title: Cyclophilin 40 is required for microRNA activity in Arabidopsis.
abstract: Loss-of-function mutations of SQUINT (SQN)-which encodes the Arabidopsis orthologue of cyclophilin 40 (CyP40)-cause the precocious expression of adult vegetative traits, an increase in carpel number, and produce abnormal spacing of flowers in the inflorescence. Here we show that the vegetative phenotype of sqn is attributable to the elevated expression of miR156-regulated members of the SPL family of transcription factors and provide evidence that this defect is a consequence of a reduction in the activity of ARGONAUTE1 (AGO1). Support for this latter conclusion was provided by the phenotypic similarity between hypomorphic alleles of AGO1 and null alleles of SQN and by the genetic interaction between sqn and these alleles. Our results suggest that AGO1, or an AGO1-interacting protein, is a major client of CyP40 and that miR156 and its targets play a central role in the regulation of vegetative phase change in Arabidopsis.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Smith
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Willmann
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.forename: Tanya Z
authors.initials: TZ
authors.lastname: Berardini
authors.forename: Barbara
authors.initials: B
authors.lastname: Möller
authors.forename: Dolf
authors.initials: D
authors.lastname: Weijers
authors.forename: R Scott
authors.initials: RS
authors.lastname: Poethig
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology; D060565:Argonaute Proteins; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000502:physiology*; D035683:MicroRNAs / Q000502:physiology*; D010641:Phenotype; D018521:Plant Physiological Phenomena / Q000235:genetics
chemical_list: C117457:AGO1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D000081406:Peptidyl-Prolyl Isomerase F; D035683:MicroRNAs; D021983:Cyclophilins