Evidence of antagonistic regulation of restart from G(1) delay in response to osmotic stress by the Hog1 and Whi3 in budding yeast

A yeast cell cycle model integrating stress, signaling, and physiology

The cell division cycle in eukaryotic cells is a series of highly coordinated molecular interactions that ensure that cell growth, duplication of genetic material, and actual cell division are precisely orchestrated to give rise to two viable progeny cells. Moreover, the cell cycle machinery is responsible for incorporating information about external cues or internal processes that the cell must keep track of to ensure a coordinated, timely progression of all related processes. This is most pronounced in multicellular organisms, but also a cardinal feature in model organisms such as baker's yeast. The complex and integrative behavior is difficult to grasp and requires mathematical modeling to fully understand the quantitative interplay of the single components within the entire system. Here, we present a self-oscillating mathematical model of the yeast cell cycle that comprises all major cyclins and their main regulators. Furthermore, it accounts for the regulation of the cell cycle machinery by a series of external stimuli such as mating pheromones and changes in osmotic pressure or nutrient quality. We demonstrate how the external perturbations modify the dynamics of cell cycle components and how the cell cycle resumes after adaptation to or relief from stress.

3,6-Epidioxy-1,10-bisaboladiene inhibits G1 -specific transcription through Swi4/Swi6 and Mbp1/Swi6 via the Hog1 stress pathway in yeast

3,6-Epidioxy-1,10-bisaboladiene (EDBD), a bisabolane sesquiterpene endoperoxide compound, was previously isolated from Cacalia delphiniifolia and C. hastata in northern Japan. EDBD has cytotoxic effects and induces apoptosis via phosphorylation of p38 mitogen-activated protein kinase in human promyelocytic leukemia HL60 cells. However, the mechanism of action of EDBD has not yet been fully elucidated. In this study, we examined the molecular mechanisms of EDBD in the budding yeast Saccharomyces cerevisiae. EDBD arrested the growth of S. cerevisiae cells by suppressing progression from the G1 phase to the S phase and from the G2 phase to the M phase. Moreover, biochemical and genetic analyses revealed that EDBD activated environmental stress-response pathways involving Hog1 and affected Cln3/G1 cyclin activity, thereby inhibiting the expression of SCB-binding factor and MCB-binding factor target genes. Our results provided important insights into the functions of EDBD in tumor cells and may facilitate the development of EDBD-based antitumor therapies.

STRUCTURED DIGITAL ABSTRACT

•Swi4 physically interacts with Swi6 by anti tag coimmunoprecipitation (View interaction).