title: The Arabidopsis SR45 Splicing Factor, a Negative Regulator of Sugar Signaling, Modulates SNF1-Related Protein Kinase 1 Stability.
abstract: The ability to sense and respond to sugar signals allows plants to cope with environmental and metabolic changes by adjusting growth and development accordingly. We previously reported that the SR45 splicing factor negatively regulates glucose signaling during early seedling development in Arabidopsis thaliana Here, we show that under glucose-fed conditions, the Arabidopsis sr45-1 loss-of-function mutant contains higher amounts of the energy-sensing SNF1-Related Protein Kinase 1 (SnRK1) despite unaffected SnRK1 transcript levels. In agreement, marker genes for SnRK1 activity are upregulated in sr45-1 plants, and the glucose hypersensitivity of sr45-1 is attenuated by disruption of the SnRK1 gene. Using a high-resolution RT-PCR panel, we found that the sr45-1 mutation broadly targets alternative splicing in vivo, including that of the SR45 pre-mRNA itself. Importantly, the enhanced SnRK1 levels in sr45-1 are suppressed by a proteasome inhibitor, indicating that SR45 promotes targeting of the SnRK1 protein for proteasomal destruction. Finally, we demonstrate that SR45 regulates alternative splicing of the Arabidopsis 5PTase13 gene, which encodes an inositol polyphosphate 5-phosphatase previously shown to interact with and regulate the stability of SnRK1 in vitro, thus providing a mechanistic link between SR45 function and the modulation of degradation of the SnRK1 energy sensor in response to sugars.
authors.affiliation: Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal.
authors.forename: Raquel F
authors.identifier: 0000-0002-6899-6516
authors.initials: RF
authors.lastname: Carvalho
authors.affiliation: Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal.
authors.forename: Dóra
authors.identifier: 0000-0002-9189-629X
authors.initials: D
authors.lastname: Szakonyi
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, United Kingdom.
authors.forename: Craig G
authors.identifier: 0000-0002-1723-1492
authors.initials: CG
authors.lastname: Simpson
authors.affiliation: Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal.
authors.forename: Inês C R
authors.initials: IC
authors.lastname: Barbosa
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, United Kingdom University of Dundee at The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, United Kingdom.
authors.forename: John W S
authors.identifier: 0000-0003-2979-779X
authors.initials: JW
authors.lastname: Brown
authors.affiliation: Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal.
authors.forename: Elena
authors.identifier: 0000-0001-6598-3579
authors.initials: E
authors.lastname: Baena-González
authors.affiliation: Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal duquep@igc.gulbenkian.pt.
authors.forename: Paula
authors.identifier: 0000-0002-4910-2900
authors.initials: P
authors.lastname: Duque
mesh_terms: D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D016601:RNA-Binding Proteins; C569740:SR45a protein, Arabidopsis; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; C499855:5PTase13 protein, Arabidopsis; D010744:Phosphoric Monoester Hydrolases