Agam P. Singh
Maharaja Sayajirao University, Vadodara, Gujrat, India
Jawaharlal Nehru University, India
International Centre for Genetic Engineering and Biotechnology, New Delhi, India
Langone Medical Centre, New York University, New York, USA
Malaria Liver-stage Biology, Key words: Parasite Knockout and Life cycle study, Antigen discovery, Drug discovery, Transcriptome, Protein-Protein interaction, Host-Parasite interaction, Genomics.
Surabhi Dixit, Afshana Quadri, Parul Sahu, Mohammad Kashif, Inderjeet Kalia and Himanshu Singh
Summary of Research
In the mammalian host, invasion of the hepatocytes is the first step towards developing malaria disease. Invasion by infective sporozoites is complex process and not understood very well. How parasite interacts with its host is the focus of my current research. We discovered that during early liver stage development a sporozoite surface protein (CSP) is introduced in the hepatocytes cytoplasm. CSP then shuttles into and out of nucleus of hepatocytes and changes the host transcription profile. CSP export into the cytoplasm of infected hepatocyte requires the presence of PEXEL / HTS motifs. The transport of CSP into the hepatocyte nucleus is then mediated by importins α3/β1 that binds to the nuclear localization signal (NLS) of CSP. The NLSs of CSP and NFκB p50 share the same importins. The entry of NFκB-p50 into the nucleus is strongly inhibited in cell lines expressing CSP, and in infected hepatocytes. Microarray data, from a N-terminal truncated CSP expressing cell line, showed that 40 NFκB targets were significantly down regulated. Presence of CSP in the host modifies thousands of host gene transcription that govern diverse biological processes such as metabolite transport, cell cycle, immune responses, cell growth, cell attachment, apoptosis and hypoxia and the overall effect is to enhance EEF growth.
We have the following two major areas of interest:
1. Understanding Host-parasite interactions during malaria liver stages development. Our focus is to identify Plasmodium proteins that modulate the hepatocyte cellular functions. Knockout of parasite genes combined with analyses of global changes (using omics techniques) in the infected host cell is used for the purpose.
2. Antigen/Drug discovery. We focus on
A] Knowledge based target identification for inhibitor design.
B] Known and novel compounds assay (ex vivo and in vivo) to test inhibitor/ drug efficacy.
C] Discovery of new antigens from liver-stage parasites and evaluation in animal models.
A multi-disciplinary approach is used to address above issues.
Awards / Fellowships
Ramalingaswami Fellow, DBT, India, 2009-2014
- Jaijyan DK, Singh H and Singh AP ## (2015) A Sporozoite and Liverstage Expressed Tryptophan Rich Protein Plays an Auxiliary Role in Plasmodium Liver Stage Development and is a Potential Vaccine Candidate. J. Biol. Chem., doi:10.1074/jbc.M114.588129
- Anand R, Shankar J, Tiwary BN and Singh AP ## (2015) Aspergillus flavus induces granulomatous cerebral aspergillosis in mice with display of distinct cytokine profile. Cytokine 72 (2), 166-172
- Dalai SK, Yadav N, Patidar M, Patel H and Singh AP (2015) Liver-stage specific response among endemic populations: diet and immunity. Frontiers in immunology doi:10.3389/fimmu.2015.00125
- Thakur R, Anand R, Tiwari S, Singh AP, Tiwary BN and Shankar J (2015) Cytokines induce effector T-helper cells during invasive aspergillosis; what we have learned about T-helper cells? Frontiers in Microbiology, doi: 10.3389/fmicb.2015.00429
- Anand R, Shankar J, Singh AP and Tiwary BN (2013). Cytokine milieu in renal cavities of immunocompetent mice in response to intravenous challenge of Aspergillus flavus leading to aspergillosis. Cytokine 61: 63–70.
- Banerjee T, Jaijyan DK, Surolia N, Singh AP ##, Surolia A # # (2012). Apicoplast triose phosphate transporter (TPT) gene knockout is lethal for Plasmodium. Molecular & Biochemical Parasitology 186: 44-50.
- Singh AP ##, Zhang Y, No JH, Docampo R, Nussenzweig V, and Oldfield E ## (2010). Lipophilic Bisphosphonates are potent inhibitors of Plasmodium liver-stage growth. Antimicrobial Agents and Chemotherapy 54: 2987–2993.
- Singh AP ##, Surolia N## and Surolia A (2009). Triclosan inhibit the growth of the late Liver-stage of Plasmodium. IUBMB Life 61: 923–928.
- Singh AP ##, Buscaglia CA, Wang Q, Levay A, Nussenzweig DR, Walker JR, Winzeler EA, Hodaka Fujii H, Fontoura BMA and Nussenzweig V (2007). Plasmodium Circumsporozoite protein promotes the development of the Liver-stages of the parasite. Cell 131: 492-504.
- Singh AP, Ozwara H, Kocken CHM, Puri SK, Thomas AW and Chitnis C (2005). Targeted disruption of Plasmodium knowlesi Duffy binding protein confirms its role in junction formation during invasion. Molecular Microbiology 55:1925-34.
- Choe H, Moore MJ, Wright PL, Vasilieva N, Li W, Singh AP, Shakri R, Chitnis C and Farzan M (2005). A Duffy Antigen/Receotor for chemokines (DARC) Sulfate group is essential for its association with the Plasmodium vivax Duffy binding protein. Molecular Microbiology 55:1413-22.
- Singh SK, Singh AP, Pandey S, Yazdani SS, Chitnis C and Sharma A (2003). Definition of structural elements in Plasmodium vivax and Plasmodium knowlesi Duffy binding domains necessary for erythrocyte invasion. Biochemical Journal 374: 193-198.
(# # denotes Corresponding author)