How do eukaryotic cells sense their environment and regulate biological processes in response to environmental signals? To address this question, my lab has studied how extracellular glucose triggers repression of transcription of the ƒbp1 gene in the fission yeast Schizosaccharomyces pombe. Combining classical yeast genetics with molecular biology, we identified genes required for both repression and derepression of ƒbp1 transcription, including almost all of the genes of the cyclic AMP (cAMP) signaling pathway.
Our work with the S. pombe cAMP pathway allowed us to develop small molecule screening platforms in which we express proteins from mammals or pathogens involved in cyclic nucleotide metabolism. Cells that express the ƒbp1-ura4 reporter can be used in 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. This work has led to the discovery of the only selective PDE11 inhibitor, BC11-38, that is commercially-available for use in studying the role of PDE11 in biological processes. Our strain collection includes strains that express 15 of the 21 mammalian PDE genes (representing ten of the PDE 11 families), as well as three Trypanosome PDE genes.
Cells that express either the ƒbp1-GFP or ƒbp1-luciferase reporter can be used to detect inhibitors of mammalian adenylyl cyclases or the human GNAS Gα that stimulates the transmembrane cyclases. Our strain collection includes strains expressing each of the 10 mammalian adenylyl cyclases as well as wild type and mutationally-activated forms of the human GNAS Gα that stimulates the transmembrane cyclases. A recent screen of more than 100,000 compounds carried out at the NCATS (National Center for Advancing Translational Sciences) screening facility identified a collection of potential cyclase or GNAS inhibitors that are cell permeable. Further characterization of these compounds is underway.
Finally, expression of the Pseudomonas aeruginosa ExoY cyclase in our strains results in endogenous production of cGMP as well as cAMP. This allows us to better characterize the substrate specificity of foreign PDEs expressed in S. pombe.
Check out my photo album of the 2017 Ninth International Fission Yeast Meeting.
I also have Photo Albums for:
Along with Facebook groups for the Copenhagen Pombe 2007, the Fifth International Fission Yeast Meeting Tokyo Pombe 2009, the Sixth International Fission Yeast Meeting (Boston USA 2011; this group includes photo albums from all of the previous international meetings), and the Seventh International Fission Yeast Meeting (London 2013), the Eighth International Fission Yeast Meeting (Kobe 2015), the Ninth International Fission Yeast Meeting (Banff 2017), and the Tenth International Fission Yeast Meeting (Barcelona 2019).
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.