Govindaswamy Chinnadurai, Ph.D.
Professor of Molecular Virology
Molecular Microbiology and Immunology
Ph.D. in Molecular Biology, University of Texas, Dallas, 1974
Our current research projects center around three areas: (1) regulation of oncogenic conversion of epithelial cells by the model viral oncogene adenovirus E1A, (2) cell death regulation by BH3-only pro-apoptotic proteins in virus-infected cells and (3) role of CtBP1 (R342W) mutant allele in neurodevelopmental delays.
Regulation of oncogenic conversion of epithelial cells by Adenovirus E1A. E1A has been extensively studied as a model dominant viral oncogene. Studies on
E1A have been instrumental in the discovery of common mechanisms by which the oncogenes
of small DNA tumor viruses promote cell proliferation by subverting the cell cycle.
The oncogenic activities of E1A are controlled by the N-terminal half of E1A (exon
1) through interaction with three major cellular protein complexes such as the pRb
family proteins, p300/CBP transcriptional co-activators and p400 chromatin remodeling
complex (Figure 1). Studies from our laboratory led to the unexpected discovery that
the E1A C-terminal region (exon 2) negatively regulates epithelial cell transformation
(in cooperation with the Ras oncogene) and oncogenesis. Mutational dissection of
the E1A C-terminal region and proteomic analysis of cellular proteins associated with
E1A C-terminal region have revealed that interaction of E1A with three different cellular
protein complexes – CtBP (C-terminal protein) corepressor complex, DYRK1A/1B/HAN11
complex and FOXK1/K2 transcription factors, collectively contribute to suppression
of oncogenic transformation. Our studies also revealed that the proto oncoprotein
c-Myc was associated with E1A through the p400 protein complex and implicated c-Myc
in E1A-mediated transforming activity. We are undertaking genomic approaches to elucidate
the molecular pathways regulated by these cellular protein complexes and to determine
the effect of E1A on the manifestation of cellular processes regulated by various
Figure 1. Schematic illustration of interaction of cellular proteins with HAdV5 E1A
proteins. The functional consequences of such protein interactions are indicated. The green
upward arrows indicate activation and the red downward arrows indicate suppression
of various cellular processes.
Figure 2. A. Domain structure of BIK protein. Three domains of human BIK and their homologies to BIK proteins from different animal species are shown. The α3 region (predicted) encompassing the BH3 domain is highly conserved. The C-terminal domain (aa121-135) that is required for maximal pro-apoptotic activity of hBIK is conserved only in mBIK. B. Domain structure of BNIP3. The BH3-like domain, the conserved domain, the trans-membrane domain (TM) and the Cys residues implicated in the stabilization of BNIP3 homodimers are indicated. The amino acid sequences of the TM domain and the sequence elements that mediate detergent-stable homodimerization are shown.
Cell death regulation by BH3-only pro-apoptotic proteins in virus-infected cells. Our work on apoptosis regulation during adenovirus infection led to the discovery of the founding member (BIK) of a class of pro-apoptotic molecules known as ‘BH3-only’ proteins (Figure 2A). The BH3-only protein BIK plays an essential role in adenovirus-induced apoptosis and is targeted by the viral anti-apoptosis protein, E1B-19K to suppress virus-induced apoptosis. Adenovirus induced apoptosis signaling is transmitted through BIK to the multi-domain pro-apoptotic protein BAX. Our current research focuses on the molecular mechanisms of BIK ‘activation’ in virus-infected cells, selective BIK-dependent cell death signaling via BAX and the role of BIK on viral pathogenesis. Our laboratory also discovered the BH3-only related molecule BNIP3 (Figure 2B). The BNIP3 subfamily proteins (BNIP3 and BNIP3L) are major effectors of mitochondrial autophagy and they also induce context-dependent apoptosis. These molecules are also targeted by the viral anti-apoptosis protein E1B-19K. We are investigating the role of BNIP3 and the related molecule BNIP3L (NIX) in virus-induced autophagy and modulation of their activities by E1B-19K.
Role of CtBP 1 (R342W) mutant allele in neurodevelopmental delays. The founding member of the C-terminal binding protein family (composed of CtBP1 and
CtBP2, and their splice forms) was discovered in our lab as a cellular protein that
interacted with a specific motif (PLDLS) at the C-terminal region of adenovirus E1A.
The CtBP proteins function as transcriptional corepressors in association with sequence
specific DNA-binding repressors as well as various chromatin modifying repression
effector molecules. These factors interact with CtBP dimers through two protein-binding
interfaces (PLDLS-binding and RRT-binding) (Figure 3). The CtBP1 corepressor complex
mediates coordinated histone modifications by deacetylation and methylation of histone
H3-K9 (H3K9) and demethylation of histone H3-K4 (H3K4). CtBP transcriptional activity
is modulated by the nuclear NADH/NAD+ ratio (regulating CtBP dimerization) and thus
is also influenced by cell metabolic status.
Whole exome sequencing studies have identifiedseveral young patients exhibiting neurodevelopmental delays such as intellectual disability, ataxia, hypotonia and tooth enamel defects, contained a specific recurrent de novo mutation in the CtBP1 gene [R342W (CtBP1-L)/R331W (CtBP1-S)]. This mutation is located within the CtBP1 region involved in interaction with the various repression factors. We are using patient-derived stem and neuronal cell models to characterize the mutant phenotypes and the deregulated transcriptional pathways to elucidate the mechanisms of CtBP-mediated developmental delays and to design interventional approaches.
Figure 3. Linear domain map of CtBP1-L. The CtBP1-S isoform lacks 13 N-terminal residues of CtBP1-L. CtBP1 has a D2-HDH homology and activity. The NAD(H)-binding domain, the substrate binding domain and the dehydrogenese catalytic residues are shown. The substrate binding domain also functions as a protein-interaction domain where protein cofactors with PLDLS-motifs bind (PLDLS-binding cleft, shown in yellow). The mutation R342W maps in the α-5 region of the PLDLS-bonding cleft. The second protein-interaction domain designated RRT-binding domain is also indicated.
Labs and Facilities
- Thirugnana Subramanian, Ph.D., associate research professor
- Selvamani Vijayalingam, Ph.D., research associate
Select Recent Publications
- Vijayalingam S, Subramanian T, Zhao LJ, Chinnadurai G. The Cellular Protein Complex Associated with a Transforming Region of E1A Contains c-MYC. J Virol. 2015 Nov 11;90(2):1070-9. doi: 10.1128/JVI.02039-15. PubMed PMID: 26559831; Pub Med Central PMCID: PMC4702669.
- Vijayalingam S, Kuppusamy M, Subramanian T, Strebeck FF, West CL, Varvares M, Chinnadurai G. Evaluation of apoptogenic adenovirus type 5 oncolytic vectors in a Syrian hamster head and neck cancer model. Cancer Gene Ther. 2014 Jun;21(6):228-237. doi: 10.1038.cgt.2014.22 Epub 2014 May 30. PubMed PMID: 24874842; PubMed Central PMCID: PMC4353496.
- Subramanian T, Zhao LJ, Chinnadurai G. Interaction of CtBP with adenovirus E1A suppresses immortalization of primary epithelial cells and enhances virus replication during productive infection. Virology. 2013 Sep 1;443(2):313-20. doi: 10.1016/j.virol.2013.05.018. Epub 2013 Jun 5. PubMed PMID: 23447199; PubMed Central PMCID: PMC3732182.
- Chinnadurai G. Opposing oncogenic activities of small DNA tumor virus transforming proteins. Trends Microbiol. 2011 Apr;19(4):174-83. Epub 2011 Feb 15. PubMed PMID: 21330137; PubMed Central PMCID: PMC3095844.
- Komorek J, Kuppuswamy M, Subramanian T, Vijayalingam S, Lomonosova E, Zhao LJ, Mymryk JS, Schmitt K, Chinnadurai G. Adenovirus type 5 E1A and E6 proteins of low-risk cutaneous beta-human papillomaviruses suppress cell transformation through interaction with FOXK1/K2 transcription factors. J Virol. 2010 Mar;84(6):2719-31. Epub 2010 Jan 6. PubMed PMID: 20053746; PubMed Central PMCID: PMC2826030.
- Zhao LJ, Kuppuswamy M, Vijayalingam S, Chinnadurai G. Interaction of ZEB and histone deacetylase with the PLDLS-binding cleft region of monomeric C-terminal binding protein 2. BMC Mol Biol. 2009 Sep 15;10:89. PubMed PMID: 19754958; PubMed Central PMCID: PMC2749851.
- Chinnadurai G, Vijayalingam S, Rashmi R. BIK, the founding member of the BH3-only family proteins: mechanisms of cell death and role in cancer and pathogenic processes. Oncogene. 2008 Dec;27 Suppl 1:S20-9. Review. PubMed PMID: 19641504; PubMed Central PMCID: PMC2928562.
- Lomonosova E, Chinnadurai G. BH3-only proteins in apoptosis and beyond: an overview. Oncogene. 2008 Dec;27 Suppl 1:S2-19. Review. PubMed PMID: 19641503; PubMed Central PMCID: PMC2928556.
- Chinnadurai G, Vijayalingam S, Gibson SB. BNIP3 subfamily BH3-only proteins: mitochondrial stress sensors in normal and pathological functions. Oncogene. 2008 Dec;27 Suppl 1:S114-27. Review. PubMed PMID: 19641497; PubMed Central PMCID: PMC2925272.
- Chinnadurai G. The transcriptional corepressor CtBP: a foe of multiple tumor suppressors. Cancer Res. 2009 Feb 1;69(3):731-4. Epub 2009 Jan 20. Review. PubMed PMID: 19155295; PubMed Central PMCID: PMC4367538.
- Kuppuswamy M, Vijayalingam S, Zhao LJ, Zhou Y, Subramanian T, Ryerse J, Chinnadurai G. Role of the PLDLS-binding cleft region of CtBP1 in recruitment of core and auxiliary components of the corepressor complex. Mol Cell Biol. 2008 Jan;28(1):269-81. Epub 2007 Oct 29. PubMed PMID: 17967884; PubMed Central PMCID: PMC2223311.
- Subramanian T, Vijayalingam S, Lomonosova E, Zhao LJ, Chinnadurai G. Evidence for involvement of BH3-only proapoptotic members in adenovirus-induced apoptosis. J Virol. 2007 Oct;81(19):10486-95. Epub 2007 Jul 25. PubMed PMID: 17652400; PubMed Central PMCID: PMC2045492.
- Chinnadurai G. Transcriptional regulation by C-terminal binding proteins. Int J Biochem Cell Biol. 2007;39(9):1593-607. Epub 2007 Feb 4. Review. PubMed PMID: 17336131.
Apoptosis regulation by adenovirus and cellular genes