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MG132

About: MG132 is a research topic. Over the lifetime, 1499 publications have been published within this topic receiving 56589 citations. The topic is also known as: MG132 & Z-Leu-leu-leu-al.


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Journal ArticleDOI
TL;DR: The study reveals that the extent of ubiquitination at mitochondria greatly increases upon proteasome inhibition, pointing to a large number of potential substrates for proteasomal degradation.

22 citations

Journal ArticleDOI
TL;DR: In this paper, the authors showed that rotenone-induced toxicity in human neuroblastoma cell lines and mouse primary cortical neurons was ameliorated by protein tyrosine phosphatase 1B (PTP1B) inhibition.
Abstract: Several lines of evidence suggest that endoplasmic reticulum (ER) stress plays a critical role in the pathogenesis of many neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis Protein tyrosine phosphatase 1B (PTP1B) is known to regulate the ER stress signaling pathway, but its role in neuronal systems in terms of ER stress remains largely unknown Here, we showed that rotenone-induced toxicity in human neuroblastoma cell lines and mouse primary cortical neurons was ameliorated by PTP1B inhibition Moreover, the increase in the level of ER stress markers (eIF2α phosphorylation and PERK phosphorylation) induced by rotenone treatment was obviously suppressed by concomitant PTP1B inhibition However, the rotenone-induced production of reactive oxygen species (ROS) was not affected by PTP1B inhibition, suggesting that the neuroprotective effect of the PTP1B inhibitor is not associated with ROS production Moreover, we found that MG132-induced toxicity involving proteasome inhibition was also ameliorated by PTP1B inhibition in a human neuroblastoma cell line and mouse primary cortical neurons Consistently, downregulation of the PTP1B homologue gene in Drosophila mitigated rotenone- and MG132-induced toxicity Taken together, these findings indicate that PTP1B inhibition may represent a novel therapeutic approach for ER stress-mediated neurodegenerative diseases

22 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the hypothesis that PCB-153 exposure coordinates cell cycle progression and cellular metabolism by inhibiting cyclin D1 accumulation, and showed that the decrease in protein levels was associated with an inhibition in AKT and GSK-3β phosphorylation.

22 citations

Journal ArticleDOI
12 Apr 2010-PLOS ONE
TL;DR: It is found that excitotoxic stimulation of cultured hippocampal neurons with glutamate leads to a time-dependent cleavage of GAD65 and GAD67 in the N-terminal region of the proteins, and decrease the corresponding mRNAs.
Abstract: Glutamic acid decarboxylase is responsible for synthesizing GABA, the major inhibitory neurotransmitter, and exists in two isoforms—GAD65 and GAD67. The enzyme is cleaved under excitotoxic conditions, but the mechanisms involved and the functional consequences are not fully elucidated. We found that excitotoxic stimulation of cultured hippocampal neurons with glutamate leads to a time-dependent cleavage of GAD65 and GAD67 in the N-terminal region of the proteins, and decrease the corresponding mRNAs. The cleavage of GAD67 was sensitive to the proteasome inhibitors MG132, YU102 and lactacystin, and was also abrogated by the E1 ubiquitin ligase inhibitor UBEI-41. In contrast, MG132 and UBEI-41 were the only inhibitors tested that showed an effect on GAD65 cleavage. Excitotoxic stimulation with glutamate also increased the amount of GAD captured in experiments where ubiquitinated proteins and their binding partners were isolated. However, no evidences were found for direct GADs ubiquitination in cultured hippocampal neurons, and recombinant GAD65 was not cleaved by purified 20S or 26S proteasome preparations. Since calpains, a group of calcium activated proteases, play a key role in GAD65/67 cleavage under excitotoxic conditions the results suggest that GADs are cleaved after ubiquitination and degradation of an unknown binding partner by the proteasome. The characteristic punctate distribution of GAD65 along neurites of differentiated cultured hippocampal neurons was significantly reduced after excitotoxic injury, and the total GAD activity measured in extracts from the cerebellum or cerebral cortex at 24h postmortem (when there is a partial cleavage of GADs) was also decreased. The results show a role of the UPS in the cleavage of GAD65/67 and point out the deregulation of GADs under excitotoxic conditions, which is likely to affect GABAergic neurotransmission. This is the first time that the UPS has been implicated in the events triggered during excitotoxicity and the first molecular target of the UPS affected in this cell death process.

22 citations

Journal ArticleDOI
TL;DR: Results demonstrate that NTS inhibits the protein expression of HIF-1α and its downstream factors TGF-β, FGF2 and α-SMA both in hypoxia-exposed fibroblasts and in lung tissues of BLM-treated mice.
Abstract: Pulmonary fibrosis may be partially the result of deregulated tissue repair in response to chronic hypoxia. In this study we explored the effects of hypoxia on lung fibroblasts and the effects of neotuberostemonine (NTS), a natural alkaloid isolated from Stemona tuberosa, on activation of fibroblasts in vitro and in vivo. PLFs (primary mouse lung fibroblasts) were activated and differentiated after exposure to 1% O2 or treatment with CoCl2 (100 μmol/L), evidenced by markedly increased protein or mRNA expression of HIF-1α, TGF-β, FGF2, α-SMA and Col-1α/3α, which was blocked after silencing HIF-1α, suggesting that the activation of fibroblasts was HIF-1α-dependent. NTS (0.1–10 μmol/L) dose-dependently suppressed hypoxia-induced activation and differentiation of PLFs, whereas the inhibitory effect of NTS was abolished by co-treatment with MG132, a proteasome inhibitor. Since prolyl hydroxylation is a critical step in initiation of HIF-1α degradation, we further showed that NTS treatment reversed hypoxia- or CoCl2-induced reduction in expression of prolyl hydroxylated-HIF-1α. With hypoxyprobe immunofiuorescence staining, we showed that NTS treatment directly reversed the lower oxygen tension in hypoxia-exposed PLFs. In a mouse model of lung fibrosis, oral administration of NTS (30 mg·kg-1·d-1, for 1 or 2 weeks) effectively attenuated bleomycin-induced pulmonary fibrosis by inhibiting the levels of HIF-1α and its downstream profibrotic factors (TGF-β, FGF2 and α-SMA). Taken together, these results demonstrate that NTS inhibits the protein expression of HIF-1α and its downstream factors TGF-β, FGF2 and α-SMA both in hypoxia-exposed fibroblasts and in lung tissues of BLM-treated mice. NTS with anti-HIF-1α activity may be a promising pharmacological agent for the treatment of pulmonary fibrosis.

22 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202386
202270
202157
202059
201962
201848