Titia de Lange to receive 47th Rosenstiel Award

Professor Titia de Lange

The 47th Lewis S. Rosenstiel Award for Distinguished Work in Basic Medical Research has been awarded to Professor Titia de Lange of Rockefeller University for her studies on the protection of chromosome ends (telomeres) from degradation and rearrangement. Professor de Lange will receive the award on April 12, 2018 at Brandeis University where de Lange will present a public lecture.

Dr. de Lange’s laboratory identified and characterized the roles of proteins that compose the shelterin complex, which binds specifically to the special telomeric DNA sequences and maintains the stability of these ends.  Dr. de Lange’s work has shown that the shelterin complex and the unusual telomere-loop structure of telomere DNA prevent these ends from being detected as broken chromosome ends and thus protect telomeres from being degraded and rearranged as are the ends at chromosome breaks.  De Lange’s work has further shown that disabling different components of shelterin triggers different cellular alarms designed to detect broken and degraded DNA ends and leads to lethal chromosome rearrangements such as the fusion of chromosomes.  In addition, her lab has gained critical insights into the mechanisms of cellular response to the presence of DNA damage and recently has defined processes that lead to massive chromosome rearrangements (chromothripsis) associated with many human cancers.

She is the Leon Hess Professor and director of the Anderson Center for Cancer Research at Rockefeller University, as well as an American Cancer Society Research Professor.  Her honors include: the Life Sciences Breakthrough Prize, the Rosalind E. Franklin Award from the National Cancer Institute, the Vilcek Prize in Biomedical Sciences, election as a foreign member of the US National Academy of Sciences and as Fellow of the American Academy of Arts and Sciences.

The Rosenstiel Award has had a distinguished record of identifying and honoring pioneering scientists who subsequently have been honored with the Lasker and Nobel Prizes.  Professor de Lange joins a long list of past awardees.

Rosenstiel Award 2012- Dr. Steven J. Elledge

The 2012 Rosenstiel award is being awarded to Dr. Steven J. Elledge of Harvard University and the Howard Hughes Medical Institute for his seminal contributions towards understanding the eukaryotic DNA damage response[1] [2] .
Cells are constantly challenged by damage to their DNA. It of no surprise therefore, that both prokaryotic and eukaryotic cells have evolved sophisticated and remarkably complex responses to deal with damaged DNA. It is for elucidating these mechanisms that Dr. Elledge is being honored with the Rosenstiel award this year.
Dr. Elledge’s interest with the DNA damage response began as a graduate student at MIT in the laboratory of Graham Walker, where he identified and cloned genes involved in DNA repair mechanism known as the SOS reponse in the bacterium E.coli[3, 4] . It was during this time that Dr. Elledge also invented an extremely useful molecular biology tool known as ‘phasmids’ which allowed for the ability to rapidly clone E.coli genes by packaging them in phages[5].
After MIT, Dr Elledge began his postdoctoral work at Stanford University where he discovered the Ribonucleotide reductase(RNR) genes in budding yeast[6, 7]. These genes are induced following DNA damage to promote the synthesis of deoxyribonucleotides which helps facilitate DNA repair. Dr. Elledge followed up on this work as a professor at Baylor University by a series of important papers that shed light on how cells arrest division after DNA damage. Most notably in 1994, his group identified the Rad53 checkpoint kinase that is activated after DNA damage and contributes to cell cycle arrest [8]. In 1998, his group also identified the mammalian homolog of Rad53 (Chk2) [9, 10].In 1999, the Elledge group reported that the DNA damage checkpoint in yeast occurs in two parallel pathways laying the foundation of our understanding of the DNA damage checkpoint[11]. More recently, work from the Elledge lab identified novel factors in the DNA damage response by performing a siRNA screen in mammalian cells[12].
Dr Steve Elledge has been an investigator of the Howard Hughes Medical Institute since 1993. In 2003 he moved to Harvard Medical School as Professor in the Departments of Genetics and as a Geneticist in the Department of Medicine, Brigham and Women’s Hospital. Dr. Elledge was elected in 2003 to both the U.S. National Academy of Sciences and the American Academy of Arts and Sciences. In addition to the Rosenstiel award, he has received the DAMD Breast Cancer Innovator Award (2003), the National Academy of Sciences Award in Molecular Biology (2002), the John B. Carter, Jr. Technology Innovation Award (2002), and the Paul Marks Prize for Cancer Research (2001[2]).

Editor’s Note: On Mar 20, 2013, Elledge was named to receive a 2013 Canada Gairdner International Award.

1. Brownlee, C., Biography of Stephen J. Elledge. Proc Natl Acad Sci U S A, 2004. 101(10): p. 3336-7.
2. Haber, J.E., The 2005 Genetics Society of America Medal. Steven J. Elledge. Genetics, 2005. 169(2): p. 506-7.
3. Elledge, S.J. and G.C. Walker, Proteins required for ultraviolet light and chemical mutagenesis. Identification of the products of the umuC locus of Escherichia coli. J Mol Biol, 1983. 164(2): p. 175-92.
4. Elledge, S.J. and G.C. Walker, The muc genes of pKM101 are induced by DNA damage. J Bacteriol, 1983. 155(3): p. 1306-15.
5. Elledge, S.J. and G.C. Walker, Phasmid vectors for identification of genes by complementation of Escherichia coli mutants. J Bacteriol, 1985. 162(2): p. 777-83.
6. Elledge, S.J. and R.W. Davis, Identification of the DNA damage-responsive element of RNR2 and evidence that four distinct cellular factors bind it. Mol Cell Biol, 1989. 9(12): p. 5373-86.
7. Elledge, S.J. and R.W. Davis, DNA damage induction of ribonucleotide reductase. Mol Cell Biol, 1989. 9(11): p. 4932-40.
8. Allen, J.B., et al., The SAD1/RAD53 protein kinase controls multiple checkpoints and DNA damage-induced transcription in yeast. Genes Dev, 1994. 8(20): p. 2401-15.
9. Hirao, A., et al., DNA damage-induced activation of p53 by the checkpoint kinase Chk2. Science, 2000. 287(5459): p. 1824-7.
10. Matsuoka, S., M. Huang, and S.J. Elledge, Linkage of ATM to cell cycle regulation by the Chk2 protein kinase. Science, 1998. 282(5395): p. 1893-7.
11. Sanchez, Y., et al., Control of the DNA damage checkpoint by chk1 and rad53 protein kinases through distinct mechanisms. Science, 1999. 286(5442): p. 1166-71.
12. Adamson, B., et al., A genome-wide homologous recombination screen identifies the RNA-binding protein RBMX as a component of the DNA-damage response. Nat Cell Biol, 2012. 14(3): p. 318-28.

Damaged DNA and self-eating (autophagy) in budding yeast.

Chromosome double-strand breaks (DSBs) threaten the integrity of the genome. Cells respond to DSBs by activating the DNA damage checkpoint that blocks cells prior to mitosis, allowing more time for the repair of damaged DNA. When the DSB can be repaired, the cell cycle checkpoint is turned off so that cells can resume cell cycle progression, a process termed recovery. If the DSB remains unrepaired, G2/M arrest persists for a long time but eventually cells adapt and – despite the persistent DNA damage – complete mitosis and divide. Much of our understanding of the DNA damage response has come from the study of the budding yeast Saccharomyces cerevisiae, where it is possible to create DSB damage synchronously in all cells of the population. This can be accomplished either by uncapping telomeres, exposing their normally protected ends or by creating a single, defined DSB by inducing the site-specific HO endonuclease. From such studies, it was possible to identify a highly evolutionarily conserved DNA damage sensing and signaling cascade that is initiated by Mec1, the yeast homolog of mammalian ATR protein kinase (reviewed in Ref. (1)). Yeast genetic approaches revealed a number of adaptation-defective mutants, a subset of which also are recovery-defective. Previous studies also demonstrated that triggering the DNA damage checkpoint affects not only mitosis and the efficiency of DNA repair within the nucleus; it also affects cytoplasmic responses (2, 3). In a new paper from the Haber lab published in PNAS, we uncovered mutations in the Golgi-Associated Retrograde Protein (GARP) complex that are adaptation-defective. We show that the defect in these mutants can be mimicked by activating the cytoplasm-to-vacuole (CVT) pathway of autophagy that prevents the nuclear accumulation of separase, Esp1, in the nucleus, thus preventing the cells both adapting and recovering from DSB damage.

In budding yeast, a single unrepaired double-strand break (DSB) triggers the Mec1-dependent cell cycle arrest prior to anaphase for 12-15 before they adapt. Adaptation is accompanied by the loss of hyperphosphorylation of Rad53, yeast’s Chk2 homolog.  Rad53 remains phosphorylated in a number of adaptation-defective mutations, including deletion of the two PP2C phosphatases, ptc2ptc3D, that normally dephosphorylate Rad53.  Adaptation is also blocked by ablating a number of proteins with diverse roles in DSB repair, including srs2D, rdh54D as well as by a mutation in yeast’s polo kinase cdc5-ad.

In our paper, we find that hyperactivation of the cytoplasm-to-vacuole (CVT) autophagy pathway causes the permanent G2/M arrest of cells with a single DSB that is reflected in the nuclear exclusion of both separase, Esp1, and its chaperone/inhibitor, securin, Pds1(See figure).  Autophagy in response to DNA damage can be induced in three different ways: (1) by deleting members of the Golgi-Associated Retrograde Protein complex (GARP) such as vps51D; (2) by adding rapamycin; or (3) by overexpressing a dominant-negative ATG13-8SA mutation.  The permanent checkpoint-mediated arrest in any of these three conditions can be overcome in three ways: (1) by blocking autophagy with mutations such as atg1D, atg5D or atg11D; (2) by deleting the vacuolar protease Prb1 or its activator, Pep4; or (3) by driving Esp1 into the nucleus with a SV40 nuclear localization signal.  In contrast, these same alterations fail to suppress the adaptation defects of ptc2ptc3D or cdc5-ad.  Transient accumulation of Pds1 in the vaucole is also seen in wild type cells lacking PEP4 after induction of a DSB.  Unlike other adaptation-defective mutations, G2/M arrest persists even as the DNA damage-dependent phosphorylation of Rad53 diminishes, suggesting that cells have become unable to activate separase to initiate anaphase after DNA damage.  In addition, we have found that cells fail to recover when VPS51 is deleted or when ATG13-8SA is overexpressed.

Increased autophagy causes the delocalization of both Pds1 (securin) and Esp1 (separase) from the nucleus in checkpoint-arrested budding yeast cells. A. GFP-tagged Pds1 and Esp1 localize to the nucleus at the neck of G2/M-arrested wild type (WT) cells that have suffered a single unrepaired chromosome double-strand break (DSB). Both rdh54Δ and vps51Δ prevent cells from adapting and resuming cell cycle progression, but only ablating Vps51 – part of the Golgi-associated retrograde protein (GARP) complex – causes the mislocalization of Pds1 and Esp1 and the partial degradation of Pds1 by vacuolar proteases. Preventing degradation of Pds1 (and possibly other mitotic regulators) results in the suppression of permanent arrest and the relocalization of sufficient Esp1 into the nucleus to release cells from their pre-anaphase arrest. A similar suppression of arrest in vps51Δ cells is obtained by disabling autophagy (not shown). B. Induction of autophagy by overexpression of ATG13-8SA (6) prevents adaptation in wild type cells. Expression of ATG13-SA was induced at the same time that a single, unrepairable DSB was created. Whereas normal cells adapt by 24 h, increased autophagy prevents cells from progressing beyond the G2/M stage of the cell cycle. Deletion of the PEP4 gene that activates vacuolar proteases or ATG1 that is required for autophagy suppresses the arrest and allows cells to divide and resume cell cycle progression.

Taken together with other recent results (4, 5), these observations emphasize that the DNA damage response can trigger the mislocalisation and cytoplasmic proteolysis of important nuclear proteins that regulate DNA repair and cell cycle progression. These results broaden our perspective on the ways in which cells respond to DNA damage and delay cell cycle progression while such damage persists.

Ex MCB grad Farokh Dotiwala, current MCB grad Vinay Eapen and ex-postdoc Jake Harrison were the co-first authors on this paper. Assistant professor Satoshi Yoshida also contributed significantly to this project.

Dotiwala F(*), Eapen VV(*), Harrison JC(*), Arbel-Eden A, Ranade V, Yoshida S & Haber JE (2012) DNA damage checkpoint triggers autophagy to regulate the initiation of anaphase, PNAS (Published online before print November 19, 2012, doi: 10.1073/pnas.1218065109)

1.         Harrison JC & Haber JE (2006) Surviving the breakup: the DNA damage checkpoint. Annu Rev Genet 40:209-235.
2.         Dotiwala F, Haase J, Arbel-Eden A, Bloom K, & Haber JE (2007) The yeast DNA damage checkpoint proteins control a cytoplasmic response to DNA damage. Proc Natl Acad Sci U S A 104(27):11358-11363.
3.         Smolka MB, et al. (2006) An FHA domain-mediated protein interaction network of Rad53 reveals its role in polarized cell growth. J Cell Biol 175(5):743-753.
4.         Robert T, et al. (2011) HDACs link the DNA damage response, processing of double-strand breaks and autophagy. Nature 471(7336):74-79.
5.         Dyavaiah M, Rooney JP, Chittur SV, Lin Q, & Begley TJ (2011) Autophagy-dependent regulation of the DNA damage response protein ribonucleotide reductase 1. Mol Cancer Res 9(4):462-475.
6.         Kamada Y (2010) Prime-numbered Atg proteins act at the primary step in autophagy: unphosphorylatable Atg13 can induce autophagy without TOR inactivation. Autophagy 6(3):415-416.

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