23 research outputs found
The effect of oxidative stress on phagocytosis and apoptosis in the earthworm Eisenia hortensis
The effect of exogenous hydrogen peroxide (H202) on phagocytic function and apoptosis in coelomocytes from Eisenia hortensis was investigated. Treating coelomocytes with H202 (0.26 to 8.4 mM) evoked a significant increase in phagocytosis for one or more of the concentrations of H202 employed in 67 % of cases. Using annexin V-FITC we show that H202 induced apoptosis of coelomocytes in vitro. We found that 100 % of viable coelomocyte populations exhibited significant increases in phosphatidylserine translocation for one or more of the concentrations of H202 tested (8.4 to 67.6 mM). Using a fluorescent inhibitor of caspases, we revealed the presence of activated caspases observing increased caspase activity in 67 % of viable coelomocyte populations treated with 33.8mM H202, and in 100 % of cases treated with 67.6 mM H202. Agarose gel electrophoresis and the TUNEL assay showed DNA fragmentation in samples treated with 16.9 and 33.8 mM H202. In addition, endogenous H202 production during phagocytosis by hyaline amoebocytes was detected using a fluorogenic substrate. Thus, free radicals not only appear to facilitate phagocytosis and are produced during phagocytosis, but they also promote an oxidative-stress-induced apoptosis that may play an important function in regulating innate immune responses in E. hortensi
Correlations between age, functional status, and the senescence-associated proteins HMGB2 and p16INK4a
N<sup>6</sup>-methylation of adenosine of FZD10 mRNA contributes to PARP inhibitor resistance
© 2019 American Association for Cancer Research. Despite the high initial response rates to PARP inhibitors (PARPi) in BRCA-mutated epithelial ovarian cancers (EOC), PARPi resistance remains a major challenge. Chemical modifications of RNAs have emerged as a new layer of epigenetic gene regulation. N6-methyladenosine (m6A) is the most abundant chemical modification of mRNA, yet the role of m6A modification in PARPi resistance has not previously been explored. Here, we show that m6A modification of FZD10 mRNA contributes to PARPi resistance by upregulating the Wnt/b-catenin pathway in BRCA-mutated EOC cells. Global m6A profile revealed a significant increase in m6A modification in FZD10 mRNA, which correlated with increased FZD10 mRNA stability and an upregulation of the Wnt/b-catenin pathway. Depletion of FZD10 or inhibition of the Wnt/b-cate-nin sensitizes resistant cells to PARPi. Mechanistically, downregulation of m6A demethylases FTO and ALKBH5 was sufficient to increase FZD10 mRNA m6A modification and reduce PARPi sensitivity, which correlated with an increase in homologous recombination activity. Moreover, combined inhibition of PARP and Wnt/b-catenin showed synergistic suppression of PARPi-resistant cells in vitro and in vivo in a xenograft EOC mouse model. Overall, our results show that m6A contributes to PARPi resistance in BRCA-deficient EOC cells by upregulating the Wnt/b-catenin pathway via stabilization of FZD10. They also suggest that inhibition of the Wnt/b-catenin pathway represents a potential strategy to overcome PARPi resistance
N<sup>6</sup>-methylation of adenosine of FZD10 mRNA contributes to PARP inhibitor resistance
© 2019 American Association for Cancer Research. Despite the high initial response rates to PARP inhibitors (PARPi) in BRCA-mutated epithelial ovarian cancers (EOC), PARPi resistance remains a major challenge. Chemical modifications of RNAs have emerged as a new layer of epigenetic gene regulation. N6-methyladenosine (m6A) is the most abundant chemical modification of mRNA, yet the role of m6A modification in PARPi resistance has not previously been explored. Here, we show that m6A modification of FZD10 mRNA contributes to PARPi resistance by upregulating the Wnt/b-catenin pathway in BRCA-mutated EOC cells. Global m6A profile revealed a significant increase in m6A modification in FZD10 mRNA, which correlated with increased FZD10 mRNA stability and an upregulation of the Wnt/b-catenin pathway. Depletion of FZD10 or inhibition of the Wnt/b-cate-nin sensitizes resistant cells to PARPi. Mechanistically, downregulation of m6A demethylases FTO and ALKBH5 was sufficient to increase FZD10 mRNA m6A modification and reduce PARPi sensitivity, which correlated with an increase in homologous recombination activity. Moreover, combined inhibition of PARP and Wnt/b-catenin showed synergistic suppression of PARPi-resistant cells in vitro and in vivo in a xenograft EOC mouse model. Overall, our results show that m6A contributes to PARPi resistance in BRCA-deficient EOC cells by upregulating the Wnt/b-catenin pathway via stabilization of FZD10. They also suggest that inhibition of the Wnt/b-catenin pathway represents a potential strategy to overcome PARPi resistance
Topical rapamycin reduces markers of senescence and aging in human skin: an exploratory, prospective, randomized trial
Topoisomerase 1 cleavage complex enables pattern recognition and inflammation during senescence
Chronic Intermittent Hypoxia Triggers a Senescence-like Phenotype in Human White Preadipocytes
P53 and Parkin co-regulate mitophagy in bone marrow mesenchymal stem cells to promote the repair of early steroid-induced osteonecrosis of the femoral head
FASN activity is important for the initial stages of the induction of senescence
Senescent cells accumulate in several tissues during ageing and contribute to several pathological processes such as
ageing and cancer. Senescence induction is a complex process not well defined yet and is characterized by a series of
molecular changes acquired after an initial growth arrest. We found that fatty acid synthase (FASN) levels increase
during the induction of senescence in mouse hepatic stellate cells and human primary fibroblasts. Importantly, we also
observed a significant increase in FASN levels during ageing in mouse liver tissues. To probe the central role of FASN in
senescence induction, we used a small-molecule inhibitor of FASN activity, C75. We found that C75 treatment
prevented the induction of senescence in mouse and human senescent cells. Importantly, C75 also reduced the
expression of the signature SASP factors interleukin 1α (IL-1α), IL-1β and IL-6, and suppressed the secretion of small
extracellular vesicles. These findings were confirmed using a shRNA targeting FASN. In addition, we find that FASN
inhibition induces metabolic changes in senescent cells. Our work underscores the importance of C75 as a
pharmacological inhibitor for reducing the impact of senescent cell accumulationChildren with Cancer UK (Number: 14–178)BBSRC (BB/P000223/1)The Royal Society (RG170399)Nacional Health Institute Carlos IIIMiguel-Servet (CP13-00234)MINECO (SAF2016-78666 R