Single‐cell profiling screen identifies microtubule‐dependent reduction of variability in signaling. Issue 4 (4th April 2018)

• Record Type: Journal Article
• Authors: Pesce, C Gustavo; Zdraljevic, Stefan; Peria, William J; Bush, Alan; Repetto, María Victoria; Rockwell, Daniel; Yu, Richard C; Colman‐Lerner, Alejandro; Brent, Roger
• Is Part Of: Molecular systems biology. Volume 14:Issue 4(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-04-04
• Subjects: cell‐to‐cell variability -- genetic screen -- MAP kinase -- microtubules -- noise; Molecular biology -- Periodicals; Systems biology -- Periodicals; 572.8
• DOI: 10.15252/msb.20167390
• Languages: English
• ISSNs: 1744-4292

Abstract

Abstract: Populations of isogenic cells often respond coherently to signals, despite differences in protein abundance and cell state. Previously, we uncovered processes in the Saccharomyces cerevisiae pheromone response system (PRS) that reduced cell‐to‐cell variability in signal strength and cellular response. Here, we screened 1, 141 non‐essential genes to identify 50 "variability genes". Most had distinct, separable effects on strength and variability of the PRS, defining these quantities as genetically distinct "axes" of system behavior. Three genes affected cytoplasmic microtubule function: BIM1, GIM2, and GIM4 . We used genetic and chemical perturbations to show that, without microtubules, PRS output is reduced but variability is unaffected, while, when microtubules are present but their function is perturbed, output is sometimes lowered, but its variability is always high. The increased variability caused by microtubule perturbations required the PRS MAP kinase Fus3 and a process at or upstream of Ste5, the membrane‐localized scaffold to which Fus3 must bind to be activated. Visualization of Ste5 localization dynamics demonstrated that perturbing microtubules destabilized Ste5 at the membrane signaling site. The fact that such microtubule perturbations cause aberrant fate and polarity decisions in mammals suggests that microtubule‐dependent signal stabilization might also operate throughout metazoans. Synopsis: A genetic screen for pheromone signal variability mutants, and subsequent experiments, showed that cytoplasmic microtubule plus end function stabilizes signaling. Perturbing plus end function impacted signal transmission by Fus3 MAPK, as well as cell polarity determinations. Screen identifies yeast microtubule mutants with increased pheromone signal variability. Such mutations, and other perturbations affecting cytoplasmic plus end function, cause erratic signaling. Signal variability affects gene expression and polarity decisions. There is substantial signal variability due to the effect of Fus3 MAP Kinase at the cell membrane signaling site. Abstract : A genetic screen for pheromone signal variability mutants, and subsequent experiments, showed that cytoplasmic microtubule plus end function stabilizes signaling. Perturbing plus end function impacted signal transmission by Fus3 MAPK, as well as cell polarity determinations.