scholarly journals Membrane protein MHZ3 stabilizes OsEIN2 in rice by interacting with its Nramp-like domain

2018 ◽  
Vol 115 (10) ◽  
pp. 2520-2525 ◽  
Author(s):  
Biao Ma ◽  
Yang Zhou ◽  
Hui Chen ◽  
Si-Jie He ◽  
Yi-Hua Huang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Ethylene Signaling ◽  
Loss Of Function ◽  
Wild Type ◽  
Protein Ubiquitination ◽  
Ethylene Response ◽  
Gene And Protein Expression ◽  
Domain Loss ◽  
Ethylene Insensitivity ◽  
Insight Into

The phytohormone ethylene regulates many aspects of plant growth and development. EIN2 is the central regulator of ethylene signaling, and its turnover is crucial for triggering ethylene responses. Here, we identified a stabilizer of OsEIN2 through analysis of the rice ethylene-response mutant mhz3. Loss-of-function mutations lead to ethylene insensitivity in etiolated rice seedlings. MHZ3 encodes a previously uncharacterized membrane protein localized to the endoplasmic reticulum. Ethylene induces MHZ3 gene and protein expression. Genetically, MHZ3 acts at the OsEIN2 level in the signaling pathway. MHZ3 physically interacts with OsEIN2, and both the N- and C-termini of MHZ3 specifically associate with the OsEIN2 Nramp-like domain. Loss of mhz3 function reduces OsEIN2 abundance and attenuates ethylene-induced OsEIN2 accumulation, whereas MHZ3 overexpression elevates the abundance of both wild-type and mutated OsEIN2 proteins, suggesting that MHZ3 is required for proper accumulation of OsEIN2 protein. The association of MHZ3 with the Nramp-like domain is crucial for OsEIN2 accumulation, demonstrating the significance of the OsEIN2 transmembrane domains in ethylene signaling. Moreover, MHZ3 negatively modulates OsEIN2 ubiquitination, protecting OsEIN2 from proteasome-mediated degradation. Together, these results suggest that ethylene-induced MHZ3 stabilizes OsEIN2 likely by binding to its Nramp-like domain and impeding protein ubiquitination to facilitate ethylene signal transduction. Our findings provide insight into the mechanisms of ethylene signaling.

Seed germination of ethylene perception mutants of tomato and Arabidopsis

2003 ◽  
Vol 13 (4) ◽  
pp. 303-314 ◽  
Author(s):  
Gunching Siriwitayawan ◽  
Robert L. Geneve ◽  
A. Bruce Downie
Keyword(s):  
Seed Quality ◽  
Lag Phase ◽  
Loss Of Function ◽  
Wild Type ◽  
Silver Thiosulphate ◽  
Seed Vigour ◽  
Subsequent Time ◽  
Radicle Protrusion ◽  
Ethylene Action ◽  
Ethylene Insensitivity

The involvement of ethylene in determining the time to radicle protrusion was investigated in ethylene-insensitive gain-of-function (GOF) receptor mutants in tomato and Arabidopsis, as well as in single and double loss-of-function (LOF) receptor mutants in Arabidopsis. Because ethylene evolution from seeds is coincident with radicle protrusion, and the ability to convert 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene is diagnostic for seed vigour, it was hypothesized that ethylene-insensitive mutants would require more time to complete germination compared to wild-type seeds. Mutant Never Ripe (Nr) tomato seeds from two genetic backgrounds refuted this hypothesis, while experiments with wild-type seeds, treated with the ethylene action inhibitors, 2,5-norbornadiene or silver thiosulphate, supported it. However, reciprocal crosses between wild-type and Nr demonstrated that ethylene insensitivity during seed development determined subsequent time to complete germination, rather than the ability of the embryo/endosperm to perceive ethylene in the mature seed during germination. Additionally, seed quality, determined by standard vigour tests, was reduced in Nr compared to wild-type seeds, establishing a disconnection between rapid completion of germination and seed vigour. In Arabidopsis, all ethylene-insensitive GOF, and five of six single LOF mutants, required more time to complete 50% radicle protrusion, while double LOF mutants required the same, or less, time to complete germination compared to wild-type seeds. These findings support a role for ethylene perception in determining the length of time Arabidopsis seeds remain in the lag phase prior to radicle protrusion.

scholarly journals Brain transcriptome analysis reveals subtle effects on mitochondrial function and iron homeostasis of mutations in the SORL1 gene implicated in early onset familial Alzheimer’s disease

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Karissa Barthelson ◽  
Stephen Martin Pederson ◽  
Morgan Newman ◽  
Michael Lardelli
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Early Onset ◽  
Iron Homeostasis ◽  
Enrichment Analysis ◽  
Loss Of Function ◽  
Wild Type ◽  
Expression Of Genes ◽  
Insight Into

Abstract To prevent or delay the onset of Alzheimer’s disease (AD), we must understand its molecular basis. The great majority of AD cases arise sporadically with a late onset after 65 years of age (LOAD). However, rare familial cases of AD can occur due to dominant mutations in a small number of genes that cause an early onset prior to 65 years of age (EOfAD). As EOfAD and LOAD share similar pathologies and disease progression, analysis of EOfAD genetic models may give insight into both subtypes of AD. Sortilin-related receptor 1 (SORL1) is genetically associated with both EOfAD and LOAD and provides a unique opportunity to investigate the relationships between both forms of AD. Currently, the role of SORL1 mutations in AD pathogenesis is unclear. To understand the molecular consequences of SORL1 mutation, we performed targeted mutagenesis of the orthologous gene in zebrafish. We generated an EOfAD-like mutation, V1482Afs, and a putatively null mutation, to investigate whether EOfAD-like mutations in sorl1 display haploinsufficiency by acting through loss-of-function mechanisms. We performed mRNA-sequencing on whole brains, comparing wild type fish with their siblings heterozygous for EOfAD-like or putatively loss-of-function mutations in sorl1, or transheterozygous for these mutations. Differential gene expression analysis identified a small number of differentially expressed genes due to the sorl1 genotypes. We also performed enrichment analysis on all detectable genes to obtain a more complete view on changes to gene expression by performing three methods of gene set enrichment analysis, then calculated an overall significance value using the harmonic mean p-value. This identified subtle effects on expression of genes involved in energy production, mRNA translation and mTORC1 signalling in both the EOfAD-like and null mutant brains, implying that these effects are due to sorl1 haploinsufficiency. Surprisingly, we also observed changes to expression of genes occurring only in the EOfAD-mutation carrier brains, suggesting gain-of-function effects. Transheterozygosity for the EOfAD-like and null mutations (i.e. lacking wild type sorl1), caused apparent effects on iron homeostasis and other transcriptome changes distinct from the single-mutation heterozygous fish. Our results provide insight into the possible early brain molecular effects of an EOfAD mutation in human SORL1. Differential effects of heterozygosity and complete loss of normal SORL1 expression are revealed.

scholarly journals Ethylene inhibits stem trichome formation in Arabidopsis

2018 ◽  
Author(s):  
Susan I Gibson
Keyword(s):  
Arabidopsis Thaliana ◽  
Substantial Reduction ◽  
Ethylene Biosynthesis ◽  
Model Systems ◽  
Wild Type ◽  
Normal Numbers ◽  
Biosynthesis Inhibitor ◽  
Ethylene Response ◽  
Normal Differentiation ◽  
Ethylene Insensitivity

Trichomes, specialized cells that form on the above ground parts of plants, are useful model systems for studying cell differentiation. In this study, the plant hormone ethylene was found to strongly inhibit formation of trichomes on stems of Arabidopsis thaliana. Plants grown in the presence of high concentrations of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid fail to form trichomes on their primary inflorescences. In addition, plants carrying mutations in CTR1 that confer a constitutive response to ethylene exhibit severe reductions in stem trichome numbers. In contrast, plants carrying mutations that confer ethylene insensitivity, and plants grown in the presence of an ethylene biosynthesis inhibitor, produce normal numbers of stem trichomes. Together, these results suggest that either excess ethylene or a constitutive ethylene response prevents the normal differentiation of cells that would otherwise form stem trichomes. Reduced ethylene levels and decreased ethylene response, in constrast, appear insufficient to cause cells that do not normally form trichomes to form trichomes. In contrast to ethylene, application of exogenous Glc results in increased stem trichome numbers. Besides affecting stem trichome numbers, ethylene may also affect branching of stem trichomes. In Arabidopsis thaliana, the vast majority of stem trichomes are unbranched. When wild-type Arabidiopsis thaliana of the Col-0 ecotype are grown in the presence of an ethylene biosynthesis inhibitor, the percentage of stem trichomes that are branched increases significantly. However, growth in the presence of an ethylene biosynthesis inhibitor does not affect stem branching in wild-type Arabidopsis thaliana of the Ler-0 ecotype. Plants carrying the etr1-1 and ein2-1 mutations, which cause ethylene insensitivity, have an increased percentage of branched stem trichomes. In contrast, plants carrying the ctr1-1 and ctr1-12 mutations have a decreased percentage of branched stem trichomes. Growth in the presence of a precursor of ethylene biosynthesis also causes a substantial reduction in branching of Arabidopsis leaf trichomes, suggesting that ethylene has a negative effect on branching of both leaf and stem trichomes in Arabidopsis.

scholarly journals Ethylene inhibits stem trichome formation in Arabidopsis

2018 ◽  
Author(s):  
Susan I Gibson
Keyword(s):  
Arabidopsis Thaliana ◽  
Substantial Reduction ◽  
Ethylene Biosynthesis ◽  
Model Systems ◽  
Wild Type ◽  
Normal Numbers ◽  
Biosynthesis Inhibitor ◽  
Ethylene Response ◽  
Normal Differentiation ◽  
Ethylene Insensitivity

Trichomes, specialized cells that form on the above ground parts of plants, are useful model systems for studying cell differentiation. In this study, the plant hormone ethylene was found to strongly inhibit formation of trichomes on stems of Arabidopsis thaliana. Plants grown in the presence of high concentrations of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid fail to form trichomes on their primary inflorescences. In addition, plants carrying mutations in CTR1 that confer a constitutive response to ethylene exhibit severe reductions in stem trichome numbers. In contrast, plants carrying mutations that confer ethylene insensitivity, and plants grown in the presence of an ethylene biosynthesis inhibitor, produce normal numbers of stem trichomes. Together, these results suggest that either excess ethylene or a constitutive ethylene response prevents the normal differentiation of cells that would otherwise form stem trichomes. Reduced ethylene levels and decreased ethylene response, in constrast, appear insufficient to cause cells that do not normally form trichomes to form trichomes. In contrast to ethylene, application of exogenous Glc results in increased stem trichome numbers. Besides affecting stem trichome numbers, ethylene may also affect branching of stem trichomes. In Arabidopsis thaliana, the vast majority of stem trichomes are unbranched. When wild-type Arabidiopsis thaliana of the Col-0 ecotype are grown in the presence of an ethylene biosynthesis inhibitor, the percentage of stem trichomes that are branched increases significantly. However, growth in the presence of an ethylene biosynthesis inhibitor does not affect stem branching in wild-type Arabidopsis thaliana of the Ler-0 ecotype. Plants carrying the etr1-1 and ein2-1 mutations, which cause ethylene insensitivity, have an increased percentage of branched stem trichomes. In contrast, plants carrying the ctr1-1 and ctr1-12 mutations have a decreased percentage of branched stem trichomes. Growth in the presence of a precursor of ethylene biosynthesis also causes a substantial reduction in branching of Arabidopsis leaf trichomes, suggesting that ethylene has a negative effect on branching of both leaf and stem trichomes in Arabidopsis.

scholarly journals Brain transcriptome analysis reveals subtle effects on mitochondrial function and iron homeostasis of mutations in the SORL1 gene implicated in early onset familial Alzheimer’s disease

2020 ◽  
Author(s):  
Karissa Barthelson ◽  
Stephen Martin Pederson ◽  
Morgan Newman ◽  
Michael Lardelli
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Early Onset ◽  
Iron Homeostasis ◽  
Mrna Translation ◽  
Complete Loss ◽  
Loss Of Function ◽  
Wild Type ◽  
Expression Of Genes ◽  
Insight Into

AbstractBackgroundTo prevent or delay the onset of Alzheimer’s disease (AD), we must understand its molecular basis. The great majority of AD cases arise sporadically with a late onset after 65 years of age (LOAD). However, rare familial cases of AD can occur due to dominant mutations in a small number of genes that cause an early onset prior to 65 years of age (EOfAD). As EOfAD and LOAD share similar pathologies and disease progression, analysis of EOfAD genetic models may give insight into both subtypes of AD. Sortilin-related receptor 1 (SORL1) is genetically associated with both EOfAD and LOAD and provides a unique opportunity to investigate the relationships between both forms of AD. Currently, the role of SORL1 mutations in AD pathogenesis is unclear.MethodsTo understand the molecular consequences of SORL1 mutation, we performed targeted mutagenesis of the orthologous gene in zebrafish. We generated an EOfAD-like mutation, V1482Afs, and a putatively null mutation, to investigate whether EOfAD-like mutations in sorl1 display haploinsufficiency by acting through loss-of-function mechanisms. We performed mRNA-sequencing on whole brains comparing normal (wild type) fish with their siblings heterozygous for EOfAD-like or complete loss-of-function mutations in sorl1 or transheterozygous for these mutations. Differential gene expression and gene set enrichment analyses identified, respectively, changes in young adult zebrafish brain transcriptomes, and putative effects on neural subcellular functions.ResultsWe identified subtle effects on expression of genes involved in energy production, mRNA translation and mTORC1 signalling in both the EOfAD-like and null mutant brains, implying that these effects are due to sorl1 haploinsufficiency. Surprisingly, we also observed changes to expression of genes occurring only in the EOfAD-mutation carrier brains, suggesting gain-of-function effects. Transheterozygosity for the EOfAD-like and null mutations (i.e. lacking wild type sorl1), caused apparent effects on iron homeostasis and other transcriptome changes distinct from the single-mutation heterozygous fish.ConclusionsOur results provide insight into the possible early brain molecular effects of an EOfAD mutation in human SORL1. Differential effects of heterozygosity and complete loss of normal SORL1 expression are revealed.

E3 ubiquitin ligases

2005 ◽  
Vol 41 ◽  
pp. 15-30 ◽  
Author(s):  
Helen C. Ardley ◽  
Philip A. Robinson
Keyword(s):  
Protein Complexes ◽  
Loss Of Function ◽  
Direct Role ◽  
Cellular Processes ◽  
Substrate Protein ◽  
Protein Ubiquitination ◽  
C Terminus ◽  
Full Complement ◽  
Spatio Temporal ◽  
Eukaryotic Organisms

The selectivity of the ubiquitin–26 S proteasome system (UPS) for a particular substrate protein relies on the interaction between a ubiquitin-conjugating enzyme (E2, of which a cell contains relatively few) and a ubiquitin–protein ligase (E3, of which there are possibly hundreds). Post-translational modifications of the protein substrate, such as phosphorylation or hydroxylation, are often required prior to its selection. In this way, the precise spatio-temporal targeting and degradation of a given substrate can be achieved. The E3s are a large, diverse group of proteins, characterized by one of several defining motifs. These include a HECT (homologous to E6-associated protein C-terminus), RING (really interesting new gene) or U-box (a modified RING motif without the full complement of Zn2+-binding ligands) domain. Whereas HECT E3s have a direct role in catalysis during ubiquitination, RING and U-box E3s facilitate protein ubiquitination. These latter two E3 types act as adaptor-like molecules. They bring an E2 and a substrate into sufficiently close proximity to promote the substrate's ubiquitination. Although many RING-type E3s, such as MDM2 (murine double minute clone 2 oncoprotein) and c-Cbl, can apparently act alone, others are found as components of much larger multi-protein complexes, such as the anaphase-promoting complex. Taken together, these multifaceted properties and interactions enable E3s to provide a powerful, and specific, mechanism for protein clearance within all cells of eukaryotic organisms. The importance of E3s is highlighted by the number of normal cellular processes they regulate, and the number of diseases associated with their loss of function or inappropriate targeting.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

scholarly journals The NALCN Channel Regulator UNC-80 Functions in a Subset of Interneurons To Regulate Caenorhabditis elegans Reversal Behavior

2019 ◽  
Vol 10 (1) ◽  
pp. 199-210 ◽  
Author(s):  
Chuanman Zhou ◽  
Jintao Luo ◽  
Xiaohui He ◽  
Qian Zhou ◽  
Yunxia He ◽  
...  
Keyword(s):  
Plant Hormone ◽  
Neuronal Excitability ◽  
Resting Membrane Potential ◽  
Loss Of Function ◽  
Wild Type ◽  
C Elegans ◽  
Link Type ◽  
Complex Functions ◽  
And Function ◽  
Multiple Loss

NALCN (Na+leak channel, non-selective) is a conserved, voltage-insensitive cation channel that regulates resting membrane potential and neuronal excitability. UNC79 and UNC80 are key regulators of the channel function. However, the behavioral effects of the channel complex are not entirely clear and the neurons in which the channel functions remain to be identified. In a forward genetic screen for C. elegans mutants with defective avoidance response to the plant hormone methyl salicylate (MeSa), we isolated multiple loss-of-function mutations in unc-80 and unc-79. C. elegans NALCN mutants exhibited similarly defective MeSa avoidance. Interestingly, NALCN, unc-80 and unc-79 mutants all showed wild type-like responses to other attractive or repelling odorants, suggesting that NALCN does not broadly affect odor detection or related forward and reversal behaviors. To understand in which neurons the channel functions, we determined the identities of a subset of unc-80-expressing neurons. We found that unc-79 and unc-80 are expressed and function in overlapping neurons, which verified previous assumptions. Neuron-specific transgene rescue and knockdown experiments suggest that the command interneurons AVA and AVE and the anterior guidepost neuron AVG can play a sufficient role in mediating unc-80 regulation of the MeSa avoidance. Though primarily based on genetic analyses, our results further imply that MeSa might activate NALCN by direct or indirect actions. Altogether, we provide an initial look into the key neurons in which the NALCN channel complex functions and identify a novel function of the channel in regulating C. elegans reversal behavior through command interneurons.

scholarly journals Salicylic Acid Accumulation Controlled by LSD1 Is Essential in Triggering Cell Death in Response to Abiotic Stress

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 962
Author(s):  
Maciej Jerzy Bernacki ◽  
Anna Rusaczonek ◽  
Weronika Czarnocka ◽  
Stanisław Karpiński
Keyword(s):  
Cell Death ◽  
Salicylic Acid ◽  
Abiotic Stress ◽  
Wild Type ◽  
Pr Genes ◽  
Genes Expression ◽  
Salicylic Acid Accumulation ◽  
Cell Death Phenotype ◽  
Insight Into

Salicylic acid (SA) is well known hormonal molecule involved in cell death regulation. In response to a broad range of environmental factors (e.g., high light, UV, pathogens attack), plants accumulate SA, which participates in cell death induction and spread in some foliar cells. LESION SIMULATING DISEASE 1 (LSD1) is one of the best-known cell death regulators in Arabidopsis thaliana. The lsd1 mutant, lacking functional LSD1 protein, accumulates SA and is conditionally susceptible to many biotic and abiotic stresses. In order to get more insight into the role of LSD1-dependent regulation of SA accumulation during cell death, we crossed the lsd1 with the sid2 mutant, caring mutation in ISOCHORISMATE SYNTHASE 1(ICS1) gene and having deregulated SA synthesis, and with plants expressing the bacterial nahG gene and thus decomposing SA to catechol. In response to UV A+B irradiation, the lsd1 mutant exhibited clear cell death phenotype, which was reversed in lsd1/sid2 and lsd1/NahG plants. The expression of PR-genes and the H2O2 content in UV-treated lsd1 were significantly higher when compared with the wild type. In contrast, lsd1/sid2 and lsd1/NahG plants demonstrated comparability with the wild-type level of PR-genes expression and H2O2. Our results demonstrate that SA accumulation is crucial for triggering cell death in lsd1, while the reduction of excessive SA accumulation may lead to a greater tolerance toward abiotic stress.

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