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Tackling the penalties of global warming in plants: the role of HSP70 and JDPs in the re-potentiation of heat-depolarized thermosensory Ca2+ channels

Applicant Guihur Anthony
Number 196689
Funding scheme Spark
Research institution Département de biologie computationnelle Faculté de biologie et de médecine Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Molecular Biology
Start/End 01.12.2020 - 30.11.2021
Approved amount 100'000.00
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All Disciplines (3)

Discipline
Molecular Biology
Genetics
Biochemistry

Keywords (8)

heat-shock response; J-domain protein; chaperone; HSP70; Cyclic nucleotide-gated ion channel; heat-stress; Arabidopsis thaliana; global warming

Lay Summary (French)

Lead
Les plantes terrestres doivent anticiper les températures et établir à temps les défenses moléculaires appropriées pour assurer leur survie. L'exposition progressive à des températures inférieures à la normale induit l'accumulation de protéines de choc thermique (HSPs) qui sont essentielles à la thermotolérance des plantes terrestres. Comprendre les mécanismes de la perception du stress à la chaleur est un enjeu majeur.
Lay summary

Le réchauffement climatique constitue un défi majeur du 21e siècle et génère de nombreuses complications dans le monde affectant et touchant les écosystèmes. Les stress abiotiques tels que la sécheresse ou la chaleur sont plus fréquents et plus longs, altérant le rendement des cultures.

Des études antérieures menées par l’équipe du Prof. Pierre Goloubinoff (unil-DBMV) ont mis en évidence le rôle de canaux calciques (CNGCs) dans la réponse à la chaleur chez les végétaux, en tant que thermosenseurs menant à la production de protéines de choc thermique (HSPs). Ces « thermomètres moléculaires » réagissent au stress thermique en dépolarisant et désensibilisant les canaux qui auront besoin d’un mécanisme (l’objet de ce projet de recherche) pour régénérer le signal en utilisant des protéines chaperonnes afin de re-charger le canal en prévention d’un futur stress.

S'ils sont confirmés, les résultats serviront de base solide à un plan de recherche étendu représentant un paradigme entièrement nouveau pour le rôle des chaperones dans le fonctionnement des canaux, et avec des implications possibles pour le domaine des canaux ioniques sensibles au stress chez les animaux, tels que les canaux ioniques nociceptifs thermosensibles TRPV qui sont structurellement et fonctionnellement liés aux CNGC, et sont par ailleurs une cible thérapeutique dans le traitement de la douleur.

Ce projet est le fruit d’une collaboration entre le  Prof. Pierre Goloubinoff (unil-DBMV) et du Dr. Anthony Guihur (unil-DBMV), travaillant sur les protéines chaperones et la perception du stress chaleur, respectivement.
Direct link to Lay Summary Last update: 10.10.2020

Lay Summary (English)

Lead
Land plants must anticipate rise of temperatures and establish an appropriate molecular defences in time to ensure their survival. Gradual exposure to below-normal temperatures induces accumulation of heat shock proteins (HSPs) which are essential for the thermotolerance of terrestrial plants. Understanding the mechanisms of heat stress perception is a major challenge for the next years.
Lay summary
Global warming is a major threat facing the 21st century and causes many complications around the world, impacting ecosystems. Abiotic stresses such as drought or heat are more frequent and longer, altering crop yields.

Previous studies conducted by Prof. Pierre Goloubinoff's group ("unil-DBMV") have highlighted the role of calcium channels (CNGCs) in the heat response in plants, as thermosensors leading to the production of heat shock proteins (HSPs). These "molecular thermometers" react to heat stress by depolarising and desensitising the channels, which will need a mechanism (the subject of this research project) to regenerate a signal using chaperone proteins in order to reload the channel to prevent future stress.

If confirmed, the results will serve as a strong basis for an extended research plan representing a completely new paradigm for the role of chaperones in channel function, and with possible implications for the field of stress-responsive ions channels in animals, such as the nociceptive heat-sensory TRPV ion channels that are structurally and functionally related to the CNGCs, and are also a therapeutic target in the treatment of pain.

This project is a collaboration between Prof. Pierre Goloubinoff (unil-DBMV) and Dr. Anthony Guihur (unil-DBMV), working on chaperone proteins and heat stress sensing, respectively.
Direct link to Lay Summary Last update: 10.10.2020

Responsible applicant and co-applicants

Employees

Abstract

Cyclic nucleotide-gated channels (CNGCs) in the plasma membrane of higher plants act as thermosensors. Land plant CNGC2 contains a C-terminal cytosolic domain that binds calmodulins and cyclic nucleotides. Upon an increase of temperature, tensed closed CNGC2 tetramers readily open and transiently mediate entry of extracellular Ca2+ ions into the cytosol, which in turn activate bound calmodulins and initiate a specific signalling cascade to produce protective heat-shock proteins. Yet, within minutes, the heat-depolarized CNGC2 channels become tightly closed again and unresponsive. Despite the ongoing heat shock, heat-signalling becomes arrested and no more HSPs are produced. Up to five hours are needed at low temperature for the plant to fully re-potentiate its heat-depolarized CNGC2 channels and effectively produce an additional full heat-shock response (Fig 1). In a yeast-two-hybrid screen, we identified a unique plant-specific J-domain protein (JDP), called JDP1, member of DNAJC family, which binds the C-terminal cytosolic domain of CNGC2. Given that JDPs generally recruit HSP70s, and that HSP70 can inject energy from ATP hydrolysis to convey a stable (misfolded) protein up a free energy landscape, and convert it into a transiently less stable native protein, we hypothesize that this new DNAJC is recruiting HSP70 to use ATP into the active re-potentiation of closed the heat-depolarized CNGC2 channels at non-HS temperatures and convert them into tensed again, closed channels poised to respond to an additional upcoming heat-shock.In this research project, we aim to generate JDP1 Arabidopsis mutants and use biochemical and in vivo cellular localization methods to address the central hypothetic role of HSP70 in the re-potentiation of heat-depolarized thermo-sensory CNGC2 channels. If confirmed, the results will serve as a strong basis for an extended research plan representing a completely new paradigm for the role of chaperones in channel function, and with possible implications for the field of stress-responsive ions channels in animals, such as the nociceptive heat-sensory TRPV ion channels that are structurally and functionally related to the CNGCs.
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