Research

Sagar Sengupta

M. Sc.
Calcutta University, India

Ph. D.
Indian Institute of Science, Bangalore, India

Postdoctoral Research
Institut de Genetique et de Biologie Moleculaire et Cellulaire, Strasbourg, France.
Laboratory of Human Carcinogenesis, National Cancer Institute, National
Institutes of Health, Bethesda, Maryland, USA.

Email
sagar@nii.ac.in

 

Research Interest

Tumour suppressors and oncogenes, DNA damage response, Ubiquitylation and phosphorylation dependent signalling mechanisms, global regulation of gene expression, mitochondrial replication, role of mitochondria in cancer

Group Members

Jyoti Kumari, Raina Priyadarshini, Swati Priya, Himanshi Agarwal, Preeti Attri, Vinoth Madhavan, Mansoor Hussain, Arun Prasath Damodaran, Vivek Tripathi, Radhey Shyam, Nitin

Summary of Research

Title: Determining the signalling and repair pathways that are altered in human cancer

Theme of Research:

The broad aim of the research program has been to study the signaling pathways which have undergone alterations during the process of cancer development. Tumor suppressors are a group of extremely specialized proteins whose mutations lead to the development of cancer. In other words they are the caretakers and gatekeepers of our body. We are focused on the mechanisms of tumour suppressor functions – how they are activated in response to DNA damage, how their turnover takes place, whether and how the regulation takes place via the post-transcriptional, post-translational, epigenetic mechanisms and how these proteins counteract the functions of the oncoproteins, which are known to drive neoplastic transformation, immortalization and tumorigenesis. Finally effort in the group is also focused in determining how the tumour suppressors, either directly or indirectly, help to maintain the fidelity of the genome by regulating the different repair processes, in conjunction with other tumour suppressors (for example p53) or with other process-specific proteins of the different repair pathways. The focus is not only on the nuclear genome maintenance – but also on the lesser-worked mitochondrial genome, specifically on the role of mitochondrial replication in the genome maintenance process. 

Our primary interest lies in an unique group of proteins called RecQ helicase family. We chose this family of helicases as three of its members, BLM, WRN and RECQL4, when mutated lead to cancer predisposition syndromes called Bloom syndrome (BS), Werner Syndrome (WS) and Rothmund-Thomson syndrome (RTS) respectively. Hence these proteins (BLM, WRN and RECQL4) classify as tumour suppressors. Work in the laboratory is focused on the functions of BLM and RECQL4 helicases. BLM is a nuclear helicase – which has been shown by the lab and others in the field to affect multiple steps in DNA damage response and DNA repair pathways. On the other hand, the lab was the first group to show that RECQL4 is a mitochondrial helicase, which play a role in the maintenance of the mitochondrial replication. The research in the near future will focus on trying to understand the mechanisms of signal transduction during genome integrity using a combination of biochemical assays, cell culture based models involving immortalized cells obtained from patients, imaging techniques, xenograft and non-immuno compromised mice models and patient samples. 

Awards / Fellowships

National Bioscience award for Career Development, Department of Biotechnology, Government of India (2011)
Member, Guha Research Conference (2011)

Selected Publications

  • Singh M, Bansal S, Kundu S, Bhargava P, Singh A, Motiani RK, Shyam R, Sreekanth V, Sengupta S, Bajaj A (2015). Synthesis, structure-activity relationship, and mechanistic investigation of lithocholic acid amphiphiles for colon cancer therapy. Med. Chem. Commun., 6: 192-201.
  • # Singh M, Kundu S, Reddy MA, Sreekanth V, Motiani RK, Sengupta S*, Srivastava A*, Bajaj A* (2014). Injectable small molecule hydrogel as a potential nanocarrier for localized and sustained in vivo delivery of doxorubicin. Nanoscale 6(21):12849-55 (* denotes co-corresponding authors).
  • Rajanala K, Sarkar A, Jhingan GD, Priyadarshini R, Jalan M, Sengupta S, Nandicoori VK. (2014). Phosphorylation of nucleoporin Tpr governs its differential localization and is required for its mitotic functions. J Cell Sci. 127(Pt 16): 3505-20.
  • # Gupta S, De S, Srivastava V, Hussain M, Kumari J, Muniyappa K, Sengupta S (2014) RECQL4 and p53 potentiate the activity of polymerase g and maintain the integrity of the human mitochondrial genome. Carcinogenesis 35(1): 34-45.
  • Sreekanth V, Bansal S, Motiani RK, Kundu S, Muppu SK, Majumdar TD, Panjamurthy S, Sengupta S, Bajaj A (2013) Design, Synthesis, and Mechanistic Investigations of Bile acid-Tamoxifen Conjugates for Breast Cancer Therapy. Bioconjug Chem. 24(9): 1468-1484.
  • Chandra S, Priyadarshini R, Madhavan V, Tikoo S, Hussain M, Mudgal R, Modi P, Srivastava V, Sengupta S (2013) Enhancement of c-Myc degradation by BLM helicase leads to delayed tumor initiation. J Cell Sci. 126(Pt 16): 3882-3795.
  • Tikoo S, Madhavan V, Hussain M, Miller ES, Arora P, Zlatanou A, Modi P, Townsend K, Stewart GS*, Sengupta S* (2013) Ubiquitin-dependent recruitment of the Bloom Syndrome helicase in response to replication stress is required to suppress homologous recombination. EMBO J. 32(12): 1778-1792 (* denotes co-corresponding authors).
  • Jadav RS, Chanduri MV, Sengupta S, Bhandari R (2013) Inositol Pyrophosphate Synthesis by Inositol Hexakisphosphate Kinase I is Required for Homologous Recombination Repair. J Biol Chem. 288(5): 3312-3321.
  • Kumar A, Tikoo S, Maity S, Sengupta S, Sengupta S, Kaur A, Bachhawat AK (2012) Mammalian proapoptotic factor ChaC1 and its homologues function as γ-glutamyl cyclotransferases acting specifically on glutathione. EMBO Rep. 13(12): 1095-1101.
  • De S, Kumari J, Mudgal R, Modi P, Gupta S, Futami K, Goto H, Lindor NM, Furuichi Y, Mohanty D, Sengupta S (2012) RECQL4 is essential for the transport of p53 to mitochondria in normal human cells in the absence of exogenous stress. J Cell Sci. 125(Pt 10): 2509-2522.
  • Tikoo S, Sengupta S (2010). Time to Bloom. Genome Integr. 1(1): 14.
  • Kaur S, Modi P, Srivastava V, Mudgal R, Tikoo S, Arora P, Mohanty D, Sengupta S (2010) Chk1-dependent constitutive phosphorylation of BLM helicase at Serine 646 decreases after DNA damage. Mol Cancer Res. 8(9): 1234-1247.
  • Larrieu D, Ythier D, Binet R, Brambilla C, Brambilla E, Sengupta S, Pedeux R (2009) ING2 controls DNA replication forks progression to maintain genome stability. EMBO Rep. 10(10): 1168-1174.
  • Mehta S, Miklos I, Sipiczki M, Sengupta S, Sharma N (2009) The Med8 mediator subunit interacts with the Rpb4 subunit of RNA polymerase II and Ace2 transcriptional activator in Schizosaccharomyces pombe. FEBS Lett. 583(19): 3115-3120.
  • Srivastava V, Modi P, Tripathi V, Mudgal R, De S, Sengupta S (2009) BLM helicase stimulates the ATPase and chromatin remodeling activities of RAD54. J Cell Sci. 122(Pt 17): 3093-3103.
  • Tripathi V, Kaur S, Sengupta S (2008) Phosphorylation-dependent interactions of BLM and 53BP1 are required for their anti-recombinogenic roles during homologous recombination. Carcinogenesis 29(1): 52-61.
  • Tripathi V, Nagarjuna T, Sengupta S (2007) BLM helicase-dependent and independent roles of 53BP1 during replication stress mediated homologous recombination. J. Cell Biol. 178(1): 9-14.

#  denotes publications as corresponding author

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