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Novel anti-inflammatory activity of chlorojanerin isolated from Sausurrea heteromalla (D. Don) Hand.-Mazz.

ABSTRACT: Medicinal plants have shown great promise as a source of novel drug compounds for the treatment of inflammatory disorders. In our search for new entities with anti-inflammatory potential, the extracts of the whole plant of Saussurea heteromalla (family-Asteraceae), collected from Himalayas, were evaluated in the high throughput screen for TNF-α and IL-6 inhibitors. The plant has been found as a new source of chlorojanerin, a guaianolide type of sesquiterpene lactone. This is the first report on the potent anti-inflammatory activity of the compound. Chlorojanerin was shown to be significantly effective in inhibiting TNF-α and IL-6 production in LPS induced THP-1 cells (TNF-α, IC50 = 3µM and IL-6, IC50 = 0.8µM). The compound also blocked TNF-α and IL-6 production from LPS induced human monocytes and synovial cells from RA patients. Chlorojanerin also inhibited the binding of NF-κB in a GFP reporter assay system. Transcriptional profiling of the LPS stimulated THP-1 cells revealed that chlorojanerin exerted its anti-inflammatory effect by inhibiting the expression of genes involved in activating the transcription factor – NF-κB. Real time analysis of these genes validated the effect of chlorojanerin on the classical downstream targets of NF-κB. Thus, this study clearly delineated 8 targets specific for the effect of chlorojanerin on NF-κB induced signaling at the mRNA level. This work is a step towards the isolation and characterization of lead anti-inflammatory agents from the extract of Saussurea heteromalla, which can be developed into better therapeutic molecules targeted towards some specific inflammatory diseases.

ORGANISM(S): Homo sapiens

PROVIDER: GSE34180 | GEO | 2011/12/14

SECONDARY ACCESSION(S): PRJNA149693

REPOSITORIES: GEO

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Project description:Microglial overactivation is actively involved in the pathogenesis of neurodegenerative diseases. Polo-like kinase 2 (PLK2) is a serine/threonine protein kinase associated with the regulation of synaptic plasticity and centriole duplication. Here, we identified PLK2 as an important early response gene in lipopolysaccharide (LPS)-stimulated microglial cells. Knockdown or inhibition of PLK2 remarkably attenuated LPS-induced expression of pro-inflammatory factors such as IL-1β, IL-6, COX2, TNF-α, and iNOS in microglial cells via suppressing the IKKβ-NF-κB signaling pathway. Notably, overexpression of PLK2 induced expression of pro-inflammatory factors and NF-κB transcriptional activation in the absence of inflammatory stimuli. Mechanistically, co-immunoprecipitation experiments revealed association between PLK2 and IKKβ, whereas GST pull-down assay showed no direct interaction between PLK2 and IKKβ. Proteomic analysis and in vitro kinase assay identified heat shock protein 90 alpha (HSP90α), a regulator of IKKβ activity, as a novel PLK2 substrate. Knockdown or pharmacological inhibition of HSP90α abolished PLK2-mediated activation of NF-κB transcriptional activity and microglial inflammatory activation. Furthermore, phosphoproteomic analysis pinpointed Ser252 and Ser263 on HSP90α as novel phosphorylation targets of PLK2. Subsequent functional studies demonstrated that re-expression of phosphor-dead mutation of these two phosphorylation sites on HSP90α failed to rescue the PLK2-induced activation of the NF-κB signaling. Lastly, conditional knockout of PLK2 in microglial cells dramatically ameliorated neuroinflammation and subsequent dopaminergic neuron loss in an intracranial LPS-induced mouse PD model. The present study revealed, for the first time, that PLK2 promoted microglial activation through the phosphorylation of HSP90α and subsequent activation of the IKKβ-NF-κB signaling pathway. Consequently, PLK2 emerges as a potential therapeutic target for the amelioration of neuroinflammation-related diseases.

Project description:Microglial overactivation is actively involved in the pathogenesis of neurodegenerative diseases. Polo-like kinase 2 (PLK2) is a serine/threonine protein kinase associated with the regulation of synaptic plasticity and centriole duplication. Here, we identified PLK2 as an important early response gene in lipopolysaccharide (LPS)-stimulated microglial cells. Knockdown or inhibition of PLK2 remarkably attenuated LPS-induced expression of pro-inflammatory factors such as IL-1β, IL-6, COX2, TNF-α,and iNOS in microglial cells via suppressing the IKKβ-NF-κB signaling pathway.Notably, overexpression of PLK2 induced expression of pro-inflammatory factors and NF-κB transcriptional activation in the absence of inflammatory stimuli. Mechanistically,co-immunoprecipitation experiments revealed association between PLK2 and IKKβ, whereas GST pull-down assay showed no direct interaction between PLK2 and IKKβ. Proteomic analysis and in vitro kinase assay identified heat shock protein 90 alpha (HSP90α), a regulator of IKKβ activity, as a novel PLK2 substrate. Knockdown or pharmacological inhibition of HSP90α abolished PLK2-mediated activation of NF-κB transcriptional activity and microglial inflammatory activation. Furthermore,phosphoproteomic analysis pinpointed Ser252 and Ser263 on HSP90α as novel phosphorylation targets of PLK2. Subsequent functional studies demonstrated that re-expression of phosphor-dead mutation of these two phosphorylation sites on HSP90α failed to rescue the PLK2-induced activation of the NF-κB signaling. Lastly, conditional knockout of PLK2 in microglial cells dramatically ameliorated neuroinflammation and subsequent dopaminergic neuron loss in an intracranial LPS-induced mouse PD model. The present study revealed, for the first time, that PLK2 promoted microglial activation through the phosphorylation of HSP90α and subsequent activation of the IKKβ-NF-κB signaling pathway. Consequently, PLK2 emerges as a potential therapeutic target for the amelioration of neuroinflammation-related diseases.

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Novel anti-inflammatory activity of chlorojanerin isolated from Sausurrea heteromalla (D. Don) Hand.-Mazz.

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