Phosphoproteomic analyses reveal novel cross‐modulation mechanisms between two signaling pathways in yeast

Molecular Systems Biology

Stefania Vaga⁴  Marti Bernardo-Faura²  Thomas Cokelaer²  Alessio Maiolica⁴  Christopher A Barnes⁴  Ludovic C Gillet⁴  Björn Hegemann³  Frank van Drogen³  Hoda Sharifian³  Edda Klipp¹  Matthias Peter³  Julio Saez-Rodriguez² 

[1] Department of Biology, Theoretical Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany;European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge, UK;Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland;Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland

关键词: cell signaling network;    crosstalk;    HOG pathway;    pheromone pathway;    phosphoproteomics;   

DOI  :  10.15252/msb.20145112

来源: Wiley

【 摘 要 】

Abstract

Cells respond to environmental stimuli via specialized signaling pathways. Concurrent stimuli trigger multiple pathways that integrate information, predominantly via protein phosphorylation. Budding yeast responds to NaCl and pheromone via two mitogen-activated protein kinase cascades, the high osmolarity, and the mating pathways, respectively. To investigate signal integration between these pathways, we quantified the time-resolved phosphorylation site dynamics after pathway co-stimulation. Using shotgun mass spectrometry, we quantified 2,536 phosphopeptides across 36 conditions. Our data indicate that NaCl and pheromone affect phosphorylation events within both pathways, which thus affect each other at more levels than anticipated, allowing for information exchange and signal integration. We observed a pheromone-induced down-regulation of Hog1 phosphorylation due to Gpd1, Ste20, Ptp2, Pbs2, and Ptc1. Distinct Ste20 and Pbs2 phosphosites responded differently to the two stimuli, suggesting these proteins as key mediators of the information exchange. A set of logic models was then used to assess the role of measured phosphopeptides in the crosstalk. Our results show that the integration of the response to different stimuli requires complex interconnections between signaling pathways.

Synopsis

A quantitative analysis of phosphoproteome dynamics by shotgun mass spectrometry, combined with mathematical modeling reveals complex crosstalk between the Hog1 and the pheromone signaling pathways in budding yeast.

• Signal integration occurs at different levels within the hyper-osmotic stress and the pheromone pathways in Saccharomyces cerevisiae.
• Pheromone induces a short but strong down-regulation of Hog1 phosphorylation.
• A set of feedback loops regulate the activation of Hog1 and Fus3.
• Ste20 and Pbs2 are key crosstalk mediators: their different phosphosites respond differently to the two stimuli.

【 授权许可】

CC BY   
© 2014 The Authors. Published under the terms of the CC BY 4.0 license

Creative Commons Attribution 4.0 License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.