professor of biology
Ph.D., Tufts University, Sackler School
Fields of Interest
Glucose sensing, signal transduction, transcriptional regulation in the fission yeast Schizosaccharomyces pombe. S. pombe as a tool to study cyclic nucleotide phosphodiesterases.
How do eukaryotic cells sense their environment and regulate biological processes in response to environmental signals? To address this question, my lab studies how glucose triggers repression of transcription of the fbp1 gene in the fission yeast Schizosaccharomyces pombe. Depending upon the carbon source in the medium, S. pombe cells regulate fbp1 transcription over a 200-fold range.
Combining classical yeast genetics with molecular biology, we have identified a number of genes required for both repression and derepression of fbp1 transcription. Glucose repression requires the function of nine git genes leading to the activation of protein kinase A (PKA; cAMP-dependent protein kinase). These genes include seven genes required for activation of adenylate cyclase, one gene encoding adenylate cyclase (git2/cyr1), and one gene encoding the catalytic subunit of PKA (pka1/git6). Four of the genes required for adenylate cyclase activation encode alpha, beta, and gamma subunits of a heterotrimeric G protein, the same type of protein that regulates mammalian adenylate cyclase activity, and a seven transmembrane protein that may function as a glucose receptor. We are presently studying the interactions between these proteins and adenylate cyclase. We have also found that both adenylate cyclase and phosphodiesterase activities are regulated to control cAMP signaling. The remaining three git genes, appear to work independently from the G protein. The git1 protein is unique to S. pombe, while git7 and git10 have orthologs in other organisms that have been shown to physically interact and to work in a variety of processes. We are currently studying the roles of these proteins in cAMP signaling, as well as the mechanisms by which they carry out these roles.
We have also made use of the fbp1 reporters and the mutations in the cAMP signaling pathway to develop strains for high throughput screens (HTSs) to identify compounds that inhibit cyclic nucleotide phosphodiesterases (PDEs). PDEs are important drug targets and the compounds we identify could be useful in the treatment of some types of cancer, as well as a large number of inflammatory and neurological diseases and even HIV infection. We have completed HTSs for PDE4, PDE7, PDE8, and PDE11 inhibitors. The compounds identified in these screens are remarkable with respect to their biological activity in mammalian cell-based assays given that they have not yet been subjected to medicinal chemistry to enhance their physiochemical and pharmacokinetic properties. Our strain collection includes strains that express 15 of the 21 mammalian PDE genes (representing 10 of the PDE 11 families), as well as three Trypanosome PDE genes.
The Paparazzi of Pombe
Check out my Photo Album of the First International Fission Yeast Meeting held in Edinburgh in September 1999.
I also have Photo Albums for
the Second International Fission Yeast Meeting held in Kyoto in March 2002,
the First East Coast Regional Fission Yeast Meeting held in Worcester, MA in July 2003,
the Third International Fission Yeast Meeting held in San Diego in August 2004,
the Second East Coast Regional Fission Yeast Meeting held in Miami, FL in November 2005,
and the Fourth International Fission Yeast Meeting held in Copenhagen in June 2007,
along with my Facebook groups for the Copenhagen Pombe 2007, the Fifth International Fission Yeast Meeting Tokyo Pombe 2009, and the Sixth International Fission Yeast Meeting (Boston USA 2011), which also included photo albums from all of the previous international meetings.
If you have any pictures that you would like to add to these albums, please email them to me or directly add pictures to the Facebook groups.
For other pombe informaton on the web, the best place to start is Susan Forsburg's Lab Page.
Demirbas, D., Wyman, A.R., Shimizu-Albergine, M., Cakici, O., Beavo, J.A., and Hoffman, C.S. (2013). A Yeast-Based High-Throughput Screen Identifies A Phosphodiesterase Inhibitor That Elevates Steroidogenesis In Mouse Leydig Cells Via PDE8 And PDE4 Inhibition. PLoS One. 2013;8(8):e71279. doi: 10.1371/journal.pone.0071279.
Link to abstract: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071279
de Medeiros, A.S., Magee, A., Nelson, K., Friedberg, L., Trocka, K., and Hoffman, C.S. (2013). Use of PKA-mediated phenotypes for genetic and small molecule screens in Schizosaccharomyces pombe. Biochem. Soc. Transactions (in press).
Ceyhan O., Birsoy K., and Hoffman C.S. 2012. Identification of biologically active PDE11-selective inhibitors using a yeast-based high throughput screen, Chemistry & Biology, 19:155-163.
Link to abstract: http://www.ncbi.nlm.nih.gov/pubmed/22284362
Mudge D.K., Hoffman C.A., Lubinski T.J., and Hoffman C.S. 2012. Use of a ura5+-lys7+ cassette to construct unmarked gene knock-ins in Schizosaccharomyces pombe, Current Genetics, 58: 59-64.
Link to abstract: http://www.ncbi.nlm.nih.gov/pubmed/22198627
Didem Demirbas, Ozge Ceyhan, Arlene R. Wyman and Charles S. Hoffman 2011. A Fission Yeast-based Platform for Phosphodiesterase Inhibitor HTSs and Analyses of Phosphodiesterase Activity, Handbook of Experimental Pharmacology (Houslay, Francis, and Conti eds.) Phosphodiesterases as Drug Targets 2011 (204): 135-149.
Link to abstract: http://www.ncbi.nlm.nih.gov/pubmed/21695638
Demirbas, D., Ceyhan, O., Wyman, A.R., Ivey, F.D., Allain, C., Wang, L., Sharuk, M.N., Francis, S.H., and Hoffman, C.S. 2011. Use of a Schizosaccharomyces pombe PKA-repressible reporter to study cGMP-metabolising phosphodiesterases. Cellular Signalling. 23(3):594-601. (link to PubMed abstract).
Ivey, F.D., Taglia, F.X., Yang, F., Lander, M.M., Kelly, D.A., and Hoffman, C.S. 2010. Activated alleles of the Schizosaccharomyces pombe gpa2+ Gα gene identify residues involved in GDP-GTP exchange. Eukaryotic Cell 9: 626–633 (link to PubMed abstract).
Alaamery, M.A., Wyman, A.R., Ivey, F.D., Allain, C., Demirbas, D., Wang, L., Ceyhan, O., and Hoffman, C.S. 2010. New classes of PDE7 inhibitors identified by a fission yeast-based HTS. Journal of Biomolecular Screening 15: 359–367 (link to PubMed abstract).
Roux, A.E., Leroux, A., Alaamery, M.A., Hoffman, C.S., Chartrand, P., Ferbeyre, G., and Rokeach, L.A. 2009. Pro-aging effects of glucose signaling through a G protein-coupled glucose receptor in fission yeast. PLoS Genetics 5(3): e1000408 (link to PubMed abstract).
Hirota, K., Miyoshi, T., Kugou, K., Hoffman, C.S., Shibata, T., and Ohta, K. 2008. Stepwise chromatin remodelling by a cascade of transcription initiation of non-coding RNAs. Nature 456: 130–134 (link to PubMed abstract).
Leem, Y.-E., Ripmaster, T., Kelly, F., Ebina, H., Heincelman, M., Zhang, K., Grewal, S.I.S., Hoffman, C. S., and Levin, H. L. 2008. The pol II promoters of Schizosaccharomyces pombe are targeted by an LTR retrotransposon that is capable of repairing the promoters it disrupts. Molecular Cell 30: 98–107 (link to PubMed abstract).
Alaamery, M.A., and Hoffman, C.S. 2008. Schizosaccharomyces pombe Hsp90/Git10 is required for glucose/cAMP signaling. Genetics 178: 1927–36 (link to PubMed abstract).
Ivey, F.D., Wang, L., Demirbas, D., Allain, C., Hoffman, C.S. 2008. Development of a fission yeast-based high-throughput screen to identify chemical regulators of cAMP phosphodiesterases. Journal of Biomolecular Screening 13: 62–71 (link to PubMed abstract).
Hoffman, C.S. 2007. Propping up our knowledge of G protein signaling pathways: diverse functions of putative noncanonical Gbeta subunits in fungi. Science's STKE 370: 3 (link to PubMed abstract).
Kao, R.S., Morreale, E., Wang, L., Ivey, F.D., Hoffman, C.S. 2006. Schizosaccharomyces pombe Git1 is a C2-domain protein required for glucose activation of adenylate cyclase. Genetics 173: 49–61 (link to PubMed abstract).
Hoffman, R.L., and Hoffman, C.S. 2006. Cloning the Schizosaccharomyces pombe lys2+ gene and construction of new molecular genetic tools. Current Genetics 49: 414–420 (link to PubMed abstract).
Wang, L., Griffiths, K., Zhang, Y.H., Ivey, F.D., Hoffman, C.S. 2005. Schizosaccharomyces pombe adenylate cyclase suppressor mutations suggest a role for cAMP phosphodiesterase regulation in feedback control of glucose/cAMP signaling. Genetics 171: 1523–1533 (link to PubMed abstract).
Ivey, F.D., and Hoffman, C.S. 2005. Direct activation of fission yeast adenylate cyclase by the Gpa2 Galpha of the glucose signaling pathway. Proceedings of the National Academy of Sciences of the USA 102: 6108–6113 (link to PubMed abstract).
Hoffman, C.S. 2005. Except in every detail: comparing and contrasting G-protein signaling in Saccharomyces cerevisiae and Schizosaccharomyces pombe. Eukaryotic Cell 4: 495–503.
Hoffman, C.S. 2005. Glucose sensing via the protein kinase A pathway in Schizosaccharomyces pombe. Biochemical Society Transactions 33: 257–60 (link to PubMed abstract).
Stiefel, J., Wang L., Kelly, D.A., Janoo, R.T., Seitz, J., Whitehall, S.K., Hoffman, C.S. 2004. Suppressors of an adenylate cyclase deletion in the fission yeast Schizosaccharomyces pombe. Eukaryotic Cell 3: 610–9 (link to PubMed abstract).
Wang, L., Kao, R., Ivey, F.D., Hoffman, C.S. 2004. Strategies for gene disruptions and plasmid constructions in fission yeast. Methods 33: 199–205 (link to PubMed abstract).
Hirota, K., Hasemi, T., Yamada, T., Mizuno, K.I., Hoffman, C.S., Shibata, T., Ohta, K. 2004. Fission yeast global repressors regulate the specificity of chromatin alteration in response to distinct environmental stresses. Nucleic Acids Research 32: 855–62 (link to PubMed abstract).
Hirota, K., Hoffman, C.S., Shibata, T., Ohta, K. 2003. Fission yeast Tup1-like repressors repress chromatin remodeling at the fbp1+ promoter and the ade6-M26 recombination hotspot. Genetics 165: 505–15 (link to PubMed abstract).
Yang, P., Du, H., Hoffman, C.S., Marcus, S. 2003. The phospholipase B homolog Plb1 is a mediator of osmotic stress response and of nutrient-dependent repression of sexual differentiation in the fission yeast Schizosaccharomyces pombe. Molecular Genetics and Genomics 269: 116–25 (link to PubMed abstract).
Greenall, A., Hadcroft, A.P., Malakasi, P., Jones, N., Morgan, B.A., Hoffman, C.S., Whitehall, S.K. 2002. Role of fission yeast Tup1-like repressors and Prr1 transcription factor in response to salt stress. Molecular Biology of the Cell 13: 2977–89 (link to PubMed abstract).
Schadick, K., Fourcade, H.M., Boumenot, P., Seitz, J.J., Morrell, J.L., Chang, L., Gould, K.L., Partridge, J.F., Allshire, R.C., Kitagawa, K., Hieter, P., and Hoffman, C.S. 2002. Schizosaccharomyces pombe Git7p, a member of the Saccharomyces cerevisiae Sgt1p family, is required for glucose and cAMP signaling, cell wall integrity, and septation. Eukaryotic Cell 1: 558–567 (link to PubMed abstract).
Ivey, F.D., and Hoffman, C.S. 2002. Preview: Pseudostructural inhibitors of G protein signaling during development. Developmental Cell 3: 154–155 (link to PubMed abstract).
Kelly, D.A., and Hoffman, C.S. 2002. Gap repair transformation in fission yeast to exchange plasmid selectable markers. Biotechniques 33: 978–982 (link to PubMed abstract).
Takagi, T., Cho, E.-J., Janoo, R.T.K., Polodny, V., Takase, Y., Keogh, M.-C., Woo, S., Fresco-Cohen, L.D., Hoffman, C.S., and Buratowski, S. 2002. Divergent subunit interactions among fungal mRNA 5'-capping machineries. Eukaryotic Cell 1: 448–457 (link to PubMed abstract).
Landry, S., and Hoffman, C.S. 2001. The git5 Gb and git11 Gg form an atypical Gbg dimer acting in the fission yeast glucose/cAMP pathway. Genetics 157: 1159–1168 (link to PubMed abstract).
Janoo, R.T.K., Neely, L.A., Braun, B.R., Whitehall, S.K., and Hoffman, C.S. 2001. Transcriptional regulators of the Schizosaccharomyces pombe fbp1 gene include two redundant Tup1p-like corepressors and the CCAAT binding factor activation complex. Genetics 157: 1205–1215 (link to PubMed abstract).
Neely, L.A., and Hoffman, C.S. 2000. PKA and MAPK pathways antagonistically regulate fission yeast fbp1 transcription by employing different modes of action at two upstream activation sites. Molecular and Cellular Biology 20: 6426–6434 (link to PubMed abstract).
Welton, R.M., and Hoffman, C.S. 2000. Glucose monitoring in fission yeast via the gpa2 G alpha , the git5 G beta, and the git3 putative glucose receptor. Genetics 156: 513–521 (link to PubMed abstract).
Landry, S., Pettit, M.T., Apolinario, E., and Hoffman, C.S. 2000. The fission yeast git5 gene encodes a Gb subunit required for glucose-triggered adenylate cyclase activation. Genetics 154: 1463–1471 (link to PubMed abstract).
Hoffman, C.S., and Welton, R. 2000. Mutagenesis and gene cloning in Schizosaccharomyces pombe using nonhomologous plasmid integration and rescue. Biotechniques 28: 532–6, 538, 540 (link to PubMed abstract).
Dal Santo, P., Blanchard, B., and Hoffman, C.S. 1996. The Schizosaccharomyces pombe pyp1 protein tyrosine phosphatase negatively regulates nutrient monitoring pathways. Journal of Cell Science 109: 1919–1925 (link to PubMed abstract).
Jin, M., Fujita, M., Culley, B.M., Apolinario, E., Yamamoto, M., Maundrell, K., and Hoffman, C.S. 1995. sck1, a high copy number suppressor of defects in the cAMP-dependent protein kinase pathway in fission yeast, encodes a protein homologous to the Saccharomyces cerevisiae SCH9 kinase. Genetics 140: 457–467 (link to PubMed abstract).
Nocero, M., Isshiki, T., Yamamoto, M., and Hoffman, C.S. 1994. Glucose repression of fbp1 transcription in Schizosaccharomyces pombe is partially regulated by adenylate cyclase activation by a G protein a subunit encoded by gpa2/git8. Genetics 138: 39–45 (link to PubMed abstract).
Hoffman, C.S., and Winston, F. 1991. Glucose repression of transcription of the Schizosaccharomyces pombe fbp1 gene occurs by a cAMP signaling pathway. Genes and Development 5: 561–571 (link to PubMed abstract).