title: ZmbZIP60 mRNA is spliced in maize in response to ER stress.
abstract: BACKGROUND
  Adverse environmental conditions produce ER stress and elicit the unfolded protein response (UPR) in plants. Plants are reported to have two "arms" of the ER stress signaling pathway-one arm involving membrane-bound transcription factors and the other involving a membrane-associated RNA splicing factor, IRE1. IRE1 in yeast to mammals recognizes a conserved twin loop structure in the target RNA.
  
  
  RESULTS
  A segment of the mRNA encoding ZmbZIP60 in maize can be folded into a twin loop structure, and in response to ER stress this mRNA is spliced, excising a 20b intron. Splicing converts the predicted protein from a membrane-associated transcription factor to one that is targeted to the nucleus. Splicing of ZmbZIP60 can be elicited in maize seedlings by ER stress agents such as dithiothreitol (DTT) or tunicamycin (TM) or by heat treatment. Younger, rather than older seedlings display a more robust splicing response as do younger parts of leaf, along a developmental gradient in a leaf. The molecular signature of an ER stress response in plants includes the upregulation of Binding Protein (BIP) genes. Maize has numerous BIP-like genes, and ER stress was found to upregulate one of these, ZmBIPb.
  
  
  CONCLUSIONS
  The splicing of ZmbZIP60 mRNA is an indicator of ER stress in maize seedlings resulting from adverse environmental conditions such as heat stress. ZmbZIP60 mRNA splicing in maize leads predictively to the formation of active bZIP transcription factor targeted to the nucleus to upregulate stress response genes. Among the genes upregulated by ER stress in maize is one of 22 BIP-like genes, ZmBIPb.
authors.affiliation: Plant Sciences Institute, Iowa State University, Ames, IA 50014, USA.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Li
authors.forename: Sabrina
authors.initials: S
authors.lastname: Humbert
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Howell
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000145:classification / Q000235:genetics*; D004229:Dithiothreitol / Q000494:pharmacology; D059865:Endoplasmic Reticulum Stress; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000187:drug effects / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D012965:Sodium Chloride / Q000494:pharmacology; D014415:Tunicamycin / Q000494:pharmacology; D003313:Zea mays / Q000187:drug effects / Q000235:genetics*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012333:RNA, Messenger; C578501:ZmbZIP60 protein, Zea mays; D014415:Tunicamycin; D012965:Sodium Chloride; D000040:Abscisic Acid; D004229:Dithiothreitol