REV-ERBα, the NR1D1 (nuclear receptor subfamily 1, group D, member 1) gene product, is a dominant transcriptional silencer that represses the expression of genes involved in numerous physiological functions, including circadian rhythm, inflammation, and metabolism, and plays a crucial role in maintaining immune functions. Microglia-mediated neuroinflammation is tightly associated with various neurodegenerative diseases and psychiatric disorders. However, the role of REV-ERBα in neuroinflammation is largely unclear. In this study, we investigated whether and how pharmacological activation of REV-ERBα affected lipopolysaccharide (LPS)-induced neuroinflammation in mouse microglia in vitro and in vivo. In BV2 cells or primary mouse cultured microglia, application of REV-ERBα agonist GSK4112 or SR9011 dose-dependently suppressed LPS-induced microglial activation through the nuclear factor kappa B (NF-κB) pathway. In BV2 cells, pretreatment with GSK4112 inhibited LPS-induced phosphorylation of the inhibitor of NF-κB alpha (IκBα) kinase (IκK), thus restraining the phosphorylation and degradation of IκBα, and blocked the nuclear translocation of p65, a NF-κB subunit, thereby suppressing the expression and secretion of the proinflammatory cytokines, such as interleukin 6 (IL-6) and tumor necrosis factor α (TNFα). Moreover, REV-ERBα agonist-induced inhibition on neuroinflammation protected neurons from microglial activation-induced damage, which were also demonstrated in mice with their ventral midbrain microinjected with GSK4112, and then stimulated with LPS. Our results reveal that enhanced REV-ERBα activity suppresses microglial activation through the NF-κB pathway in the central nervous system.
GGGGCC repeat expansions in the C9ORF72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9ALS/FTD). It has been reported that hexanucleotide repeat expansions in C9ORF72 produce five dipeptide repeat (DPR) proteins by an unconventional repeat-associated non-ATG (RAN) translation. Within the five DPR proteins, poly-PR and poly-GR that contain arginine are more toxic than the other DPRs (poly-GA, poly-GP, and poly-PA). Here, we demonstrated that poly-PR peptides transferred into cells by endocytosis in a clathrin-dependent manner, leading to endoplasmic reticulum stress and cell death. In SH-SY5Y cells and primary cortical neurons, poly-PR activated JUN amino-terminal kinase (JNK) and increased the levels of p53 and Bax. The uptake of poly-PR peptides by cells was significantly inhibited by knockdown of clathrin or by chlorpromazine, an inhibitor that blocks clathrin-mediated endocytosis. Inhibition of clathrin-dependent endocytosis by chlorpromazine significantly blocked the transfer of poly-PR peptides into cells, and attenuated poly-PRinduced JNK activation and cell death. Our data revealed that the uptake of poly-PR undergoes clathrin-dependent endocytosis and blockade of this process prevents the toxic effects of synthetic poly-PR peptides.
The major biological function of the sperm cell is to transmit the paternal genetic and epigenetic information to the embryo as well as the following offspring. Sperm has a unique epigenome. An increasing body of epidemiological study supports that paternal stress induced by environmental exposures and lifestyle can modulate the sperm epigenome (including histone modification, DNA methylation, and noncoding RNA expression), sperm-egg fusion, embryo development, and offspring health. Based on the existing literature, we have summarized the paternal exposure on sperm epigenome along with the representative phenotypes of offspring and the possible mechanism involved.
(Haigang Ren) The abbreviations used were: 5-HT, serotonin; AHI1, Abelson helper integration site 1; BMAL1, brain and muscle arnt-like protein 1; CLOCK, locomotor output cycle kaput; DA, dopamine; KO, knockout; FST, forced swim test; MAOA, monoamine oxidase A; RORα, RAR-related orphan receptor alpha; NURR1, nuclear receptor-related protein 1; TH, tyrosine hydroxylase; TST, suspension test; VMB, ventral midbrain; VTA, ventral tegmental area. AbstractAbelson helper integration site 1 (AHI1) is associated with several neuropsychiatric and brain developmental disorders such as schizophrenia, depression, autism, and Joubert syndrome. Ahi1 deficiency in mice leads to behaviors typical of depression. However, the mechanisms by which AHI1 regulates behavior remain to be elucidated. Here, we found that down-regulation of expression of the rate-limiting enzyme in dopamine biosynthesis, tyrosine hydroxylase (TH), in the midbrains of Ahi1-knockout (KO) mice is responsible for Ahi1-deficiency-mediated depressive symptoms. We also found that Rev-Erbα, a TH transcriptional repressor and circadian regulator, is up-regulated in the Ahi1-KO mouse midbrains and Ahi1-knockdown Neuro-2a cells. Moreover, brain and muscle Arnt-like protein 1 (BMAL1), the Rev-Erbα transcriptional regulator, is also increased in the Ahi1-KO mouse midbrains and Ahi1-knockdown cells. Our results further revealed that AHI1 decreases BMAL1/Rev-Erbα expression by interacting with and repressing RAR-related orphan receptor alpha (RORα), a nuclear receptor and transcriptional regulator of circadian genes. Of note, Bmal1 deficiency reversed the reduction in TH expression induced by Ahi1 deficiency. Moreover, microinfusion of the Rev-Erbα inhibitor SR8278 into the ventral midbrain of Ahi1-KO mice significantly increased TH expression in the ventral tegmental area and improved their depressive symptoms. These findings provide a mechanistic explanation for a link between AHI1-related behaviors and the circadian clock pathway, indicating an involvement of circadian regulatory proteins in AHI1-regulated mood and behavior.
Lack of dopamine production and neurodegeneration of dopaminergic neurons in the substantia nigra are considered as the major characteristics of Parkinson's disease, a prevalent movement disorder worldwide. DJ-1 mutation leading to loss of its protein functions is a genetic factor of PD. In this study, our results illustrated that DJ-1 can directly interact with Ca 2+ /calmodulin-dependent protein kinase kinase β (CaMKKβ) and modifies the cAMP-responsive element binding protein 1 (CREB1) activity, thus regulates tyrosine hydroxylase (TH) expression. In Dj-1 knockout mouse substantia nigra, the levels of TH and the phosphorylation of CREB1 Ser133 are significantly decreased. Moreover, Dj-1 deficiency suppresses the phosphorylation of CaMKIV (Thr196/200) and CREB1 (Ser133), subsequently inhibits TH expression in vitro.Furthermore, Knockdown of Creb1 abolishes the effects of DJ-1 on TH regulation.Our data reveal a novel pathway in which DJ-1 regulates CaMKKβ/CaMKIV/CREB1 activities to facilitate TH expression.
Background: Signet-ring cell carcinoma (SRCC) is a specific subtype of stomach cancer with unique epidemiology. Here, we sought to explore the role of KRAS in SRCC.Methods: KRAS status was studied both in The Cancer Genome Atlas (TCGA) and internal cohorts.Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were performed in formalinfixed and paraffin-embedded (FFPE) samples. We explored patients' survival and clinicopathological characteristics in terms of KRAS mutation and expression. We also explored KRAS status and drug response curve of MEK/mTOR inhibitors in SRCC cell lines.Results: Patients with KRAS mutations and copy number variation (CNV) showed higher mRNA level compared to non-mutant cases (P=0.003 and P<0.001). In internal cohort, 15 samples harbored KRAS mutations. Survival analysis showed that these patients had significantly lower overall survival (OS) (P=0.048).We further analyzed 75 patients with sufficient FFPE samples. Eight patients showed KRAS mutations and one patient showed KRAS amplification. The median OS was 12.5 months for patients with KRAS mutation, and 19.5 months for patients without KRAS mutation (P=0.005). Positive expression of KRAS as shown by IHC was detected in majority of SRCC samples, which was higher than our intestinal cohort (28% vs.12.6%, P=0.033). We further explored the correlation between KRAS status and drug sensitivity in 4 SRCC cell lines. SNU601 and SNU668, which harbored KRAS mutation, were hypersensitive to MEK and mTOR inhibitors than KRAS wide type cell lines KATO-III and NUGC-4. Conclusions:Our findings demonstrate that KRAS gene plays an important role in SRCC and reveals therapeutic potential of targeting tumors by inhibiting MEK and mTOR pathways.
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