title: Regulation of HSD1 in seeds of Arabidopsis thaliana.
abstract: The hydroxysteroid dehydrogenase HSD1, identified in the proteome of oil bodies from mature Arabidopsis seeds, is encoded by At5g50600 and At5g50700, two gene copies anchored on a duplicated region of chromosome 5. Using a real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) approach, the accumulation of HSD1 mRNA was shown to be specifically and highly induced in oil-accumulating tissues of maturing seeds. HSD1 mRNA disappeared during germination. The activity of HSD1 promoter and the localization of HSD1 transcripts by in situ hybridization were consistent with this pattern. A complementary set of molecular and genetic analyses showed that HSD1 is a target of LEAFY COTYLEDON2, a transcriptional regulator able to bind the promoter of HSD1. Immunoblot analyses and immunolocalization experiments using anti-AtHSD1 antibodies established that the pattern of HSD1 deposition faithfully reflected mRNA accumulation. At the subcellular level, the study of HSD1:GFP fusion proteins showed the targeting of HSD1 to the surface of oil bodies. Transgenic lines overexpressing HSD1 were then obtained to test the importance of proper transcriptional regulation of HSD1 in seeds. Whereas no impact on oil accumulation could be detected, transgenic seeds exhibited lower cold and light requirements to break dormancy, germinate and mobilize storage lipids. Interestingly, overexpressors of HSD1 over-accumulated HSD1 protein in seeds but not in vegetative organs, suggesting that post-transcriptional regulations exist that prevent HSD1 accumulation in tissues deprived of oil bodies.
authors: Institut Jean-Pierre Bourgin, UMR Biologie des semences, INRA/AgroParisTech, F-78000 Versailles, France.
authors: Sébastien
authors: S
authors: Baud
authors: Neel Reinhard
authors: NR
authors: Dichow
authors: Zsolt
authors: Z
authors: Kelemen
authors: Sabine
authors: S
authors: d'Andréa
authors: Alexandra
authors: A
authors: To
authors: Nathalie
authors: N
authors: Berger
authors: Michel
authors: M
authors: Canonge
authors: Jocelyne
authors: J
authors: Kronenberger
authors: David
authors: D
authors: Viterbo
authors: Bertrand
authors: B
authors: Dubreucq
authors: Loïc
authors: L
authors: Lepiniec
authors: Thierry
authors: T
authors: Chardot
authors: Martine
authors: M
authors: Miquel
mesh_terms: D042842:11-beta-Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D029681:Arabidopsis Proteins; D018076:DNA, Complementary; C504240:LEC2 protein, Arabidopsis; D012333:RNA, Messenger; D018749:RNA, Plant; D014157:Transcription Factors; D014280:Triglycerides; D042842:11-beta-Hydroxysteroid Dehydrogenases; C525375:HSD1 protein, Arabidopsis