DNA replication stress: Causes, resolution and disease

AbstractDNA replication is a fundamental process of the cell that ensures accurate duplication of the genetic information and subsequent transfer to daughter cells. Various pertubations, originating from endogenous or exogenous sources, can interfere with proper progression and completion of the replication process, thus threatening genome integrity. Coordinated regulation of replication and the DNA damage response is therefore fundamental to counteract these challenges and ensure accurate synthesis of the genetic material under conditions of replication stress. In this review, we summarize the main sources of replication stress and the DNA damage signaling pathways that are activated in order to preserve genome integrity during DNA replication. We also discuss the association of replication stress and DNA damage in human disease and future perspectives in the field

Parallel genome-wide screens identify synthetic viable interactions between the BLM helicase complex and Fanconi anemia.

Maintenance of genome integrity via repair of DNA damage is a key biological process required to suppress diseases, including Fanconi anemia (FA). We generated loss-of-function human haploid cells for FA complementation group C (FANCC), a gene encoding a component of the FA core complex, and used genome-wide CRISPR libraries as well as insertional mutagenesis to identify synthetic viable (genetic suppressor) interactions for FA. Here we show that loss of the BLM helicase complex suppresses FANCC phenotypes and we confirm this interaction in cells deficient for FA complementation group I and D2 (FANCI and FANCD2) that function as part of the FA I-D2 complex, indicating that this interaction is not limited to the FA core complex, hence demonstrating that systematic genome-wide screening approaches can be used to reveal genetic viable interactions for DNA repair defects

ZAK beta is activated by cellular compression and mediates contraction-induced MAP kinase signaling in skeletal muscle

Mechanical inputs give rise to p38 and JNK activation, which mediate adaptive physiological responses in various tissues. In skeletal muscle, contraction-induced p38 and JNK signaling ensure adaptation to exercise, muscle repair, and hypertrophy. However, the mechanisms by which muscle fibers sense mechanical load to activate this signaling have remained elusive. Here, we show that the upstream MAP3K ZAK beta is activated by cellular compression induced by osmotic shock and cyclic compression in vitro, and muscle contraction in vivo. This function relies on ZAKO's ability to recognize stress fibers in cells and Z-discs in muscle fibers when mechanically perturbed. Consequently, ZAK-deficient mice present with skeletal muscle defects characterized by fibers with centralized nuclei and progressive adaptation towards a slower myosin profile. Our results highlight how cells in general respond to mechanical compressive load and how mechanical forces generated during muscle contraction are translated into MAP kinase signaling.Peer reviewe

A survey on multi-agent based collaborative intrusion detection systems

Multi-Agent Systems (MAS) have been widely used in many areas like modeling and simulation of complex phenomena, and distributed problem solving. Likewise, MAS have been used in cyber-security, to build more efficient Intrusion Detection Systems (IDS), namely Collaborative Intrusion Detection Systems (CIDS). This work presents a taxonomy for classifying the methods used to design intrusion detection systems, and how such methods were used alongside with MAS in order to build IDS that are deployed in distributed environments, resulting in the emergence of CIDS. The proposed taxonomy, consists of three parts: 1) general architecture of CIDS, 2) the used agent technology, and 3) decision techniques, in which used technologies are presented. The proposed taxonomy reviews and classifies the most relevant works in this topic and highlights open research issues in view of recent and emerging threats. Thus, this work provides a good insight regarding past, current, and future solutions for CIDS, and helps both researchers and professionals design more effective solutions

Functional variants of human APE1 rescue the DNA repair defects of the yeast AP endonuclease/3′-diesterase-deficient strain

International audienc

Vasohibins encode tubulin detyrosinating activity

Tubulin is subjected to a number of posttranslational modifications to generate heterogeneous microtubules. The modifications include removal and ligation of the carboxy-terminal tyrosine of ⍺-tubulin. Whereas enzymes for most modifications have been assigned, the enzymes responsible for detyrosination, an activity observed forty years ago, have remained elusive. We applied a haploid genetic screen to find regulators of tubulin detyrosination. We identified SVBP, a peptide that regulates the abundance of Vasohibins (VASH1 and VASH2). Vasohibins, but not SVBP alone, increased detyrosination of ⍺-tubulin and purified Vasohibins removed the carboxy-terminal tyrosine of ⍺-tubulin. Vasohibins played a cell-type dependent role in detyrosination, but cells also contain an additional detyrosinating activity. Thus Vasohibins, hitherto studied as secreted angiogenesis regulators, constitute a long-sought missing link in the tubulin tyrosination cycle

Vasohibins encode tubulin detyrosinating activity

Tubulin is subjected to a number of posttranslational modifications to generate heterogeneous microtubules. The modifications include removal and ligation of the C-terminal tyrosine of ⍺-tubulin. The enzymes responsible for detyrosination, an activity first observed 40 years ago, have remained elusive. We applied a genetic screen in haploid human cells to find regulators of tubulin detyrosination. We identified SVBP, a peptide that regulates the abundance of vasohibins (VASH1 and VASH2). Vasohibins, but not SVBP alone, increased detyrosination of ⍺-tubulin, and purified vasohibins removed the C-terminal tyrosine of ⍺-tubulin. We found that vasohibins play a cell type-dependent role in detyrosination, although cells also contain an additional detyrosinating activity. Thus, vasohibins, hitherto studied as secreted angiogenesis regulators, constitute a long-sought missing link in the tubulin tyrosination cycle

DNA Repair Cofactors ATMIN and NBS1 Are Required to Suppress T Cell Activation

<div><p>Proper development of the immune system is an intricate process dependent on many factors, including an intact DNA damage response. The DNA double-strand break signaling kinase ATM and its cofactor NBS1 are required during T cell development and for the maintenance of genomic stability. The role of a second ATM cofactor, ATMIN (also known as ASCIZ) in T cells is much less clear, and whether ATMIN and NBS1 function in synergy in T cells is unknown. Here, we investigate the roles of ATMIN and NBS1, either alone or in combination, using murine models. We show loss of NBS1 led to a developmental block at the double-positive stage of T cell development, as well as reduced TCRα recombination, that was unexpectedly neither exacerbated nor alleviated by concomitant loss of ATMIN. In contrast, loss of both ATMIN and NBS1 enhanced DNA damage that drove spontaneous peripheral T cell hyperactivation, proliferation as well as excessive production of proinflammatory cytokines and chemokines, leading to a highly inflammatory environment. Intriguingly, the disease causing T cells were largely proficient for both ATMIN and NBS1. <i>In vivo</i> this resulted in severe intestinal inflammation, colitis and premature death. Our findings reveal a novel model for an intestinal bowel disease phenotype that occurs upon combined loss of the DNA repair cofactors ATMIN and NBS1.</p></div

Loss of ATMIN and NBS1 leads to intestinal inflammation due to infiltration of cytokine-producing T cells.

<p>(A) Histological analysis by H&E staining of large intestine of control, ATM^-/-, ATMIN^ΔL, NBS1^ΔL, ATMIN^ΔLNBS1^ΔL mice at 12 weeks of age. (B) Histological scores of the large intestine of control, ATM^-/-, ATMIN^ΔL, NBS1^ΔL, ATMIN^ΔLNBS1^ΔL and 3 individual moribund ATMIN^ΔLNBS1^ΔL mice. (C) Histological analysis by anti-CD3 staining of the large intestine of control and a moribund ATMIN^ΔLNBS1^ΔL mouse. (D) Representative flow cytometry data of CD4 and CD8 expression, as well as (E) TCRβ and TCRγδ expression on isolated IELs from the small intestine of control, ATMIN^ΔL, NBS1^ΔL and ATMIN^ΔLNBS1^ΔL mice, along with the quantification of D-E. N = 5–8 mice per genotype. (F) Representative flow cytometry data of IL17A and IFNγ production by YFP^- and YFP⁺ IELs (gated on the CD4⁺ population) isolated from the small intestine of control and ATMIN^ΔLNBS1^ΔL mice after PMA and ionomycin stimulation. (G) Large intestinal sections from control, ATM^-/-, ATMIN^ΔL, NBS1^ΔL and ATMIN^ΔLNBS1^ΔL mice were stained for γH2AX and DAPI. Error bars represent SEM (**<i>P</i><0.01, ***<i>P</i><0.001).</p