Distinguished Foundation Professor of The Biological Sciences

Lewis Hall
Office: (757) 446-5662
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Education

• B.A., Pomona College, Claremont, CA
• Ph.D., Yale University, New Haven, CT
• Postdoctoral Training, The Rockefeller University, New York, NY Memorial Sloan-Kettering Cancer Center, New York, NY

Positions and Honors

Professional Positions:

Honors:

Research Interests

 Areas of interest: AIDS, DNA replication, neurovirology, virology, environmental carcinogenesis, nucleic acids, cancer, cell cycle, tumor suppressors, lung cancer, chromatin,  gene, transcription, brain pathology, HIV.

Work in the laboratory of Dr. Edward M. Johnson is concerned with control of DNA replication in cancer and AIDS. An important current project involves an opportunistic infection of the brain, caused by the virus JCV, in AIDS patients. We have hypothesized that activation of JCV in glial cells of the brain is influenced by HIV-1 infection. We have found that JCV late gene transcription is stimulated by the HIV-1 Tat protein through action at sequence elements bound by the cellular protein, Pur-alpha. A complex between Tat and Pur-alpha acts to stimulate transcription at both the HIV-1 TAR RNA element and the JCV late promoter. The complex also interacts with T-antigen to enhance JCV DNA replication. Pur-alpha is a frequent partner of Cyclin/Cdk complexes, as is another Tat-binding protein, Cyclin T1.

 A major project involving lung cancer aims to elucidate the mechanism by which cells distinguish newly-replicated DNA, and its associated proteins, in S and G2 phases of the cell cycle and prevent that DNA from reinitiating replication in the same cycle. A primary hypothesis is that alterations in activity of an MCM4, 6, 7 helicase complex, necessary for initiation or reinitiation, are mediated by Cdk-dependent phosphorylation.  We are pursuing findings that Cyclin A/Cdk2 and sequence-specific single-stranded DNA-binding protein, Pur-alpha, are colocalized with once-replicated DNA in S and G2, that Pur-alpha modulates activity of Cdk2 and that Pur-alpha colocalizes with MCM7 on chromatin. We shall ascertain using chromatin immunoprecipitation (ChIP) and re-ChIP with successive antibodies the location and timing of assembly and dissociation of MCM4, 6 and 7 helicase components and the helicase inhibitor, MCM2, upstream of the c-MYC gene in the cell cycle of small-cell lung carcinoma cells and normal controls. We are examining whether Pur-alpha modulates the MCM4, 6, 7 helicase, either by association with Cyclin A/Cdk2 or by DNA unwinding. Results allow identification of links between control of initiation of replication and imposition of checkpoint controls that are critical in preventing progression to cancer.

 We are exploring the dynamics of the interactions between Tat, T-antigen and Pur-alpha during the course of JCV infection of oligodendrocytes and are determining whether transcriptional activation involves activity of Cyclin T1/Cdk9. We are detailing the mechanism by which Tat enhances replication initiated at the JCV origin in human oligodendrocytes both in vivo and using a new in vitro system. We are also examining the ability of TAT and Pur-alpha to interact with Smad effectors of the TGF-beta1 pathway. Results will help elucidate pathways of activation of HIV-1 and JCV in the brain and will help target particular molecular interactions for therapy.

 Our laboratory has generated five patents.

 Selected Publications in Chronological Order (from more than 140):

1)    Bergemann, A.D., Ma, Z.-W. and Johnson E.M. (1992) Sequence of cDNA comprising the human PUR gene and sequence-specific single-stranded-DNA-binding properties of the encoded protein. Mol. Cell. Biol. 12:5673-5682. PMCID: PMC360507

2)    Johnson, E.M., Chen, P.-L., Krachmarov, C.P., Barr, S.M., Kanovsky, M., Ma, Z.-W., Lee, W.-H. (1995) Association of human Pura with the retinoblastoma protein, Rb, regulates binding to the single-stranded DNA Pura recognition element., J.Biol. Chem., 270:24352-24360. PMID: 7592647

3)    Krachmarov, C.P., Chepenik, L.G., Barr-Vagell, S., Khalili, K., Johnson, E.M. (1996) Activation of the JC virus Tat-responsive transcriptional control element by association of the Tat-protein of HIV-1 with cellular protein Pura. PNAS. 93:14112-14117. PMCID: PMC34556

4)    Itoh, H., Wortman, M.J., Kanovsky, M., Uson, R.R., Gordon, R.E., Alfano, N., Johnson, E.M., (1998) Alterations of Pura levels and intracellular localization in the CV-1 cell cycle. Cell Growth & Diff., 9:651-665. PMID 759647

5)    Wortman, M.J., Krachmarov, C.P., Kim, J.H., Gordon, R.G., Chepenik, L.G., Brady, J.N., Gallia, G.L., Khalili, K., Johnson, E.M. (2000) Interaction of HIV-1 Tat with Pura in nuclei of human glial cells: Characterization of RNA-mediated protein-protein binding. J. Cell Biochem. 77:65-74. PMID: 10679817

6)    Daniel, D.C., Wortman, M.J., Schiller, R.J., Liu, H., Gan, L., Mellen, J.S., Chang, C-F., Gallia, G.L., Rappaport, J., Khalili, K., Johnson, E.M. (2001) Coordinate effects of human immunodeficiency virus type-1 protein, Tat, and cellular protein, Pura on DNA replication initiated at the JC virus origin. J. Gen. Virol, 82:1543-1553. PMID: 11413364

7)    Khalili, K., Del Valle, L., Muralidharan, V., Gault, W.J., Darbinian, N., Otte, J., Meier, E., Johnson, E.M., Daniel, D.C., Kinoshita, Y., Amini, S. and Gordon, J. (2003) Pura is essential for postnatal brain development and developmentally-coupled cellular proliferation as revealed by genetic inactivation in the mouse. Mol. Cell. Biol., 23, 6857-6875. PMCID: PMC193944

8)    Johnson, E.M. (2003) The Pur Protein Family: Clues to function from recent studies on Cancer and Aids. Anticancer Res. 23: 2093-2100. PMID: 12894583

9)    Kinoshita, Y. and Johnson, E.M. (2004) Site-specific loading of an MCM protein complex in an initiation zone of DNA replication located upstream of the c-MYC gene in the HeLa cell cycle. J. Biol. Chem., 279, 35879-35889. PMID: 15190069

10) Daniel, D.C., Kinoshita, Y., Khan, M.A., Del Valle, L., Khalili, K., Rappaport, J. and Johnson, E.M. (2004) Internalization of exogenous human immunodeficiency virus-1 protein, Tat, by KG-1 oligodendroglioma cells followed by stimulation of DNA replication initiated at the JC virus origin. DNA and Cell Biol. 23, 858-867. PMID: 15684713

11) Wortman, M.J., Johnson, E.M. and Bergemann, A.D. (2005) Mechanism of DNA binding and localized strand separation by Pura and comparison with Pur family member, Purb. Biochim. Biophys. Acta, Mol. Cell. Res. 1743, 64-78. PMID: 15777841  

12) White, M. K., Johnson, E. M. & Khalili, K. (2009). Multiple roles for Pur-alpha in cellular and viral regulation. Cell Cycle 8, 1-7. PMCID: PMC2683411

13) Stettner, M.R., Nance, J.A., Wright, C.A., Kinoshita, Y., Kim, W.-K., Morgello, S., Rappaport, J., Khalili, K., Gordon, J.G., and Johnson, E.M. (2009)  SMAD proteins of oligodendroglial cells regulate transcription of JC viral early and late genes coordinately with the Tat protein of human immunodeficiency virus type 1. J. Gen. Virology, 90, 2005–2014. PMCID: PMC2871392

14) Johnson, E.M. (2010) Structural evaluation of new polyomaviruses provides clues to pathobiology. Trends in Microbiology, 5, 215-223. PMCID: PMC2864792

15) Wortman, M.J.,Hanson, L.K., Campbell, AE, Martinez-Sobrido, L., Garcia-Sastre, A., Nance, J.A. and Johnson, E.M. (2010) hPURA: a gene expressing a highly-conserved coding sequence under control of three distinct promoters, each generating a differently-spliced 5’-UTR. BMC Molecular Biology 11, 81 Epub. PMCID:PMC2992531

16) Daniel, D.C and Johnson E.M. (2011). Addressing the Enigma of MCM8 in DNA Replication, Fundamental Aspects of DNA Replication, Jelena Kusic-Tisma (Ed.), InTech. ISBN: 978-953-307-259-3 http://www.intechopen.com/articles/show/title/addressing-the-enigma-of-mcm8-in-dna-replication

The following is a link to an interview with Dr. Johnson: http://conversations.org/story.php?sid=174

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