ERC FUNDED PROJECTS

Obesity and diabetes have reached pandemic proportions and new therapeutic strategies are critically needed. Brown adipose tissue (BAT), a major source of heat production, possesses significant energy-dissipating capacity and therefore represents a promising target to use in combating these diseases. Recently, I discovered a novel link between circadian rhythm and thermogenic stress in the control of the conserved, calorie-burning functions of BAT. Circadian and thermogenic signaling to BAT incorporates blood-borne hormonal and nutrient cues with direct neuronal input. Yet how these responses coordinately shape BAT energy-expending potential through the regulation of cell surface receptors, metabolic enzymes, and transcriptional effectors is still not understood. My primary goal is to investigate this previously unappreciated network of crosstalk that allows mammals to effectively orchestrate daily rhythms in BAT metabolism, while maintaining their ability to adapt to abrupt changes in energy demand. My group will address this question using gain and loss-of-function in vitro and in vivo studies, newly-generated mouse models, customized physiological phenotyping, and cutting-edge advances in next generation RNA sequencing and mass spectrometry. Preliminary, small-scale validations of our methodologies have already yielded a number of novel candidates that may drive key facets of BAT metabolism. Additionally, we will extend our circadian and thermogenic studies into humans to evaluate the translational potential. Our results will advance the fundamental understanding of how daily oscillations in bioenergetic networks establish a framework for the anticipation of and adaptation to environmental challenges. Importantly, we expect that these mechanistic insights will reveal pharmacological targets through which we can unlock evolutionary constraints and harness the energy-expending potential of BAT for the prevention and treatment of obesity and diabetes.

1 497 008 €

Start date: 2015-05-01, End date: 2020-04-30

"Understanding how organisms regulate size is one of the most fascinating open questions in biology. The aim of the AMAIZE project is to unravel how growth of maize leaves is controlled. Maize leaf development offers great opportunities to study the dynamics of growth regulatory networks, essentially because leaf development is a linear system with cell division at the leaf basis followed by cell expansion and maturation. Furthermore, the growth zone is relatively large allowing easy access of tissues at different positions. Four different perturbations of maize leaf size will be analyzed with cellular resolution: wild-type and plants having larger leaves (as a consequence of GA20OX1 overexpression), both grown under either well-watered or mild drought conditions. Firstly, a 3D cellular map of the growth zone of the fourth leaf will be made. RNA-SEQ of three different tissues (adaxial- and abaxial epidermis; mesophyll) obtained by laser dissection with an interval of 2.5 mm along the growth zone will allow for the analysis of the transcriptome with high resolution. Additionally, the composition of fifty selected growth regulatory protein complexes and DNA targets of transcription factors will be determined with an interval of 5 mm along the growth zone. Computational methods will be used to construct comprehensive integrative maps of the cellular and molecular processes occurring along the growth zone. Finally, selected regulatory nodes of the growth regulatory networks will be further functionally analyzed using a transactivation system in maize. AMAIZE opens up new perspectives for the identification of optimal growth regulatory networks that can be selected for by advanced breeding or for which more robust variants (e.g. reduced susceptibility to drought) can be obtained through genetic engineering. The ability to improve the growth of maize and in analogy other cereals could have a high impact in providing food security"

2 418 429 €

Start date: 2014-02-01, End date: 2019-01-31

Work conducted in my laboratory on the trypanosome killing factor of human serum led to the identification of the primate-specific Apolipoprotein L1 (APOL1) as a novel pore-forming protein with striking similarities with proteins of the apoptotic BCL2 family. APOL1 belongs to a family of proteins induced under inflammatory conditions in myeloid and endothelial cells. APOL1 is efficiently neutralized by the SRA protein of Trypanosoma rhodesiense, accounting for the ability of this trypanosome subspecies to infect humans and cause sleeping sickness. We found that natural APOL1 variants escaping SRA neutralization and therefore conferring human resistance to T. rhodesiense are associated with chronic kidney disease. Moreover, transgenic mice expressing these APOL1 variants exhibit an obese phenotype. Our unpublished results also indicate that APOLs control the lifespan of dendritic cells and podocytes activated by viral stimuli. Therefore, we propose that the pathology of APOL variants is due to their deregulated activity on the control of the cellular lifespan in myeloid/endothelial cells activated by pathogen detection. This project aims at characterizing (i) the molecular mechanism by which APOLs control the lifespan of activated dendritic cells and podocytes, which has direct impact on innate immunity and inflammation, and (ii) the mechanism by which APOL1 variants cause pathology. In addition, we plan to detail the physiological function of APOLs by studying the phenotype of transgenic mice either expressing human APOL1 (wild-type and variants) or devoid of APOL genes, which we have recently generated. Finally, we propose to exploit the extraordinary potential of trypanosomes for antigenic variation in order to produce SRA variants able to neutralize the pathogenic APOL1 variants. Preliminary experiments suggest that in podocytes SRA antagonizes APOL1 induction by viral stimulus and subsequent cell death, opening new perspectives to treat kidney disease.

2 250 000 €

Start date: 2015-09-01, End date: 2020-08-31

"The deregulation of transcription is an important driver of leukemia development. Typically, transcription in leukemia cells is altered by the ectopic expression of transcription factors, by modulation of signaling pathways or by epigenetic changes. In addition to these factors that affect the production of RNAs, also changes in the processing of RNA (its splicing, transport and decay) may contribute to determine steady-state RNA levels in leukemia cells. Indeed, acquired mutations in various genes encoding RNA splice factors have recently been identified in myeloid leukemias and in chronic lymphocytic leukemia. In our study of T-cell acute lymphoblastic leukemia (T-ALL), we have identified mutations in RNA decay factors, including mutations in CNOT3, a protein believed to function in deadenylation of mRNA. It remains, however, unclear how mutations in RNA processing can contribute to the development of leukemia. In this project, we aim to further characterize the mechanisms of RNA regulation in T-cell acute lymphoblastic leukemia (T-ALL) to obtain insight in the interplay between RNA generation and RNA decay and its role in leukemia development. We will study RNA decay in human T-ALL cells and mouse models of T-ALL, with the aim to identify the molecular consequences that contribute to leukemia development. We will use new technologies such as RNA-sequencing in combination with bromouridine labeling of RNA to measure RNA transcription and decay rates in a transcriptome wide manner allowing unbiased discoveries. These studies will be complemented with screens in Drosophila melanogaster using an established eye cancer model, previously also successfully used for the studies of T-ALL oncogenes. This study will contribute to our understanding of the pathogenesis of T-ALL and may identify new targets for therapy of this leukemia. In addition, our study will provide a better understanding of how RNA processing is implicated in cancer development in general."

1 998 300 €

Start date: 2014-05-01, End date: 2019-04-30