scholarly journals Increased expression of ANAC017 primes for accelerated senescence

2021 ◽  
Author(s):  
Martyna Broda ◽  
Kasim Khan ◽  
Brendan O’Leary ◽  
Adriana Pružinská ◽  
Chun Pong Lee ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Target Genes ◽  
Promoter Sequence ◽  
Time Resolved ◽  
Nac Domain ◽  
Knock Out ◽  
Age Related ◽  
Knockout Mutants ◽  
Accelerated Senescence ◽  
Late Stages

Abstract Recent studies in Arabidopsis (Arabidopsis thaliana) have reported conflicting roles for NAC DOMAIN CONTAINING PROTEIN 17 (ANAC017), a transcription factor regulating mitochondria-to-nuclear signalling, and its closest paralog NAC DOMAIN CONTAINING PROTEIN 16 (ANAC016), in leaf senescence. By synchronising senescence in individually darkened leaves of knock-out and overexpressing mutants from these contrasting studies, we demonstrate that elevated ANAC017 expression consistently causes accelerated senescence and cell death. A time-resolved transcriptome analysis revealed that senescence-associated pathways such as autophagy are not constitutively activated in ANAC017 overexpression lines, but require a senescence-stimulus to trigger accelerated induction. ANAC017 transcript and ANAC017-target genes are constitutively upregulated in ANAC017 overexpression lines, but surprisingly show a transient ‘super-induction’ one day after senescence-induction. This induction of ANAC017 and its target genes is observed during the later stages of age-related and dark induced senescence, indicating the ANAC017 pathway is also activated in natural senescence. In contrast, knockout mutants of ANAC017 showed lowered senescence-induced induction of ANAC017 target genes during the late stages of dark-induced senescence. Finally, promotor binding analyses show that the ANAC016 promoter sequence is directly bound by ANAC017, so ANAC016 likely acts downstream of ANAC017 and is directly transcriptionally controlled by ANAC017 in a feed-forward loop during late senescence.

scholarly journals Total reducing capacity in Arabidopsis thaliana cat2cat3 knockout mutants under heat stress

2017 ◽  
Vol 15 (1) ◽  
pp. 47-51
Author(s):  
I. I. Panchuk ◽  
I. M. Buzduga ◽  
R. A. Volkov
Keyword(s):  
Molecular Weight ◽  
Arabidopsis Thaliana ◽  
Heat Stress ◽  
Water Soluble ◽  
Antioxidant Defenses ◽  
Low Molecular Weight ◽  
Wild Type ◽  
Knock Out ◽  
Knockout Mutants ◽  
Reducing Capacity

Aim. It was investigated whether the simultaneous loss of the two catalase isoforms CAT2 and CAT3 can be compensated by the increase in content of low-molecular weight antioxidants. To clarify this question, the total reducing capacity in Arabidopsis wild type and cat2cat3 knockout mutants was evaluated under optimal growth conditions and after heat stress. Methods. Leaves of Arabidopsis thaliana wild type and cat2cat3 knockout mutants were exposed to high temperatures. The content of water-soluble low molecular weight antioxidants was evaluated by determining the total reducing capacity using iodometry. Results. In intact cat2cat3 mutants there is an 1.7 times increase in the content of low-molecular weight antioxidants compared to wild type plants. A high content of these compounds in knockout plants was also observed upon heat stress. Patterns of changes in total reducing capacity differ between wild type and knockout lines. Conclusion. The loss of activity of the catalase isoforms CAT2 and CAT3 in knock-out mutants of Arabidopsis results in activation of non-enzymatic antioxidant defenses. The increase of the content of low-molecular weight antioxidants is one of the mechanisms that provide protection of mutant plants from chronic oxidative stress, both under optimal cultivation conditions and under the influence of elevated temperatures.Keywords: multigenic family, heat shock, total reducing capacity, knockout mutants, Arabidopsis thaliana.

Flavonoid profiling by LC-MS IN 14 – 3-3ν knockout mutants of Arabidopsis thaliana during drought stress conditions

Planta Medica ◽  
2014 ◽  
Vol 80 (10) ◽  
Author(s):  
F Nabbie ◽  
O Shperdheja ◽  
J Millot ◽  
J Lindberg ◽  
B Peethambaran
Keyword(s):  
Arabidopsis Thaliana ◽  
Drought Stress ◽  
Stress Conditions ◽  
Knockout Mutants

scholarly journals Alternative splicing landscapes in Arabidopsis thaliana across tissues and stress conditions highlight major functional differences with animals

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Guiomar Martín ◽  
Yamile Márquez ◽  
Federica Mantica ◽  
Paula Duque ◽  
Manuel Irimia
Keyword(s):  
Gene Expression ◽  
Arabidopsis Thaliana ◽  
Alternative Splicing ◽  
Stress Responses ◽  
Target Genes ◽  
Intron Retention ◽  
Single Gene ◽  
Exon Skipping ◽  
Environmental Response ◽  
Biotic Stresses

Abstract Background Alternative splicing (AS) is a widespread regulatory mechanism in multicellular organisms. Numerous transcriptomic and single-gene studies in plants have investigated AS in response to specific conditions, especially environmental stress, unveiling substantial amounts of intron retention that modulate gene expression. However, a comprehensive study contrasting stress-response and tissue-specific AS patterns and directly comparing them with those of animal models is still missing. Results We generate a massive resource for Arabidopsis thaliana, PastDB, comprising AS and gene expression quantifications across tissues, development and environmental conditions, including abiotic and biotic stresses. Harmonized analysis of these datasets reveals that A. thaliana shows high levels of AS, similar to fruitflies, and that, compared to animals, disproportionately uses AS for stress responses. We identify core sets of genes regulated specifically by either AS or transcription upon stresses or among tissues, a regulatory specialization that is tightly mirrored by the genomic features of these genes. Unexpectedly, non-intron retention events, including exon skipping, are overrepresented across regulated AS sets in A. thaliana, being also largely involved in modulating gene expression through NMD and uORF inclusion. Conclusions Non-intron retention events have likely been functionally underrated in plants. AS constitutes a distinct regulatory layer controlling gene expression upon internal and external stimuli whose target genes and master regulators are hardwired at the genomic level to specifically undergo post-transcriptional regulation. Given the higher relevance of AS in the response to different stresses when compared to animals, this molecular hardwiring is likely required for a proper environmental response in A. thaliana.

scholarly journals Arabidopsis thaliana G3BP Ortholog Rescues Mammalian Stress Granule Phenotype across Kingdoms

2021 ◽  
Vol 22 (12) ◽  
pp. 6287
Author(s):  
Hendrik Reuper ◽  
Benjamin Götte ◽  
Lucy Williams ◽  
Timothy J. C. Tan ◽  
Gerald M. McInerney ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Fusion Proteins ◽  
Biological Function ◽  
Protein Complexes ◽  
Protein Family ◽  
Knock Out ◽  
Marker Proteins ◽  
Interaction Partners ◽  
Functional Analyses ◽  
Rna Protein Complexes

Stress granules (SGs) are dynamic RNA–protein complexes localized in the cytoplasm that rapidly form under stress conditions and disperse when normal conditions are restored. The formation of SGs depends on the Ras-GAP SH3 domain-binding protein (G3BP). Formations, interactions and functions of plant and human SGs are strikingly similar, suggesting a conserved mechanism. However, functional analyses of plant G3BPs are missing. Thus, members of the Arabidopsis thaliana G3BP (AtG3BP) protein family were investigated in a complementation assay in a human G3BP knock-out cell line. It was shown that two out of seven AtG3BPs were able to complement the function of their human homolog. GFP-AtG3BP fusion proteins co-localized with human SG marker proteins Caprin-1 and eIF4G1 and restored SG formation in G3BP double KO cells. Interaction between AtG3BP-1 and -7 and known human G3BP interaction partners such as Caprin-1 and USP10 was also demonstrated by co-immunoprecipitation. In addition, an RG/RGG domain exchange from Arabidopsis G3BP into the human G3BP background showed the ability for complementation. In summary, our results support a conserved mechanism of SG function over the kingdoms, which will help to further elucidate the biological function of the Arabidopsis G3BP protein family.

scholarly journals Ca2+-Dependent Protein Kinase 6 Enhances KAT2 Shaker Channel Activity in Arabidopsis thaliana

2021 ◽  
Vol 22 (4) ◽  
pp. 1596
Author(s):  
Elsa Ronzier ◽  
Claire Corratgé-Faillie ◽  
Frédéric Sanchez ◽  
Christian Brière ◽  
Tou Cheu Xiong
Keyword(s):  
Arabidopsis Thaliana ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Physical Interaction ◽  
Fluorescence Lifetime Imaging ◽  
Dependent Manner ◽  
In Planta ◽  
Knock Out ◽  
Calcium Dependent ◽  
Dependent Protein

Post-translational regulations of Shaker-like voltage-gated K+ channels were reported to be essential for rapid responses to environmental stresses in plants. In particular, it has been shown that calcium-dependent protein kinases (CPKs) regulate Shaker channels in plants. Here, the focus was on KAT2, a Shaker channel cloned in the model plant Arabidopsis thaliana, where is it expressed namely in the vascular tissues of leaves. After co-expression of KAT2 with AtCPK6 in Xenopuslaevis oocytes, voltage-clamp recordings demonstrated that AtCPK6 stimulates the activity of KAT2 in a calcium-dependent manner. A physical interaction between these two proteins has also been shown by Förster resonance energy transfer by fluorescence lifetime imaging (FRET-FLIM). Peptide array assays support that AtCPK6 phosphorylates KAT2 at several positions, also in a calcium-dependent manner. Finally, K+ fluorescence imaging in planta suggests that K+ distribution is impaired in kat2 knock-out mutant leaves. We propose that the AtCPK6/KAT2 couple plays a role in the homeostasis of K+ distribution in leaves.

SGLT2 inhibitors as calorie restriction-mimetics: insights on longevity pathways and age-related diseases

Endocrinology ◽  
2021 ◽  
Author(s):  
Caroline W S Hoong ◽  
Marvin W J Chua
Keyword(s):  
Calorie Restriction ◽  
Stress Resistance ◽  
Target Genes ◽  
Metabolic Diseases ◽  
Vascular Inflammation ◽  
Sglt2 Inhibitors ◽  
Acid Oxidation ◽  
The Metabolic Syndrome ◽  
Age Related ◽  
Energy Deprivation

Abstract SGLT2 inhibitors induce glycosuria, reduce insulin levels, promote fatty acid oxidation and ketogenesis. By promoting a nutrient deprivation state, SGLT2 inhibitors upregulate the energy deprivation sensors AMPK and SIRT1, inhibit the nutrient sensors mTOR and insulin/IGF-1, and modulate the closely-linked HIF-2α/HIF-1α pathways. Phosphorylation of AMPK and upregulation of adiponectin and PPAR-α favour a reversal of the metabolic syndrome which have been linked to suppression of chronic inflammation. Downregulation of insulin/IGF1 pathways and mTOR signalling from a reduction in glucose and circulating amino acids promote cellular repair mechanisms including autophagy and proteostasis which confer cellular stress resistance and attenuate cellular senescence. SIRT1, another energy sensor activated by NAD+ in nutrient-deficient states, is reciprocally activated by AMPK, and can deacetylate and activate transcription factors such as PCG-1α, TFAM and NRF2 that regulate mitochondrial biogenesis. FOXO3 transcription factor which target genes in stress resistance, is also activated by AMPK and SIRT1. Modulation of these pathways by SGLT2 inhibitors have been shown to alleviate metabolic diseases, attenuate vascular inflammation and arterial stiffness, improve mitochondrial function and reduce oxidative stress-induced tissue damage. Compared to other calorie restriction mimetics such as metformin, rapamycin, resveratrol and NAD+ precursors, SGLT2 inhibitors appear to be the most promising in the treatment of ageing-related diseases, due to its regulation of multiple longevity pathways that closely resemble that achieved by calorie restriction, and their established efficacy in reduction in cardiovascular events and all-cause mortality. Evidence is compelling for the role of SGLT2 inhibitors as a calorie restriction mimetic in anti-ageing therapeutics.

Role of oxidative stress in age-related reduction of NO-cGMP-mediated vascular relaxation in SHR

2003 ◽  
Vol 285 (3) ◽  
pp. R542-R551 ◽  
Author(s):  
Jason A. Payne ◽  
Jane F. Reckelhoff ◽  
Raouf A. Khalil
Keyword(s):  
Oxidative Stress ◽  
Drinking Water ◽  
Arterial Pressure ◽  
Vascular Relaxation ◽  
Adult Rats ◽  
Vascular Contraction ◽  
Aging Rats ◽  
Age Related ◽  
Nitrite Nitrate ◽  
Late Stages

The incidence of hypertension increases during the late stages of aging; however, the vascular mechanisms involved are unclear. We investigated whether the late stages of aging are associated with impaired nitric oxide (NO)-mediated vascular relaxation and enhanced vascular contraction and whether oxidative stress plays a role in the age-related vascular changes. Aging (16 mo) male spontaneously hypertensive rats (SHR) nontreated or treated for 8 mo with the antioxidant tempol (1 mM in drinking water) or vitamin E (E; 5,000 IU/kg chow) and vitamin C (C; 100 mg · kg-1· day-1in drinking water) and adult (12 wk) male SHR were used. After the arterial pressure was measured, aortic strips were isolated from the rats for measurement of isometric contraction. The arterial pressure and phenylephrine (Phe)-induced vascular contraction were enhanced, and the ACh-induced vascular relaxation and nitrite/nitrate production were reduced in aging compared with adult rats. In aging rats, the arterial pressure was nontreated (188 ± 4), tempol-treated (161 ± 6), and E + C-treated (187 ± 1 mmHg). Phe (10-5M) caused an increase in active stress in nontreated aging rats (14.3 ± 1.0) that was significantly ( P < 0.05) reduced in tempol-treated (9.0 ± 0.7) and E + C-treated rats (9.8 ± 0.6 × 104N/m2). ACh produced a small relaxation of Phe contraction in nontreated aging rats that was enhanced ( P < 0.05) in tempol- and E + C-treated rats. l-NAME (10-4M), inhibitor of NO synthase, or ODQ (10-5M), inhibitor of cGMP production in smooth muscle, inhibited ACh relaxation and enhanced Phe contraction in tempol- and E + C-treated but not the nontreated aging rats. ACh-induced vascular nitrite/nitrate production was not different in nontreated, tempol- and E + C-treated aging rats. Relaxation of Phe contraction with sodium nitroprusside, an exogenous NO donor, was smaller in aging than adult rats but was not different between nontreated, tempol- and E + C-treated aging rats. Thus, during the late stages of aging in SHR rats, an age-related inhibition of a vascular relaxation pathway involving not only NO production by endothelial cells but also the bioavailability of NO and the smooth muscle response to NO is partially reversed during chronic treatment with the antioxidants tempol and vitamins E and C. The data suggest a role for oxidative stress in the reduction of vascular relaxation and thereby the promotion of vascular contraction and hypertension during the late stages of aging.

scholarly journals Aged xCT-Deficient Mice Are Less Susceptible for Lactacystin-, but Not 1-Methyl-4-Phenyl-1,2,3,6- Tetrahydropyridine-, Induced Degeneration of the Nigrostriatal Pathway

2021 ◽  
Vol 15 ◽  
Author(s):  
Eduard Bentea ◽  
Laura De Pauw ◽  
Lise Verbruggen ◽  
Lila C. Winfrey ◽  
Lauren Deneyer ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Proteasome Inhibition ◽  
Cell Loss ◽  
Redox Balance ◽  
Nigrostriatal Pathway ◽  
Knock Out ◽  
Aged Mice ◽  
Adult Mice ◽  
Age Related ◽  
Nigrostriatal Degeneration

The astrocytic cystine/glutamate antiporter system xc– (with xCT as the specific subunit) imports cystine in exchange for glutamate and has been shown to interact with multiple pathways in the brain that are dysregulated in age-related neurological disorders, including glutamate homeostasis, redox balance, and neuroinflammation. In the current study, we investigated the effect of genetic xCT deletion on lactacystin (LAC)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced degeneration of the nigrostriatal pathway, as models for Parkinson’s disease (PD). Dopaminergic neurons of adult xCT knock-out mice (xCT–/–) demonstrated an equal susceptibility to intranigral injection of the proteasome inhibitor LAC, as their wild-type (xCT+/+) littermates. Contrary to adult mice, aged xCT–/– mice showed a significant decrease in LAC-induced degeneration of nigral dopaminergic neurons, depletion of striatal dopamine (DA) and neuroinflammatory reaction, compared to age-matched xCT+/+ littermates. Given this age-related protection, we further investigated the sensitivity of aged xCT–/– mice to chronic and progressive MPTP treatment. However, in accordance with our previous observations in adult mice (Bentea et al., 2015a), xCT deletion did not confer protection against MPTP-induced nigrostriatal degeneration in aged mice. We observed an increased loss of nigral dopaminergic neurons, but equal striatal DA denervation, in MPTP-treated aged xCT–/– mice when compared to age-matched xCT+/+ littermates. To conclude, we reveal age-related protection against proteasome inhibition-induced nigrostriatal degeneration in xCT–/– mice, while xCT deletion failed to protect nigral dopaminergic neurons of aged mice against MPTP-induced toxicity. Our findings thereby provide new insights into the role of system xc– in mechanisms of dopaminergic cell loss and its interaction with aging.

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