Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces no heat, so its effects can be selective. In order to exploit the potential for clinical applications, including wound healing, sterilization, blood coagulation, and cancer treatment, a mechanistic understanding of the interaction of non-thermal plasma with living tissues is required. Using mammalian cells in culture, it is shown here that non-thermal plasma created by dielectric barrier discharge (DBD) has dose-dependent effects that range from increasing cell proliferation to inducing apoptosis. It is also shown that these effects are primarily due to formation of intracellular reactive oxygen species (ROS). We have utilized γ-H2AX to detect DNA damage induced by non-thermal plasma and found that it is initiated by production of active neutral species that most likely induce formation of organic peroxides in cell medium. Phosphorylation of H2AX following non-thermal plasma treatment is ATR dependent and ATM independent, suggesting that plasma treatment may lead to replication arrest or formation of single-stranded DNA breaks; however, plasma does not lead to formation of bulky adducts/thymine dimers.

Advances in stem cell biology have generated intense interest in the prospect of transplanting stem cells into the nervous system for the treatment of neurodegenerative diseases. Here, we report the results of an ongoing phase

Heart transplant rejection is characterized pathologically by myocyte necrosis and apoptosis associated with interstitial mononuclear cell infiltration. Any one of these components can be targeted for noninvasive detection of transplant rejection. During apoptotic cell death, phosphatidylserine, a phospholipid that is normally confined to the inner leaflet of cell membrane bilayer, gets exteriorized. Technetium-99m-labeled annexin-V, an endogenous protein that has high affinity for binding to phosphatidylserine, has been administered intravenously for noninvasive identification of apoptotic cell death. In the present study of 18 cardiac allograft recipients, 13 patients had negative and five had positive myocardial uptake of annexin. These latter five demonstrated at least moderate transplant rejection and caspase-3 staining, suggesting apoptosis in their biopsy specimens. This study reveals the clinical feasibility and safety of annexin-V imaging for noninvasive detection of transplant rejection by targeting cell membrane phospholipid alterations that are commonly associated with the process of apoptosis.

ALS is a devastating neurodegenerative disease whose causes are still poorly understood. To identify additional genetic risk factors, here we assess the role of de novo mutations in ALS by sequencing the exomes of 47 ALS patients and both of their unaffected parents (n=141 exomes). We found that amino acid-altering de novo mutations are enriched in genes encoding chromatin regulators, including the neuronal chromatin remodeling complex component SS18L1/CREST. CREST mutations inhibit activity-dependent neurite outgrowth in primary neurons, and CREST associates with the ALS protein FUS. These findings expand our understanding of the ALS genetic landscape and provide a resource for future studies into the pathogenic mechanisms contributing to sporadic ALS.

In ALS, increased pNF-H concentration in plasma, serum and CSF appears to be associated with faster disease progression. Factors affecting pNF-H levels or their detection in serum and plasma in relation to disease course may differ from those in CSF. Data raising the possibility that site of ALS onset (bulbar vs spinal) may influence pNF-H levels in peripheral blood seems noteworthy but requires confirmation. These data support further study of pNF-H in CSF, serum and plasma as a potential ALS biomarker.

Sp1, a transcription factor that regulates expression of a wide array of essential genes, contains two SQ/TQ cluster domains, which are characteristic of ATM kinase substrates. ATM substrates are transducers and effectors of the DNA damage response, which involves sensing damage, checkpoint activation, DNA repair, and/or apoptosis. A role for Sp1 in the DNA damage response is supported by our findings: Activation of ATM induces Sp1 phosphorylation with kinetics similar to H2AX; inhibition of ATM activity blocks Sp1 phosphorylation; depletion of Sp1 sensitizes cells to DNA damage and increases the frequency of double strand breaks. We have identified serine 101 as a critical site phosphorylated by ATM; Sp1 with serine 101 mutated to alanine (S101A) is not significantly phosphorylated in response to damage and cannot restore increased sensitivity to DNA damage of cells depleted of Sp1. Together, these data show that Sp1 is a novel ATM substrate that plays a role in the cellular response to DNA damage. (Mol Cancer Res 2007;5(12):1319 -30)

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cSp1 is a ubiquitously expressed transcription factor that is phosphorylated by ataxia telangiectasia mutated kinase (ATM) in response to ionizing radiation and H 2 O 2 . Here, we show by indirect immunofluorescence that Sp1 phosphorylated on serine 101 (pSp1) localizes to ionizing radiation-induced foci with phosphorylated histone variant ␥H2Ax and members of the MRN (Mre11, Rad50, and Nbs1) complex. More precise analysis of occupancy of DNA double-strand breaks (DSBs) by chromatin immunoprecipitation (ChIP) shows that Sp1, like Nbs1, resides within 200 bp of DSBs. Using laser microirradiation of cells, we demonstrate that pSp1 is present at DNA DSBs by 7.5 min after induction of damage and remains at the break site for at least 8 h. Depletion of Sp1 inhibits repair of site-specific DNA breaks, and the N-terminal 182-amino-acid peptide, which contains targets of ATM kinase but lacks the zinc finger DNA binding domain, is phosphorylated, localizes to DSBs, and rescues the repair defect resulting from Sp1 depletion. Together, these data demonstrate that Sp1 is rapidly recruited to the region immediately adjacent to sites of DNA DSBs and is required for DSB repair, through a mechanism independent of its sequence-directed transcriptional effects.T ranscription factor Sp1 regulates the expression of genes involved in cell proliferation, DNA repair, and apoptosis/ senescence (9). DNA binding of Sp1 is mediated through three zinc fingers in the C-terminal region, which recognize GC-rich elements in a large number of promoters that are frequently found in euchromatic CpG islands. Posttranslational modifications throughout Sp1, including phosphorylation, acetylation, O-linked glycosylation, and sumoylation, modulate its interaction with chromatin remodeling factors, DNA, transcription machinery, and other transcription factors to enhance or repress gene expression (13,35,36,40,51,53,56,69,82). Our group and others have shown that transcription factor Sp1, which contains two S/TQ cluster domains (SCDs), characteristic of phosphoinositide 3-kinase-like kinase (PI3KK) substrates, is phosphorylated by the ataxia telangiectasia mutated kinase (ATM) in response to ionizing radiation, H 2 O 2 (64), and other DNA-damaging agents (unpublished data), as well as herpesvirus infection (33).Genomic stability is maintained by the cellular response to DNA damage. In response to DNA double-strand breaks (DSBs), ATM is activated (80) and initiates a cascade of DNA damage signals by phosphorylation of hundreds of proteins involved in cell cycle checkpoint activation, DNA repair, and apoptosis, including p53, Chk2, ␥H2Ax, BRCA1, and Nbs1 (48, 57). Mutations in the ATM gene result in the autosomal recessive disorder ataxia telangiectasia (AT), which is characterized by radiation sensitivity, immunodeficiency, neurodegeneration, and cancer predisposition (79). Cells derived from AT patients exhibit increased chromosome breaks, defects in cell cycle checkpoints, and increased sensitivity to ionizing radiation (IR) (66,78). Inactive ATM forms...