Yeast-based screening to identify modulators of G-protein signaling using uncontrolled cell division cycle by overexpression of Stm1

Stm1, a G-protein coupled receptor, which senses nutritional state drives cells to stop the proliferative cell cycle and enter meiosis under nutritionally deficient conditions in Schizosaccharomyces pombe. It was shown that overexpression of Stm1 led growth inhibition and uncontrolled mitotic haploidization presumably by the premature initiation of mitosis. Sty1 and Gpa2 seem to play important roles for Stm1 to deliver starvation signal to induce downstream function. Based on the observation that conversion of diploid to haploid by overexpression of Stm1 can be easily detected as pink or red colonies in the media containing low adenine, HTS drug screening system to identify modulators of GPCR was established and tested using 413 compounds. Four very potent modulators of GPCR including Biochanin A, which possess strong inhibitory activity against uncontrolled cell division, were identified in this screening. This study provides the yeast-based platform that allows robust cellular assays to identify novel modulators of G-protein signaling and MAP kinase pathway.