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Expression of suppressor of cytokine signaling genes in human elderly and Alzheimer's disease brains and human microglia.

ABSTRACT: Multiple cellular systems exist to prevent uncontrolled inflammation in brain tissues; the suppressor of cytokine signaling (SOCS) proteins have key roles in these processes. SOCS proteins are involved in restricting cellular signaling pathways by enhancing the degradation of activated receptors and removing the stimuli for continued activation. There are eight separate SOCS genes that code for proteins with similar structures and properties. All SOCS proteins can reduce signaling of activated transcription factors Janus kinase (JAK) and signal transducer and activator of transcription (STAT), but they also regulate many other signaling pathways. SOCS-1 and SOCS-3 have particular roles in regulating inflammatory processes. Chronic inflammation is a key feature of the pathology present in Alzheimer's disease (AD)-affected brains resulting from responses to amyloid plaques or neurofibrillary tangles, the pathological hallmarks of AD. The goal of this study was to examine SOCS gene expression in human non-demented (ND) and AD brains and in human brain-derived microglia to determine if AD-related pathology resulted in a deficit of these critical molecules. We demonstrated that SOCS-1, SOCS-2, SOCS-3 and cytokine-inducible SH2 containing protein (CIS) mRNA expression was increased in amyloid beta peptide (A?)- and inflammatory-stimulated microglia, while SOCS-6 mRNA expression was decreased by both types of treatments. Using human brain samples from the temporal cortex from ND and AD cases, SOCS-1 through SOCS-7 and CIS mRNA and SOCS-1 through SOCS-7 protein could be detected constitutively in ND and AD human brain samples. Although, the expression of key SOCS genes did not change to a large extent as a result of AD pathology, there were significantly increased levels of SOCS-2, SOCS-3 and CIS mRNA and increased protein levels of SOCS-4 and SOCS-7 in AD brains. In summary, there was no evidence of a deficit of these key inflammatory regulating proteins in aged or AD brains.

SUBMITTER: Walker DG

PROVIDER: S-EPMC4385752 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Expression of suppressor of cytokine signaling genes in human elderly and Alzheimer's disease brains and human microglia.

Walker D G DG Whetzel A M AM Lue L-F LF

Neuroscience 20141005

Multiple cellular systems exist to prevent uncontrolled inflammation in brain tissues; the suppressor of cytokine signaling (SOCS) proteins have key roles in these processes. SOCS proteins are involved in restricting cellular signaling pathways by enhancing the degradation of activated receptors and removing the stimuli for continued activation. There are eight separate SOCS genes that code for proteins with similar structures and properties. All SOCS proteins can reduce signaling of activated t ...[more]

PMID: 25286386

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Project description:BACKGROUND:Neuroinflammation plays an important role in the pathogenesis of various neurodegenerative diseases including Alzheimer's disease (AD). Suppressor of cytokine signaling 3 (SOCS3) is an anti-inflammatory molecule that suppresses cytokine signaling and inflammatory gene expression in different cells including microglia. OBJECTIVE:The pathways through which SOCS3 could be upregulated are poorly described. Cinnamic acid is a metabolite of cinnamon, a natural compound that is being widely used all over the world as a spice or flavoring agent. Here, we examined if cinnamic acid could upregulate SOCS3 in microglia. METHOD:Microglia and astroglia isolated from mouse brain as well as BV-2 microglial cells were treated with cinnamic acid followed by monitoring the level of SOCS3 and different proinflammatory molecules by RT-PCR and real-time PCR. To nail down the mechanism, we also performed ChIP analysis to monitore the recruitment of cAMP response element binding (CREB) to the socs3 gene promoter and carried out siRNA knockdown of CREB. RESULTS:Cinnamic acid upregulated the expression of SOCS3 mRNA and protein in mouse BV-2 microglial cells in dose- and time-dependent manner. Accordingly, cinnamic acid also increased the level of SOCS3 and suppressed the expression of inducible nitric oxide synthase and proinflammatory cytokines (TNF?, IL-1? and IL-6) in LPSstimulated BV-2 microglial cells. Similar to BV-2 microglial cells, cinnamic acid also increased the expression of SOCS3 in primary mouse microglia and astrocytes. We have seen that cAMP response element is present in the promoter of socs3 gene, that cinnamic acid induces the activation of CREB, that siRNA knockdown of CREB abrogates cinnamic acid-mediated upregulation of SOCS3, and that cinnamic acid treatment leads to the recruitment of CREB to the socs3 gene. CONCLUSIONS:These studies suggest that cinnamic acid upregulates the expression of SOCS3 in glial cells via CREB pathway, which may be of importance in neuroinflammatory and neurodegenerative disorders.

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Dataset Information

Expression of suppressor of cytokine signaling genes in human elderly and Alzheimer's disease brains and human microglia.

Publications

Expression of suppressor of cytokine signaling genes in human elderly and Alzheimer's disease brains and human microglia.

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