Trans-regulation of the expression of the transcription factor MtHAP2-1 by a uORF controls root nodule development.
MtHAP2-1 is a CCAAT-binding transcription factor from the model legume Medicago truncatula. We previously showed that MtHAP2-1 expression is regulated both spatially and temporally by microRNA169. Here we present a novel regulatory mechanism controlling MtHAP2-1 expression. Alternative splicing of an intron in the MtHAP2-1 5'leader sequence (LS) becomes predominant during the development of root nodules, leading to the production of a small peptide, uORF1p. Our results indicate that binding of uORF1p to MtHAP2-1 5'LS mRNA leads to reduced accumulation of the MtHAP2-1 transcript and may contribute to spatial restriction of MtHAP2-1 expression within the nodule. We propose that miR169 and uORF1p play essential, sequential, and nonredundant roles in regulating MtHAP2-1 expression. Importantly, in contrast to previously described cis-acting uORFs, uORF1p is able to act in trans to down-regulate gene expression. Our work thus contributes to a better understanding of the action of upstream ORFs (uORFs) in the regulation of gene expression.
Combier
Jean Philippe
JP
Laboratoire des Interactions Plantes Micro-organismes (LIPM), Centre National de la Recherche Scientifique-Institut National de la Recherche Agronomique UMR 2594/441, F-31320 Castanet Tolosan, France. jpcombier@yahoo.fr
de Billy
Françoise
F
Gamas
Pascal
P
Niebel
Andreas
A
Rivas
Susana
S
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D046913:Medicago truncatula / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D053204:Root Nodules, Plant / Q000254:growth & development*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D014157:Transcription Factors