The dynamic status of actin in the regulation of environmental sensing and homeostatic control in Saccharomyces cerevisiae

Actin is a highly conserved protein in eukaryotes which forms dynamic cytoskeletal structures. Rapid remodeling of actin filaments is important for the regulation of a broad range of critical cellular processes. The cytoskeleton is acutely responsive to stresses and there are multiple interactions between actin and signaling pathways, positioning it centrally to a cells ability to adapt and respond to their environment. Here I provide further evidence that a dynamic actin cytoskeleton regulates processes including endocytosis, mitochondrial respiration, and signal transduction. Results presented here show that actin is embedded in the signaling networks which control the responses to environmental change. Change to the dynamic status of actin modulates the activity of the transcription factor Ste12p which regulates both the mating and filamentous/invasive growth responses. The activity of these pathways are linked to cortical patch organisation, and our data suggests that there is crosstalk between multiple pathways. I propose that the links between actin dynamics and environmental sensing pathways leave it well positioned for a role as a biosensor. Actin dynamics is altered by changes in internal or external conditions, leading to adapted of cellular responses which may provide a protective function for a population.