Mostrando recursos 1 - 5 de 5

  1. Telomeres in aging and disease: lessons from zebrafish

    Carneiro, Madalena C.; de Castro, Inês Pimenta; Ferreira, Miguel Godinho
    Age is the highest risk factor for some of the most prevalent human diseases, including cancer. Telomere shortening is thought to play a central role in the aging process in humans. The link between telomeres and aging is highlighted by the fact that genetic diseases causing telomerase deficiency are associated with premature aging and increased risk of cancer. For the last two decades, this link has been mostly investigated using mice that have long telomeres. However, zebrafish has recently emerged as a powerful and complementary model system to study telomere biology. Zebrafish possess human-like short telomeres that progressively decline with...
    - 13-ago-2016

  2. TERT promoter mutations in pancreatic endocrine tumours are rare and mainly found in tumours from patients with hereditary syndromes

    Vinagre, João; Nabais, Joana; Pinheiro, Jorge; Batista, Rui; Oliveira, Rui Caetano; Gonçalves, António Pedro; Pestana, Ana; Reis, Marta; Mesquita, Bárbara; Pinto, Vasco; Lyra, Joana; Cipriano, Maria Augusta; Ferreira, Miguel Godinho; Lopes, José Manuel; Sobrinho-Simões, Manuel; Soares, Paula
    One of the hallmarks of cancer is its unlimited replicative potential that needs a compensatory mechanism for the consequential telomere erosion. Telomerase promoter (TERTp) mutations were recently reported as a novel mechanism for telomerase re-activation/expression in order to maintain telomere length. Pancreatic endocrine tumors (PETs) were so far recognized to rely mainly on the alternative lengthening of telomeres (ALT) mechanism. It was our objective to study if TERTp mutations were present in pancreatic endocrine tumors (PET) and could represent an alternative mechanism to ALT. TERTp mutations were detected in 7% of the cases studied and were mainly associated to patients...
    - 22-jul-2016

  3. Cdk1 Restrains NHEJ through Phosphorylation of XRCC4-like Factor Xlf1

    Hentges, Pierre; Waller, Helen; Reis, Clara C.; Ferreira, Miguel Godinho; Doherty, Aidan J.
    Eukaryotic cells use two principal mechanisms for repairing DNA double-strand breaks (DSBs): homologous recombination (HR) and nonhomologous end-joining (NHEJ). DSB repair pathway choice is strongly regulated during the cell cycle. Cyclin-dependent kinase 1 (Cdk1) activates HR by phosphorylation of key recombination factors. However, a mechanism for regulating the NHEJ pathway has not been established. Here, we report that Xlf1, a fission yeast XLF ortholog, is a key regulator of NHEJ activity in the cell cycle. We show that Cdk1 phosphorylates residues in the C terminus of Xlf1 over the course of the cell cycle. Mutation of these residues leads to...
    - 15-may-2016

  4. Short Telomeres in Key Tissues Initiate Local and Systemic Aging in Zebrafish

    Carneiro, Madalena C.; Henriques, Catarina M.; Nabais, Joana; Ferreira, Tânia; Carvalho, Tânia; Ferreira, Miguel Godinho
    Telomeres shorten with each cell division and telomere dysfunction is a recognized hallmark of aging. Tissue proliferation is expected to dictate the rate at which telomeres shorten. We set out to test whether proliferative tissues age faster than non-proliferative due to telomere shortening during zebrafish aging. We performed a prospective study linking telomere length to tissue pathology and disease. Contrary to expectations, we show that telomeres shorten to critical lengths only in specific tissues and independently of their proliferation rate. Short telomeres accumulate in the gut but not in other highly proliferative tissues such as the blood and gonads. Notably,...
    - 27-ene-2016

  5. Positive Epistasis Drives the Acquisition of Multidrug Resistance

    Trindade, S.; Sousa, A.; Xavier, KB.; Dionisio, F.; Ferreira, MG.; Gordo, I.
    The evolution of multiple antibiotic resistance is an increasing global problem. Resistance mutations are known to impair fitness, and the evolution of resistance to multiple drugs depends both on their costs individually and on how they interact-epistasis. Information on the level of epistasis between antibiotic resistance mutations is of key importance to understanding epistasis amongst deleterious alleles, a key theoretical question, and to improving public health measures. Here we show that in an antibiotic-free environment the cost of multiple resistance is smaller than expected, a signature of pervasive positive epistasis among alleles that confer resistance to antibiotics. Competition assays reveal...
    - 08-jul-2016

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