title: Centromeric cohesion is protected twice at meiosis, by SHUGOSHINs at anaphase I and by PATRONUS at interkinesis.
abstract: BACKGROUND
  At meiosis, two successive rounds of chromosome segregation lead to ploidy halving. This is achieved through a stepwise release of sister chromatid cohesion, along chromosome arms to allow homolog segregation at anaphase I and at centromeres to allow sister chromatid segregation at anaphase II. Cohesins, the protein complex that ensures cohesion, must then be protected at centromeres throughout meiosis, until the onset of anaphase II. Members of the Shugoshin protein family have been shown to protect centromeric cohesins at anaphase I, but much less is known about the protection of cohesion during interkinesis, the stage between meiosis I and meiosis II.
  
  
  RESULTS
  Here, we (1) show that both Arabidopsis SHUGOSHINs paralogs are required for complete protection of centromeric cohesins during meiosis I, without apparent somatic function, and (2) identified PATRONUS (PANS1), a novel protein required for protection of meiotic centromeric cohesion. Although AtSGO1 and AtSGO2 protect centromeric cohesion during anaphase I, PANS1 is required at a later stage, during interkinesis. Additionally, we identified PANS2, a paralog of PANS1, whose mutation is synthetically lethal with pans1 suggesting that PANS genes are also essential for mitosis. PANS1 interacts directly with the CDC27b and the CDC20.1 subunit of the Anaphase Promoting Complex (APC/C), in a manner suggesting that PANS1 could be both a regulator and a target of the APC/C.
  
  
  CONCLUSIONS
  This study reveals that centromeric cohesion is actively protected at two successive stages of meiosis, by SHUGOSHINs at anaphase I and by PATRONUS at interkinesis.
authors.affiliation: INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, 78000 Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, RD10, 78000 Versailles, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Cromer
authors.forename: Sylvie
authors.initials: S
authors.lastname: Jolivet
authors.forename: Christine
authors.initials: C
authors.lastname: Horlow
authors.forename: Liudmila
authors.initials: L
authors.lastname: Chelysheva
authors.forename: Jefri
authors.initials: J
authors.lastname: Heyman
authors.forename: Geert
authors.initials: G
authors.lastname: De Jaeger
authors.forename: Csaba
authors.initials: C
authors.lastname: Koncz
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
authors.forename: Raphael
authors.initials: R
authors.lastname: Mercier
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D020090:Chromosome Segregation; D008540:Meiosis; D009154:Mutation; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; C000589332:SGO1 protein, Arabidopsis; C000589333:SGO2 protein, Arabidopsis; C000589331:patronus protein, Arabidopsis