Abstract
Mechanisms for regulation of gene expression at the translational level have been reported at specific developmental stages in eukaryotes. Control of eukaryotic initiation factor (eIF) 4E availability by insulin/growth factors constitutes a main point of translational regulation. The aim of the present research was to understand the regulatory mechanism(s) behind the differential expression of two main 4E factors present in maize embryonic axes during germination. De novo synthesis of eIFiso4E initiates earlier and is faster than that of eIF4E in maize axes. Insulin addition to maize axes stimulated de novo synthesis of the eIFiso4E protein, but not that of eIF4E. Specific recruitment of the eIFiso4E transcript into polysomes was observed in these axes after insulin stimulation. Inhibitors of the insulin signal-transduction pathway, wortmannin and rapamycin, reversed the insulin effect. In vitro translation of maize poly(A)+ RNAs by S6 ribosomal protein (rp)-phosphorylated ribosomes demonstrated a strong increase in eIFiso4E synthesis, as compared with its translation by S6 rp-non-phosphorylated ribosomes. Other mRNAs from the poly(A)+ RNA set, including the eIF4E mRNA, did not show differential translation with regard to the S6-phosphorylated status of the ribosomes. The overall results indicate that eIFiso4E, but not eIF4E, cell content is regulated by de novo synthesis in maize axes during germination, most probably by specific mRNA recruitment into polysomes via a signal-transduction pathway involving S6 rp phosphorylation.
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Claims 9
Claim · model-written summary
De novo eIFiso4E synthesis starts earlier and proceeds faster than eIF4E synthesis in maize axes.
- Organ / stage
- axese0
- Gene
- eIFiso4Ee0
- Outcome
- De novo synthesis of eIFiso4Ee0
- Direction
- earlier and is fastere0
- Comparator
- eIF4Ee0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“De novo synthesis of eIFiso4E initiates earlier and is faster than that of eIF4E in maize axes.”
Claim · model-written summary
Insulin stimulated de novo eIFiso4E synthesis in maize axes.
- Treatment
- Insulin additione0
- Gene
- eIFiso4Ee0
- Outcome
- de novo synthesis of the eIFiso4E proteine0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Insulin addition to maize axes stimulated de novo synthesis of the eIFiso4E protein, but not that of eIF4E.”
Claim · model-written summary
Insulin did not stimulate de novo eIF4E synthesis in maize axes.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Insulin addition to maize axes stimulated de novo synthesis of the eIFiso4E protein, but not that of eIF4E.”
Claim · model-written summary
Insulin stimulation led to specific recruitment of the eIFiso4E transcript into polysomes in maize axes.
- Treatment
- insulin stimulatione0
- Gene
- eIFiso4Ee0
- Outcome
- Specific recruitment of the eIFiso4E transcript into polysomese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Specific recruitment of the eIFiso4E transcript into polysomes was observed in these axes after insulin stimulation.”
t0“maize”
Claim · model-written summary
Wortmannin reversed the insulin effect on maize eIFiso4E synthesis.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inhibitors of the insulin signal-transduction pathway, wortmannin and rapamycin, reversed the insulin effect.”
t0“maize”
Claim · model-written summary
Rapamycin reversed the insulin effect on maize eIFiso4E synthesis.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inhibitors of the insulin signal-transduction pathway, wortmannin and rapamycin, reversed the insulin effect.”
t0“maize”
Claim · model-written summary
S6 phosphorylated ribosomes increased in vitro translation of maize eIFiso4E relative to nonphosphorylated ribosomes.
- Treatment
- S6 ribosomal protein (rp)-phosphorylated ribosomese0
- Gene
- eIFiso4Ee0
- Outcome
- eIFiso4E synthesise0
- Direction
- strong increasee0
- Comparator
- S6 rp-non-phosphorylated ribosomese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In vitro translation of maize poly(A)+ RNAs by S6 ribosomal protein (rp)-phosphorylated ribosomes demonstrated a strong increase in eIFiso4E synthesis, as compared with its translation by S6 rp-non-phosphorylated ribosomes.”
Claim · model-written summary
Other maize mRNAs, including eIF4E, showed no differential translation by ribosomal S6 phosphorylation status.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Other mRNAs from the poly(A)+ RNA set, including the eIF4E mRNA, did not show differential translation with regard to the S6-phosphorylated status of the ribosomes.”
t0“maize”
Claim · model-written summary
Authors infer that eIFiso4E cell content is regulated by de novo synthesis during maize axis germination, probably through selective transcript recruitment involving S6 phosphorylation.
- Gene
- eIFiso4Ee0
- Outcome
- eIFiso4E, but not eIF4E, cell contente0
- Qualifier
- most probably by specific mRNA recruitment into polysomes via a signal-transduction pathway involving S6 rp phosphorylatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The overall results indicate that eIFiso4E, but not eIF4E, cell content is regulated by de novo synthesis in maize axes during germination, most probably by specific mRNA recruitment into polysomes via a signal-transduction pathway involving S6 rp phosphorylation.”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.