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Reference : USR3505-CAMLIB-016
Workplace : TOULOUSE
Date of publication : Wednesday, June 24, 2020
Scientific Responsible name : Dr. Valérie LOBJOIS
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
The cell cycle is the fundamental process by which a mother cell gives birth to two genetically identical daughter cells. The chekpoints of the cell cycle are signaling pathways, whose activation in response to different intra- or extracellular signals leads to the inactivation of the CDK-cyclin complexes and to the cell cycle arrest at G1/S, intra-S, G2/M or intra M transitions. The progression during the G1 phase of the cell cycle is dependent on mitogenic signals which regulate a major checkpoint of the cell cycle dynamics, the restriction point or R-point, which controls the engagement of the cells in the cell cycle and whose molecular mechanisms are based on the regulation of the activity of the G1 phase Cdk and of the retinoblastoma protein. In the absence of mitogenic signals, the cells can leave the cell cycle and reach a state of non-division, called G0, which depending on the cell type can be reversible. All the molecular mechanisms controlling cell cycle progression, in particular G1 or G2 phase, are involved in controlling the balance between proliferation and cell differentiation or migration in many physiological contexts.
Adipose stromal cells (ASCs) are mesenchymal stromal cells that reside in adipose tissue and are characterized by a high potential for regeneration. Recent works in the laboratory have shown that a pool of ASCs can be mobilized in response to various pathophysiological contexts and that ASCs released by the adipose tissue infiltrate the target organ and participate in its remodeling and/or regeneration. Several studies demonstrate that the dynamics of ASC cell proliferation control their fate and recently, a subpopulation of ASCs with a high proliferative profile has been identified and could play an important role in regeneration.
The objective of the proposed thesis project is to study the involvement of regulatory mechanisms of cell cycle dynamics in the inter-organ mobilization of ASCs in response to stress and its alteration during aging. The model of study will be the mobilization of ASCs from subcutaneous fat tissue in response to skeletal muscle injury and its contribution to muscle regeneration.
A first part of the work will be devoted to the characterization of the cell cycle progression dynamics of ASC populations in adipose tissue and skeletal muscle from mouse models. This study will be based on the analysis of ASC generation time, expression and activation of cell cycle regulators using biochemical approaches and the analysis of ASC distribution in the cell cycle by flow cytometry. A second part of the project will be devoted to the study of the implication of a modification of the cell cycle control dynamics in the inter-organ mobilization of ASCs and their potential for regeneration. Prior to this functional study, a miniaturized ex vivo model, composed of an ASC compartment, a migration pathway and a target compartment, will be developed to mimic the inter-organ dialogue of ASCs and to monitor the dynamics of ASCs under microscopy. Thanks to this model, the impact of ASC synchronization and pharmacological targeting of cell cycle regulators on their mobilization will be studied. These results will be complemented by gain and loss of function experiments of candidate regulators to study their involvement. This model will also be used to explore and characterize the impact of the properties of the microenvironment (rigidity, physioxia, ...) on the mobilization and dynamics of ASCs.
All this work will make it possible to characterize the involvement of signaling pathways of cell cycle checkpoints in the regulation of the inter-organ dialogue of ASCs and their potential for regeneration, opening up the prospect of identifying new therapeutic levers for treating muscle degeneration observed, for example, in elderly patients responsible for the onset of a fragile state.
Conduct a research project to investigate the involvement of mechanisms for regulating cell cycle dynamics in the mobilization of CSAs in response to stress.
To carry out a state-of-the-art scientific literature in connection with the project
Ensure scientific and technological monitoring in the field of activity
Putting experimental protocols in place, carrying out experiments and analysing the results
Present the project and the results obtained in meetings, seminars or congresses in French and English in the form of a posted or oral communication
Write the thesis manuscript and scientific articles from the results
Skills : Master degree
- In-depth knowledge of the cell cycle
- Very good general knowledge of cellular and molecular biology,
- Expertise acquired in cell culture and good skills in microscopy and image analysis.
- Expertise acquired in the quantitative study of the dynamics of tumor cell populations in video-microscopy
- Carrying out experiments, observations, ensuring reproducible methods and reliable results;
- Demonstrating rigour and scientific integrity
- Presenting and discuting the results
- Taking a step back from the progress and scope of its project, its influence in national and international contexts
- Taking an objective and critical assessment of the progress of its own work, identifying the added value compared to previous work
- Working as a team
The project is part of the creation on 1/01/2021 of the RESTORE Institute, a laboratory resulting from the merge of ITAV, Stromalab, the Adipolab team (I2MC) and the MRN2i team (Pharmadev). The project will be conducted within the new Stromagics team, "Stromal aging dynamics", co-directed by C. Sengenes, Inserm researcher, and Valérie Lobjois, assistant professor. This team will bring together researchers, assistant-professors, engineers and technicians with highly complementary expertise in MSC physiology, cell cycle regulation, cell migration and large-scale genome analysis. The PhD student will benefit from the support of all team members. The project will be co-supervised by Valérie Lobjois and Jacques Rouquette (head of the future Centre d'Expertises et de Ressources Technologiques (CERT) at Restore and specialist in fluorescence microscopy). During the first year of the thesis, weekly follow-up meetings with the two co-supervisors will be organized and the PhD student will also be asked to present his results during team meetings and internal seminars at the laboratory. The frequency of the follow-up by the supervisors will be adapted according to the autonomy of the PhD student. The doctoral student will also be encouraged to present his/her work in at least one national and one international congress during his/her doctorate. A referent person, internal to the laboratory, will also be identified, who will be able to play the role of mediator. An annual interview will take place every year in order to accompany the doctoral student in the construction of his/her professional project from the beginning of the doctorate.
Constraints and risks
Laboratory work (risks related to chemicals, biological agents, pressured materials)
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