Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Dganit Shkedy is active.

Publication


Featured researches published by Dganit Shkedy.


Molecular Cell | 2011

Requirement of ATM-Dependent Monoubiquitylation of Histone H2B for Timely Repair of DNA Double-Strand Breaks

Lilach Moyal; Yaniv Lerenthal; Mali Gana-Weisz; Gilad Mass; Sairei So; Shih Ya Wang; Berina Eppink; Young Min Chung; Gil Shalev; Efrat Shema; Dganit Shkedy; Nechama I. Smorodinsky; Nicole van Vliet; Bernhard Kuster; Matthias Mann; Aaron Ciechanover; Jochen Dahm-Daphi; Roland Kanaar; Mickey C T Hu; David J. Chen; Moshe Oren; Yosef Shiloh

The cellular response to DNA double-strand breaks (DSBs) is mobilized by the protein kinase ATM, which phosphorylates key players in the DNA damage response (DDR) network. A major question is how ATM controls DSB repair. Optimal repair requires chromatin relaxation at damaged sites. Chromatin reorganization is coupled to dynamic alterations in histone posttranslational modifications. Here, we show that in human cells, DSBs induce monoubiquitylation of histone H2B, a modification that is associated in undamaged cells with transcription elongation. We find that this process relies on recruitment to DSB sites and ATM-dependent phosphorylation of the responsible E3 ubiquitin ligase: the RNF20-RNF40 heterodimer. H2B monoubiquitylation is required for timely recruitment of players in the two major DSB repair pathways-nonhomologous end-joining and homologous recombination repair-and optimal repair via both pathways. Our data and previous data suggest a two-stage model for chromatin decondensation that facilitates DSB repair.


FEBS Letters | 1997

On the involvement of calpains in the degradation of the tumor suppressor protein p53

Hedva Gonen; Dganit Shkedy; Sivia Barnoy; Nechama S. Kosower; Aaron Ciechanover

A crude fraction that contains ubiquitin–protein ligases contains also a proteolytic activity of ∼100 kDa that cleaves p53 to several fragments. The protease does not require ATP and is inhibited in the crude extract by an endogenous ∼250 kDa inhibitor. The proteinase can be inhibited by chelating the Ca2+ ions, by specific cysteine proteinase inhibitors and by peptide aldehyde derivatives that inhibit calpains. Purified calpain demonstrates an identical activity that can be inhibited by calpastatin, the specific protein inhibitor of the enzyme. Thus, it appears that the activity we have identified in the extract is catalyzed by calpain. The calpain in the extract degrades also N‐myc, c‐Fos and c‐Jun, but not lysozyme. In crude extract, the calpain activity can be demonstrated only when the molar ratio of the calpain exceeds that of its native inhibitor. Recent experimental evidence implicates both the ubiquitin proteasome pathway and calpain in the degradation of the tumor suppressor, and it was proposed that the two pathways may play a role in targeting the protein under various conditions. The potential role of the two systems in this important metabolic process is discussed.


Oncogene | 2001

Ataxia-telangiectasia: chronic activation of damage-responsive functions is reduced by α-lipoic acid

Magtouf Gatei; Dganit Shkedy; Kum Kum Khanna; Tamar Uziel; Yosef Shiloh; Tej K. Pandita; Martin F. Lavin; Galit Rotman

Cells from patients with the genetic disorder ataxia-telangiectasia (A-T) are hypersensitive to ionizing radiation and radiomimetic agents, both of which generate reactive oxygen species capable of causing oxidative damage to DNA and other macromolecules. We describe in A-T cells constitutive activation of pathways that normally respond to genotoxic stress. Basal levels of p53 and p21WAF1/CIP1, phosphorylation on serine 15 of p53, and the Tyr15-phosphorylated form of cdc2 are chronically elevated in these cells. Treatment of A-T cells with the antioxidant α-lipoic acid significantly reduced the levels of these proteins, pointing to the involvement of reactive oxygen species in their chronic activation. These findings suggest that the absence of functional ATM results in a mild but continuous state of oxidative stress, which could account for several features of the pleiotropic phenotype of A-T.


Human Mutation | 1998

Identification of ATM mutations using extended RT-PCR and restriction endonuclease fingerprinting, and elucidation of the repertoire of A-T mutations in Israel.

Shlomit Gilad; Rami Khosravi; Reli Harnik; Yael Ziv; Dganit Shkedy; Yaron Galanty; Moshe Frydman; Jacov Levi; Ozden Sanal; Luciana Chessa; Dominique Smeets; Yosef Shiloh; Anat Bar-Shira

Ataxia‐telangiectasia (A‐T) is an autosomal recessive disorder characterized by neurodegeneration, immunodeficiency, cancer predisposition, and radiation sensitivity. The responsible gene, ATM, has an extensive genomic structure and encodes a large transcript with a 9.2 kb open reading frame (ORF). A‐T mutations are extremely variable and most of them are private. We streamlined a high throughput protocol for the search for ATM mutations. The entire ATM ORF is amplified in a single RT‐PCR step requiring a minimal amount of RNA. The product can serve for numerous nested PCRs in which overlapping portions of the ORF are further amplified and subjected to restriction endonuclease fingerprinting (REF) analysis. Splicing errors are readily detectable during the initial amplification of each portion. Using this protocol, we identified 5 novel A‐T mutations and completed the elucidation of the molecular basis of A‐T in the Israeli population. Hum Mutat 11:69–75, 1998.


FEBS Letters | 1994

Complete reconstitution of conjugation and subsequent degradation of the tumor suppressor protein p53 by purified components of the ubiquitin proteolytic system

Dganit Shkedy; Hedva Gonen; Beatrice Bercovich; Aaron Ciechanover

The wild‐type tumor suppressor protein p53 is a short‐lived protein that plays important roles in regulation of cell cycle, differentiation, and survival. Mutations that inactivate or alter the tumor suppressor activity of the protein seem to be the most common genetic change in human cancer and are frequently associated with changes in its stability. The ubiquitin system has been implicated in the degradation of p53 both in vivo and in vitro. A mutant cell line that harbors a thermolabile ubiquitin‐activating enzyme, E1, fails to degrade p53 at the nonpermissive temperature. Studies in cell‐free extracts have shown that covalent attachment of ubiquitin to the protein requires the three conjugating enzymes: E1, a novel species of ubiquitin‐carrier protein (ubiquitin‐conjugating enzyme; UBC),E2‐F1, and an ubiquitin‐protein ligase, E3. Recognition of p53 by the ligase is facilitated by formation of a complex between the protein and the human papillomavirus (HPV) oncoprotein E6. Therefore, the ligase has been designated E6‐associated protein (E6‐AP). However, these in vitro studies have not demonstrated that the conjugates serve as essential intermediates in the proteolytic process. In fact, in many cases, conjugation of ubiquitin to the target protein does not signal its degradation. Thus, it is essential to demonstrate that p53‐ubiquitin adducts serve as essential proteolytic intermediates and are recognized and degraded by the 26S protease complex, the proteolytic arm of the ubiquitin pathway. In this study, we demonstrate that conjugates of p53 generated in the presence of purified, E1, E2, E6‐AP, E6, ubiquitin and ATP, are specifically recognized by the 26S protease complex and degraded. In contrast, unconjugated p53 remains stable. The ability to reconstitute the system from purified components will enable detailed analysis of the recognition process and the structural motifs involved in targeting the protein for degradation.


Cell Cycle | 2015

Regulation of Elg1 activity by phosphorylation

Dganit Shkedy; Nishant Singh; Keren Shemesh; Ayelet Amir; Tamar Geiger; Batia Liefshitz; Yaniv Harari; Martin Kupiec

ELG1 is a conserved gene with important roles in the maintenance of genome stability. Elg1s activity prevents gross chromosomal rearrangements, maintains proper telomere length regulation, helps repairing DNA damage created by a number of genotoxins and participates in sister chromatid cohesion. Elg1 is evolutionarily conserved, and its Fanconi Anemia-related mammalian ortholog (also known as ATAD5) is embryonic lethal when lost in mice and acts as a tumor suppressor in mice and humans. Elg1 encodes a protein that forms an RFC-like complex that unloads the replicative clamp, PCNA, from DNA, mainly in its SUMOylated form. We have identified 2 different regions in yeast Elg1 that undergo phosphorylation. Phosphorylation of one of them, S112, is dependent on the ATR yeast ortholog, Mec1, and probably is a direct target of this kinase. We show that phosphorylation of Elg1 is important for its role at telomeres. Mutants unable to undergo phosphorylation suppress the DNA damage sensitivity of Δrad5 mutants, defective for an error-free post-replicational bypass pathway. This indicates a role of phosphorylation in the regulation of DNA repair. Our results open the way to investigate the mechanisms by which the activity of Elg1 is regulated during DNA replication and in response to DNA damage.


Genes & Development | 2001

ATM-dependent phosphorylation of Mdm2 on serine 395: role in p53 activation by DNA damage

Ruth Maya; Moshe Balass; Seong-Tae Kim; Dganit Shkedy; Juan-Fernando Martinez Leal; Ohad Shifman; Miri Moas; Thomas Buschmann; Ze'ev Ronai; Yosef Shiloh; Michael B. Kastan; Ephraim Katzir; Moshe Oren


Proceedings of the National Academy of Sciences of the United States of America | 1999

Rapid ATM-dependent phosphorylation of MDM2 precedes p53 accumulation in response to DNA damage

Rami Khosravi; Ruth Maya; Tanya Gottlieb; Moshe Oren; Yosef Shiloh; Dganit Shkedy


Human Molecular Genetics | 1996

Predominance of Null Mutations in Ataxia-Telangiectasia

Shlomit Gilad; Rami Khosravi; Dganit Shkedy; Tamar Uziel; Yael Ziv; Kinneret Savitsky; Galit Rotman; Sara Smith; Luciana Chessa; Timothy J. Jorgensen; Reli Harnik; Moshe Frydman; Ozden Sanal; Sima Portnoi; Zipora Goldwicz; Nicolaas G. J. Jaspers; Richard A. Gatti; Gilbert M. Lenoir; Martin F. Lavin; Kouichi Tatsumi; Rolf Wegner; Yosef Shiloh; Anat Bar-Shira


Proceedings of the National Academy of Sciences of the United States of America | 2005

Phosphorylation of Hdmx mediates its Hdm2- and ATM-dependent degradation in response to DNA damage

Yaron Pereg; Dganit Shkedy; Petra de Graaf; Erik Meulmeester; Marina Edelson-Averbukh; Mogjiborahman Salek; Sharon Biton; Amina Teunisse; Wolf D. Lehmann; Aart G. Jochemsen; Yosef Shiloh

Collaboration


Dive into the Dganit Shkedy's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar

Aaron Ciechanover

Technion – Israel Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

Moshe Oren

Weizmann Institute of Science

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Anat Bar-Shira

Tel Aviv Sourasky Medical Center

View shared research outputs
Top Co-Authors

Avatar

Beatrice Bercovich

Technion – Israel Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

Efrat Shema

Weizmann Institute of Science

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Hedva Gonen

Technion – Israel Institute of Technology

View shared research outputs
Researchain Logo
Decentralizing Knowledge