Imaging. Gene. Expression.

We study gene regulation by applying single cell and single molecule approaches to fundamental questions in RNA biology, with the aim of establishing the basis for a better understanding and treatment of complex diseases.

 

Studying the role of mRNP organization in regulating translation and mRNA metabolism

Pascal Raymond

mRNAs are long nucleic acid polymers that get bound by proteins to form ribonucleoprotein complexes (mRNPs). While the mRNP proteome is well characterized, little is known about the organization of mRNP as 3D assemblies. 3D organization however is critical for regulating many aspects of RNA metabolism, such as translation, transport or degradation. We use single molecule approaches to study mRNA organization in cells and unravel its role in regulating different aspects of mRNA metabolism.


Key papers:

Adivarahan S, Livingston N, Nicholson B, Rahman S, Wu B, Rissland O, Zenklusen D. Spatial organization of single mRNPs at different stages of the gene expression pathway. Molecular Cell Published: November 8, 2018.

 

The nuclear pore complex and its role in mRNA export and retention

Pascal Raymond

We study the mechanisms of mRNA transport from the nucleus to the cytoplasm, and the role of the nuclear pore complex (NPC) in this process. Transport to the cytoplasm is essential for mRNAs to meet with ribosomes for protein synthesis. On the other hand, many other RNA classes have to be retained in the nucleus, such us various long-non coding RNAs (lncRNAs) or mRNAs that have not been fully processed. The rules that define who is exported and who stays in the nucleus are not clear. Furthermore, many of the protein implicated in the export or in retention are found mutated in various diseases, such as ALS. Our projects investigate the relationship between the nuclear pore complex and RNA binding proteins in regulating export and retention using yeast and higher eukaryotes as model systems.

Key papers:

Fernandez-Martinez J, Kim SJ, Shi Y, Upla P, Pellarin R, Gagnon M, Chemmama IE, Wang J, Nudelman I, Zhang W, Williams R, Rice WJ, Stokes DL, Zenklusen D, Chait BT, Sali A, Rout MP. Structure and Function of the Nuclear Pore Complex Cytoplasmic mRNA Export Platform. Cell 2016 Nov 17;167(5):1215-1228.e25

Saroufim MA, Bensidoun P, Raymond P, Rahman S, Krause MR, Oeffinger M, Zenklusen D. The nuclear basket mediates perinuclear mRNA scanning in budding yeast. Journal of Cell Biology 2015 Dec 21;211(6):1131-40.

 

Single molecule tools for RNA imaging in cells

 

Pascal Raymond

Developing new experimental approaches allow us to ask new questions or to revisit questions we long thought to have solved, and to look at them with ‘new eyes’; often to realize that we are far from understanding what is happening. We are continually looking for new ways to image mRNAs in cells and to improve the tools we are already have.

Key papers:

Bensidoun P, Raymond P, Oeffinger M, Zenklusen D. Imaging single mRNAs to study dynamics of mRNA export in the yeast Saccharomyces cerevisiae. Methods 2016 Jan 16;S1046-2023(16) link

Hocine S, Raymond P, Zenklusen D, Chao JA and Singer RH. Single-molecule analysis of gene expression using two-color RNA labeling in live yeast. Nature Methods 2013 Feb;10(2):119-21 link

 

Role of ncRNAs in transcription regulation

 

Pascal Raymond

Non-coding RNA have been implicated in many aspects of transcription regulation. We are studying the role of different classes of ncRNAs in this process, including anti-sense transcription and RNAs expressed from enhancer regions (eRNAs).

Key papers:

Rahman S, Zorca C, Traboulsi T, Noutahi E, Krause M, Mader S and Zenklusen D. Single-cell profiling reveals that eRNA accumulation at enhancer-promoter loops is not required to sustain transcription. Nucleic Acid Research 2017, Apr 7;45(6):3017-3030. link

Castelnuovo M, Rahman S, Guffanti E, Infantino V, Stutz F and Zenklusen D. Bimodal expression of PHO84 is modulated by early termination of antisense transcription. Nat Struct Mol Biol. 2013 Jul;20(7):851-8. link