title: Crosstalks between myo-inositol metabolism, programmed cell death and basal immunity in Arabidopsis.
abstract: BACKGROUND
  Although it is a crucial cellular process required for both normal development and to face stress conditions, the control of programmed cell death in plants is not fully understood. We previously reported the isolation of ATXR5 and ATXR6, two PCNA-binding proteins that could be involved in the regulation of cell cycle or cell death. A yeast two-hybrid screen using ATXR5 as bait captured AtIPS1, an enzyme which catalyses the committed step of myo-inositol (MI) biosynthesis. atips1 mutants form spontaneous lesions on leaves, raising the possibility that MI metabolism may play a role in the control of PCD in plants. In this work, we have characterised atips1 mutants to gain insight regarding the role of MI in PCD regulation.
  
  
  RESULTS
  - lesion formation in atips1 mutants depends of light intensity, is due to PCD as evidenced by TUNEL labelling of nuclei, and is regulated by phytohormones such as salicylic acid - MI and galactinol are the only metabolites whose accumulation is significantly reduced in the mutant, and supplementation of the mutant with these compounds is sufficient to prevent PCD - the transcriptome profile of the mutant is extremely similar to that of lesion mimic mutants such as cpr5, or wild-type plants infected with pathogens.
  
  
  CONCLUSIONS
  Taken together, our results provide strong evidence for the role of MI or MI derivatives in the regulation of PCD. Interestingly, there are three isoforms of IPS in Arabidopsis, but AtIPS1 is the only one harbouring a nuclear localisation sequence, suggesting that nuclear pools of MI may play a specific role in PCD regulation and opening new research prospects regarding the role of MI in the prevention of tumorigenesis. Nevertheless, the significance of the interaction between AtIPS1 and ATXR5 remains to be established.
authors.affiliation: Institut de Biotechnologie des Plantes, UMR CNRS 8618, Université Paris-Sud XI, bât 630, Plateau de Moulon, Orsay, France.
authors.forename: Ping Hong
authors.initials: PH
authors.lastname: Meng
authors.forename: Cécile
authors.initials: C
authors.lastname: Raynaud
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tcherkez
authors.forename: Sophie
authors.initials: S
authors.lastname: Blanchet
authors.forename: Kamal
authors.initials: K
authors.lastname: Massoud
authors.forename: Séverine
authors.initials: S
authors.lastname: Domenichini
authors.forename: Yves
authors.initials: Y
authors.lastname: Henry
authors.forename: Ludivine
authors.initials: L
authors.lastname: Soubigou-Taconnat
authors.forename: Caroline
authors.initials: C
authors.lastname: Lelarge-Trouverie
authors.forename: Patrick
authors.initials: P
authors.lastname: Saindrenan
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Renou
authors.forename: Catherine
authors.initials: C
authors.lastname: Bergounioux
mesh_terms: D017209:Apoptosis; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002453:Cell Cycle; D016923:Cell Death; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007107:Immune System; D007294:Inositol / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism; D009154:Mutation; D018521:Plant Physiological Phenomena; D010940:Plant Proteins / Q000378:metabolism; D013997:Time Factors; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; D007294:Inositol; C542364:ATXR5 protein, Arabidopsis; C542365:ATXR6 protein, Arabidopsis; D008780:Methyltransferases