G-quadruplexes (G4s) are functional elements of the human genome, some of which inhibit DNA replication. We investigated replication of G4s within highly abundant microsatellite (GGGA, GGGT) and transposable element (L1 and SVA) sequences. We found that genome-wide, numerous motifs are located preferentially on the replication leading strand and the transcribed strand templates. We directly tested replicative polymerase ϵ and δ holoenzyme inhibition at these G4s, compared to low abundant motifs. For all G4s, DNA synthesis inhibition was higher on the G-rich than C-rich strand or control sequence. No single G4 was an absolute block for either holoenzyme; however, the inhibitory potential varied over an order of magnitude. Biophysical analyses showed the motifs form varying topologies, but replicative polymerase inhibition did not correlate with a specific G4 structure. Addition of the G4 stabilizer pyridostatin severely inhibited forward polymerase synthesis specifically on the G-rich strand, enhancing G/C strand asynchrony. Our results reveal that replicative polymerase inhibition at every G4 examined is distinct, causing complementary strand synthesis to become asynchronous, which could contribute to slowed fork elongation. Altogether, we provide critical information regarding how replicative eukaryotic holoenzymes navigate synthesis through G4s naturally occurring thousands of times in functional regions of the human genome.

• MeSH
• DNA-polymerasa II * antagonisté a inhibitory   metabolismus   MeSH
• DNA-polymerasa III * antagonisté a inhibitory   metabolismus   MeSH
• DNA chemie   MeSH
• G-kvadruplexy * MeSH
• genom lidský * MeSH
• holoenzymy metabolismus   MeSH
• kyseliny pikolinové farmakologie   MeSH
• lidé MeSH
• mikrosatelitní repetice MeSH
• replikace DNA * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aminochinoliny MeSH
• DNA-polymerasa II * MeSH
• DNA-polymerasa III * MeSH
• DNA MeSH
• holoenzymy MeSH
• kyseliny pikolinové MeSH
• POLD3 protein, human MeSH Prohlížeč
• POLE protein, human MeSH Prohlížeč
• proteiny vázající poly-ADP-ribosu MeSH
• pyridostatin MeSH Prohlížeč

Elevated levels of reactive oxygen species (ROS) reduce replication fork velocity by causing dissociation of the TIMELESS-TIPIN complex from the replisome. Here, we show that ROS generated by exposure of human cells to the ribonucleotide reductase inhibitor hydroxyurea (HU) promote replication fork reversal in a manner dependent on active transcription and formation of co-transcriptional RNA:DNA hybrids (R-loops). The frequency of R-loop-dependent fork stalling events is also increased after TIMELESS depletion or a partial inhibition of replicative DNA polymerases by aphidicolin, suggesting that this phenomenon is due to a global replication slowdown. In contrast, replication arrest caused by HU-induced depletion of deoxynucleotides does not induce fork reversal but, if allowed to persist, leads to extensive R-loop-independent DNA breakage during S-phase. Our work reveals a link between oxidative stress and transcription-replication interference that causes genomic alterations recurrently found in human cancer.

• MeSH
• DNA vazebné proteiny * metabolismus   MeSH
• DNA MeSH
• hydroxymočovina farmakologie   MeSH
• lidé MeSH
• reaktivní formy kyslíku MeSH
• replikace DNA * MeSH
• S fáze genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA vazebné proteiny * MeSH
• DNA MeSH
• hydroxymočovina MeSH
• reaktivní formy kyslíku MeSH

Accumulation of senescent cells may drive age-associated alterations and pathologies. Senolytics are promising therapeutics that can preferentially eliminate senescent cells. Here, we performed a high-throughput automatized screening (HTS) of the commercial LOPAC®Pfizer library on aphidicolin-induced senescent human fibroblasts, to identify novel senolytics. We discovered the nociceptin receptor FQ opioid receptor (NOP) selective ligand 1-[1-(1-methylcyclooctyl)-4-piperidinyl]-2-[(3R)-3-piperidinyl]-1H-benzimidazole (MCOPPB, a compound previously studied as potential anxiolytic) as the best scoring hit. The ability of MCOPPB to eliminate senescent cells in in vitro models was further tested in mice and in C. elegans. MCOPPB reduced the senescence cell burden in peripheral tissues but not in the central nervous system. Mice and worms exposed to MCOPPB also exhibited locomotion and lipid storage changes. Mechanistically, MCOPPB treatment activated transcriptional networks involved in the immune responses to external stressors, implicating Toll-like receptors (TLRs). Our study uncovers MCOPPB as a NOP ligand that, apart from anxiolytic effects, also shows tissue-specific senolytic effects.

• Klíčová slova
• Aging, NOP, Senescence, Senolytic,
• MeSH
• anxiolytika * farmakologie   MeSH
• Caenorhabditis elegans MeSH
• léky proti stárnutí * MeSH
• lidé MeSH
• ligandy MeSH
• myši MeSH
• narkotika - antagonisté farmakologie   MeSH
• nociceptin MeSH
• opioidní analgetika MeSH
• opioidní peptidy MeSH
• piperidiny farmakologie   MeSH
• receptory opiátové MeSH
• rychlé screeningové testy MeSH
• stárnutí buněk * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• anxiolytika * MeSH
• léky proti stárnutí * MeSH
• ligandy MeSH
• narkotika - antagonisté MeSH
• opioidní analgetika MeSH
• opioidní peptidy MeSH
• piperidiny MeSH
• receptory opiátové MeSH

Autophagy is an evolutionarily conserved process that captures aberrant intracellular proteins and/or damaged organelles for delivery to lysosomes, with implications for cellular and organismal homeostasis, aging and diverse pathologies, including cancer. During cancer development, autophagy may play both tumour-supporting and tumour-suppressing roles. Any relationships of autophagy to the established oncogene-induced replication stress (RS) and the ensuing DNA damage response (DDR)-mediated anti-cancer barrier in early tumorigenesis remain to be elucidated. Here, assessing potential links between autophagy, RS and DDR, we found that autophagy is enhanced in both early and advanced stages of human urinary bladder and prostate tumorigenesis. Furthermore, a high-content, single-cell-level microscopy analysis of human cellular models exposed to diverse genotoxic insults showed that autophagy is enhanced in cells that experienced robust DNA damage, independently of the cell-cycle position. Oncogene- and drug-induced RS triggered first DDR and later autophagy. Unexpectedly, genetic inactivation of autophagy resulted in RS, despite cellular retention of functional mitochondria and normal ROS levels. Moreover, recovery from experimentally induced RS required autophagy to support DNA synthesis. Consistently, RS due to the absence of autophagy could be partly alleviated by exogenous supply of deoxynucleosides. Our results highlight the importance of autophagy for DNA synthesis, suggesting that autophagy may support cancer progression, at least in part, by facilitating tumour cell survival and fitness under replication stress, a feature shared by most malignancies. These findings have implications for better understanding of the role of autophagy in tumorigenesis, as well as for attempts to manipulate autophagy as an anti-tumour therapeutic strategy.

• MeSH
• autofagie * MeSH
• autofagozomy účinky léků   metabolismus   MeSH
• biologické modely MeSH
• fyziologický stres * účinky léků   MeSH
• kamptothecin farmakologie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• onkogeny * MeSH
• replikace DNA * účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kamptothecin MeSH