It is well-known that DNA-damaging agents induce genome instability, but only recently have we begun to appreciate chromosomes are fragile per se and frequently subject DNA breakage. replication further magnifies such fragility, because it leads accumulation of single-stranded DNA. Recent findings suggest chromosome fragility similarly increased during transcription. Transcripts produced by RNA polymerase II (RNAPII) multiple processing steps, including maturation 5' 3' ends splicing,...

The neurotransmitter dopamine (DA) at a 10 μM concentration elicited stimulation of intracellular cyclic AMP (cAMP) accumulation in cultured astrocytes derived from embryonic rat striatum. This was partially blocked by the β-adrenergic receptors antagonist propranolol, mimicked D1 agonist SKF 38393 and mixed D1/D2 apomorphine. A regional heterogeneity magnitude dopamine-induced cAMP observed obtained different brain areas. maximum effect striatal astrocytes, lower cortical no increase...

In skeletal muscle differentiation, the retinoblastoma protein (pRb) is absolutely necessary to establish definitive mitotic arrest. It widely assumed that pRb equally essential sustain postmitotic state, but this contention has never been tested. Here, we show terminal proliferation arrest maintained in cells by a pRb-independent mechanism. Acute Rb excision from conditional knockout myotubes caused reexpression of E2F transcriptional activity, cyclin-E and -A kinase activities, PCNA, DNA...

46BR.1G1 cells derive from a patient with genetic syndrome characterized by drastically reduced replicative DNA ligase I (LigI) activity and delayed joining of Okazaki fragments. Here we show that the replication defect in results accumulation both single-stranded double-stranded breaks. This is accompanied phosphorylation H2AX histone variant formation gammaH2AX foci mark damaged DNA. Single-cell analysis demonstrates number LigI-defective fluctuates during cell cycle: they form S phase,...

DNA ligase I-deficient 46BR.1G1 cells show a delay in the maturation of replicative intermediates resulting accumulation single- and double-stranded breaks. As consequence ataxia telangiectasia mutated protein kinase (ATM) is constitutively phosphorylated at basal level. Here, we use as model system to study cell response chronic replication-dependent damage. Starting from proteomic approach, demonstrate that phosphorylation level factors controlling constitutive alternative splicing...

We have studied the regulation of mammalian DNA ligase I gene by using a cDNA probe in Northern blot experiments with RNA extracted from several cell types different growth conditions. mRNA is detected all analysed systems, regardless their proliferation state, including mature rat neurons. A significant increase level observed when cells are induced to proliferate, agreement raise joining activity found same systems. The parallels start synthesis, but messenger remains at high beyond end S...

In eukaryotes, initiation of DNA replication requires the activity origin recognition complex (ORC). The largest subunit this complex, Orc1p, has a critical role in activity. Here we have studied subnuclear distribution overexpressed human Orc1p during cell cycle. is progressively degraded S-phase according to spatio-temporal program and it never colocalizes with factories. resynthesized G1. early G1, protein distributed throughout nucleus, but successively preferentially associates...

The ability to alter DNA tertiary structure of ten anthracycline derivatives whose antitumor potency is known was studied by an assay that makes use nicked circular and bacteriophage T4 ligase. This allows the detection alterations caused binding both intercalating non-intercalating drugs. determination these events can be obtained at different temperatures in range activity results indicate anthracyclines but this property does not correlate with their cytotoxic or activities. An additional...

Abstract In mammalian cells, DNA replication takes place in functional subnuclear compartments, called factories, where replicative factors accumulate. The distribution pattern of factories is diagnostic the different moments (early, mid, and late) S phase. This dynamic organization affected by agents that induce cell cycle checkpoint activation via damage or stalling forks. Here, we explore response to etoposide, an anticancer drug belonging topoisomerase II poisons. Etoposide does not...

Ribosomal S6 kinase 2 (S6K2) acts downstream of the mammalian target rapamycin (mTOR). Here, we show that some S6K2 localize at centrosome throughout cell cycle. is found in pericentriolar area centrosome. centrosomal localization unaffected by serum withdrawal or treatment with rapamycin, wortmannin, U0126, phorbol-12-myristate-13-acetate (PMA). Unlike S6K2, 1 (S6K1) does not centrosome, suggesting two kinases may also have nonoverlapping functions. Our data suggest a role...

Abstract Fragile sites are hot spots for sister chromatid exchanges, translocations, deletions, complex rearrangements, and gene amplification. It has been hypothesized that rearrangements at fragile derive from unreplicated regions resulting stalled forks escape the ATR replication checkpoint. In present study, we investigated role of Claspin ( CLSPN ) gene, which codes an adaptor protein in pathway, during DNA stress human cells. We show inhibition leads to both genome instability site...

Abstract Genome integrity is continuously threatened by endogenous sources of DNA damage including reactive oxygen species (ROS) produced cell metabolism. Factors the RNA interference (RNAi) machinery have been recently involved in cellular response to (DDR) proliferating cells. To investigate impact component RNAi on DDR activation terminally differentiated cells, we exploited cytoplasmic hybrid (cybrid) lines which mitochondria sporadic Parkinson’s disease patients repopulate neuroblastoma...

Heat shock activates the transcription of arrays Satellite III (SatIII) DNA repeats in pericentromeric heterochromatic domains specific human chromosomes, longest which is on chromosome 9. Long non-coding SatIII RNAs remain associated with sites where they form nuclear stress bodies or nSBs. The biology still poorly understood. Here, we show that and nSBs are detectable up to four days after thermal linked defects behavior during mitosis. perturbs execution Cells reaching mitosis first 3 h...