Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The level of stem cell proliferation must be tightly controlled for proper development and tissue homeostasis. Multiple levels of gene regulation are often employed to regulate stem cell proliferation to ensure that the amount of proliferation is aligned with the needs of the tissue. Here we focus on proteasome-mediated protein degradation as a means of regulating the activities of proteins involved in controlling the stem cell proliferative fate in the C. elegans germ line. We identify five potential E3 ubiquitin ligases, including the RFP-1 RING finger protein, as being involved in regulating proliferative fate. RFP-1 binds to MRG-1, a homologue of the mammalian chromodomain-containing protein MRG15 (MORF4L1), which has been implicated in promoting the proliferation of neural precursor cells. We find that C. elegans with reduced proteasome activity, or that lack RFP-1 expression, have increased levels of MRG-1 and a shift towards increased proliferation in sensitized genetic backgrounds. Likewise, reduction of MRG-1 partially suppresses stem cell overproliferation. MRG-1 levels are controlled independently of the spatially regulated GLP-1/Notch signalling pathway, which is the primary signal controlling the extent of stem cell proliferation in the C. elegans germ line. We propose a model in which MRG-1 levels are controlled, at least in part, by the proteasome, and that the levels of MRG-1 set a threshold upon which other spatially regulated factors act in order to control the balance between the proliferative fate and differentiation in the C. elegans germ line.
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PMID:Proteasome regulation of the chromodomain protein MRG-1 controls the balance between proliferative fate and differentiation in the C. elegans germ line. 2556 23

Although a number of RING E3 ligases in plants have been demonstrated to play key roles in a wide range of abiotic stresses, relatively few studies have detailed how RING E3 ligases exert their cellular actions. We describe Oryza sativa RING finger protein with microtubule-targeting domain 1 (OsRMT1), a functional RING E3 ligase that is likely involved in a salt tolerance mechanism. Functional characterization revealed that OsRMT1 undergoes homodimer formation and subsequently autoubiquitination-mediated protein degradation under normal conditions. By contrast, OsRMT1 is predominantly found in the nucleus and microtubules and its degradation is inhibited under salt stress. Domain dissection of OsRMT1 indicates that the N-terminal domain is required for microtubule targeting. Bimolecular fluorescence complementation analysis and degradation assay revealed that OsRMT1-interacted proteins localized in various organelles were degraded via the ubiquitin (Ub)/26S proteasome-dependent pathway. Interestingly, when OsRMT1 and its target proteins were co-expressed in N. benthamiana leaves, the protein-protein interactions appeared to take place mainly in the microtubules. Overexpression of OsRMT1 in Arabidopsis resulted in increased tolerance to salt stress. Our findings suggest that the abundance of microtubule-associated OsRMT1 is strictly regulated, and OsRMT1 may play a relevant role in salt stress response by modulating levels of its target proteins.
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PMID:Molecular dissection of a rice microtubule-associated RING finger protein and its potential role in salt tolerance in Arabidopsis. 2635 44

Investigation of the endoplasmic reticulum-associated degradation (ERAD) system in plants led to the identification of ERAD-mediating RING finger protein (EMR) as a plant-specific ERAD E3 ligase from Arabidopsis. EMR was significantly up-regulated under endoplasmic reticulum (ER) stress conditions. The EMR protein purified from bacteria displayed high E3 ligase activity, and tobacco leaf-produced EMR mediated mildew resistance locus O-12 (MLO12) degradation in a proteasome-dependent manner. Subcellular localization and coimmunoprecipitation analyses showed that EMR forms a complex with ubiquitin-conjugating enzyme 32 (UBC32) as a cytosolic interaction partner. Mutation of EMR and RNA interference (RNAi) increased the tolerance of plants to ER stress. EMR RNAi in the bri1-5 background led to partial recovery of the brassinosteroid (BR)-insensitive phenotypes as compared with the original mutant plants and increased ER stress tolerance. The presented results suggest that EMR is involved in the plant ERAD system that affects BR signaling under ER stress conditions as a novel Arabidopsis ring finger E3 ligase mainly present in cytosol while the previously identified ERAD E3 components are typically membrane-bound proteins.
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PMID:EMR, a cytosolic-abundant ring finger E3 ligase, mediates ER-associated protein degradation in Arabidopsis. 2993 18

Abscisic acid (ABA) is a plant hormone that plays a key role in the environmental stress response, especially the induction of ABA-responsive and stress-responsive genes and modulation of the stomatal aperture in response to drought stress. Here, we identified CaDILZ1 (Capsicum annuum Drought-Induced Leucine Zipper 1) belonging to subgroup D of the bZIP protein family; gene functions of this family in response to ABA and drought signaling still remain unknown. CaDILZ1 expression was significantly induced in pepper leaves after exposure to ABA, drought, and NaCl. The CaDILZ1 protein localized in the nucleus of plant cells. In response to drought stress, CaDILZ1-silenced pepper and CaDILZ1-overexpressing Arabidopsis plants exhibited drought-sensitive and drought-tolerant phenotypes, respectively, via altered ABA content, stomatal closure, and expression of ABA-responsive and drought-responsive marker genes. We isolated the RING finger protein CaDSR1 (Capsicum annuum Drought Sensitive RING finger protein 1), which interacted with CaDILZ1 in the nucleus. The CaDSR1 protein exhibited E3 ligase activity and promoted CaDILZ1 degradation via the 26S proteasome pathway. Under drought stress conditions, CaDSR1-silenced pepper and CaDSR1-overexpressing Arabidopsis plants exhibited contrasting phenotypes to those of CaDILZ1-silenced pepper and CaDILZ1-overexpressing Arabidopsis plants. Taken together, our data suggest that CaDSR1 and CaDILZ1 function in ABA-mediated drought stress signaling in pepper plants.
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PMID:Roles of pepper bZIP protein CaDILZ1 and its interacting partner RING-type E3 ligase CaDSR1 in modulation of drought tolerance. 3005 16

The ubiquitin/26S proteasome pathway is widely related to plant growth and metabolism and response to treatment by specifically degrading ubiquitin-modified proteins, including RING-finger-type E3 ubiquitin ligase (RING). The RING finger protein (RFP) gene family, determining the specificity of the ubiquitination process, is numerous and complex in function. In this study, we constructed a pCEGFP-StRFP2 fusion protein expression vector and transformed it into tobacco to achieve transient expression, thereby confirming that StRFP2 is localized in the cell membrane and cytoplasm. The result of qRT-PCR analysis showed that StRFP2 gene was significantly expressed in potato leaves, and the expression level of StRFP2 was significantly up-regulated under drought treatment. The transgenic plants of overexpressing StRFP2 gene were obtained with Agrobacterium tumefaciens-mediated transformation. Plant height, stem diameter, root length, fresh weight and root-shoot ratio of transgenic plants were significantly higher than those of non-transgenic plants (WT), indicating that the growth of plants was significantly promoted after overexpression of StRFP2 gene. Under PEG osmotic stress, the expressional level of StRFP2 in transgenic potato plants was significantly higher than that of WT. Furthermore, the free proline content and CAT activity in transgenic plants were higher than WT, on the contrary, MDA was lower than WT, and transgenic plants have stronger water retention capacity under simulated drought stress treatment, which indicated that StRFP2 could strengthen the tolerance of plants responding to drought stress. The above evidence strongly suggested that the StRFP2 gene is obviously up-regulated expression by drought stress, thereby enhancing the drought tolerance of the potato.
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PMID:A potato RING-finger protein gene StRFP2 is involved in drought tolerance. 3181 9


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