TY  - GEN
T1  - cAMP export by the fission yeast Schizosaccharomyces pombe
AU  - Eberhard, Jeremy
AU  - Hoffman, Charles S.
DO  - 10.17912/micropub.biology.000384
UR  - http://beta.micropublication.org/journals/biology/micropub-biology-000384/
AB  - Signaling by the second messenger cyclic 3’-5’ adenosine monophosphate (cAMP) plays critical roles in most, if not all, organisms. Most of the genes of the Schizosaccharomyces pombe glucose-cAMP signaling pathway were identified by mutations that allow transcription of an fbp1-ura4 reporter that is normally repressed by the cAMP-dependent protein kinase PKA in cells growing under high glucose conditions (Hoffman and Winston 1990). This screening identified eight genes of the pathway, including the git2/cyr1 adenylyl cyclase (AC) gene (Hoffman and Winston 1991). The dynamic change in intracellular cAMP levels in response to glucose exposure was subsequently examined in wild type and mutant strains (Byrne and Hoffman 1993) following a procedure used to study cAMP signaling in budding yeast (Fedor-Chaiken et al. 1990). Wild type cells display a rapid response to glucose with a peak at around 20 minutes after glucose addition, followed by a gradual reduction in cAMP levels, while strains carrying mutations in git1, git3, git5, git7, git8 (gpa2) and git10 (hsp90) fail to elevate cAMP levels in response to glucose. These genes comprise a G protein-mediated signaling pathway, in which the Gpa2 Gα stimulates AC activity (de Medeiros et al. 2013). More recently, we developed platforms for small molecule screening to identify chemical inhibitors of heterologously-expressed cyclic nucleotide phosphodiesterases (PDEs) or ACs, along with mass spectrometry assays to demonstrate a direct impact on cAMP levels (Ivey et al. 2008; Getz et al. 2019). Once again, we focused on intracellular cAMP levels by collecting cells on a glass filter and releasing cAMP by immersing the filter in 1M formic acid. However, while studying candidate AC inhibitors, we investigated the possibility that a compound could lower intracellular cAMP by causing cAMP to be exported from the cell rather than by inhibiting its synthesis. It was through these experiments, we observed that most of the cAMP was already being exported into the medium. This should not have been a surprise as it had been shown previously that cAMP is present in both S. pombe cells and the growth medium in steady state cultures (Schlanderer and Dellweg 1974). Here we examine the dynamics of cAMP export and test whether PKA or a collection of ABC transporters play a role in this process.
PY  - 2021
JO  - microPublication Biology
ER  -