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TRANSLATION INITIATION CONTROL IN PLANTS: THE ROLE OF TOR (TARGET OF RAPAMYCIN)

Project description

Dissecting gene regulation in plants

Regulation of gene expression in eukaryotes is fundamental for cell survival, differentiation and development. Regulation at the protein synthesis stage is critical and involves the target of rapamycin (TOR) protein kinase, which suppresses the function of translation repressor proteins. To achieve this, the TOR signalling pathway integrates nutrient and energy sufficiency information as well as hormone and growth factor levels. The EU-funded TOR in acTIon project has set out to understand how plants employ TOR to regulate protein synthesis. The key objective is to identify regulatory factors that function under the control of TOR in translation initiation and to decipher the role of the plant hormone auxin, a key coordinator of plant growth.

Objective

Translation is a critical step in the regulation of gene expression in eukaryotes. Most of the control occurs at the level of translation initiation, which is a rate-limiting step in protein synthesis. In mammals, cap-dependent translation initiation is under the regulation of the target of rapamycin (TOR) protein kinase, which suppresses the function of translation repressor proteins, the eIF4E-binding proteins (4E-BPs) that sequester the cap-binding factor eIF4E at the 5′-end of mRNA. The TOR signaling pathway integrates nutrient and energy sufficiency, hormones and growth factors to regulate protein synthesis in mammals and plants. How TOR signals environmental changes to regulate mRNA translation and ribosome production in plants is at present unknown. This project aims to define the role of the plant TOR kinase in translation regulation and to understand how plants have rewired the TOR signalling pathway for their specific translational programs. We have discovered putative plant translation repressor (TR) proteins that harbour eIF4E binding sites and TOR phosphorylation sites, and will study translation initiation mechanisms and their control by TOR in the shoot apical meristem—a specialized tissue containing a stem cell niche responsible for building the shoot. The main objective of proposed research is to uncover regulatory factors that function under the control of TOR in translation initiation and to identify their targets among meristematic mRNAs. A search for cellular mRNAs whose initiation is regulated by TOR and/or TR proteins will be performed using a global ribosomal profiling approach. The plant hormone auxin is an upstream effector of TOR and impacts stem cell niche activity. Thus, we shall study whether TOR mediates signaling from auxin to control TR activity and translation initiation. Finally, we will test whether TOR couples amino acid sensing to regulation of translation initiation.

Coordinator

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Net EU contribution
€ 184 707,84
Address
RUE MICHEL ANGE 3
75794 Paris
France

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Region
Ile-de-France Ile-de-France Paris
Activity type
Research Organisations
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Total cost
€ 184 707,84