INCREASED SIZE EXCLUSION LIMIT 2 encodes a putative DEVH box RNA helicase involved in plasmodesmata function during Arabidopsis embryogenesis.
Here, we characterize the Arabidopsis thaliana embryo-defective mutant increased size exclusion limit2 (ise2). In contrast with wild-type embryos, ise2 mutants continue to traffic 10-kD fluorescent dextran in the mid-torpedo stage of development. ise2 embryos contain branched as well as simple plasmodesmata (PD) compared with wild-type embryos, which only contain simple PD. Positional cloning reveals that the ISE2 gene encodes a putative DEVH box RNA helicase that shares sequence homology with RNA helicases involved in RNA degradation pathways in other organisms. ISE2 localizes to granule-like structures in the cytoplasm. These granules increase in number when plant cells are stressed. These features are characteristic of stress granules (SGs) in mammalian cells, suggesting that ISE2 granules represent plant-specific SGs. Genetic data demonstrate that the ISE2 helicase is involved in posttranscriptional gene silencing and the determination of cell fate. These data together suggest that ISE2 function affects PD structure and function through the regulation of RNA metabolism and consequent gene expression.
Kobayashi
Ken
K
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Otegui
Marisa S
MS
Krishnakumar
Sujatha
S
Mindrinos
Michael
M
Zambryski
Patricia
P
D017360:Arabidopsis / Q000166:cytology / Q000196:embryology* / Q000201:enzymology* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D015415:Biomarkers / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018548:Cotyledon / Q000648:ultrastructure; D003911:Dextrans; D015536:Down-Regulation / Q000235:genetics; D047108:Embryonic Development; D020868:Gene Silencing; D035683:MicroRNAs / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D031425:Plasmodesmata / Q000201:enzymology*; D021381:Protein Transport; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism / Q000648:ultrastructure; D012639:Seeds / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000378:metabolism
D029681:Arabidopsis Proteins; D015415:Biomarkers; D003911:Dextrans; D035683:MicroRNAs; D012333:RNA, Messenger; C523445:INCREASED SIZE EXCLUSION LIMIT2 protein, Arabidopsis; D020365:RNA Helicases