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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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Induction of ZmbZIP60 splicing under heat stress. Maize seedlings were grown at room temperature (RT) and then incubated at 42°C for the times indicated. Some of the seedlings were recovered at RT after heat treatment for 1 hour. RNA was extracted from (A) roots and (B) shoots and analyzed using the RT-PCR assays described in Figure 2. (C) Temperature dependence of the RNA splicing reaction. Seedlings were incubated at elevated temperature for the times indicated.
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Figure 4: Induction of ZmbZIP60 splicing under heat stress. Maize seedlings were grown at room temperature (RT) and then incubated at 42°C for the times indicated. Some of the seedlings were recovered at RT after heat treatment for 1 hour. RNA was extracted from (A) roots and (B) shoots and analyzed using the RT-PCR assays described in Figure 2. (C) Temperature dependence of the RNA splicing reaction. Seedlings were incubated at elevated temperature for the times indicated.

Mentions: It should be pointed out again that ER stress agents are conveniently used in the laboratory only as proxies to elicit ER stress. Therefore, we tested naturally occurring environmental stresses for their effects on ZmbZIP60 RNA splicing. In Arabidopsis, heat is an efficient inducer of UPR [27], and for this reason we treated corn seedlings with elevated temperatures. When seedlings were exposed to 42°C, ZmbZIP60 mRNA was rapidly spliced (within 15 min) in both roots (Figure 4A) and shoots (Figure 4B), while the level of unspliced RNA was about the same before and after treatment. Unlike treatment with ER stress agents, ZmbZIP60 was spliced in shoots in response to heat stress, demonstrating that shoots are capable of splicing ZmbZIP60 mRNA.


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

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

Induction of ZmbZIP60 splicing under heat stress. Maize seedlings were grown at room temperature (RT) and then incubated at 42°C for the times indicated. Some of the seedlings were recovered at RT after heat treatment for 1 hour. RNA was extracted from (A) roots and (B) shoots and analyzed using the RT-PCR assays described in Figure 2. (C) Temperature dependence of the RNA splicing reaction. Seedlings were incubated at elevated temperature for the times indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Induction of ZmbZIP60 splicing under heat stress. Maize seedlings were grown at room temperature (RT) and then incubated at 42°C for the times indicated. Some of the seedlings were recovered at RT after heat treatment for 1 hour. RNA was extracted from (A) roots and (B) shoots and analyzed using the RT-PCR assays described in Figure 2. (C) Temperature dependence of the RNA splicing reaction. Seedlings were incubated at elevated temperature for the times indicated.
Mentions: It should be pointed out again that ER stress agents are conveniently used in the laboratory only as proxies to elicit ER stress. Therefore, we tested naturally occurring environmental stresses for their effects on ZmbZIP60 RNA splicing. In Arabidopsis, heat is an efficient inducer of UPR [27], and for this reason we treated corn seedlings with elevated temperatures. When seedlings were exposed to 42°C, ZmbZIP60 mRNA was rapidly spliced (within 15 min) in both roots (Figure 4A) and shoots (Figure 4B), while the level of unspliced RNA was about the same before and after treatment. Unlike treatment with ER stress agents, ZmbZIP60 was spliced in shoots in response to heat stress, demonstrating that shoots are capable of splicing ZmbZIP60 mRNA.

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