Abstract
GCN2 (GENERAL CONTROL NONREPRESSED2) is a serine/threonine-protein kinase that regulates translation in response to stressors such as amino acid and purin deprivation, cold shock, wounding, cadmium and UV-C exposure. Activated GCN2 phosphorylates the α-subunit of the eukaryotic translation initiation factor 2 (eIF2) leading to a drastic inhibition of protein synthesis and shifting translation to specific mRNAs. To investigate the role of GCN2 in responses to UV-B radiation its activity was analyzed through eIF2α phosphorylation assays in mutants of the specific UV-B and stress signaling pathways of Arabidopsis thaliana. EIF2α phosphorylation was detectable 30 min after UV-B exposure, independent of the UV-B photoreceptor UV RESISTANCE LOCUS8 and its downstream signaling components. GCN2 dependent phosphorylation of eIF2α was also detectable in mutants of the stress related MAP kinases, MPK3 and MPK6 and their negative regulator MAP KINASE PHOSPHATASE1 (MKP1). Transcription of downstream components of the UV-B signaling pathway, the CHALCONE SYNTHASE (CHS) was constitutively higher in gcn2-1 compared to wildtype and further increased upon UV-B while GLUTATHIONE PEROXIDASE7 (GPX7) behaved similarly to wildtype. The UVR8 independent FAD-LINKED OXIDOREDUCTASE (FADox) had a lower basal expression in gcn2-1 which was increased upon UV-B. Since high fluence rates of UV-B induce DNA damage the expression of the RAS ASSOCIATED WITH DIABETES PROTEIN51 (RAD51) was quantified before and after UV-B. While the basal expression was similar to wildtype it was significantly less induced upon UV-B in the gcn2-1 mutant. This expression pattern correlates with the finding that gcn2 mutants develop less cyclobutane pyrimidine dimers (CPDs) after UV-B exposure. Quantification of translation with the puromycination assay revealed that gcn2 mutants have an increased rate of translation which was also higher upon UV-B. Growth of gcn2 mutants to chronic UV-B exposure support GCN2’s role as a negative regulator of UV-B responses. The elevated resistance of gcn2 mutants towards repeated UV-B exposure points to a critical role of GCN2 in the regulation of translation upon UV-B.
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Claims 9
Claim · model-written summary
UV-B induced eIF2α phosphorylation by 30 minutes independently of UVR8 signaling.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Treatment
- UV-B exposuree0
- Gene
- UV RESISTANCE LOCUS8e0
- Outcome
- EIF2α phosphorylatione0
- Value
- 30 mine0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“EIF2α phosphorylation was detectable 30 min after UV-B exposure, independent of the UV-B photoreceptor UV RESISTANCE LOCUS8 and its downstream signaling components.”
t0“Arabidopsis thaliana”
Claim · model-written summary
GCN2-dependent eIF2α phosphorylation remained detectable in MPK3, MPK6, and MKP1 mutants.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- mutants of the stress related MAP kinases, MPK3 and MPK6 and their negative regulator MAP KINASE PHOSPHATASE1 (MKP1)e0
- Outcome
- GCN2 dependent phosphorylation of eIF2αe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GCN2 dependent phosphorylation of eIF2α was also detectable in mutants of the stress related MAP kinases, MPK3 and MPK6 and their negative regulator MAP KINASE PHOSPHATASE1 (MKP1).”
e1“Arabidopsis thaliana”
Claim · model-written summary
CHS transcription was higher at baseline in gcn2-1 than wildtype and increased further under UV-B.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- gcn2-1e0
- Treatment
- UV-Be0
- Outcome
- CHALCONE SYNTHASE (CHS)e0
- Direction
- highere0
- Comparator
- wildtypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the CHALCONE SYNTHASE (CHS) was constitutively higher in gcn2-1 compared to wildtype and further increased upon UV-B”
e1“Arabidopsis thaliana”
Claim · model-written summary
GPX7 transcription in gcn2-1 behaved similarly to wildtype.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Outcome
- GLUTATHIONE PEROXIDASE7 (GPX7)e0
- Direction
- similarlye0
- Comparator
- wildtypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GLUTATHIONE PEROXIDASE7 (GPX7) behaved similarly to wildtype”
e1“Arabidopsis thaliana”
Claim · model-written summary
FADox expression was lower at baseline in gcn2-1 and increased under UV-B.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- gcn2-1e0
- Treatment
- UV-Be0
- Outcome
- FAD-LINKED OXIDOREDUCTASE (FADox)e0
- Direction
- lowere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The UVR8 independent FAD-LINKED OXIDOREDUCTASE (FADox) had a lower basal expression in gcn2-1 which was increased upon UV-B.”
e1“Arabidopsis thaliana”
Claim · model-written summary
RAD51 induction after UV-B was significantly lower in gcn2-1 than wildtype.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Material
- gcn2-1 mutante0
- Treatment
- UV-Be0
- Outcome
- RAS ASSOCIATED WITH DIABETES PROTEIN51 (RAD51)e1
- Direction
- less inducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it was significantly less induced upon UV-B in the gcn2-1 mutant”
e1“RAS ASSOCIATED WITH DIABETES PROTEIN51 (RAD51)”
e2“Arabidopsis thaliana”
Claim · model-written summary
gcn2 mutants developed fewer cyclobutane pyrimidine dimers after UV-B.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- gcn2 mutantse0
- Treatment
- UV-B exposuree0
- Outcome
- cyclobutane pyrimidine dimers (CPDs)e0
- Direction
- lesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gcn2 mutants develop less cyclobutane pyrimidine dimers (CPDs) after UV-B exposure”
e1“Arabidopsis thaliana”
Claim · model-written summary
Translation rate was higher in gcn2 mutants, including upon UV-B.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- gcn2 mutantse0
- Treatment
- UV-Be0
- Outcome
- rate of translatione0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gcn2 mutants have an increased rate of translation which was also higher upon UV-B”
e1“Arabidopsis thaliana”
Claim · model-written summary
gcn2 mutants had elevated resistance to repeated UV-B exposure.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Material
- gcn2 mutantse0
- Treatment
- repeated UV-B exposuree0
- Outcome
- resistancee0
- Direction
- elevatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The elevated resistance of gcn2 mutants towards repeated UV-B exposure”
e1“Arabidopsis thaliana”
The same questions in other papers
uv · molecular: expression · Arabidopsis thaliana (thale cress)Positive and negative results
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- no effect
- negative
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