Sessions científiques, CRG Group Leader Seminars
Cell Signaling Research Group, CEXS-UPF
Francesc Posas is Professor of Biochemistry and Molecular Biology at the Department of Experimental and Health Sciences of the Universitat Pompeu Fabra. After obtaining his doctorate in Biochemistry and Molecular Biology at the Universitat Autònoma de Barcelona (1995), he made his postdoctoral stay at Harvard University (Boston, USA). He joined the UPF in 1999, and he is leading together with Dr. de Nadal the Cell Signaling Research Group (UPF). In 2007 he was elected as DCEXS Director and in 2013 as Vicerector of Scientific Policy at the UPF.
His group addresses how cells sense and respond to environmental changes, focusing on the characterization of signaling pathways in response to stress, particularly those controlled by the stress-activated MAP kinases of the Hog1/p38 family (SAPK). Using yeast S. cerevisiae as a model organism as well as higher eukaryotic cells, they have focused their studies on the identification of sensing mechanisms required for detection of changes in extracellular osmolarity as well as the properties of the signaling process, the characterization of the biological targets for SAPK action as well as the study of the cellular responses required for stress adaptation such as cell cycle and gene expression regulation. Moreover, in the field of synthetic biology, they have implemented complex engineered networks to perform in vivo cellular computation.
Exposure of cells to increases in extracellular osmolarity results in the activation of the Hog1 stress-activated protein kinase (SAPK). Activation of these SAP kinases is required to generate a set of osmoadaptive responses essential to survive under high osmolarity. Adaptation to osmostress requires the induction of a large number of genes, which indicates the necessity to regulate several aspects of the cell physiology. Induction of gene expression is highly dependent on the presence of the SAP kinase, which suggests a key role for the HOG signaling pathway in the regulation of gene expression in response to osmostress. The SAPK also controls cell cycle by delaying different phases of cell cycle. We will present two examples of a coordinated control of gene expression and cell cycle control by Hog1 upon stress.