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ZmbZIP60 mRNA is spliced in maize in response to ER stress.

Li Y, Humbert S, Howell SH - BMC Res Notes (2012)

Bottom Line: Splicing converts the predicted protein from a membrane-associated transcription factor to one that is targeted to the nucleus.Maize has numerous BIP-like genes, and ER stress was found to upregulate one of these, ZmBIPb.Among the genes upregulated by ER stress in maize is one of 22 BIP-like genes, ZmBIPb.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Sciences Institute, Iowa State University, Ames, IA 50014, USA.

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.

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Expression of selected BIP-like genes in maize following heat (42°C) and 2.5 mM DTT treatment for the time indicated. RT-PCR assays were conducted using the gene-specific primers as indicated in Table S1.
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Figure 6: Expression of selected BIP-like genes in maize following heat (42°C) and 2.5 mM DTT treatment for the time indicated. RT-PCR assays were conducted using the gene-specific primers as indicated in Table S1.

Mentions: To determine which, if any, maize BIP-like gene is regulated by ER stress, we picked the top six from a blast search using AtBIP3 as the query sequence and for convenience referred to these genes as ZmBIPa-f. We subjected seedlings to heat and DTT treatment. Of the six maize BIP genes, only ZmBIPb (GRMZM2G471196P01) responded significantly to ER stress. ZmBIPb was upregulated within 15 min and reached a peak at 1-2 hr after the beginning of treatment (Figure 6A). ZmBIPb was upregulated somewhat more slowly by DTT than by heat treatment reaching a peak around 4 hr (Figure 6B). It is still unclear whether ZmbZIP60 is directly involved in the upregulation of ZmBIPb by ER stress. However, the accumulation pattern of ZmBIPb mRNA is consistent with the proposition that the gene might be a ZmbZIP60 transcriptional target because the accumulation of ZmBIPb mRNA slightly lags the accumulation of spliced ZmbZIP60 mRNA. In addition, within 150 bp upstream from the start of the ZmBIPb gene in maize line B73 are five core sequences (CACG) from the p-PURE and ERSE promoter elements, which are known to regulate genes involved in ER stress responses [35].


ZmbZIP60 mRNA is spliced in maize in response to ER stress.

Li Y, Humbert S, Howell SH - BMC Res Notes (2012)

Expression of selected BIP-like genes in maize following heat (42°C) and 2.5 mM DTT treatment for the time indicated. RT-PCR assays were conducted using the gene-specific primers as indicated in Table S1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369818&req=5

Figure 6: Expression of selected BIP-like genes in maize following heat (42°C) and 2.5 mM DTT treatment for the time indicated. RT-PCR assays were conducted using the gene-specific primers as indicated in Table S1.
Mentions: To determine which, if any, maize BIP-like gene is regulated by ER stress, we picked the top six from a blast search using AtBIP3 as the query sequence and for convenience referred to these genes as ZmBIPa-f. We subjected seedlings to heat and DTT treatment. Of the six maize BIP genes, only ZmBIPb (GRMZM2G471196P01) responded significantly to ER stress. ZmBIPb was upregulated within 15 min and reached a peak at 1-2 hr after the beginning of treatment (Figure 6A). ZmBIPb was upregulated somewhat more slowly by DTT than by heat treatment reaching a peak around 4 hr (Figure 6B). It is still unclear whether ZmbZIP60 is directly involved in the upregulation of ZmBIPb by ER stress. However, the accumulation pattern of ZmBIPb mRNA is consistent with the proposition that the gene might be a ZmbZIP60 transcriptional target because the accumulation of ZmBIPb mRNA slightly lags the accumulation of spliced ZmbZIP60 mRNA. In addition, within 150 bp upstream from the start of the ZmBIPb gene in maize line B73 are five core sequences (CACG) from the p-PURE and ERSE promoter elements, which are known to regulate genes involved in ER stress responses [35].

Bottom Line: Splicing converts the predicted protein from a membrane-associated transcription factor to one that is targeted to the nucleus.Maize has numerous BIP-like genes, and ER stress was found to upregulate one of these, ZmBIPb.Among the genes upregulated by ER stress in maize is one of 22 BIP-like genes, ZmBIPb.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Sciences Institute, Iowa State University, Ames, IA 50014, USA.

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.

Show MeSH
Related in: MedlinePlus