https://www.bakkenistlab.com/publications daily 0.75 2020-04-16 https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586996160298-4BXTK1E6LHHNTOWL0D46/Tcells.png Recent Publications - We are interested in mechanisms that coordinate DNA replication and transcription in T regulatory and CD8+ T cells cultured ex vivo. Naive mice contain about 200 CD8+ T cells for a given p:MHC I complex. These 200 cells expand 500,000-fold in a few days to generate 10^7 cells at the peak of the primary response. CD8+ T cells have evolved with unique mechanisms that facilitate rapid DNA replication and cell division. Vendetti FP, Karukonda P, Clump DA, Teo T, Lalonde R, Nugent K, Ballew M, Kiesel BF, Beumer JH, Sarkar SN, Conrads TP, O’Connor MJ, Ferris RL, Tran PT, Delgoffe GM, Bakkenist CJ (2018) ATR kinase inhibitor AZD6738 potentiates CD8+ T cell activity in the tumor microenvironment following radiation. Journal of Clinical Investigation, 128, 3926-3940. PMID: 29952768 Vendetti FP, Leibowitz BJ, Barnes J, Schamus S, Kiesel BF, Abberbock S, Conrads T, Clump DA, Cadogan E, O’Connor MJ, Yu J, Beumer JH, Bakkenist CJ (2017) Pharmacologic ATM but not ATR kinase inhibition abrogates p21-dependent G1 arrest and promotes gastrointestinal syndrome after total body irradiation. Scientific Reports, 7, 41892. PMID: 28145510; PMCID: PMC 5286430. Vendetti FP, Lau A, Schamus S, Conrads TP, O’Connor MJ, Bakkenist CJ (2015) The orally active and bioavailable ATR kinase inhibitor AZD6738 potentiates the anti-tumor effects of cisplatin to resolve ATM-deficient non-small cell lung cancer in vivo. Oncotarget, 6, 44289-44305. PMID: 26517239; PMCID: PMC4792557 https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1587056402892-YFGNCL3T5W7QNELPJ6UJ/DSBoval.jpg Recent Publications - We are interested in mechanisms that distinguish the DNA damage responses associated with normal DNA metabolism that remain localized at a DNA double-strand break or damaged replication fork, and the cellular DNA damage response above some threshold of lesions that induces cell cycle checkpoints. ATM kinase activity is increased within seconds of exposure to 0.05 Gy ionizing radiation or following the induction of just two DNA double-strand breaks and this activity orchestrates DNA repair. More than 50% of ATM molecules are activated following exposure to 0.5 Gy ionizing radiation and this activity induces the G1 cell cycle checkpoint as well as DNA repair. Understanding the mechanisms that distinguish these DNA damage responses is important as the sequence of treatment with a DNA damaging chemotherapy and DNA damage response inhibitor will determine the damage induced by the combination. Bakkenist CJ, Czambel RK, Lin Y, Yates NA, Zeng X, Shogan J, Schmitz JC (2019) Quantitative analysis of ATM phosphorylation in lymphocytes. DNA Repair, 80, 1 Bakkenist CJ, Czambel RK, Hershberger P, Tawbi H, Beumer JH, Schmitz JC (2015) A quasi-quantitative dual multiplexed immunoblot method to simultaneously analyze ATM and H2AX phosphorylation in human peripheral blood mononuclear cells. Oncoscience, 2, 542-554. PMID: 26097887; PMCID: PMC4468340 Bakkenist CJ, Czambel RK, Clump DA, Greenberger JS, Beumer JH and Schmitz JC (2013) Radiation therapy induces the DNA damage response in peripheral blood. Oncotarget 4, 1143-1148. PMID: 23900392; PMCID: PMC3787146 https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1587056220133-92F7CERHEYZI7L9I72C9/tugofwarATRCDK1.jpg Recent Publications - We are interested in origin firing through S phase. We showed that this is controlled by gradients of kinase activities. Basal ATR and CHK1 kinase activities inhibit origin firing in undamaged cells and this limits origin firing and DNA replication to accommodate rate-limiting concentrations of dNTPs and key replication proteins. The cyclin-dependent kinase CDK1 induces origin firing through S phase and then when it’s activity spikes the onset of mitosis. ATR and CHK1 kinase activities increase in cells treated with agents that damage replication forks and this arrests origin firing and DNA replication - the S phase cell cycle checkpoint. Moiseeva TN, Yin Y, Calderon MJ, Qian C, Schamus-Haynes S, Sugitani N, Osmanbeyoglu HU, Rothenberg E, Watkins SC, Bakkenist CJ (2019) An ATR and CHK1 kinase signaling mechanism that limits origin firing during unperturbed DNA replication. PNAS, 116, 13374 Moiseeva TN, Qian C, Sugitani N, Osmanbeyoglu HU, Bakkenist CJ (2019) WEE1 kinase inhibitor AZD1775 induces CDK1 kinase-dependent origin firing in unperturbed G1 and S phase cells. PNAS, 116, 23891-23893 Moiseeva T, Hood B, Schamus S, O’Connor MJ, Conrads TP, Bakkenist CJ (2017) ATR kinase inhibition induces unscheduled origin firing through a Cdc7-dependent association between GINS and And-1. Nature Communications 8, 1392. PMID: 29123096; PMCID: PMC 5680267 Moiseeva, TN, Bakkenist CJ (2019) Dormant origin signaling during unperturbed replication. DNA Repair, 81, 102655 https://www.bakkenistlab.com/people daily 0.75 2021-05-26 https://www.bakkenistlab.com/home daily 1.0 2021-05-26 https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586979994806-D3VWGSW3TJSQLV9SHSI2/WebCBFig6_11.png Home - DNA Damage Signaling in Cancer Patients ATM kinase activity is associated with ATM autophosphorylation on serine-1981, and antisera that recognize phosphorylated serine-1981 are the most sensitive marker of exposure to radiation and DNA damaging agents that has been identified. We developed a quantitative assay for ATM phosphorylation on serine-1981 and showed that ATM kinase-dependent DNA damage signaling is increased in the peripheral blood mononuclear cells (PBMCs) of patients treated with targeted radiation therapy. We showed that the circulation of blood through small tumors targeted with radiation for as little as 164 or 100 seconds was sufficient to induce DNA damage signaling in PBMCs throughout the patients body. We are interested in whether this is a predictive biomarker of response to radiation therapy and whether this changes the activity of immune cells in patients treated with radiation. Remarkably, we showed that ATM kinase-dependent DNA damage signaling is higher per unit dose of ionizing radiation in women than men. We believe this finding is highly significant and has far reaching implications for the management of cancer in women and men. . https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586886509381-0717C2B9QESHGD0BOABP/WebCBFig1.png Home - DNA Damage Response Inhibitors We are interested in the impact of DNA damage response inhibitors in cells that have not been treated with a DNA damaging agent as well as in cells treated with radiation and DNA damaging chemotherapy. ATM and ATR are apical signaling kinases whose activities are increased at DNA double-strand breaks and damaged replication forks, respectively. ATM and ATR orchestrate DNA repair and cell survival. ATM kinase inhibitors increase DNA damage and death in cells treated with radiation and other agents that induce DNA double-strand breaks. ATR kinase inhibitors increase DNA damage and death in cells treated with agents that damage replication forks. We study the impact of ATM and ATR kinase inhibitors in cells grown in tissue culture, tumor bearing mice, and cancer patients enrolled in clinical trials. We are particularly interested in the impact of DNA damage response inhibitors in cancer cells, T regulatory cells, and CD8+ T cells. https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586979512397-766ZYQUY7ZT06OTYM9AF/GraphicalAbstract.jpg Home - Immune Responses We are interested in immune responses to radiation and DNA damaging agents. We showed that ATR kinase inhibitors combine with radiation to generate a CD8+ T cell-dependent response in tumors that is associated with immunologic memory. We showed that ATR kinase inhibitors block radiation-induced immune checkpoint PD-L1 expression on cancer cells and that this indirectly increases CD8+ T cell activity in irradiated tumors. We also showed that ATR kinase inhibitors reduce the proliferation of T regulatory cells and CD8+ T cells. https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586867080702-IFJ3S06DCM186FL10YQ6/Banner+Chris_2.png Home Bakkenist Lab, University of Pittsburgh We have openings for Postdoctoral Fellows, Graduate Students, and Technicians. Please email: bakkenistcj@upmc.edu https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586980020349-YFCRPZQLNQB270R1YRWA/WebCBFig2_3.png Home - DNA Replication We are interested in basic mechanisms that control DNA replication. We showed that pharmacologic ATR and CHK1 kinase inhibitors induce origin firing in mammalian cells that have not been treated with a DNA damaging agent . Accordingly, ATR and CHK1 kinase activities limit origin firing in mammalian cells in undamaged cells. This unanticipated finding is highly significant because patients enrolled in clinical trials are being treated with ATR and CHK1 inhibitors prior to radiation and DNA damaging chemotherapy. https://www.bakkenistlab.com/contact daily 0.75 2020-04-16 https://images.squarespace-cdn.com/content/v1/5e94a084aa92821de07affad/1586811735482-0Z2M8DKMYV8IXK872WH1/shutterstock_646100272.jpg Contact https://www.bakkenistlab.com/our-team daily 0.75 2020-04-13 https://images.squarespace-cdn.com/content/v1/5c5a514d65019f01a2cb2be5/1560270383883-RD0ZZ5IWYVTAZQLOPC5S/image-asset.jpeg Our Team - First Name Last Name Tobias Keene, D.D.S. Hailing from Richmond, Virginia, Dr. Tobias Keene brings a bit of unabashed Southern hospitality to all his patients. He moved to Washington, D.C. over thirty years ago as a freshman at Ivy College. Right after graduation, he attended World University’s School of Dentistry. Before opening Keene Dental in 1994, he worked for free clinics and some of the finest practices in the District. He is part of the 123 Dental Association and stays up-to-date on the latest dental discoveries. When not striving to keep his patients happy and healthy, he’s enjoys hiking with his family in Rock Creek Park. https://images.squarespace-cdn.com/content/v1/5c5a514d65019f01a2cb2be5/1565704487180-E5RP62PX84ONAOCUM5SN/erin.jpg Our Team - First Name Last Name Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Eget velit aliquet sagittis id consectetur purus ut faucibus pulvinar. Commodo quis imperdiet massa tincidunt. At in tellus integer feugiat. Tincidunt vitae semper quis lectus nulla at. Turpis cursus in hac habitasse platea dictumst quisque. Volutpat commodo sed egestas egestas fringilla phasellus faucibus scelerisque. Lorem donec massa sapien faucibus et molestie ac feugiat. Vitae turpis massa sed elementum tempus egestas sed. Purus faucibus ornare suspendisse sed nisi. Vitae semper quis lectus nulla at. Arcu odio ut sem nulla pharetra diam sit amet. Sit amet purus gravida quis blandit turpis cursus in. https://images.squarespace-cdn.com/content/v1/5cdb0b54755be25d5d92bfb3/1565794729131-IK7N1Y5COUG95DEBNMK1/edward.jpg Our Team - First Name Last Name Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Eget velit aliquet sagittis id consectetur purus ut faucibus pulvinar. Commodo quis imperdiet massa tincidunt. At in tellus integer feugiat. Tincidunt vitae semper quis lectus nulla at. Turpis cursus in hac habitasse platea dictumst quisque. Volutpat commodo sed egestas egestas fringilla phasellus faucibus scelerisque. Lorem donec massa sapien faucibus et molestie ac feugiat. Vitae turpis massa sed elementum tempus egestas sed. Purus faucibus ornare suspendisse sed nisi. Vitae semper quis lectus nulla at. Arcu odio ut sem nulla pharetra diam sit amet. Sit amet purus gravida quis blandit turpis cursus in. https://www.bakkenistlab.com/donate daily 0.75 2025-05-09