Orchestration by the Wnt/Hippo/CD95 signalosome of stem- and EMT-like phenotypes
This project aims at identifying signaling nodes that act in concert with the Wnt pathway, Wnt nodes, in imposing distinct cellular states found along the normal NSC lineage and its malignant counterpart in GBM tumors. Our approach combines the use of a reporter of canonical Wnt activity, single cell RNA sequencing (scRNA-seq), tissue histology, mathematical modeling and in vitro assays for distinct cellular phenotypes in mouse and human. Specifically, we will examine fluctuations of Wnt activity throughout the murine NSC lineage using various Wnt reporter systems. This lineage involves transitions between dormancy, cycling, migration, and network integration. Quantification of reporter activity will be used to build a mathematical model parameterized according to Wnt ligands, receptors and antagonists to explore how they control transitions between cellular states. To identify other signaling pathways concomitantly activated/inhibited at each state, we will use scRNA-seq deploying various droplet and in-plate methods that we set up in the first funding period. Combined transcriptomics and phenotypic analysis of single cells shall inform on phenotype-related modes of Wnt activation and the crosstalk with other pathways. In parallel, we will use the same approach to interrogate the Wnt signaling hubs in the malignant GBM-lineage, which we showed to recapitulate cell phenotypes found in the NSC-lineage. Evaluation of both data sets across health and disease, different patients, and species will be used to build a universal classifier acting as surrogate of Wnt activity for exploration of Wnt signaling hubs in other RNA sequencing data sets. Wnt components and their interaction partners that mediate specific cellular phenotypes of interest will be identified via CRISPR-Cas screening and will be further validated in tailored assays. Ultimately, our analysis shall enable the design of improved therapies for repair or cancer treatment of the adult brain.
- Kalamakis, G., D. Bruene, S. Ravichandran, J. Bolz, W. Fan, F. Ziebell, T. Stiehl, F. Catalá-Martinez, J. Kupke, S. Zhao, E. Llorens-Bobadilla, K. Bauer, S, Limpert, B. Berger, U. Christen, P. Schmezer, J.P. Mallm, B. Berninger, S. Anders, A. Del Sol, A. Marciniak-Czochra, A. Martin-Villalba. 2019. Quiescence modulates stem cell maintenance and regenerative capacity in the aging brain. Cell. 176:1407-1419. PMID:30827680.
- Ziebell, F., S. Dehler, A. Martin-Villalba, A., and A. Marciniak-Czochra. 2018. Revealing age-related changes of adult hippocampal neurogenesis using mathematical models. Development. 145:dev153544. PMID:29229768.
- Seib, D., N.S. Corsini, K. Ellwanger, C. Plaas, A. Mateos, C. Pitzer, C. Niehrs, T. Celikel, and A. Martin-Villalba. 2013. Loss of Dickkopf-1 Restores Neurogenesis in Old Age and Counteracts Cognitive Decline. Cell Stem Cell. 12:204-214. PMID:23395445.