News Team Expression Génétique et Développement

(2021, June) Master internships - Spring, 2021

Study of the involvement of the RNA-binding protein CELF1 in the physiopathology of the lens
Medical and scientific context
The eye lens is the organ that allows light to converge on the retina. The transparency of the lens is obtained by the very regular assembly of highly specialized cells called fiber cells and by the loss of all their intracellular organelles, including nuclei. Genetic predispositions or age-related changes can lead to the development of a cataract (opacification of the lens). Despite efficient treatment by surgery, this ocular pathology remains a major public health problem.
Our team has been involved for several years in the study of the physiopathology of the lens. In particular, we have identified the RNA-binding protein CELF1 as a major player in lens development. For example, mice in which the Celf1 gene is inactivated develop a congenital cataract resulting from nuclear retention and severe disorganization of lens fibers (Siddam et al., 2018). We are currently working to identify CELF1 targets involved in lens fiber assembly. To this end, we searched by iCLIPseq for CELF1-bound mRNAs to identify its potential targets.
Objectives and methodology
Among the direct targets of CELF1, we are particularly interested in mRNAs encoding proteins involved in endocytosis, cell junctions and actin cytoskeleton dynamics. The objective of the internship will be to understand how CELF1 influences these different cellular functions. To do so, we will use WT epithelial cell or cells invalidated for Celf1 expression. We will culture these cells in 2D or 3D, as spheroids mimicking the organization of lens, to determine which defects affect the expression or the localization of specific markers of each function. From a technical point of view, this internship will involve experiments of invalidation / exogenous expression of genes encoding proteins of interest, immuno-fluorescence labeling and wide field, confocal or light sheet imaging.
Relevance of the results obtained to cataract
All these results should allow a better understanding of the involvement of CELF1 in the physiopathology of the lens. In the long term, they will contribute to the improvement of the understanding of the cellular anomalies leading to the appearance of a cataract and should open the way to new non-surgical therapeutic approaches.
Siddam, A.D., Gautier-Courteille, C., Perez-Campos, L., Anand, D., Kakrana, A., Dang, C.A., Legagneux, V., Méreau, A., Viet, J., Gross, J.M., et al. (2018). The RNA-binding protein Celf1 post-transcriptionally regulates p27Kip1 and Dnase2b to control fiber cell nuclear degradation in lens development. PLoS Genet. 14, e1007278.

Control of MYC oncogene activity by MM-1/PFDN5 in HNSCC
Supervision: and
Key words Oncogene / protein regulation / cancer / cell culture / qPCR /siRNA
The MYC oncogene is a transcription factor that is deregulated in many cancers. In Head and Neck Squamous Cell Carcinoma (HNSCC) patients, the prognosis is often poor due to late detection (because of the absence of early diagnostic markers) and/or resistance to targeted therapies. MYC is often hyper-activated in these cancers. The Myc Modulator 1 (MM-1) protein inhibits the activity of the MYC oncogene. This protein, called PFDN5, is also incorporated into the co-chaperone prefoldin complex, which is involved in the folding of neo-synthesised proteins in the cytoplasm. MM-1/PFDN5 may therefore act both as an inhibitor of MYC and as a molecular chaperone whose activity may promote tumour progression. The PFDN5 gene generates two isoforms by alternative splicing, and we observed that their relative abundance correlates with the prognosis of HNSCC patients. To investigate their respective roles in the regulation of the MYC oncogene, both Flag-PFDN5 isoforms will be overexpressed in cultured HNSCC cell lines and the effect on MYC activity will be measured by RT-qPCR and with a luciferase reporter system. The effect of PFDN5 isoform knock-down on MYC activity will also be tested by RNA interference.


(2021, January) Three new M2 students joined the team!

Welcome to Célia, Laure and Florian

(2020, October) Yannick Arlot partner of an ANR grant

This 3-year project is carried by Betty Gardie, Nantes

(2020, October) Publication in PLoS Genetics: the degradation of the tumor suppressor VHL

(2020, June): A new publication with our partner Salil Lachke

This fruitful collaboration has already resulted in 3 joint publications. Matthieu Duot will start a PhD co-directed by the two teams in October 2020. The work together continues!