Dean W. Ballard, Ph.D.
Professor of Pathology, Microbiology and Immunology
Vanderbilt University Medical Center
813 Light Hall
Nashville, TN 37232
Molecular Mechanisms in Normal and Malignant T Cell Growth; Regulatory Protein Modifications in Immunoreceptor Signaling
During an immune response, antigen-stimulated T lymphocytes execute a genetic program that mediates their clonal expansion and the acquisition of specific effector functions. This activation process involves the transient expression of select transcription units required for cell-cycle progression. In lymphocytes harboring the type 1 human immunodeficiency virus (HIV-1), activation of this program concomitantly triggers the induction of retroviral gene expression, assembly of infectious viral particles, and T cell death. In sharp contrast, infection with the type 1 human T-cell leukemia virus (HTLV-1) leads to the constitutive expression of these growth-related gene products and the onset of neoplastic transformation.
Our laboratory is investigating the intracellular events that initiate these divergent processes and the host transcriptional machinery that regulates the relevant genes. A major link between these processes is an inducible transcription factor called NF-kB. In contrast to its transient pattern of expression in normal T lymphocytes, NF-kB is constitutively activated in cells expressing the Tax transforming protein of HTLV-1. We have recently explored (i) the mechanism of NF-kB action, (ii) the biochemical events that mediate NF-kB induction during T cell activation, and (iii) the host regulatory components that couple HTLV-1 Tax to this signal-dependent pathway.
In resting T cells, NF-kB is trapped in the cytoplasm by an inhibitor called IkB. During the process of cellular activation, IkB is phosphorylated, ubiquitinated, and degraded, thus permitting NF-kB access to the nuclear compartment. This information led us to design dominant forms of IkB which escape from signal-dependent inactivation and repress NF-kB in a constitutive manner. These IkB "super-repressors" have provided powerful genetic tools to dissect the role of NF-kB in both B and T cell development. In combination with differential display technology, we have also used these IkB super-repressors to capture immediate-early genes under NF-kB control, one of which functions to regulate the apoptotic response.
More recent studies demonstrated that the HTLV1 Tax protein binds to a cellular IkB kinase, called IKK, resulting in its persistent funtional expression. These results provide a unifying molecular explanation for the constitutive activation of NF-kB in HTLV1-infected cells. We are currently investigating how the formation of Tax/IKK complexes leads to persistent NF-kB signaling at the level of post-translational modifications. These studies are focused on the role of both phosphorylation and ubiquitination in IKK subunit regulation, which should yield insights into the mechanisms underlying chronic versus transient NF-kB signaling.
- Hansberger, MW, Campbell, JA, Danthi, P, Arrate, P, Pennington, KN, Marcu, KB, Ballard, DW, Dermody, TS IkappaB kinase subunits alpha and gamma are required for activation of NF-kappaB and induction of apoptosis by mammalian reovirus. J Virol, 81(3), 1360-71, 2007.
- Zhao T, Yang L, Sun Q, Arguellow M, Ballard DW, Hiscott J, and Lin R "NEMO has an essential function in the regulation of type I interferon production." Nature Immunol, 8(6), 592-600, 2007.
- O''Donnell, SM, Holm, GH, Pierce, JM, Tian, B, Watson, MJ, Chari, RS, Ballard, DW, Brasier, AR, Dermody, TS Identification of an NF-kappaB-dependent gene network in cells infected by mammalian reovirus. J Virol, 80(3), 1077-86, 2006.
- Kray, AE, Carter, RS, Pennington, KN, Gomez, RJ, Sanders, LE, Llanes, JM, Khan, WN, Ballard, DW, Wadzinski, BE Positive regulation of IkappaB kinase signaling by protein serine/threonine phosphatase 2A. J Biol Chem, 280(43), 35974-82, 2005.
- Carter, RS, Pennington, KN, Arrate, P, Oltz, EM, Ballard, DW Site-specific monoubiquitination of IkappaB kinase IKKbeta regulates its phosphorylation and persistent activation. J Biol Chem, 280(52), 43272-9, 2005.
- Liu, Danya, Liu, Xue Yan, Robinson, Daniel, Burnett, Christie, Jackson, Charity, Seele, Louis, Veach, Ruth Ann, Downs, Sheila, Collins, Robert D., Ballard, Dean W., Hawiger, Jacek Suppression of staphylococcal enterotoxin B-induced toxicity by a nuclear import inhibitor. J Biol Chem, 2004.
- Mora, A L, Corn, R A, Stanic, A K, Goenka, S, Aronica, M, Stanley, S, Ballard, D W, Joyce, S, Boothby, M Antiapoptotic function of NF-kappaB in T lymphocytes is influenced by their differentiation status: roles of Fas, c-FLIP, and Bcl-xL. Cell Death Differ, 10(9), 1032-44, 2003.
- Carter, Robert S, Pennington, Kevin N, Ungurait, Bradley J, Ballard, Dean W In vivo identification of inducible phosphoacceptors in the IKKgamma/NEMO subunit of human IkappaB kinase. J Biol Chem, 278(22), 19642-8, 2003.
- Carter, Robert S, Pennington, Kevin N, Ungurait, Bradley J, Arrate, Pia, Ballard, Dean W Signal-induced ubiquitination of I kappaB Kinase-beta. J Biol Chem, 278(49), 48903-6, 2003.
- Ballard, D W Molecular mechanisms in lymphocyte activation and growth. Immunol Res, 23(2-3), 157-66, 2001.
- Carter, R S, Geyer, B C, Xie, M, Acevedo-SuÃ¡rez, C A, Ballard, D W Persistent activation of NF-kappa B by the tax transforming protein involves chronic phosphorylation of IkappaB kinase subunits IKKbeta and IKKgamma. J Biol Chem, 276(27), 24445-8, 2001.
- McKinsey, T A, Chu, Z, Tedder, T F, Ballard, D W Transcription factor NF-kappaB regulates inducible CD83 gene expression in activated T lymphocytes. Mol Immunol, 37(12-13), 783-8, 2001.
- Petro, J B, Rahman, S M, Ballard, D W, Khan, W N Bruton's tyrosine kinase is required for activation of IkappaB kinase and nuclear factor kappaB in response to B cell receptor engagement. J Exp Med, 191(10), 1745-54, 2000.
- Jo, H, Zhang, R, Zhang, H, McKinsey, T A, Shao, J, Beauchamp, R D, Ballard, D W, Liang, P NF-kappa B is required for H-ras oncogene induced abnormal cell proliferation and tumorigenesis. Oncogene, 19(7), 841-9, 2000.
- Connolly, J L, Rodgers, S E, Clarke, P, Ballard, D W, Kerr, L D, Tyler, K L, Dermody, T S Reovirus-induced apoptosis requires activation of transcription factor NF-kappaB. J Virol, 74(7), 2981-9, 2000.
- Bendall, H H, Sikes, M L, Ballard, D W, Oltz, E M An intact NF-kappa B signaling pathway is required for maintenance of mature B cell subsets. Mol Immunol, 36(3), 187-95, 1999.
- Mori N, Fujii M, Ikeda S, Yamada Y, Tomonaga M, Ballard DW, Yamamoto N "Constitutive activation of NF- kappaB in primary adult T-cell leukemia cells." Blood, 59(6), 1372-1377, 1999.
- Devalaraja, M N, Wang, D Z, Ballard, D W, Richmond, A Elevated constitutive IkappaB kinase activity and IkappaB-alpha phosphorylation in Hs294T melanoma cells lead to increased basal MGSA/GRO-alpha transcription. Cancer Res, 59(6), 1372-7, 1999.
- Byrd, V M, Ballard, D W, Miller, G G, Thomas, J W Fibroblast growth factor-1 (FGF-1) enhances IL-2 production and nuclear translocation of NF-kappaB in FGF receptor-bearing Jurkat T cells. J Immunol, 162(10), 5853-9, 1999.
- Chu, Z L, Shin, Y A, Yang, J M, DiDonato, J A, Ballard, D W IKKgamma mediates the interaction of cellular IkappaB kinases with the tax transforming protein of human T cell leukemia virus type 1. J Biol Chem, 274(22), 15297-300, 1999.
- Hawiger, J, Veach, R A, Liu, X Y, Timmons, S, Ballard, D W IkappaB kinase complex is an intracellular target for endotoxic lipopolysaccharide in human monocytic cells. Blood, 94(5), 1711-6, 1999.
- Bash J, Zong WX, Banga S, Rivera A, Ballard DW, Ron Y, Gelinas C "Rel/NF-kappaB can trigger the Notch signaling pathway by inducing the expression of Jagged1, a ligand for Notch receptors." EMBO J, 18:(10), 2803-2811, 1999.
- Mori, N., Mukaida, N., Ballard, D.W., Matsushima, K., and Yamamoto, N "Human T-cell leukemia virus type I Tax transactivates human interleukin-8 gene through acting concurrently on AP-1 and nuclear factor kB-like sites." Cancer Res. , 58:(3993), 1998.
- Chu, Z L, DiDonato, J A, Hawiger, J, Ballard, D W The tax oncoprotein of human T-cell leukemia virus type 1 associates with and persistently activates IkappaB kinases containing IKKalpha and IKKbeta. J Biol Chem, 273(26), 15891-4, 1998.
- Boothby, M R, Mora, A L, Scherer, D C, Brockman, J A, Ballard, D W Perturbation of the T lymphocyte lineage in transgenic mice expressing a constitutive repressor of nuclear factor (NF)-kappaB. J Exp Med, 185(11), 1897-907, 1997.
- McKinsey, T A, Chu, Z L, Ballard, D W Phosphorylation of the PEST domain of IkappaBbeta regulates the function of NF-kappaB/IkappaBbeta complexes. J Biol Chem, 272(36), 22377-80, 1997.
- Chu, Z L, McKinsey, T A, Liu, L, Gentry, J J, Malim, M H, Ballard, D W Suppression of tumor necrosis factor-induced cell death by inhibitor of apoptosis c-IAP2 is under NF-kappaB control. Proc Natl Acad Sci U S A, 94(19), 10057-62, 1997.
- Bendall, H H, Scherer, D C, Edson, C R, Ballard, D W, Oltz, E M Transcription factor NF-kappaB regulates inducible Oct-2 gene expression in precursor B lymphocytes. J Biol Chem, 272(46), 28826-8, 1997.
- Chu, Z L, McKinsey, T A, Liu, L, Qi, X, Ballard, D W Basal phosphorylation of the PEST domain in the I(kappa)B(beta) regulates its functional interaction with the c-rel proto-oncogene product. Mol Cell Biol, 16(11), 5974-84, 1996.
- Scherer, D C, Brockman, J A, Bendall, H H, Zhang, G M, Ballard, D W, Oltz, E M Corepression of RelA and c-rel inhibits immunoglobulin kappa gene transcription and rearrangement in precursor B lymphocytes. Immunity, 5(6), 563-74, 1996.
- McKinsey, T A, Brockman, J A, Scherer, D C, Al-Murrani, S W, Green, P L, Ballard, D W Inactivation of IkappaBbeta by the tax protein of human T-cell leukemia virus type 1: a potential mechanism for constitutive induction of NF-kappaB. Mol Cell Biol, 16(5), 2083-90, 1996.
- Brockman, J A, Scherer, D C, McKinsey, T A, Hall, S M, Qi, X, Lee, W Y, Ballard, D W Coupling of a signal response domain in I kappa B alpha to multiple pathways for NF-kappa B activation. Mol Cell Biol, 15(5), 2809-18, 1995.
- Donald, R, Ballard, D W, Hawiger, J Proteolytic processing of NF-kappa B/I kappa B in human monocytes. ATP-dependent induction by pro-inflammatory mediators. J Biol Chem, 270(1), 9-12, 1995.
- Scherer, D C, Brockman, J A, Chen, Z, Maniatis, T, Ballard, D W Signal-induced degradation of I kappa B alpha requires site-specific ubiquitination. Proc Natl Acad Sci U S A, 92(24), 11259-63, 1995.
- Chen, Z., Hagler, J., Palombella, V., Melandri, F., Scherer, D., Ballard, D., and Maniatis, T "Signal-induced site- specific phosphorylation targets IkBa to the ubiquitin-proteasome pathway." Genes Dev., 9:(1586), 1995.
- Beraud, C., Sun, S., Ganchi, P., Ballard, D., and Greene, W "Human T-cell leukemia virus type I tax associat s with and is negatively regulated by the NF-kB2 p100 gene product: implications for viral latency." Mol. Cell Biol. , 14:(1374), 1994.
- Ganchi, P., Sun, S., Greene, W., and Ballard, D "A novel NF-kB complex containing p65 homodimers: implications for transcriptional control at the level of subunit dimerization." Mol. Cell. Biol. , 13:(7826), 1993.
- Sun, S., Ganchi, P., Ballard, D., and Greene, W "NF-kB controls expression of inhibitor Ik-Ba: evidence for an inducible autoregulatory pathway." Science , 259:(1912), 1993.
- Doerre, S., Sista, P., Ballard, D., and Greene, W "The c-rel proto-oncogene product represses NF-kB p65- mediated transcriptional activation of the HIV-1 long terminal repeat." Proc. Natl. Acad. Sci. USA , 90:(1023), 1993.
- Ganchi, P., Sun, S., Greene, W., and Ballard, D "IkB/MAD-3 masks the nuclear localization signal of NF-kB and requires the transactivation domain to inhibit NF-kB p65 DNA binding." Mol. Biol. Cell , 3:(1339), 1992.
- Ballard, D., Dixon, E., Peffer, N., Bogerd, H., Doerre, S., and Greene, W "The 65-kD DNA binding subunit of human NF-kB functions as a potent transcriptional activator and a target for repression by the v-Rel oncoprotein." , 89:(1875), 1992.
- Walker, W., Stein, B., Ganchi, P., Hoffman, J., Kaufman, P., Ballard, D., Hannink, M., and Greene, W "The v-rel oncogene: insights into the mechanism of transcriptional activation, repression, and transformation." J. Virol. , 66:(5018), 1992.