Regulation of mRNA homeostasis by Poly(A) binding proteins

Description du projet

Étudier le rôle des PABPC dans la régulation et l’homéostasie de l’ARN

L’ARN est essentiel à la vie et les cellules maintiennent sa concentration (homéostasie de l’ARN) en équilibrant la synthèse et la dégradation. Un mécanisme de rétroaction peut coordonner les niveaux d’ARNm par le biais d’un «capteur» qui communique les concentrations d’ARNm aux contrôles de transcription et de dégradation. Les protéines cytoplasmiques de liaison au poly(A) (PABPC) se lient aux ARNm pour réguler leur stabilité et leur traduction, mais leur rôle dans le maintien de l’homéostasie de l’ARN dans des conditions physiologiques n’est pas encore clair. Soutenu par le programme Actions Marie Skłodowska-Curie, le projet RNAhome utilisera le titrage PABPC, le marquage métabolique et l’imagerie multiplexée pour analyser la dynamique de l’ARN en réponse à la variation des niveaux et de la localisation du PABPC, dans le but de révéler les mécanismes fondamentaux de l’homéostasie de l’ARN et les principes plus larges de la régulation des gènes.

Objectif

RNA is a biomolecule central to all life forms, and cells regulate RNA production and degradation rates to maintain stable RNA concentrations (RNA homeostasis) through a largely unexplored mechanism. Increasing evidence indicates that a feedback mechanism coordinates mRNA synthesis and degradation, allowing cells to buffer mRNA concentration. For the coordination of these processes, I hypothesise the existence of a “sensor” that “measures” mRNA concentration and conveys this information to the transcription and/or degradation machinery, establishing a coordinated response.

Cytoplasmic Poly(A)-binding proteins (PABPCs) are highly conserved across eukaryotes, and specifically bind to polyadenylated mRNAs, regulating their stability, translation, and degradation. Several properties of PABPCs, such as nuclear shuttling and transcription inhibition in response to viral infection, make them ideal candidates as mRNA sensors, yet it is unclear whether they control mRNA homeostasis in physiological conditions.

RNAhome will characterise the role of PABPCs in mRNA buffering and homeostasis using a systemic approach. I will conduct PABPC titration, followed by metabolic labelling and multiplexed imaging, to analyse RNA dynamics in response to varying PABPC expression and localisation. I will use my extensive expertise in nanoinjection to introduce mRNA into live cells and assess if PABPCs can directly sense mRNA levels and modulate transcription/turnover accordingly. Finally, I will use SLAMseq to measure genome-wide RNA dynamics with transcript-level resolution, establishing the impact of PABPC expression on mRNA dynamics.

RNAhome is a prime example of interdisciplinary science, combining the researcher’s expertise in bio-nanotechnology and physical sciences with RNA dynamics knowledge of the host group, and world-class facilities of the host organisation to unravel the fundamental mechanisms governing RNA homeostasis and drive innovation in RNA-based technologies.