DGH - Capítulos (ou partes) de livros
Permanent URI for this collection
Browse
Browsing DGH - Capítulos (ou partes) de livros by Issue Date
Now showing 1 - 10 of 32
Results Per Page
Sort Options
- Signaling Pathways of Proteostasis Network Unraveled by Proteomic Approaches on the Understanding of Misfolded Protein RescuePublication . Gomes-Alves, Patricia; Neves, Sofia; Penque, DeborahAttempts to promote normal processing and function of F508del-CFTR, the most common mutant in cystic fibrosis (CF), have been described as potential therapeutic strategies in the management of this disease. Here we described the proteomic approaches, namely two-dimensional electrophoresis (2DE), mass spectrometry (MS), and bioinformatics tools used in our recent studies to gain insight into the proteins potentially involved in lowtemperature or mutagenic treatment-induced rescue process of F508del-CFTR. The proteins identified are part of the proteostasis network, such as the unfolded protein response (UPR) signaling pathways that may regulate the processing of CF transmembrane conductance regulator (CFTR) through the folding and trafficking progression. The complete characterization of these signaling pathways and their regulators in CF will certainly contribute to the development of novel therapeutic strategies against CF.
- Signaling Pathways of Proteostasis Network Unraveled by Proteomic Approaches on the Understanding of Misfolded Protein RescuePublication . Gomes-Alves, Patricia; Neves, Sofia; Penque, DeborahAttempts to promote normal processing and function of F508del-CFTR, the most common mutant in cystic fibrosis (CF), have been described as potential therapeutic strategies in the management of this disease. Here we described the proteomic approaches, namely two-dimensional electrophoresis (2DE), mass spectrometry (MS), and bioinformatics tools used in our recent studies to gain insight into the proteins potentially involved in lowtemperature or mutagenic treatment-induced rescue process of F508del-CFTR. The proteins identified are part of the proteostasis network, such as the unfolded protein response (UPR) signaling pathways that may regulate the processing of CF transmembrane conductance regulator (CFTR) through the folding and trafficking progression. The complete characterization of these signaling pathways and their regulators in CF will certainly contribute to the development of novel therapeutic strategies against CF.
- The deleterious effect of missense mutations on pre-mRNA splicingPublication . Gonçalves, Vânia; Jordan, PeterThe presence of missense mutations detected during genetic testing makes it difficult to classify their pathogenic effect. It is possible that the predicted amino acid change affects protein function; however, it is also possible that a missense mutation does not act at the protein level but rather at the nucleotide level by interfering with the correct assembly of the pre-mRNA splicing machinery. In this chapter we describe that short 6 to 9 nucleotides-containing sequence motifs act as exonic splicing regulatory elements. They are specifically recognized by corresponding splicing factors, which then assist in the recognition of the conserved splice site motifs by the spliceosome. Many examples show that a point mutation in these exonic splicing regulatory elements is sufficient to change splicing factor binding, which impairs inclusion of an exon during the splicing reaction. Thus, the molecular consequence of a missense mutation can be exon skipping and thus cause a frameshift in the messenger RNA that results in a premature stop codon and loss of function of the affected allele. Although several bioinformatic tools exist to predict splicing factor binding to mRNA, this effect of a missense mutation on splicing cannot yet be accurately predicted by sequence analysis alone. In order to determine whether a missense mutation has a deleterious effect on splicing of the corresponding mRNA, experimental analysis with either patient RNA or splicing reporter minigenes is required.
- Cost/Benefit of Mutation Induction under PARP1 Deficiency: From Genomic Instability to TherapyPublication . Louro, Henriqueta; Silva, Maria João; Urbano, Kevin V.Mutation is a possible consequence of DNA damage and it is the most prominent event of the carcinogenic process. Spontaneous mutations originate from endogenous metabolic processes, such as inaccurate DNA replication or repair, whereas induced mutations arise from exposure to exogenous agents. Once DNA damage occurs, a complex network of repair functions is triggered to protect cells against the deleterious consequences of mutations and in order to maintain genomic stability. Among the several DNA repair pathways available in eukaryotic cells, base excision repair (BER) is required to repair non-bulky DNA adducts such as oxidized bases. Poly (ADP-ribose) polymerase-1 (PARP1) is a ubiquitous protein in mammalian cells, with a relevant role in BER and participating also in other complex biochemical processes including double strand break repair, chromatin remodelling and cell death. Hence, defective PARP1 activity would be expected to influence the number or type of gene and/or chromosome mutations resultant from exposure to genotoxic agents and, eventually, to be implicated in cancer. Recently, we generated a Parp1-/- lacZ transgenic mouse model to investigate the effect of PARP1 deficiency in vivo on the mutagenic and clastogenic responses to carcinogens. In this chapter, we present data showing the occurrence of a higher spontaneous genomic instability and a modified mutagenic response to genotoxic insults in Parp1-deficient mice. Particularly, the higher level of deletion mutations in the germ line of those mice might constitute an added risk for hereditary diseases. Inversely, it might provide genetic diversity, representing an advantage for survival. Interestingly, although we found that PARP1 inactivation causes some genomic instability in vivo, cancer propensity was not observed either in this mouse line or in two other different Parp1-deficient mouse models. Even though, defects in DNA damage responses that are not directly responsible for a disease can be important and exploited to be used for the benefit of health. This has been the case of molecules acting as PARP inhibitors, which have been developed to enhance the effectiveness of anticancer drugs or even to function as chemotherapeutic agents per se. The rational for their therapeutic application is based, precisely, on the increase of mutations in tumor cells upon PARP1 abrogation, triggering cell death. However, considering the present knowledge about the impact of PARP1 deficiency in mutation accumulation and the uncertainties about its association with somatic or hereditary diseases, the cost/benefit of the clinical use of PARP inhibitors in humans should be carefully evaluated.
- Biomedical Application of FullerenesPublication . Milic Torres, Vukosava; Srdjenovic, Branislava; Verner, Robert F.; Benvegnu, CarlosFullerene, the third carbon allotrope, is a classical engineered material with the potential application in biomedicine. Since their discovery in 1985, fullerenes have been extensively investigated. The biological activities of fullerenes are considerably influenced by their chemical modifications and light treatment. The most relevant feature of fullerene C60 is the ability to act as a free radical scavenges. Properties attributed to the delocalized π double bond system of fullerene cage allow C60 to quench various free radicals more efficiently than conventional antioxidants. However, extremely high hydrophobicity of fullerene hampers its direct biomedical evaluation and application. To overcome this problem, several approaches for the transfer fullerenes into physiological friendly media have been developed: chemical modification of the fullerene carbon cage, incorporation of fullerenes into water soluble micellar supramolecular structures, solvent exchange and long term stirring of pure C60 in water. These steps created army of different classes of functionalized fullerenes which exhibit vast range of biological activities, especially in the field of photodynamic therapy, neuroprotection, apoptosis, drug and gene delivery. It was found that certain classes of functionalized fullerenes can be used for diagnostic purposes. So far, the most promising applications include the use of gadolinium endohedral complexes in magnetic resonance imaging and therpautic (as a primary or adjuvant) exploration of tris-adducts and polyhidroxlated C60 fullerenes. In this chapter we are summarizing and discussing main biological and medicinal aspects of fullerenes and its functionalized derivates with special regards to the recent achievements.
- Doxorubicin-induced oxidative injury of cardiomyocytes - do we have right strategies for prevention?Publication . Milic Torres, Vukosava; Dragojevic Simic, ViktorijaAnthracyclines are among the most utilised antitumour drugs ever developed. The discovery of one of the leading compounds, doxorubicin (DOX) in early 1960s was a major advance in the fight against cancer. According to the WHO, it belongs to the group of 17 essential drugs that are used to treat curable cancers or cancers for which the cost-benefit ratio clearly favours drug treatment (Sikora et al., 1999). It is used, often with other antineoplastic, in the treatment of Hodgkin's disease, non-Hodgkin's lymphomas, acute leukaemias, bone and soft-tissue sarcoma, neuroblastoma, Wilm's tumour, and malignant neoplasms of the bladder, breast, lung, ovary, and stomach. The mechanisms of cytotoxicity of DOX in cancer cells is complex including: inhibition of both DNA replication and RNA transcription; free radicals generation, leading to DNA damage or lipid peroxidation; DNA cross-linking; DNA alkylation; direct membrane damage due to lipid oxidation and inhibition of topoisomerase II (Gewirtz, 1999; Minotti et al., 2004). Today, topoisomarase II is generally recognized to be the cellular target of DOX, which act by stabilizing a reaction intermediate in which DNA strands are cut and covalently linked to this enzyme (Simunek et al., 2009). It blocks subsequent DNA resealing. Failure to relax the supercoiled DNA blocks DNA replication and transcription. Furthermore, DNA strand breaks may trigger apoptosis of cancer cells. However, as with all traditional antineoplastic drugs, DOX administration is accompanied by adverse drug reactions arising from the limited selectivity of their anticancer action (Aronson et al., 2006; McEvoy et al., 2010). Particularly common are bone marrow depression, which may be dose-limiting. White cell count reaches a nadir 10 to 15 days after a dose and usually recovers by about 21 days. Gastrointestinal disturbances include moderate or sometimes severe nausea and vomiting; stomatitis and oesophagitis may progress to ulceration. Alopecia occurs in the majority of patients. Occasional hypersensitivity reactions may also occur. However, a cumulative-dose dependent cardiac toxicity has been a major limitation of DOX use.
- Nuclear-Mitochondrial Intergenomic Communication DisordersPublication . Almeida, L.S.; Nogueira, C.; Vilarinho, L.The focus of this chapter is to review the clinical and molecular etiologies of nuclear defects involved in mtDNA stability and in mitochondrial protein synthesis. The overview done here will hopefully provide insights towards best diagnostic strategies of mitochondrial cross–talk disorders, being useful for clinicians when facing similar cases. Additionally we will present a diagnostic algorithm for these diseases based on our knowledge.
- Erythropoietin in Familial Amyloidosis ATTR V30MPublication . Beirão, I.; Costa, P.P.Familial amyloidosis ATTR V30M is an hereditary disorder, the most frequent type of transthyretin related amyloidosis. The main manifestation of the disease is a sensory-motor and autonomic polyneuropathy. Other manifestations occur such as cardiovascular, gastrointestinal, ocular, renal and hematological disorders. Anemia is a common feature, and occurs late in the disease course. It is associated with low erythropoietin production. Decreased production can start early in the course of the disease and precede clinical symptoms. The possible underlying pathogenic mechanisms are discussed.
- Genoma: bem público ou privado?Publication . Lavinha, JoãoPara responder à questão "genoma: bem público ou privado?" apresenta-se a complexidade dos sistemas vivos e a relevância da interação de fatores ambientais e genéticos e até das leis do acaso na dinâmica vital das espécies e da biosfera no seu conjunto. Questiona-se, em particular, a ideia de que o genoma seria uma espécie de "livro (de instruções) da vida" ou de que o ADN possuiria o estatuto de molécula-mestra determinante da própria natureza dos organismos vivos. Sustenta-se que a informação genética não é fundamentalmente diferente de outros tipos de informação de saúde, desmontando-se a visão simplista e reducionista segundo a qual os traços fenotípicos dos seres humanos são uma consequência direta da sua constituição genética.
- The LacZ plasmid-based transgenic mouse model: an integrative approach to study the genotoxicity of nanomaterialsPublication . Louro, Henriqueta; Pinto, Miguel; Vital, Nádia; Tavares, Ana; Costa, Pedro M.; Silva, Maria JoãoNumerous in vitro studies have been performed to address the potential genotoxicity of chemicals and of emerging products, e.g., nanomaterials. Although valuable for hazard assessment, the in vitro assays do not reflect the complexity of an organism, including, bioavailability, toxicokinetics and immune responses. Moreover, the biological effects at the target organs are known to be greatly influenced by factors as cell proliferative rate, metabolic and DNA repair capacities. In this sense, data from suitable in vivo assays are useful to evaluate the performance of in vitro assays and to strengthen the knowledge about the genotoxicity of chemicals and nanomaterials, using several routes of exposure, at a whole organism level. This chapter provides an overview of an integrated experimental design, based on the use of a LacZ-plasmid based transgenic mouse model to investigate multiple genotoxicity endpoints in several organs, towards the safety evaluation of nanomaterials. This approach includes the analysis of chromosome instability, assessed by the micronucleus assay in blood or bone marrow cells and by sister chromatid exchanges in splenocytes, the analysis of DNA breaks and oxidative DNA damage by the comet assay, and the quantification of gene mutations in multiple organs. Furthermore, histological markers e.g., of inflammation and apoptosis, can add information about other relevant cell responses. A key point is that all assays are performed on the same animal, therefore increasing the efficiency while reducing the cost and the number of animals under experimentation, in compliance with the EU recommendations. Overall, gathering the data from the several endpoints and organs of the same animal depicts the complex response of a whole-organism to nanomaterials exposure, thereby providing a better prediction of the effects on humans.