We regularly train Master students and welcome spontaneous application from motivated students. We commit to train and mentor each Master student with the following objectives in mind: learn how to design and perform experiments, to maintain a laboratory notebook, to interpret and present data, to participate to our weekly labmeetings, to read papers and to keep bibliography up-to-date.
We currently have two research topics for which Master internship projects are available in our group.
Project #1: Gene expression regulation by chaperones in yeast.
The balance between proliferation and quiescence is crucial for all organisms and is perturbed in cancer cells. Recent results from our laboratory and others indicate that the TTT complex, which is a novel HSP90 cochaperone, controls this balance by controlling the assembly of complexes involved in nutrient signaling and transcription regulation [1-3]. We have recently discovered that TTT promotes the cotranslational assembly of specific subunits of these complexes [4]. The goal of this internship will be to characterize the roles of TTT during translation of these subunits, the subcellular localization of TTT and how changes in nutrient availability affect TTT activities.
Techniques:
Microbiology, Molecular biology, Yeast genetics, Biochemistry, Microscopy, Proteomics, Genomics.
References:
[1] Takai H., Wang R.C., Takai K.K., Yang H., and de Lange T. (2007). Tel2 Regulates the Stability of PI3K-Related Protein Kinases. Cell 131, 1248–1259.
[2] Hayashi T., HatanakaM., Nagao K., Nakaseko Y., Kanoh J., Kokubu A., Ebe M., and Yanagida M. (2007). Rapamycin sensitivity of the Schizosaccharomyces pombe tor2 mutant and organization of two highly phosphorylated TOR complexes by specific and common subunits. Genes to Cells 12, 1357–1370.
[3] Elías-Villalobos A., Fort P., and Helmlinger D. (2019). New insights into the evolutionary conservation of the sole PIKK pseudokinase Tra1/TRRAP. Biochem. Soc. Trans. 47, 1597–1608.
[4] Toullec D.*, Elías-Villalobos A.*, Faux C., Lledo G., Séveno M., Helmlinger D. The Hsp90 cochaperone TTT promotes cotranslational maturation of PIKK kinases prior to assembly. In revision at Cell Reports and available as a preprint here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3742245
Project #2: Transcription regulation by co-activator complexes in cancer cells.
Background:
Many studies have established that aberrant gene expression is a hallmark of tumor initiation and maintenance. As a consequence, the dependency of certain cancers on specific transcriptional regulators has emerged as a novel therapeutic opportunity [1]. However, such dependencies are typically not identified by cancer genome sequencing, but, rather, through focused mechanistic studies. The overall objective of the project is to characterize the contribution of the SAGA and TIP60 co-activator complexes to cancer cell transcriptional addiction, in the context of colorectal tumorigenesis.
Several SAGA and TIP60 subunits have been implicated in cell growth and survival in cancer cells [2]. The shared TRRAP subunit represents a compelling example because it was first identified in a screen for cofactors that are essential for MYC-dependent transcription and malignant transformation. Similar to MYC, TRRAP is recurrently overexpressed in colorectal tumors, but its role in tumorigenesis remains unclear. This issue is important because SAGA and TIP60 have opposite roles on proliferation, DNA damage, and Wnt-pathway activation in the context of colorectal cancer. We therefore aim to determine the contribution of TRRAP to the recruitment, regulation, and activities of SAGA and TIP60.
Specific goal of the internship:
Work from our lab, using yeast as a model system, identified unique TRRAP separation-of-function alleles that specifically disrupt TRRAP-SAGA interaction, without affecting TIP60 [3]. The goal of the Master student will be to identify an analogous region in human TRRAP, using a combination of molecular, genetic, and biochemical approaches that we implemented in colorectal cancer cells [4]. This mutant will then allow her/him to study how TRRAP controls SAGA activities during transcription and cellular transformation in cancer cells.
Techniques:
Molecular and cellular biology. CRISPR-Cas9-mediated genome editing to create inducible loss-of-function alleles. Nascent transcription analyses. Native chromatin binding analyses.
References:
[1] Bradner JE, Hnisz D, Young RA. (2017) Transcriptional Addiction in Cancer. Cell 168: 629–643.
[2] Helmlinger D.* and Tora L.* (2017) Sharing the SAGA. Trends in Biochem. Sci. 42(11):850-861.
[3] Elías-Villalobos A., Toullec D., Faux C., Séveno M., Helmlinger D. (2019) Chaperone-mediated ordered assembly of the SAGA and NuA4 transcription co-activator complexes in yeast. Nature Communications 10(1):5237. Featured in Editors’ Highlights webpage.
[4] Detilleux D., Raynaud P., Pradet-Balade B., Helmlinger D. The TRRAP transcription cofactor represses interferon-stimulated genes in colorectal cancer cells. Submitted. Available as a preprint on biorXiv: https://doi.org/10.1101/2021.04.13.439699