Pleiotropic signaling pathways orchestrate yeast development

Abstract

Developmental phenotypes in Saccharomyces cerevisiae and related yeasts include responses such as filamentous growth, sporulation, and the formation of biofilms and complex colonies. These developmental phenotypes are regulated by evolutionarily conserved, nutrient-responsive signaling networks. The signaling mechanisms that control development in yeast are highly pleiotropic--all the known pathways contribute to the regulation of multiple developmental outcomes. This degree of pleiotropy implies that perturbations of these signaling pathways, whether genetic, biochemical, or environmentally induced, can manifest in multiple (and sometimes unexpected) ways. We summarize the current state of knowledge of developmental pleiotropy in yeast and discuss its implications for understanding functional relationships.

Figure 1

Developmental pathways in Saccharomyces cerevisiae. Yeast cells detect and transduce information on nutrients and pH through the combined action of the cAMP-PKA, SNF1/AMPK, TOR, Kss1-MAPK, and Rim101 pathways. The networks on the left (A,C,E) depict the effects of the inducing signals on each pathway and the effects of each pathway on three developmental phenotypes: pseudohyphal growth (B), complex colony morphology (D), and sporulation (F). Arrows indicate enhancing/activating effects; bars indicate repressive effects. The dashed lines indicate pathway activity in the face of repressive signals.