Prohibitin inhibits tumor necrosis factor alpha-induced nuclear factor-kappa B nuclear translocation via the novel mechanism of decreasing importin alpha3 expression

Importin α4 deficiency induces psychiatric disorder-related behavioral deficits and neuroinflammation in mice

Importin α4, which is encoded by the Kpna4 gene, is a well-characterized nuclear-cytoplasmic transport factor known to mediate transport of transcription factors including NF-κB. Here, we report that Kpna4 knock-out (KO) mice exhibit psychiatric disorder-related behavioral abnormalities such as anxiety-related behaviors, decreased social interaction, and sensorimotor gating deficits. Contrary to a previous study predicting attenuated NF-κB activity as a result of Kpna4 deficiency, we observed a significant increase in expression levels of NF-κB genes and proinflammatory cytokines such as TNFα, Il-1β or Il-6 in the prefrontal cortex or basolateral amygdala of the KO mice. Moreover, examination of inflammatory responses in primary cells revealed that Kpna4 deficient cells have an increased inflammatory response, which was rescued by addition of not only full length, but also a nuclear transport-deficient truncation mutant of importin α4, suggesting contribution of its non-transport functions. Furthermore, RNAseq of sorted adult microglia and astrocytes and subsequent transcription factor analysis suggested increases in polycomb repressor complex 2 (PRC2) activity in Kpna4 KO cells. Taken together, importin α4 deficiency induces psychiatric disorder-related behavioral deficits in mice, along with an increased inflammatory response and possible alteration of PRC2 activity in glial cells.

Lactobacillus acidophilus inhibits the TNF-α-induced increase in intestinal epithelial tight junction permeability via a TLR-2 and PI3K-dependent inhibition of NF-κB activation

BACKGROUND

Defective intestinal epithelial tight junction (TJ), characterized by an increase in intestinal TJ permeability, has been shown to play a critical role in the pathogenesis of inflammatory bowel disease (IBD). Tumor necrosis factor-α (TNF-α) is a key pro-inflammatory cytokine involved in the immunopathology of IBD and has been shown to cause an increase in intestinal epithelial TJ permeability. Although TNF-α antibodies and other biologics have been advanced for use in IBD treatment, these therapies are associated with severe side effects and have limited efficacy, and there is an urgent need for therapies with benign profiles and high therapeutic efficacy. Probiotic bacteria have beneficial effects and are generally safe and represent an important class of potential therapeutic agents in IBD. Lactobacillus acidophilus (LA) is one of the most used probiotics for wide-ranging health benefits, including in gastrointestinal, metabolic, and inflammatory disorders. A specific strain of LA, LA1, was recently demonstrated to have protective and therapeutic effects on the intestinal epithelial TJ barrier. However, the mechanisms of actions of LA1 remain largely unknown.

METHODS

The primary aim of this study was to investigate microbial-epithelial interactions and novel signaling pathways that regulate the effect of LA1 on TNF-α-induced increase in intestinal epithelial TJ permeability, using cell culture and animal model systems.

RESULTS AND CONCLUSION

Pre-treatment of filter-grown Caco-2 monolayers with LA1 prevented the TNF-α-induced increase in intestinal epithelial TJ permeability by inhibiting TNF-α-induced activation of NF-κB p50/p65 and myosin light chain kinase (MLCK) gene and kinase activity in a TLR-2-dependent manner. LA1 produced a TLR-2- and MyD88-dependent activation of NF-κB p50/p65 in immune cells; however, LA1, in intestinal cells, inhibited the NF-κB p50/p65 activation in a TLR-2-dependent but MyD88-independent manner. In addition, LA1 inhibition of NF-κB p50/p65 and MLCK gene was mediated by TLR-2 pathway activation of phosphatidylinositol 3-kinase (PI3K) and IKK-α phosphorylation. Our results demonstrated novel intracellular signaling pathways by which LA1/TLR-2 suppresses the TNF-α pathway activation of NF-κB p50/p65 in intestinal epithelial cells and protects against the TNF-α-induced increase in intestinal epithelial TJ permeability.

Pan-cancer Analysis Combined with Experiments Deciphers PHB Regulation for Breast Cancer Cell Survival and Predicts Biomarker Function

BACKGROUND

Breast carcinoma has become the leading fatal disease among women. The location of prohibitin in the chromosome is close to the breast cancer susceptibility gene 1 (BRCA1). Accumulated research reported that prohibitin could interact with a variety of transcription factors and cell cycle-regulating proteins.

OBJECTIVE

This present study aims to comprehensively explore and reveal the biological functions of prohibitin on breast cancer via The Cancer Genome Atlas (TCGA) and validation experiment in vitro.

METHODS

Exploring the expression level of prohibitin across 27 tumors based on the TGGA database by bioinformatic methods and its relationship with tumor immune infiltration. Furthermore, we thus analyzed the biological roles of prohibitin on human breast cancer cell line MCF- 7 with pEGFP-prohibitin overexpression plasmid by western blotting and transwell-assay.

RESULTS

Firstly, we found prohibitin is overexpressed in most tumors based on The Cancer Genome Atlas database, and the negative relationships between prohibitin and tumors infiltrating lymphocytes including B lymphocyte, CD4 T lymphocyte, CD8 T lymphocyte, Neutrophil, Macrophage and Dendritic, and its significant correlation with the prognosis of human cancer. In vitro, expression not only inhibited cell viability and invasive abilities but also increased the apoptosis percentage of cells with a decreased percentage of the S phase and an increased G2 phase. The reduction of Bcl-2 was observed when prohibitin was upregulated, although the expression of E2F-1 did not change.

CONCLUSION

Although prohibitin is over-expressed in various cancer types, it functions as an important tumor suppressor that may suppress breast cancer cell proliferation and the invasive ability of MCF-7 by influencing its DNA synthesis and promoting cell apoptosis. All these may be likely associated with P53, erbB-2, and Bcl-2.

The prohibitin-binding compound fluorizoline induces the pro-inflammatory cytokines interleukin-8 and interleukin-6 through the activation of JNK and p38 MAP kinases

Fluorizoline is a prohibitin (PHB)-binding compound that induces apoptosis in several cancer cell lines as well as in primary cells from hematologic malignancies. In this study, we show that fluorizoline treatment triggers the activation of the stress-activated kinases c-Jun N-terminal kinase (JNK) and p38 prior to caspase activation in human cell lines. However, the blockage of p38 and JNK activity with chemical inhibitors or siRNA-mediated downregulation of MAPK14 (p38) does not prevent fluorizoline-induced apoptosis, suggesting that the activation of these kinases plays an alternative role in the cell response to fluorizoline treatment. Here, we describe that fluorizoline treatment leads to the secretion of pro-inflammatory cytokines interleukin-8 (IL-8) and interleukin-6 (IL-6). Importantly, we demonstrate that the activation of the stress-activated kinases JNK and p38 mediates the secretion of both IL-8 and IL-6. This study shows novel insights into the pro-inflammatory role exhibited by a compound that binds to PHB, thus supporting the potential of PHBs as anti-inflammatory proteins.

Prohibitin1 facilitates viral replication by impairing the RIG-I-like receptor signaling pathway

IMPORTANCE

Type I interferon (IFN-I), produced by the innate immune system, plays an essential role in host antiviral responses. Proper regulation of IFN-I production is required for the host to balance immune responses and prevent superfluous inflammation. IFN regulatory factor 3 (IRF3) and subsequent sensors are activated by RNA virus infection to induce IFN-I production. Therefore, proper regulation of IRF3 serves as an important way to control innate immunity and viral replication. Here, we first identified Prohibitin1 (PHB1) as a negative regulator of host IFN-I innate immune responses. Mechanistically, PHB1 inhibited the nucleus import of IRF3 by impairing its binding with importin subunit alpha-1 and importin subunit alpha-5. Our study demonstrates the mechanism by which PHB1 facilitates the replication of multiple RNA viruses and provides insights into the negative regulation of host immune responses.

Mitochondrial Control in Inflammatory Gastrointestinal Diseases

Mitochondria play a central role in the pathophysiology of inflammatory bowel disease (IBD) and colorectal cancer (CRC). The maintenance of mitochondrial function is necessary for a stable immune system. Mitochondrial dysfunction in the gastrointestinal system leads to the excessive activation of multiple inflammatory signaling pathways, leading to IBD and increased severity of CRC. In this review, we focus on the mitochondria and inflammatory signaling pathways and its related gastrointestinal diseases.

Prohibitin 1 Regulates Inflammatory Mediators and Reactive Oxygen Species in Retinal Endothelial Cells

Diabetic retinopathy is associated with increased inflammatory mediator levels. In these studies, we focused on prohibitin 1. We performed western blotting for retinal lysates from diabetic mice and Epac1 floxed and cdh5Cre-Epac1 mice. We also grew primary retinal endothelial cells (REC) in normal (5 mM) and high (25 mM) glucose, and treated some cells with an Epac 1 agonist or prohibitin 1 siRNA. Western blotting was done to confirm knockdown of prohibitin 1 and Epac 1 agonism. We measured the tumor necrosis factor alpha (TNFα), interleukin-1-beta (IL-1β), phosphorylated prohibitin 1, phosphorylated nuclear factor kappa beta (NFkB), high mobility group box 1 (HMGB1) and reactive oxygen species (ROS) levels in REC after transfection with prohibitin 1 siRNA. Results showed that high glucose increased the inflammatory mediators, as well as HMGB1 and ROS. The levels of ROS, HMGB1, and inflammatory pathways were all reduced after cells were transfected with prohibitin 1 siRNA. Epac1 reduced prohibitin 1 phosphorylation. In conclusion, decreased prohibitin 1 significantly reduced the inflammatory mediator and ROS levels in REC. Epac1 regulates the prohibitin 1 levels in REC.

Prohibitin-1 Is a Dynamically Regulated Blood Protein With Cardioprotective Effects in Sepsis

Background In sepsis, circulating cytokines and lipopolysaccharide elicit mitochondrial dysfunction and cardiomyopathy, a major cause of morbidity and mortality with this condition. Emerging research places the PHB1 (lipid raft protein prohibitin-1) at the nexus of inflammation, metabolism, and oxidative stress. PHB1 has also been reported in circulation, though its function in this compartment is completely unknown. Methods and Results Using a wide-ranging approach across multiple in vitro and in vivo models, we interrogated the functional role of intracellular and circulating PHB1 in the heart during sepsis, and elucidated some of the mechanisms involved. Upon endotoxin challenge or sepsis induction in rodent models, PHB1 translocates from mitochondria to nucleus in cardiomyocytes and is secreted into the circulation from the liver in a manner dependent on nuclear factor (erythroid-derived 2)-like 2, a key transcriptional regulator of the antioxidant response. Overexpression or treatment with recombinant human PHB1 enhances the antioxidant/anti-inflammatory response and protects HL-1 cardiomyocytes from mitochondrial dysfunction and toxicity from cytokine stress. Importantly, administration of recombinant human PHB1 blunted inflammation and restored cardiac contractility and ATP production in mice following lipopolysaccharide challenge. This cardioprotective, anti-inflammatory effect of recombinant human PHB1 was determined to be independent of nuclear factor (erythroid-derived 2)-like 2, but partially dependent on PI3K/AKT  signaling in the heart. Conclusions These findings reveal a previously unknown cardioprotective effect of PHB1 during sepsis, and illustrate a pro-survival, protective role for PHB1 in the circulation. Exploitation of circulating PHB1 as a biomarker and/or therapeutic could have widespread benefit in the clinical management of sepsis and other severe inflammatory disorders.

Prohibitin-1 Contributes to Cell-to-Cell Transmission of Herpes Simplex Virus 1 via the MAPK/ERK Signaling Pathway

Viral cell-to-cell spread, a method employed by several viral families for entrance via cell junctions, is highly relevant to the pathogenesis of various viral infections. Cell-to-cell spread of herpes simplex virus 1 (HSV-1) is known to depend greatly on envelope glycoprotein E (gE). However, the molecular mechanism by which gE acts in HSV-1 cell-to-cell spread and the mechanisms of cell-to-cell spread by other herpesviruses remain poorly understood. Here, we describe our identification of prohibitin-1 as a novel gE-interacting host cell protein. Ectopic expression of prohibitin-1 increased gE-dependent HSV-1 cell-to-cell spread. As observed with the gE-null mutation, decreased expression or pharmacological inhibition of prohibitin-1 reduced HSV-1 cell-to-cell spread without affecting the yield of virus progeny. Similar effects were produced by pharmacological inhibition of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, wherein prohibitin-1 acts as a protein scaffold and is required for induction of this pathway. Furthermore, artificial activation of the MAPK/ERK pathway restored HSV-1 cell-to-cell spread impaired by the gE-null mutation. Notably, pharmacological inhibition of prohibitins or the MAPK/ERK pathway reduced viral cell-to-cell spread of representative members in all herpesvirus subfamilies. Our results suggest that prohibitin-1 contributes to gE-dependent HSV-1 cell-to-cell spread via the MAPK/ERK pathway and that this mechanism is conserved throughout the Herpesviridae, whereas gE is conserved only in the Alphaherpesvirinae subfamily.IMPORTANCE Herpesviruses are ubiquitous pathogens of various animals, including humans. These viruses primarily pass through cell junctions to spread to uninfected cells. This method of cell-to-cell spread is an important pathogenic characteristic of these viruses. Here, we show that the host cell protein prohibitin-1 contributes to HSV-1 cell-to-cell spread via a downstream intracellular signaling cascade, the MAPK/ERK pathway. We also demonstrate that the role of the prohibitin-1-mediated MAPK/ERK pathway in viral cell-to-cell spread is conserved in representative members of every herpesvirus subfamily. This study has revealed a common molecular mechanism of the cell-to-cell spread of herpesviruses.

Lipopolysaccharide-induced innate immune responses are exacerbated by Prohibitin 1 deficiency and mitigated by S-adenosylmethionine in murine macrophages

Prohibitin 1 (Phb1) is a pleiotropic protein with multiple functions in mammalian cells including cell cycle regulation and mitochondrial protein stabilization. It has been proposed as a potential therapeutic target for a variety of diseases including inflammatory diseases. In this study, we investigated the potential immune-modulatory functions of Phb1 and anti-inflammatory properties of S-adenosylmethionine (SAMe) using macrophages, which play a major role in the innate immune system. The results showed that expressions of Phb1 mRNA and protein were reduced in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells (p<0.05). Phb1 knockdown further ameliorated the mRNA expression of pro- and anti-inflammatory cytokines such as TNF-α, IL-1α, IL-1β, IL-6, and IL10 in LPS-stimulated RAW 264.7 cells. SAMe significantly attenuated LPS-induced inflammatory responses such as IL-1β, IL-10, Nos2, and NO production in the presence of siPhb1. Luciferase reporter assay was conducted to determine the mechanisms underlying the effects of Phb1 and SAMe on the immune system. The luciferase activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was significantly increased in LPS-treated RAW 264.7 cells. In addition, the luciferase reporter assay showed increased NF-κB activation in Phb1 knockdown RAW 264.7 cells (p<0.1) and SAMe treatment attenuated the NF-κB luciferase activity in Phb1 knockdown RAW 264.7 cells. Based on the results, we concluded that Phb1 possibly modulates the inflammatory response whereas SAMe has an anti-inflammatory effect on Phb1 knockdown macrophage cells. Furthermore, Phb1 expression level has potential properties of affecting on innate immune system by modulating the NF-κB signaling pathway.

A Functional Variant of the miR-15 Family Is Associated with a Decreased Risk of Esophageal Squamous Cell Carcinoma

MicroRNAs (miRNAs)-related single-nucleotide polymorphisms (SNPs) have been shown to be implicated in the susceptibility to different types of cancer, including esophageal squamous cell carcinoma (ESCC). Identification of miRNA-related SNPs may provide candidate biomarkers for early diagnosis of ESCC. We performed a genome-wide microarray assay to identify differentially expressed miRNAs, which indicated that the miR-15 family may play an important role in ESCC biology. We then investigated the association of miR-15 family-related SNPs with ESCC. Five miR-15 family-related SNPs were genotyped in 300 patients and 418 controls. Unconditional logistic regression was used to evaluate the relationships of these SNPs with ESCC. Generalized multifactor dimensionality reduction was employed to analyze the SNP-SNP and SNP-smoking interactions. The expression quantitative trait loci (eQTL) databases were queried for in silico functional validation. We found that miR-15b SNP rs1451761T>G was associated with a significantly decreased risk of ESCC and there was a significant SNP-SNP interaction between rs1451761 and rs2740545. SNP-smoking interaction analysis also indicated that the association between rs1451761 and ESCC risk could be changed by smoking status. Additionally, the eQTL analysis revealed that rs1451761 was significantly correlated with structural maintenance of chromosomes 4 and karyopherin subunit alpha 4 mRNA expression. Our results suggest that miR-15b SNP rs1451761 may affect an individual's susceptibility to ESCC, alone and in SNP-SNP and SNP-smoking interaction manners.

An epilepsy-associated mutation in the nuclear import receptor KPNA7 reduces nuclear localization signal binding

KPNA7 is a member of the Importin-α family of nuclear import receptors. KPNA7 forms a complex with Importin-β and facilitates the translocation of signal-containing proteins from the cytoplasm to the nucleus. Exome sequencing of siblings with severe neurodevelopmental defects and clinical features of epilepsy identified two amino acid-altering mutations in KPNA7. Here, we show that the E344Q substitution reduces KPNA7 binding to nuclear localization signals, and that this limits KPNA7 nuclear import activity. The P339A substitution, by contrast, has little effect on KPNA7 binding to nuclear localization signals. Given the neuronal phenotype described in the two patients, we used SILAC labeling, affinity enrichment, and mass spectrometry to identify KPNA7-interacting proteins in human induced pluripotent stem cell-derived neurons. We identified heterogeneous nuclear ribonucleoproteins hnRNP R and hnRNP U as KPNA7-interacting proteins. The E344Q substitution reduced binding and KPNA7-mediated import of these cargoes. The c.1030G > C allele which generates E344Q is within a predicted CTCF binding site, and we found that it reduces CTCF binding by approximately 40-fold. Our data support a role for altered neuronal expression and activity of KPNA7 in a rare type of pediatric epilepsy.

Prohibitin 1 in liver injury and cancer

Prohibitin 1 is an evolutionary conserved and ubiquitously expressed protein that exerts different biological functions depending on its subcellular localization. The role of prohibitin 1 in liver cancer is controversial as it can be pro- or anti-tumorigenic. However, most of the studies to date have described prohibitin 1 primarily as a tumor suppressor in the liver. Its deficiency sensitizes the liver to cholestatic liver injury, non-alcoholic fatty liver disease, inflammatory insults, and cancer. Liver-specific Phb1-knockout mice spontaneously develop hepatocellular carcinoma, Phb1 heterozygotes are more susceptible to develop cholangiocarcinoma, and the majority of human hepatocellular carcinomas and cholangiocarcinomas have reduced prohibitin 1 expression. Consistent with a tumor suppressive role in the liver, prohibitin 1 negatively regulates proliferation in hepatocytes and human hepatocellular carcinoma and cholangiocarcinoma cell lines, and multiple oncogenic signaling pathways are activated when prohibitin 1 is deficient. Although best known as a mitochondrial chaperone, prohibitin 1 can protect the liver by mitochondrial-independent mechanisms. This review summarizes what’s known about prohibitin 1’s role in liver pathology, with the focus on hepatoprotection and carcinogenesis.

Impact statement

This review summarizes the last decades of research on PHB1 in liver pathobiology. PHB1 is a key player for liver health as it is hepatoprotective and tumor suppressive. We highlight the importance of PHB1’s subcellular localization, post-translational modifications, and interacting proteins as major determinants of PHB1 cytoprotective function and anti-tumor activity in the liver.

A Small Compound Targeting Prohibitin with Potential Interest for Cognitive Deficit Rescue in Aging mice and Tau Pathology Treatment

Neurodegenerative diseases, including Alzheimer’s and Parkinson’s disease, are characterized by increased protein aggregation in the brain, progressive neuronal loss, increased inflammation, and neurogenesis impairment. We analyzed the effects of a new purine derivative drug, PDD005, in attenuating mechanisms involved in the pathogenesis of neurodegenerative diseases, using both in vivo and in vitro models. We show that PDD005 is distributed to the brain and can rescue cognitive deficits associated with aging in mice. Treatment with PDD005 prevents impairment of neurogenesis by increasing sex-determining region Y-box 2, nestin, and also enhances synaptic function through upregulation of synaptophysin and postsynaptic density protein 95. PDD005 treatment also reduced neuro-inflammation by decreasing interleukin-1β expression, activation of astrocytes, and microglia. We identified prohibitin as a potential target in mediating the therapeutic effects of PDD005 for the treatment of cognitive deficit in aging mice. Additionally, in the current study, glycogen synthase kinase appears to attenuate tau pathology.

Azithromycin Polarizes Macrophages to an M2 Phenotype via Inhibition of the STAT1 and NF-κB Signaling Pathways

Azithromycin is effective at controlling exaggerated inflammation and slowing the long-term decline of lung function in patients with cystic fibrosis. We previously demonstrated that the drug shifts macrophage polarization toward an alternative, anti-inflammatory phenotype. In this study we investigated the immunomodulatory mechanism of azithromycin through its alteration of signaling via the NF-κB and STAT1 pathways. J774 murine macrophages were plated, polarized (with IFN-γ, IL-4/-13, or with azithromycin plus IFN-γ) and stimulated with LPS. The effect of azithromycin on NF-κB and STAT1 signaling mediators was assessed by Western blot, homogeneous time-resolved fluorescence assay, nuclear translocation assay, and immunofluorescence. The drug's effect on gene and protein expression of arginase was evaluated as a marker of alternative macrophage activation. Azithromycin blocked NF-κB activation by decreasing p65 nuclear translocation, although blunting the degradation of IκBα was due, at least in part, to a decrease in IKKβ kinase activity. A direct correlation was observed between increasing azithromycin concentrations and increased IKKβ protein expression. Moreover, incubation with the IKKβ inhibitor IKK16 decreased arginase expression and activity in azithromycin-treated cells but not in cells treated with IL-4 and IL-13. Importantly, azithromycin treatment also decreased STAT1 phosphorylation in a concentration-dependent manner, an effect that was reversed with IKK16 treatment. We conclude that azithromycin anti-inflammatory mechanisms involve inhibition of the STAT1 and NF-κB signaling pathways through the drug's effect on p65 nuclear translocation and IKKβ.

LPLUNC1 stabilises PHB1 by counteracting TRIM21-mediated ubiquitination to inhibit NF-κB activity in nasopharyngeal carcinoma

Long-palate, lung and nasal epithelium clone 1 (LPLUNC1) is a tumour suppressor gene in nasopharyngeal carcinoma (NPC), and low expression of LPLUNC1 is associated with poor prognosis. Our previous study showed that LPLUNC1 upregulates Prohibitin 1 (PHB1), a pleiotropic protein that functions as a tumour suppressor gene in various cancers. Low expression of PHB1 was also found to be associated with the poor prognosis of NPC patients. However, the mechanisms by which LPLUNC1 upregulates PHB1 and the potential role of PHB1 in NPC are unclear. Here, we found that LPLUNC1 stabilised PHB1 by inhibiting PHB1 ubiquitination, which is mediated by E3 ligase TRIM21. LPLUNC1 competitively impaired the binding of PHB1 to TRIM21 due to its stronger binding affinity to PHB1, suppressing the ubiquitination of PHB1. Therefore, our study indicates that PHB1 acted as a tumour suppressor gene by inhibiting NF-κB activity. Depletion of PHB1 significantly attenuated the anti-tumour effects of LPLUNC1 in NPC cells, and the inhibitory effect of LPLUNC1 on NF-κB activity was thus reversed. Together, our findings revealed a novel mechanism underlying the anticancer effect of LPLUNC1 and clarified that PHB1 may represent a novel, promising candidate tumour suppressor gene in NPC, with potential therapeutic target value.

The mitochondrial chaperone Prohibitin 1 negatively regulates interleukin-8 in human liver cancers

Prohibitin 1 (PHB1) is a mitochondrial chaperone whose expression is dysregulated in cancer. In liver cancer, PHB1 acts as a tumor suppressor, but the mechanisms of tumor suppression are incompletely understood. Here we aimed to determine PHB1 target genes to better understand how PHB1 influences liver tumorigenesis. Using RNA-Seq analysis, we found interleukin-8 (IL-8) to be one of the most highly up-regulated genes following PHB1 silencing in HepG2 cells. Induction of IL-8 expression also occurred in multiple liver and nonliver cancer cell lines. We examined samples from 178 patients with hepatocellular carcinoma (HCC) and found that IL-8 mRNA levels were increased, whereas PHB1 mRNA levels were decreased, in the tumors compared with adjacent nontumorous tissues. Notably, HCC patients with high IL-8 expression have significantly reduced survival. An inverse correlation between PHB1 and IL-8 mRNA levels is found in HCCs with reduced PHB1 expression. To understand the molecular basis for these observations, we altered PHB1 levels in liver cancer cells. Overexpression of PHB1 resulted in lowered IL-8 expression and secretion. Silencing PHB1 increased c-Jun N-terminal kinase (JNK) and NF-κB activity, induced nuclear accumulation of c-JUN and p65, and enhanced their binding to the IL-8 promoter containing AP-1 and NF-κB elements. Conditioned medium from PHB1-silenced HepG2 cells increased migration and invasion of parental HepG2 and SK-hep-1 cells, and this was blocked by co-treatment with neutralizing IL-8 antibody. In summary, our findings show that reduced PHB1 expression induces IL-8 transcription by activating NF-κB and AP-1, resulting in enhanced IL-8 expression and release to promote tumorigenesis.

Importins α and β signaling mediates endothelial cell inflammation and barrier disruption

Nucleocytoplasmic shuttling via importins is central to the function of eukaryotic cells and an integral part of the processes that lead to many human diseases. In this study, we addressed the role of α and β importins in the mechanism of endothelial cell (EC) inflammation and permeability, important pathogenic features of many inflammatory diseases such as acute lung injury and atherosclerosis. RNAi-mediated knockdown of importin α4 or α3 each inhibited NF-κB activation, proinflammatory gene (ICAM-1, VCAM-1, and IL-6) expression, and thereby endothelial adhesivity towards HL-60 cells, upon thrombin challenge. The inhibitory effect of α4 and α3 knockdown was associated with impaired nuclear import and consequently, DNA binding of RelA/p65 subunit of NF-κB and occurred independently of IκBα degradation. Intriguingly, knockdown of importins α4 and α3 also inhibited thrombin-induced RelA/p65 phosphorylation at Ser536, showing a novel role of α importins in regulating transcriptional activity of RelA/p65. Similarly, knockdown of importin β1, but not β2, blocked thrombin-induced activation of RelA/p65 and its target genes. In parallel studies, TNFα-mediated inflammatory responses in EC were refractory to knockdown of importins α4, α3 or β1, indicating a stimulus-specific regulation of RelA/p65 and EC inflammation by these importins. Importantly, α4, α3, or β1 knockdown also protected against thrombin-induced EC barrier disruption by inhibiting the loss of VE-cadherin at adherens junctions and by regulating actin cytoskeletal rearrangement. These results identify α4, α3 and β1 as critical mediators of EC inflammation and permeability associated with intravascular coagulation.

Inhibition of KPNA4 attenuates prostate cancer metastasis

Prostate cancer (PCa) is a common cancer in men. Although current treatments effectively palliate symptoms and prolong life, the metastatic PCa remains incurable. It is important to find biomarkers and targets to improve metastatic PCa diagnosis and treatment. Here we report a novel correlation between karyopherin α4 (KPNA4) and PCa pathological stages. KPNA4 mediates the cytoplasm-to-nucleus translocation of transcription factors, including nuclear factor kappa B, although its role in PCa was largely unknown. We find that knockdown of KPNA4 reduces cell migration in multiple PCa cell lines, suggesting a role of KPNA4 in PCa progression. Indeed, stable knockdown of KPNA4 significantly reduces PCa invasion and distant metastasis in mouse models. Functionally, KPNA4 alters tumor microenvironment in terms of macrophage polarization and osteoclastogenesis by modulating tumor necrosis factor (TNF)-α and -β. Further, KPNA4 is proved as a direct target of miR-708, a tumor-suppressive microRNA. We disclose the role of miR-708-KPNA4-TNF axes in PCa metastasis and KPNA4's potential as a novel biomarker for PCa metastasis.

RNA interference-based nanosystems for inflammatory bowel disease therapy

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease, is a chronic, recrudescent disease that invades the gastrointestinal tract, and it requires surgery or lifelong medicinal therapy. The conventional medicinal therapies for IBD, such as anti-inflammatories, glucocorticoids, and immunosuppressants, are limited because of their systemic adverse effects and toxicity during long-term treatment. RNA interference (RNAi) precisely regulates susceptibility genes to decrease the expression of proinflammatory cytokines related to IBD, which effectively alleviates IBD progression and promotes intestinal mucosa recovery. RNAi molecules generally include short interfering RNA (siRNA) and microRNA (miRNA). However, naked RNA tends to degrade in vivo as a consequence of endogenous ribonucleases and pH variations. Furthermore, RNAi treatment may cause unintended off-target effects and immunostimulation. Therefore, nanovectors of siRNA and miRNA were introduced to circumvent these obstacles. Herein, we introduce non-viral nanosystems of RNAi molecules and discuss these systems in detail. Additionally, the delivery barriers and challenges associated with RNAi molecules will be discussed from the perspectives of developing efficient delivery systems and potential clinical use.

Vitamin D Deficiency Accelerates Coronary Artery Disease Progression in Swine

OBJECTIVE

The role of vitamin D deficiency in coronary artery disease (CAD) progression is uncertain. Chronic inflammation in epicardial adipose tissue (EAT) has been implicated in the pathogenesis of CAD. However, the molecular mechanism underlying vitamin D deficiency-enhanced inflammation in the EAT of diseased coronary arteries remains unknown. We examined a mechanistic link between 1,25-dihydroxyvitamin D-mediated suppression of nuclear factor-κB (NF-κB) transporter, karyopherin α4 (KPNA4) expression and NF-κB activation in preadipocytes. Furthermore, we determined whether vitamin D deficiency accelerates CAD progression by increasing KPNA4 and nuclear NF-κB levels in EAT.

APPROACH AND RESULTS

Nuclear protein levels were detected by immunofluorescence and Western blot. Exogenous KPNA4 was transported into cells by a transfection approach and constituted lentiviral vector. Swine were administered vitamin D-deficient or vitamin D-sufficient hypercholesterolemic diet. After 1 year, the histopathology of coronary arteries and nuclear protein expression of EAT were assessed. 1,25-dihydroxyvitamin D inhibited NF-κB activation and reduced KPNA4 levels through increased vitamin D receptor expression. Exogenous KPNA4 rescued 1,25-dihydroxyvitamin D-dependent suppression of NF-κB nuclear translocation and activation. Vitamin D deficiency caused extensive CAD progression and advanced atherosclerotic plaques, which are linked to increased KPNA4 and nuclear NF-κB levels in the EAT.

CONCLUSIONS

1,25-dihydroxyvitamin D attenuates NF-κB activation by targeting KPNA4. Vitamin D deficiency accelerates CAD progression at least, in part, through enhanced chronic inflammation of EAT by upregulation of KPNA4, which enhances NF-κB activation. These novel findings provide mechanistic evidence that vitamin D supplementation could be beneficial for the prevention and treatment of CAD.

Flavaglines Ameliorate Experimental Colitis and Protect Against Intestinal Epithelial Cell Apoptosis and Mitochondrial Dysfunction

BACKGROUND

Flavaglines are a family of natural compounds shown to have anti-inflammatory and cytoprotective effects in neurons and cardiomyocytes. Flavaglines target prohibitins as ligands, which are scaffold proteins that regulate mitochondrial function, cell survival, and transcription. This study tested the therapeutic potential of flavaglines to promote intestinal epithelial cell homeostasis and to protect against a model of experimental colitis in which inflammation is driven by epithelial ulceration.

METHODS

Survival and homeostasis of Caco2-BBE and IEC-6 intestinal epithelial cell lines were measured during treatment with the flavaglines FL3 or FL37 alone and in combination with the proinflammatory cytokines tumor necrosis factor (TNF) α and interferon γ. Wild-type mice were intraperitoneally injected with 0.1 mg/kg FL3 or vehicle once daily for 4 days during dextran sodium sulfate-induced colitis to test the in vivo anti-inflammatory effect of FL3.

RESULTS

FL3 and FL37 increased basal Caco2-BBE and IEC-6 cell viability, decreased apoptosis, and decreased epithelial monolayer permeability. FL3 and FL37 inhibited TNFα- and interferon γ-induced nuclear factor kappa B and Cox2 expression, apoptosis, and increased permeability in Caco2-BBE cells. FL3 and FL37 protected against TNFα-induced mitochondrial superoxide generation by preserving respiratory chain complex I activity and prohibitin expression. p38-MAPK activation was essential for the protective effect of FL3 and FL37 on barrier permeability and mitochondrial-derived reactive oxygen species production during TNFα treatment. Mice administered FL3 during dextran sodium sulfate colitis exhibited increased colonic prohibitin expression and p38-MAPK activation, preserved barrier function, and less inflammation.

CONCLUSIONS

These results suggest that flavaglines exhibit therapeutic potential against colitis and preserve intestinal epithelial cell survival, mitochondrial function, and barrier integrity.

Mitochondrial dysfunction in inflammatory bowel disease

Inflammatory Bowel Disease (IBD) represents a group of idiopathic disorders characterized by chronic or recurring inflammation of the gastrointestinal tract. While the exact etiology of disease is unknown, IBD is recognized to be a complex, multifactorial disease that results from an intricate interplay of genetic predisposition, an altered immune response, changes in the intestinal microbiota, and environmental factors. Together, these contribute to a destruction of the intestinal epithelial barrier, increased gut permeability, and an influx of immune cells. Given that most cellular functions as well as maintenance of the epithelial barrier is energy-dependent, it is logical to assume that mitochondrial dysfunction may play a key role in both the onset and recurrence of disease. Indeed several studies have demonstrated evidence of mitochondrial stress and alterations in mitochondrial function within the intestinal epithelium of patients with IBD and mice undergoing experimental colitis. Although the hallmarks of mitochondrial dysfunction, including oxidative stress and impaired ATP production are known to be evident in the intestines of patients with IBD, it is as yet unclear whether these processes occur as a cause of consequence of disease. We provide a current review of mitochondrial function in the setting of intestinal inflammation during IBD.

Prohibitin as a novel autoantigen in rheumatoid arthritis

The aim of this study

The aim of this study was to verify whether prohibitin is a novel autoantigen in rheumatoid arthritis.

Material and methods

First, recombinant human prohibitin (rhPHB) protein was cloned, expressed, and purified. Then the anti-prohibitin autoantibodies were detected by western blotting by using rhPHB protein to incubate sera from patients with rheumatoid arthritis (RA). Next, immunoprecipitation was employed to further illustrate whether anti-prohibitin antibodies exist in RA patients. And finally, autoantibodies against the rhPHB protein were investigated using a homemade ELISA kit through the assessment of 258 real clinical samples.

Results

It was revealed that anti-prohibitin antibodies existed in the sera of patients with RA. Reactivity of serum IgG against rhPHB was detected in 26 of 86 RA patients (30.3%), 7 of 86 systemic lupus erythematosus (SLE) patients (8.1%), and 1 of 86 apparently healthy donors (HC) (1.2%).

Conclusions

Prohibitin was proved to be a novel autoantigen and the corresponding anti-prohibitin autoantibodies were present in the RA patients' blood circulation.

Tissue proteomics of splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a rare chronic B lymphoproliferative disease, whose molecular pathogenesis has still not been well established. For the first time, a proteomic approach was undertaken to analyse the protein profiles of SMZL tissue. 1D and 2D Western blot, immunohistochemical analysis, and functional data mining were also performed in order to validate results, investigate protein species specific regulation, classify proteins, and explore their potential relationships. We demonstrated that SMZL is characterized by modulation of protein species related to energetic metabolism and apoptosis pathways. We also reported specific protein species (such as biliverdin reductase A, manganese superoxide dismutase, beta-2 microglobulin, growth factor receptor-bound protein 2, acidic leucine-rich nuclear phosphoprotein 32 family member A, and Set nuclear oncogene) directly involved in NF-kB and BCR pathways, as well as in chromatin remodelling and cytoskeleton. Our findings shed new light on SMZL pathogenesis and provide a basis for the future development of novel biomarkers. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the dataset identifier PXD001124.

Diversification of importin-α isoforms in cellular trafficking and disease states

The human genome encodes seven isoforms of importin α which are grouped into three subfamilies known as α1, α2 and α3. All isoforms share a fundamentally conserved architecture that consists of an N-terminal, autoinhibitory, importin-β-binding (IBB) domain and a C-terminal Arm (Armadillo)-core that associates with nuclear localization signal (NLS) cargoes. Despite striking similarity in amino acid sequence and 3D structure, importin-α isoforms display remarkable substrate specificity in vivo. In the present review, we look at key differences among importin-α isoforms and provide a comprehensive inventory of known viral and cellular cargoes that have been shown to associate preferentially with specific isoforms. We illustrate how the diversification of the adaptor importin α into seven isoforms expands the dynamic range and regulatory control of nucleocytoplasmic transport, offering unexpected opportunities for pharmacological intervention. The emerging view of importin α is that of a key signalling molecule, with isoforms that confer preferential nuclear entry and spatiotemporal specificity on viral and cellular cargoes directly linked to human diseases.

Changes in the proteomic profile during the differential polarization status of the human monocyte-derived macrophage THP-1 cell line

Macrophages are heterogeneous and plastic populations that are an essential component of inflammation and host defense. To understand how macrophages respond to cytokine signals, we used 2DE to identify protein profiles in macrophages stimulated with interleukin 4 (M2) and those stimulated with lipopolysaccharide and interferon γ (M1). In total, 32 differentially expressed proteins in THP-1 cells were identified by MALDI-TOF MS/MS analysis. The different proteins were mainly involved in cellular structure, protein metabolism, stress response, oxidative response, and nitric oxide production during macrophage polarization. In particular, proteins playing important roles in production of nitric oxide (NO) were downregulated in M2 macrophages. Many antioxidant and heat shock proteins, which are related to oxidative response, were upregulated in M2 macrophages. More importantly, a remarkable decrease in intracellular ROS and NO production were detected in M2 macrophages. Our results provide a proteomic profile of differentially polarized macrophages and validate the function of the identified proteins, which may indicate possible mechanism of macrophage polarization process.

Prohibitin 1 modulates mitochondrial function of Stat3

Mitochondrial dysfunction in intestinal epithelial cells (IEC) is thought to precede the onset of inflammatory bowel diseases (IBD). Expression of Prohibitin 1 (PHB), a mitochondrial protein required for optimal electron transport chain (ETC) activity, is decreased in mucosal biopsies during active and inactive IBD. In addition to its activities as a transcription factor, Signal Transducer and Activator of Transcription 3 (Stat3) resides in the mitochondria of cells where phosphorylation at S727 is required for optimal ETC activity and protects against stress-induced mitochondrial dysfunction. Here, we show that PHB overexpression protects against mitochondrial stress and apoptosis of cultured IECs induced by TNFα, which is a pro-inflammatory cytokine involved in IBD pathogenesis. Expression of pS727-Stat3 dominant negative eliminates protection by PHB against TNFα-induced mitochondrial stress and apoptosis. PHB interacts with pS727-Stat3 in the mitochondria of cultured IECs and in colonic epithelium from wild-type mice. Our data suggest a protective role of PHB that is dependent on pS727-Stat3 to prevent mitochondrial dysfunction in IECs. Reduced levels of PHB during IBD may be an underlying factor promoting mitochondrial dysfunction of the intestinal epithelium.

Oxymatrine prevents NF-κB nuclear translocation and ameliorates acute intestinal inflammation

Oxymatrine is a traditional Chinese herbal product that exhibits anti-inflammatory effects in models of heart, brain and liver injury. We investigated the impact of oxymatrine in an acute model of intestinal injury and inflammation. Oxymatrine significantly decreased LPS-induced NF-κB-driven luciferase activity, correlating with diminished induction of Cxcl2, Tnfα and Il6 mRNA expression in rat IEC-6 and murine BMDC. Although oxymatrine decreased LPS-induced p65 nuclear translocation and binding to the Cxcl2 gene promoter, this effect was independent of IκBα degradation/phosphorylation. DSS-induced weight loss and histological damage were ameliorated in oxymatrine-treated C57BL/6-WT-mice. While this effect correlated with reduced colonic Il6 and Il1β mRNA accumulation, global NF-κB activity as measured in NF-κB^EGFP mice was unaffected. Our data demonstrate that oxymatrine reduces LPS-induced NF-κB nuclear translocation and activity independently of IκBα status, prevents intestinal inflammation through blockade of inflammatory signaling and ameliorates overall intestinal inflammation in vivo.

Endothelial microRNAs and atherosclerosis

The vascular endothelium, a thin layer of endothelial cells (ECs) that line the inner surface of blood vessels, is a critical interface between blood and all tissues. EC activation, dysfunction, and vascular inflammation occur when the endothelium is exposed to various insults such as proinflammatory cytokines, oxidative stress, hypertension, hyperglycemia, aging, and shear stress. These insults lead to the pathogenesis of a range of disease states, including atherosclerosis. Several signaling pathways, especially nuclear factor κB mediated signaling, play crucial roles in these pathophysiological processes. Recently, microRNAs (miRNAs) have emerged as important regulators of EC function by fine-tuning gene expression. In this review, we discuss how miRNAs regulate EC function and vascular inflammation in response to a variety of pathophysiologic stimuli. An understanding of the role of miRNAs in EC activation and dysfunction may provide novel targets and therapeutic opportunities for controlling atherosclerosis and other chronic inflammatory disease states.

Importin-α7 is required for enhanced influenza A virus replication in the alveolar epithelium and severe lung damage in mice

Influenza A viruses recruit components of the nuclear import pathway to enter the host cell nucleus and promote viral replication. Here, we analyzed the role of the nuclear import factor importin-α7 in H1N1 influenza virus pulmonary tropism by using various ex vivo imaging techniques (magnetic resonance imaging, confocal laser scanning microscopy, and correlative light-electron microscopy). We infected importin-α7 gene-deficient (α7(-/-)) mice with a recombinant H1N1 influenza virus and compared the in vivo viral kinetics with those in wild-type (WT) mice. In WT mice, influenza virus replication in the bronchial and alveolar epithelium already occurred a few days after infection. Accordingly, extensive mononuclear infiltration and alveolar destruction were present in the lungs of infected WT mice, followed by 100% lethality. Conversely, in α7(-/-) mice, virus replication was restricted mostly to the bronchial epithelium with marginal alveolar infection, resulting in significantly reduced lung damage and enhanced animal survival. To investigate the host immune response during alveolar virus replication, we studied the role of primary macrophages in virus propagation and clearance. The ability of macrophages to support or clear the virus infection, as well as the host cellular immune responses, did not significantly differ between WT and α7(-/-) mice. However, cytokine and chemokine responses were generally elevated in WT mice, likely reflective of increased viral replication in the lung. In summary, these data show that a cellular factor, importin-α7, is required for enhanced virus replication in the alveolar epithelium, resulting in elevated cytokine and chemokine levels, extensive mononuclear infiltration, and thus, severe pneumonia and enhanced virulence in mice. Importance: Influenza A viruses are respiratory pathogens that may cause pneumonia in humans. Viral infection and replication in the alveoli of the respiratory tract are believed to be crucial for the development of the acute respiratory distress syndrome associated with fatal outcomes in influenza virus-infected patients. Here, we report the requirement of a cellular factor, importin-α7, for efficient virus replication in the alveolar epithelium of mice. Using complementary ex vivo imaging approaches, we show that influenza virus replication is restricted to the bronchial epithelium, followed by enhanced survival in importin-α7-deficient mice. In contrast, the presence of this gene results in enhanced virus replication in the alveoli, elevated cytokine and chemokine responses, mononuclear infiltration, alveolar destruction, and 100% lethality in wild-type mice. Taken together, our results show that importin-α7 is particularly required for virus replication in the alveolar epithelium in association with severe pneumonia and death in mice.

Prohibitin viral gene transfer protects hippocampal CA1 neurons from ischemia and ameliorates postischemic hippocampal dysfunction

BACKGROUND AND PURPOSE

Prohibitin is a multi-functional protein involved in numerous cellular activities. Prohibitin overexpression protects neurons from injury in vitro, but it is unclear whether prohibitin can protect selectively vulnerable hippocampal CA1 neurons in a clinically relevant injury model in vivo and, if so, whether the salvaged neurons remain functional.

METHODS

A mouse model of transient forebrain ischemia that mimics the brain damage produced by cardiac arrest in humans was used to test whether prohibitin expression protects CA1 neurons from injury. Prohibitin-expressing viral vector was microinjected in mouse hippocampus to upregulate prohibitin.

RESULTS

Prohibitin overexpression protected CA1 neurons from transient forebrain ischemia. The protection was associated with dampened postischemic reactive oxygen species generation, reduced mitochondrial cytochrome c release, and decreased caspase-3 activation. Importantly, the improvement in CA1 neuronal viability translated into an improvement in hippocampal function: prohibitin expression ameliorated the spatial memory deficit induced by ischemia, assessed by the Y-maze test, and restored postischemic synaptic plasticity assessed by long-term potentiation, indicating that the neurons spared form ischemic damage were functionally competent.

CONCLUSIONS

These data demonstrate that prohibitin overexpression protects highly vulnerable CA1 neurons from ischemic injury in vivo and suggest that the effect is mediated by reduction of postischemic reactive oxygen species generation and preservation of mitochondrial outer membrane integrity that prevents activation of apoptosis. Measures to enhance prohibitin expression could have translational value in ischemic brain injury and, possibly, other forms of brain injury associated with mitochondrial dysfunction.

Importins and exportins regulating allergic immune responses

Nucleocytoplasmic shuttling of macromolecules is a well-controlled process involving importins and exportins. These karyopherins recognize and bind to receptor-mediated intracellular signals through specific signal sequences that are present on cargo proteins and transport into and out of the nucleus through nuclear pore complexes. Nuclear localization signals (NLS) present on cargo molecules to be imported while nuclear export signals (NES) on the molecules to be exported are recognized by importins and exportins, respectively. The classical NLS are found on many transcription factors and molecules that are involved in the pathogenesis of allergic diseases. In addition, several immune modulators, including corticosteroids and vitamin D, elicit their cellular responses by regulating the expression and activity of importin molecules. In this review article, we provide a comprehensive list of importin and exportin molecules and their specific cargo that shuttled between cytoplasm and the nucleus. We also critically review the role and regulation of specific importin and exportin involved in the transport of activated transcription factors in allergic diseases, the underlying molecular mechanisms, and the potential target sites for developing better therapeutic approaches.

Vitamin D supplementation reduces airway hyperresponsiveness and allergic airway inflammation in a murine model

BACKGROUND

Asthma is a chronic disease associated with airway hyperresponsiveness (AHR), airway obstruction and airway remodelling. NF-κB is a transcriptional factor that regulates and co-ordinates the expression of various inflammatory genes. The NF-κB subunits, p50 and Rel-A, are translocated to the nucleus by importin α3 and importin α4. There is growing evidence that vitamin D is a potent immunomodulator. However, the evidence for beneficial or adverse effects of vitamin D in asthma is still unclear.

OBJECTIVE

In this study, we examined the effect of vitamin D status on AHR, airway inflammation and cytokines in the bronchoalveolar lavage fluid (BALF) in a murine model of allergic asthma.

METHODS

Female BALB/c mice were fed with special vitamin D-deficient or vitamin D-sufficient (2000 IU/kg) or vitamin D-supplemented (10,000 IU/kg) diet for 13 weeks. Mice were sensitized and challenged with ovalbumin (OVA). The effect of vitamin D on lung histology, AHR, T regulatory cells (Tregs) and BALF cytokines was examined. The expression of importin-α3 and Rel-A in the lung of OVA-sensitized mice was analysed using immunofluorescence.

RESULTS

Vitamin D deficiency was associated with higher AHR in OVA-sensitized and challenged mice than those in vitamin D-sufficient mice. This was accompanied with marked signs of airway remodelling, high BALF eosinophilia, increased BALF pro-inflammatory cytokines, reduced BALF IL-10 levels, reduced blood Tregs, increased expression of importin-α3 and Rel-A in the lung tissue. Vitamin D supplementation attenuated the pro-inflammatory effects, but did not completely reverse the features of allergic airway inflammation.

CONCLUSION AND CLINICAL RELEVANCE

Vitamin D could be beneficial as an adjunct therapy in the treatment of allergic asthma.

Immunoproteomic to identify antigens in the intestinal mucosa of Crohn's disease patients

Incidences of Crohn disease (CD) have increased significantly in the last decade. Immunoproteomics are a promising method to identify biomarkers of different diseases. In the present study, we used immunoproteomics to study proteins of intestinal mucosal lesions and neighboring normal intestinal mucosa of 8 CD patients. Reactive proteins were validated by Western blotting. Approximately 50 protein spots localized in the 4 to 7 pI range were detected on two-dimensional electrophoresis gels, and 6 differentially expressed protein spots between 10 and 100 kDa were identified. Reactive proteins were identified as prohibitin, calreticulin, apolipoprotein A-I, intelectin-1, protein disulfide isomerase, and glutathione s-transferase Pi. Western blotting was conducted on the intestinal mucosa of another 4 CD patients to validate the reactive proteins. We found that intestinal mucosal lesions had high levels of prohibitin expression. Glutathione s-transferase expression was detected in 100% of the intestinal mucosa examined. Thus, we report 6 autoantigens of CD, including 3 new and 3 previously reported autoantigens. Intelectin-1, protein disulfide isomerase, and glutathione-s-transferases may be used as biomarkers for CD pathogenesis.

Inflammatory bowel disease: mechanisms, redox considerations, and therapeutic targets

Oxidative stress is thought to play a key role in the development of intestinal damage in inflammatory bowel disease (IBD), because of its primary involvement in intestinal cells' aberrant immune and inflammatory responses to dietary antigens and to the commensal bacteria. During the active disease phase, activated leukocytes generate not only a wide spectrum of pro-inflammatory cytokines, but also excess oxidative reactions, which markedly alter the redox equilibrium within the gut mucosa, and maintain inflammation by inducing redox-sensitive signaling pathways and transcription factors. Moreover, several inflammatory molecules generate further oxidation products, leading to a self-sustaining and auto-amplifying vicious circle, which eventually impairs the gut barrier. The current treatment of IBD consists of long-term conventional anti-inflammatory therapy and often leads to drug refractoriness or intolerance, limiting patients' quality of life. Immune modulators or anti-tumor necrosis factor α antibodies have recently been used, but all carry the risk of significant side effects and a poor treatment response. Recent developments in molecular medicine point to the possibility of treating the oxidative stress associated with IBD, by designing a proper supplementation of specific lipids to induce local production of anti-inflammatory derivatives, as well as by developing biological therapies that target selective molecules (i.e., nuclear factor-κB, NADPH oxidase, prohibitins, or inflammasomes) involved in redox signaling. The clinical significance of oxidative stress in IBD is now becoming clear, and may soon lead to important new therapeutic options to lessen intestinal damage in this disease.

Role of miR-181 family in regulating vascular inflammation and immunity

The microRNA family, miR-181, plays diverse roles in regulating key aspects of cellular growth, development, and activation. Accumulating evidence supports a central role for the miR-181 family in vascular inflammation by controlling critical signaling pathways, such as downstream NF-κB signaling, and targets relevant to endothelial cell activation and immune cell homeostasis. This review examines the current knowledge of the miR-181 family's role in key cell types that critically control cardiovascular inflammation under pathological and physiological stimuli.

Prohibitin ligands in cell death and survival: mode of action and therapeutic potential

Prohibitins (PHBs) are scaffold proteins that modulate many signaling pathways controlling cell survival, metabolism, and inflammation. Several drugs that target PHBs have been identified and evaluated for various clinical applications. Preclinical and clinical studies indicate that these PHB ligands may be useful in oncology, cardiology, and neurology, as well as against obesity. This review covers the physiological role of PHBs in health and diseases and current developments concerning PHB ligands.

Proteomic changes induced by histone demethylase JMJD3 in TNF alpha-treated human monocytic (THP-1) cells

JMJD3, a Jumonji C family histone demethylase, plays an important role in the regulation of inflammation induced by the transcription factor nuclear factor-kappa B (NF-κB) in response to various stimuli. JMJD3 is a histone-3 lysine-27 trimethylation (H3K27me3) demethylase, a histone mark associated with transcriptional repression and activation of a diverse set of genes. The present study assessed stable JMJD3 knockdown (KD)-dependent proteomic profiling in human leukemia monocyte (THP-1) cells to analyze the JMJD3-mediated differential changes of marker expression in inflammatory cells. To analyze the protein expression profile of tumor necrosis factor-alpha (TNF-α)-stimulated JMJD3-kd THP-1 cells, we employed matrix-assisted-laser-desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Additionally, Ingenuity Pathways Analysis (IPA) was applied to establish the molecular networks. A comparative proteomic profile was determined in TNF-α-treated both of JMJD3-kd THP-1 cells and THP-1 scrambled (sc) cells. The expression of tripartite motif protein (TRIM5), glutathione peroxidase (GPx), glia maturation factor-γ (GMFG), caspase recruitment domain family, member 14 (CARMA2), and dUTP pyrophosphatase were significantly down-regulated, whereas heat shock protein beta-1 (HspB1) and prohibition were significantly up-regulated in JMJD3-kd THP-1 cells. The molecular and signaling networks of the differentially expressed proteins in JMJD3-kd THP-1 cells were determined by IPA. The molecular network signatures and functional proteomics obtained in this study may facilitate the suppression of different key inflammatory regulators through JMJD3-attenuation, which would be crucial to evaluate potential therapeutic targets and to elucidate the molecular mechanism of JMJD3-kd dependent effects in THP-1 cells.

Nrf2 is not required for epithelial prohibitin-dependent attenuation of experimental colitis

Inflammatory bowel disease is associated with increased reactive oxygen species (ROS) and decreased antioxidant response in the intestinal mucosa. Expression of the mitochondrial protein prohibitin (PHB) is also decreased during intestinal inflammation. Our previous study showed that genetic restoration of colonic epithelial PHB expression [villin-PHB transgenic (PHB Tg) mice] attenuated dextran sodium sulfate (DSS)-induced colitis/oxidative stress and sustained expression of colonic nuclear factor erythroid 2-related factor 2 (Nrf2), a cytoprotective transcription factor. This study investigated the role of Nrf2 in mediating PHB-induced protection against colitis and expression of the antioxidant response element (ARE)-regulated antioxidant genes heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 (NQO-1). PHB-transfected Caco-2-BBE human intestinal epithelial cells maintained increased ARE activation and decreased intracellular ROS levels compared with control vector-transfected cells during Nrf2 knockdown by small interfering RNA. Treatment with the ERK inhibitor PD-98059 decreased PHB-induced ARE activation, suggesting that ERK constitutes a significant portion of PHB-mediated ARE activation in Caco-2-BBE cells. PHB Tg, Nrf2(-/-), and PHB Tg/Nrf2(-/-) mice were treated with DSS or 2,4,6-trinitrobenzene sulfonic acid (TNBS), and inflammation and expression of HO-1 and NQO-1 were assessed. PHB Tg/Nrf2(-/-) mice mimicked PHB Tg mice, with attenuated DSS- or TNBS-induced colitis and induction of colonic HO-1 and NQO-1 expression, despite deletion of Nrf2. PHB Tg/Nrf2(-/-) mice exhibited increased activation of ERK during colitis. Our results suggest that maintaining expression of intestinal epithelial cell PHB, which is decreased during colitis, reduces the severity of inflammation and increases colonic levels of the antioxidants HO-1 and NQO-1 via a mechanism independent of Nrf2.

Genetic polymorphisms of miR-146a and miR-27a, H. pylori infection, and risk of gastric lesions in a Chinese population

Background

MicroRNAs (miRNAs) have been implicated in various human diseases. Single nucleotide polymorphisms (SNPs) in inflammation-related miRNA may play an important role in Helicobacter pylori (H. pylori)-induced gastric lesions. To evaluate the associations between miRNA SNPs, H. pylori and gastric lesions, a population-based study was conducted in Linqu County, China.

Methodology/Principal Findings

Based on serum miRNA array conducted in this population, two SNP loci (miR-146a rs2910164: G>C and miR-27a rs895819: T>C) were determined by polymerase chain reaction-restriction fragment length polymorphism in 2,380 participants with diverse gastric lesions. Using participants with superficial gastritis and mild chronic atrophic gastritis as the reference group, we found that rs2910164 CC carriers had a significantly increased risk of intestinal metaplasia [adjusted odds ratio (OR), 1.42; 95% confidence interval (CI), 1.03–1.97] and dysplasia (OR, 1.54; 95% CI, 1.05–2.25) compared to GG carriers, whereas no significant association was observed for rs895819. Stratified analysis by H. pylori infection indicated that rs2910164 C allele was associated with an increased risk of intestinal metaplasia and dysplasia only among individuals infected with H. pylori (CC vs. GG: OR, 1.53; 95% CI, 1.12–2.08, P for trend = 0.004). Participants who simultaneously carried variant alleles and H. pylori infection were more likely to develop intestinal metaplasia and dysplasia, although the interaction between genetic variants and H. pylori infection was not significant (P for interaction = 0.35 for rs2910164 and 0.92 for rs895819).

Conclusions/Significance

These findings suggest that miR-146a rs2910164 polymorphism may contribute to the evolution of H. pylori-associated gastric lesions in this high-risk population.

Prohibitin attenuates colitis-associated tumorigenesis in mice by modulating p53 and STAT3 apoptotic responses

Although inflammatory bowel disease is associated with higher risk of colorectal cancer, the precise pathogenic mechanisms underlying this association are not completely understood. Prohibitin 1 (PHB), a protein implicated in the regulation of proliferation, apoptosis, and transcription, is decreased in intestinal inflammation. In this study, we have established a key function for PHB in mediating colitis-associated cancer. Wild-type and transgenic (Tg) mice specifically overexpressing PHB in intestinal epithelial cells were subjected to a classical two-stage protocol of colitis-associated carcinogenesis. In addition, wild-type and p53 null human cell models were used to assess PHB interaction with STAT3 and p53. Wild-type mice exhibited decreased mucosal PHB protein expression during colitis-associated carcinogenesis. Tg mice exhibited decreased susceptibility in a manner associated with increased apoptosis, p53, Bax, and Bad expression plus decreased Bcl-xL and Bcl-2 expression. PHB overexpression in wild-type but not p53 null human cells increased expression of Bax, Bad, and caspase-3 cleavage. In wild-type p53 cells, PHB overexpression decreased basal and interleukin-6-induced STAT3 activation and expression of the STAT3 responsive genes Bcl-xL and Bcl-2. PHB coimmunoprecipitated with phospho-STAT3 in addition to p53 in cultured cell lysates and colon mucosa. This is the first study to show interaction between PHB and STAT3 in vivo. In summary, our findings suggest that PHB protects against colitis-associated cancer by modulating p53- and STAT3-mediated apoptosis. Modulation of PHB expression in intestinal epithelial cells may offer a potential therapeutic approach to prevent colitis-associated carcinogenesis.

MicroRNA-181b regulates NF-κB-mediated vascular inflammation

EC activation and dysfunction have been linked to a variety of vascular inflammatory disease states. The function of microRNAs (miRNAs) in vascular EC activation and inflammation remains poorly understood. Herein, we report that microRNA-181b (miR-181b) serves as a potent regulator of downstream NF-κB signaling in the vascular endothelium by targeting importin-α3, a protein that is required for nuclear translocation of NF-κB. Overexpression of miR-181b inhibited importin-α3 expression and an enriched set of NF-κB-responsive genes such as adhesion molecules VCAM-1 and E-selectin in ECs in vitro and in vivo. In addition, treatment of mice with proinflammatory stimuli reduced miR-181b expression. Rescue of miR-181b levels by systemic administration of miR-181b "mimics" reduced downstream NF-κB signaling and leukocyte influx in the vascular endothelium and decreased lung injury and mortality in endotoxemic mice. In contrast, miR-181b inhibition exacerbated endotoxin-induced NF-κB activity, leukocyte influx, and lung injury. Finally, we observed that critically ill patients with sepsis had reduced levels of miR-181b compared with control intensive care unit (ICU) subjects. Collectively, these findings demonstrate that miR-181b regulates NF-κB-mediated EC activation and vascular inflammation in response to proinflammatory stimuli and that rescue of miR-181b expression could provide a new target for antiinflammatory therapy and critical illness.

Calcitriol decreases expression of importin α3 and attenuates RelA translocation in human bronchial smooth muscle cells

PURPOSE

A potent immunomodulatory role of Vitamin D in both innate and adaptive immunity has recently been appreciated. In allergic asthma, activation of NF-кB induces transcription of various cytokines and chemokines involved in allergic airway inflammation. The nuclear import of activated NF-кB p50/RelA subunit is dependent on importin α3 (KPNA4) and importin α4 (KPNA3). In this study, we examined the role of importin α3 in immunomodulatory effect of calcitriol in human bronchial smooth muscle cells (HBSMCs).

METHODS

Cultured HBSMCs were stimulated with calcitriol in the presence and absence of cytokines, TNF-α, IL-1β, and IL-10. The mRNA transcripts of importin α3 and α4 were analyzed using qPCR while protein expression of importin α3, α4 and nuclear RelA was analyzed by immunoblotting.

RESULTS

Calcitriol significantly decreased mRNA and protein expression of importin α3 as well as nuclear protein expression of NF-кB p65 (RelA). The decreased activation of RelA by calcitriol was confirmed by decreased release of RelA-inducible molecules, including IL-5, IL-6 and IL-8, by HBSMCs upon calcitriol treatment. Calcitriol attenuated the effect of TNF-α and IL-1β to upregulate mRNA and protein expression of importin α3. IL-10 significantly decreased the TNF-α induced expression of importin α3 and this effect was further potentiated by calcitriol.

CONCLUSIONS

These data suggest that under inflammatory conditions, calcitriol decreases the expression of importin α3 resulting in decreased nuclear import of activated RelA. This could be a novel mechanism by which calcitriol could exert its immunomodulatory effects to reduce allergic airway inflammation and thus may alleviate the symptoms in allergic asthma.

Vitamin D deficiency decreases the expression of VDR and prohibitin in the lungs of mice with allergic airway inflammation

AIMS

Asthma is one of the most common chronic inflammatory diseases of the airways. Calcitriol exerts its action through Vitamin D receptor (VDR), which is a high affinity nuclear receptor. VDR is a transcription factor that alters the transcription of target genes which are involved in a wide spectrum of biological responses. Lower serum vitamin D levels are associated with airway hyperresponsiveness and increased asthma severity. Prohibitin is a ubiquitously expressed protein localized to the cell and mitochondrial membranes and the nucleus.

METHODS AND RESULTS

HBSMCs were cultured and treated with calcitriol and/or TNF-α. The mRNA and protein expression of prohibitin and VDR were analyzed using qPCR and immunoblotting, respectively. In the in vivo studies, female BALB/c mice were fed with special vitamin D-deficient or 2000IU/kg of vitamin D-supplemented diet for 13weeks. Mouse model of allergic airway inflammation was developed by OVA-sensitization and challenge. The expression pattern of TNF-α, prohibitin and VDR in the lung of OVA-sensitized mice was analyzed using immunofluorescence. Calcitriol significantly increased and TNF-α decreased the protein and mRNA expression of prohibitin and VDR in HBSMCs. There was significantly increased expression of TNF-α and decreased expression of VDR and prohibitin in the lung of vitamin D-deficient mouse model of allergic airway inflammation.

CONCLUSION

These results suggest that under inflammatory conditions there is decreased expression of VDR resulting in decreased expression of prohibitin, which is a vitamin D target gene. Vitamin D deficiency causes increase in the expression of TNF-α, thereby increasing inflammation and decreases the expression of VDR and prohibitin. Supplementation with vitamin D might reduce the levels of TNF-α, thereby increasing the expression of VDR and prohibitin that could be responsible for reducing allergic airway inflammation.

Prohibitin 1 modulates mitochondrial stress-related autophagy in human colonic epithelial cells

Introduction

Autophagy is an adaptive response to extracellular and intracellular stress by which cytoplasmic components and organelles, including damaged mitochondria, are degraded to promote cell survival and restore cell homeostasis. Certain genes involved in autophagy confer susceptibility to Crohn's disease. Reactive oxygen species and pro-inflammatory cytokines such as tumor necrosis factor α (TNFα), both of which are increased during active inflammatory bowel disease, promote cellular injury and autophagy via mitochondrial damage. Prohibitin (PHB), which plays a role in maintaining normal mitochondrial respiratory function, is decreased during active inflammatory bowel disease. Restoration of colonic epithelial PHB expression protects mice from experimental colitis and combats oxidative stress. In this study, we investigated the potential role of PHB in modulating mitochondrial stress-related autophagy in intestinal epithelial cells.

Methods

We measured autophagy activation in response to knockdown of PHB expression by RNA interference in Caco2-BBE and HCT116 WT and p53 null cells. The effect of exogenous PHB expression on TNFα- and IFNγ-induced autophagy was assessed. Autophagy was inhibited using Bafilomycin A₁ or siATG16L1 during PHB knockdown and the affect on intracellular oxidative stress, mitochondrial membrane potential, and cell viability were determined. The requirement of intracellular ROS in siPHB-induced autophagy was assessed using the ROS scavenger N-acetyl-L-cysteine.

Results

TNFα and IFNγ-induced autophagy inversely correlated with PHB protein expression. Exogenous PHB expression reduced basal autophagy and TNFα-induced autophagy. Gene silencing of PHB in epithelial cells induces mitochondrial autophagy via increased intracellular ROS. Inhibition of autophagy during PHB knockdown exacerbates mitochondrial depolarization and reduces cell viability.

Conclusions

Decreased PHB levels coupled with dysfunctional autophagy renders intestinal epithelial cells susceptible to mitochondrial damage and cytotoxicity. Repletion of PHB may represent a therapeutic approach to combat oxidant and cytokine-induced mitochondrial damage in diseases such as inflammatory bowel disease.