. Experimentally validated functional motifs are annotated (and also collated as the UTRsite database) and cross-links to genomic and protein data are provided. The integration of UTRdb with genomic and protein data has allowed the implementation of a powerful retrieval resource for the selection and extraction of UTR subsets based on their genomic coordinates and/or features of the protein encoded by the relevant mRNA (e.g. GO term, PFAM domain, etc.). All internet resources implemented for retrieval and functional analysis of 5' and 3' untranslated regions of eukaryotic mRNAs are accessible at http://www.ba.itb.cnr.it/UTR/.

3' Untranslated Regions↗

PubMed2004

DNAfan: a software tool for automated extraction and analysis of user-defined sequence regions.

SUMMARY: DNAfan (DNA Feature ANalyzer) is a tool combining sequence-filtering and pattern searching. DNAfan automatically extracts user-defined sets of sequence fragments from large sequence sets. Fragments are defined by annotated gene feature keys and co- or non-occurring patterns within the feature or close to it. A gene feature parser and a pattern-based filter tool localizes and extracts the specific subset of sequences. The selected sequence data can subsequently be retrieved for analyses or further processed with DNAfan to find the occurrence of specific patterns or structural motifs. DNAfan is a powerful tool for pattern analysis. Its filter features restricts the pattern search to a well-defined set of sequences, allowing drastic reduction in false positive hits. AVAILABILITY: http://bighost.ba.itb.cnr.it:8080/Framework.

Algorithms↗

PubMed2004

The evolution of the adenine nucleotide translocase family.

Homologous genes are grouped into families whose evolution may be different in the various organisms. For the variety of the processes and the well-known mechanism of gene gain and gene loss, which takes place in genome evolution, we deal in comparative analyses with a "one-to-many" or a "many-to-many" relationship between homologous genes going from invertebrates to vertebrates. In this scenario, it is important to understand how gene function has been preserved and in addition the innovations originated in a given lineage or species. The phylogenetic relations between gene family members and their molecular clock behavior may be very helpful to elucidate their functional fates in various organisms. This in turn can direct laboratory experiments and practical applications. In order to track the evolutionary history of the ANT gene family, we have collected and analyzed 46 sequences from fungi to mammals. Phylogenetic analyses have been performed on nucleotide and amino acidic sequences which have produced basically the same results. We observe the presence of multiple isoforms both in lower and higher eukaryotic species, thus a "many-to-many" correspondence between genes. The molecular phylogeny of ANT genes, reported in the present study, allows to date the time of divergence of ANT isoforms in various lineages. Furthermore, the logo analysis has been carried out to characterize the conservation features of ANT proteins particularly in their three similar domains originated by duplication.

Amino Acid Sequence↗

PubMed2004

Comparative genomics: the evolutionary history of the Bcl-2 family.

The Bcl-2 family is a huge family composed of various members, occurring in all animals, which are key regulators of apoptosis, the cell death program critical for cell survival and development, tissue homeostasis, and protection against pathogens. The members of the Bcl-2 family can be divided into pro-apoptotic and anti-apoptotic proteins. A delicate balance between these members exists in each cell and the regulations of these two groups of proteins determines whether the cell survives or undergoes apoptosis. Bcl-2 family proteins are characterized by distinct domains. All members possess at least one of the four motifs known as Bcl-2 homology domains (BH1 to BH4). Most pro-survival members which can inhibit apoptosis facing a wide variety of cytotoxic insults, contain at least BH1 and BH2 domains; those most similar to Bcl-2 have all four BH domains. All the pro-apoptosis family members possess BH3 domain which is the central domain. For the first time, a global phylogenetic analysis of all Bcl-2 family members is presented here. We have analyzed the genes known so far that have a different composition of the functional domains BH1, BH2, BH3 and BH4. The analyses were performed both on complete sequences (124 sites analyzed) and on single domains. We present the results obtained using both approaches. We have also analyzed the amino acid profile and the degree of conservation of the BH3 domains of pro- and anti-apoptotic proteins. The results of our phylogenetic analyses show that a clear-cut clustering into pro- and anti-apoptotic products, reproducible with different evolutionary methods, could also be obtained by analyzing restricted areas such as the BH1 and BH2 domains. It is noteworthy that even when the analysis is performed only on the BH3 domain, we have two clear-cut clusters. The evolutionary analysis of gene family members is a valuable tool to predict their functions and guide experimental assays to validate predictions. Once the functions of all the components are known, it will be possible to study the process in a holistic way.

Amino Acid Sequence↗

PubMed2004

Pseudogenes in metazoa: origin and features.

The complete genome sequences with their annotations are a considerable resource in biology, particularly in understanding the global structure of the genetic material at the molecular level. The reason why some eukaryotic genomes contain large quantities of apparently unnecessary DNA, namely pseudogenes, while others seem to invest in more efficient thinning processes or are equipped with protection systems against parasitic elements still remains a mystery. Several genome-wide surveys have been undertaken to identify pseudogenes in the completely sequenced genome, bringing to light some differences both in their amount and distribution. Since pseudogenes are important resources in evolutionary and comparative genomics - as 'molecular fossils' - in this paper, a survey on the origins, features, abundance and localisation of the different pseudogenes is reported. As an example of genes producing processed pseudogenes, some experimental data obtained in the authors' laboratories from the study of a nuclear gene coding for the mitochondrial transcription factor A (mtTFA), a key regulator of mitochondrial biogenesis, are also reported.

Animals↗

PubMed2003

Congruent mammalian trees from mitochondrial and nuclear genes using Bayesian methods.

Analyses of mitochondrial and nuclear gene sequences have often produced different mammalian tree topologies, undermining confidence in the merit of molecular approaches with respect to "traditional" morphological classification. The recent sequencing of the complete mitochondrial genomes of two additional rodents (Spalax judaei and Jaculus jaculus) and one lagomorph (Ochotona princeps) has prompted us to reinvestigate the issue. Using Bayesian phylogenetics, we found phylogenetic relationships between mammalian species highly congruent with previous results based on nuclear genes. Our results show the existence of four primary lineages of placental mammals: Xenarthra, Afrotheria, Laurasiatheria, and Euarchontoglires. Relationships between and within these lineages strongly suggest that the gene trees may also be congruent with the underlying species phylogeny.

Animals↗

PubMed2003

Adenosine deaminase, a key enzyme in DNA precursors control, is a new p73 target.

The discovery of the p73 and p63 genes, homologous to p53 tumor suppressor has uncovered a family of transcription factors and widened the scenario of cell cycle control and apoptosis. We have identified a putative p53-responsive element in the human adenosine deaminase (ADA) gene, an important enzyme involved in nucleotide metabolism, the deficit of which causes the inhibition of DNA synthesis and repair. Here, we demonstrate that the ectopic expression of p73 isoforms leads to the ADA gene upregulation, showing for the first time a correlation between p73 and ADA. We found that p73 promotes ADA gene expression following a dNTP unbalance generated by ADA enzyme deficiency and 2'deoxyadenosine accumulation. The abrogation of p73 transcriptional activity by the specific dominant-negative p73DD abolishes ADA induction. By contrast, the ADA gene does not appear to be a functional p53 target in the physiological conditions we tested. On the whole, our results contribute to the emerging picture that p73 could play a different role from p53 in normal growth and development by inducing alternative target genes, which are not shared by p53.

Adenosine Deaminase↗

PubMed2003

DNA sequence variation in the mitochondrial control region of subterranean mole rats, Spalax ehrenbergi superspecies, in Israel.

The complete mitochondrial control region was sequenced for 60 individuals representing different populations for each of the four species of the subterranean mole rat Spalax ehrenbergi superspecies in Israel: Spalax galili (2n = 52), S. golani (2n = 54), S. carmeli (2n = 58), and S. judaei (2n = 60). The control region of all species and populations is very similar both in length (979 to 983 bp) and in base composition. As in agreement with previous surveys on mitochondrial control regions on mammals, the mole rat control region can be divided into a central domain and two flanking domains, ETAS (extended termination associated sequences) and CSB (conserved sequence blocks). Along with the common conserved blocks found in these domains (ETAS1, ETAS2, CSB1, CSB2, and CSB3), we have also detected in all individuals an ETAS1-like and a CSB1-like element, both in the ETAS domain. The most conserved region was the central domain, followed by the CSB and ETAS domains, showing important differences in the four species analyzed. Phylogenetic analysis supported the existence of two clades. One clade contained individuals belonging to Spalax galili (2n = 52) and S. golani (2n = 54), separated in two different branches depending on the species. The other clade contained individuals belonging to S. carmeli (2n = 58) and S. judaei (2n = 60) mixed together, suggesting a more recent event of speciation. Within species we have observed a southward trend of increasing variability. These results have been explained as a consequence of the adaptation of the species to ecological factors such as aridity and temperature stresses.

Animals↗

PubMed2003

Molecular clock and gene function.

Molecular phylogenies based on the molecular clock require the comparison of orthologous genes. Orthologous and paralogous genes usually have very different evolutionary fates. In general, orthologs keep the same functions in species, whereas, particularly over a long time span, paralogs diverge functionally and may become pseudogenes or get lost. In eukaryotic genomes, because of the degree of redundancy of genetic information, homologous genes are grouped in gene families, the evolution of which may differ greatly between the various organisms. This implies that each gene in a species does not always have an ortholog in another species and thus, due to multiple duplication events following a speciation, many orthologous clades of paralogs are generated. We are often dealing with a one-to-many or many-to-many relationship between genes. In this paper, we analyze the evolution of two gene families, the p53 gene family and the porin gene family. The evolution of the p53 family shows a one-to-many gene relationship going from invertebrates to vertebrates. In invertebrates only a single gene has been found, while in vertebrates three members of the family, namely p53, p63, and p73, are present. The evolution of porin (VDAC) genes (VDAC1, VDAC2, and VDAC3) is an example of a many-to-many gene relationship going from yeast to mammals. However, the porin gene redundancy found in invertebrates and possibly in some fishes may indicate a tendency to duplicate the genetic material, rather than a real need for function innovation.

Animals↗

PubMed2002

Molecular strategies in Metazoan genomic evolution.

During the evolution of Metazoa, the mitochondrial genome has remained practically unchanged as indicated by its small size and constant gene content in each lineage, although several evolutionary processes have taken place. In contrast, the nuclear genome of Metazoa has undergone dramatic changes, as is demonstrated by some entire genomes completely sequenced so far. The expansion of gene families and the appearance of new functions and new regulatory circuits are among the most prominent features. Here, we report a description of the evolution of the p53 gene family as an example of expansion of both genetic complexity and gene expression of the nuclear genome.

Alternative Splicing↗

PubMed2002

Mitochondrial DNA in metazoa: degree of freedom in a frozen event.

The mitochondrial genome (mtDNA), due to its peculiar features such as exclusive presence of orthologous genes, uniparental inheritance, lack of recombination, small size and constant gene content, certainly represents a major model system in studies on evolutionary genomics in metazoan. In 800 million years of evolution the gene content of metazoan mitochondrial genomes has remained practically frozen but several evolutionary processes have taken place. These processes, reviewed here, include rearrangements of gene order, changes in base composition and arising of compositional asymmetry between the two strands, variations in the genetic code and evolution of codon usage, lineage-specific nucleotide substitution rates and evolutionary patterns of mtDNA control regions.

Animals↗

PubMed2002

MitoNuc: a database of nuclear genes coding for mitochondrial proteins. Update 2002.

Mitochondria, besides their central role in energy metabolism, have recently been found to be involved in a number of basic processes of cell life and to contribute to the pathogenesis of many degenerative diseases. All functions of mitochondria depend on the interaction of nuclear and organelle genomes. Mitochondrial genomes have been extensively sequenced and analysed and data have been collected in several specialised databases. In order to collect information on nuclear coded mitochondrial proteins we developed MitoNuc, a database containing detailed information on sequenced nuclear genes coding for mitochondrial proteins in Metazoa. The MitoNuc database can be retrieved through SRS and is available via the web site http://bighost.area.ba.cnr.it/mitochondriome where other mitochondrial databases developed by our group, the complete list of the sequenced mitochondrial genomes, links to other mitochondrial sites and related information, are available. The MitoAln database, related to MitoNuc in the previous release, reporting the multiple alignments of the relevant homologous protein coding regions, is no longer supported in the present release. In order to keep the links among entries in MitoNuc from homologous proteins, a new field in the database has been defined: the cluster identifier, an alpha numeric code used to identify each cluster of homologous proteins. A comment field derived from the corresponding SWISS-PROT entry has been introduced; this reports clinical data related to dysfunction of the protein. The logic scheme of MitoNuc database has been implemented in the ORACLE DBMS. This will allow the end-users to retrieve data through a friendly interface that will be soon implemented.

Animals↗

PubMed2002

UTRdb and UTRsite: specialized databases of sequences and functional elements of 5' and 3' untranslated regions of eukaryotic mRNAs. Update 2002.

The 5'- and 3'-untranslated regions (5'- and 3'-UTRs) of eukaryotic mRNAs are known to play a crucial role in post-transcriptional regulation of gene expression modulating nucleo-cytoplasmic mRNA transport, translation efficiency, subcellular localization and stability. UTRdb is a specialized database of 5' and 3' untranslated sequences of eukaryotic mRNAs cleaned from redundancy. UTRdb entries are enriched with specialized information not present in the primary databases including the presence of nucleotide sequence patterns already demonstrated by experimental analysis to have some functional role. All these patterns have been collected in the UTRsite database so that it is possible to search any input sequence for the presence of annotated functional motifs. Furthermore, UTRdb entries have been annotated for the presence of repetitive elements. All Internet resources we implemented for retrieval and functional analysis of 5'- and 3'-UTRs of eukaryotic mRNAs are accessible at http://bighost.area.ba.cnr.it/BIG/UTRHome/.

3' Untranslated Regions↗

PubMed2002

Lineage specificity of the evolutionary dynamics of the mtDNA D-loop region in rodents.

This paper reports an intraorder study on the D-loop-containing region of the mitochondrial DNA in rodents. A complete multialignment of this region is not feasible with the exception of some conserved regions. The comparative analysis of 25 complete rodent sequences from 23 species plus one lagomorph has revealed that only the central domain (CD), a conserved region of about 80 bp in the extended termination-associated sequences (ETAS) domain, adjacent to the CD, the ETAS1, and conserved sequence block (CSB) 1 blocks are present in all rodent species, whereas the presence of CSB2 and CSB3 is erratic within the order. We have also found a conserved region of 90 bp located between tRNAPro and ETAS1 present in fat dormouse, squirrel, guinea pig, and rabbit. Repeated sequences are present in both the ETAS and the CSB domain, but the repeats differ in length, copy number, and base composition in different species. The potential use of the D-loop for evolutionary studies has been investigated; the presence/absence of conserved blocks and/or repeated sequences cannot be used as a reliable phylogenetic marker, since in some cases they may be shared by distantly related organisms but not by close ones, while in other ones a relationship between tree topology and presence/absence of such motifs is observed. Better results can be obtained by the use of the CD, which, however, due to its reduced size, when used for tracing a phylogenetic tree, shows some nodes with low statistical support.

Animals↗