title: Overexpression of the lily p70(s6k) gene in Arabidopsis affects elongation of flower organs and indicates TOR-dependent regulation of AP3, PI and SUP translation.
abstract: The p70 ribosomal S6 kinase (p70(s6k)) signaling pathway plays a key role in regulating the cell cycle via translational regulation of specific 5'TOP mRNAs. However, the function of this signaling pathway is still poorly understood in plants. Ectopic expression of the lily putative p70(s6k) gene, LS6K1, resulted in up-regulation of NAP (NAC-LIKE, ACTIVATED BY AP3/PI) and PISTILLATA (PI) expression, and significantly inhibited cell expansion for petals and stamens, resulting in the male sterility phenotype in transgenic Arabidopsis. Sequence analysis revealed that the genes involved in petal and stamen development, such as APETALA3 (AP3), PI and SUPERMAN (SUP), probably encode 5'TOP mRNAs. Green fluorescent protein (GFP), fused to oligopyrimidine tract sequences that were identified in the 5'-untranslated region (UTR) of AP3, PI and SUP, was translationally regulated in human cells in response to mitogen stimulation and inhibition by the macrolide antibiotic rapamycin. Furthermore, 35S::LS6K1 significantly up-regulated beta-glucuronidase (GUS) activity in the flower buds of transgenic plants carrying the GUS transgene fused to the AP3 promoter and the 5' UTR. These results have identified a novel role for the p70(s6k) gene in regulating cell division and the expansion of petals and stamens by translational regulation of the 5'TOP mRNAs once ectopically expressed in Arabidopsis.
authors: Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan ROC.
authors: Tsai-Yu
authors: TY
authors: Tzeng
authors: Lih-Ren
authors: LR
authors: Kong
authors: Chun-Hung
authors: CH
authors: Chen
authors: Chih-Chi
authors: CC
authors: Shaw
authors: Chang-Hsien
authors: CH
authors: Yang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D001483:Base Sequence; D002455:Cell Division; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006801:Humans; D027762:Lilium / Q000235:genetics*; D026161:MADS Domain Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D051479:Plant Infertility; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D038641:RNA 5' Terminal Oligopyrimidine Sequence; D018749:RNA, Plant / Q000235:genetics; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C101342:APETALA 3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D026161:MADS Domain Proteins; C090225:PISTILLATA protein, Arabidopsis; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; C096661:superman protein, Arabidopsis; D038762:Ribosomal Protein S6 Kinases, 70-kDa