Trimerization profile of type IV collagen COL4A5 exon deletion in X-linked Alport syndrome

BACKGROUND

Alport syndrome (AS) is a genetic kidney disease caused by a mutation in type IV collagen α3, α4, and α5, which are normally secreted as heterotrimer α345(IV). Nonsense mutation in these genes causes severe AS phenotype. We previously revealed that the exon-skipping approach to remove a nonsense mutation in α5(IV) ameliorated the AS pathology. However, the effect of removing an exon on trimerization is unknown. Here, we assessed the impact of exon deletion on trimerization to evaluate their possible therapeutic applicability and to predict the severity of mutations associated with exon-skipping.

METHODS

We produced exon deletion constructs (ΔExon), nonsense, and missense mutants by mutagenesis and evaluated their trimer formation and secretion activities using a nanoluciferase-based assay that we previously developed.

RESULTS

Exon-skipping had differential effects on the trimer secretion of α345(IV). Some ΔExons could form and secrete α345(IV) trimers and had higher activity compared with nonsense mutants. Other ΔExons had low secretion activity, especially for those with exon deletion near the C-terminal end although the intracellular trimerization was normal. No difference was noted in the secretion of missense mutants and their ΔExon counterpart.

CONCLUSION

Exon skipping is advantageous for nonsense mutants in AS with severe phenotypes and early onset of renal failure but applications may be limited to ΔExons capable of normal trimerization and secretion. This study provides information on α5(IV) exon-skipping for possible therapeutic application and the prediction of the trimer behavior associated with exon-skipping in Alport syndrome.

T3 Intratracheal Therapy Alleviates Pulmonary Pathology in an Elastase-Induced Emphysema-Dominant COPD Mouse Model

Chronic obstructive pulmonary disease (COPD) is a complex pulmonary condition characterized by bronchitis, emphysema, and mucus stasis. Due to the variability in symptoms among patients, traditional approaches to treating COPD as a singular disease are limited. This led us to focus on phenotype/endotype classifications. In this study, we explore the potential therapeutic role of thyroid hormone (T3) by using mouse models: emphysema-dominant elastase-induced COPD and airway-dominant C57BL/6-βENaC-Tg to represent different types of the disease. Here, we showed that intratracheal T3 treatment (40, 80 μg/kg, i.t., every other day) resulted in significant improvements regarding emphysema and the enhancement of respiratory function in the elastase-induced COPD model. T3-dependent improvement is likely linked to the up-regulation of Ppargc1a, a master regulator of mitochondrial biogenesis, and Gclm, a factor associated with oxidative stress. Conversely, neither short- nor long-term T3 treatments improved COPD pathology in the C57BL/6-βENaC-Tg mice. Because the up-regulation of extrathyroidal T3-producing enzyme Dio2, which is also considered a marker of T3 requirement, was specifically observed in elastase-induced COPD lungs, these results demonstrate that exogenous T3 supplementation may have therapeutic potential for acute but not chronic COPD exacerbation. Moreover, this study highlights the relevance of considering not only COPD phenotypes but also COPD endotypes (expression levels of Ppargc1a and/or Dio2) in the research and development of better treatment approaches for COPD.

CyclosporinA Derivative as Therapeutic Candidate for Alport Syndrome by Inducing Mutant Type IV Collagen Secretion

Key Points

Screening of natural product extracts to find candidate compounds that increase mutant type IV collagen α 3,4,5 (α 345(IV)) trimer secretion in Alport syndrome (AS). Cyclosporin A (CsA) and alisporivir (ALV) increase mutant α 345(IV) trimer secretion in AS. PPIF/cyclophilin D mediates the effect of CsA and ALV on mutant trimer secretion.

Background

Type IV collagen α 3,4,5 (α 345(IV)) is an obligate trimer that is secreted to form a collagen network, which is the structural foundation of basement membrane. Mutation in one of the genes (COL4A3 , A4 , A5 ) encoding these proteins underlies the progressive genetic nephropathy Alport syndrome (AS) due to deficiency in trimerization and/or secretion of the α 345(IV) trimer. Thus, improving mutant α 345(IV) trimerization and secretion could be a good therapeutic approach for AS.

Methods

Using the nanoluciferase-based platform that we previously developed to detect α 345(IV) formation and secretion in HEK293T cells, we screened libraries of natural product extracts and compounds to find a candidate compound capable of increasing mutant α 345(IV) secretion.

Results

The screening of >13,000 extracts and >600 compounds revealed that cyclosporin A (CsA) increased the secretion of mutant α 345(IV)-G1244D. To elucidate the mechanism of the effect of CsA, we evaluated CsA derivatives with different ability to bind to calcineurin (Cn) and cyclophilin (Cyp). Alisporivir (ALV), which binds to Cyp but not to Cn, increased the trimer secretion of mutant α 345(IV). Knockdown studies on Cyps showed that PPIF/cyclophilin D was involved in the trimer secretion-enhancing activity of CsA and ALV. We confirmed that other α 345(IV) mutants are also responsive to CsA and ALV.

Conclusions

CsA was previously reported to improve proteinuria in patients with AS, but owing to its nephrotoxic effect, CsA is not recommended for treatment in patients with AS. Our data raise the possibility that ALV could be a safer option than CsA. This study provides a novel therapeutic candidate for AS with an innovative mechanism of action and reveals an aspect of the intracellular regulatory mechanism of α 345(IV) that was previously unexplored.

Novel Keap1-Nrf2 Protein-Protein Interaction Inhibitor UBE-1099 Ameliorates Progressive Phenotype in Alport Syndrome Mouse Model

BACKGROUND

Bardoxolone methyl activates nuclear factor erythroid 2-related factor 2 (Nrf2) via covalent binding and irreversible inhibition of Kelch-like ECH-associated protein 1 (Keap1), the negative regulator of Nrf2. Ongoing clinical trials of bardoxolone methyl show promising effects for patients with CKD. However, the direct inhibition of Keap1-Nrf2 protein-protein interaction (PPI) as an approach to activate Nrf2 is less explored.

METHODS

We developed a noncovalent Nrf2 activator UBE-1099, which highly selectively inhibits Keap1-Nrf2 PPI, and evaluated its efficacy on the progressive phenotype in an Alport syndrome mouse model (Col4a5-G5X).

RESULTS

Similar to bardoxolone methyl, UBE-1099 transiently increased proteinuria and reduced plasma creatinine in Alport mice. Importantly, UBE-1099 improved the glomerulosclerosis, renal inflammation, and fibrosis, and prolonged the life span of Alport mice. UBE-1099 ameliorated the dysfunction of Nrf2 signaling in the renal tissue of Alport mice. Moreover, transcriptome analysis in the glomerulus showed that UBE-1099 induced the expression of genes associated with the cell cycle and cytoskeleton, which may explain its unique mechanism of improvement such as glomerular morphologic change.

CONCLUSIONS

UBE-1099 significantly ameliorates the progressive phenotype in Alport mice. Our results revealed the efficacy of Keap1-Nrf2 PPI inhibitor for glomerulosclerosis and present a potential therapeutic drug for CKD.

Seamless Gene Correction in the Human Cystic Fibrosis Transmembrane Conductance Regulator Locus by Vector Replacement and Vector Insertion Events

Background: Gene correction via homology directed repair (HDR) in patient-derived induced pluripotent stem (iPS) cells for regenerative medicine are becoming a more realistic approach to develop personalized and mutation-specific therapeutic strategies due to current developments in gene editing and iPSC technology. Cystic fibrosis (CF) is the most common inherited disease in the Caucasian population, caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Since CF causes significant multi-organ damage and with over 2,000 reported CFTR mutations, CF patients could be one prominent population benefiting from gene and cell therapies. When considering gene-editing techniques for clinical applications, seamless gene corrections of the responsible mutations, restoring native "wildtype" DNA sequence without remnants of drug selectable markers or unwanted DNA sequence changes, would be the most desirable approach. Result: The studies reported here describe the seamless correction of the W1282X CFTR mutation using CRISPR/Cas9 nickases (Cas9n) in iPS cells derived from a CF patient homozygous for the W1282X Class I CFTR mutation. In addition to the expected HDR vector replacement product, we discovered another class of HDR products resulting from vector insertion events that created partial duplications of the CFTR exon 23 region. These vector insertion events were removed via intrachromosomal homologous recombination (IHR) enhanced by double nicking with CRISPR/Cas9n which resulted in the seamless correction of CFTR exon 23 in CF-iPS cells. Conclusion: We show here the removal of the drug resistance cassette and generation of seamless gene corrected cell lines by two independent processes: by treatment with the PiggyBac (PB) transposase in vector replacements or by IHR between the tandemly duplicated CFTR gene sequences.

The role of discoidin domain receptor 2 in the renal dysfunction of alport syndrome mouse model

Alport syndrome (AS) is a hereditary glomerular nephritis caused by mutation in one of the type IV collagen genes α3/α4/α5 that encode the heterotrimer COL4A3/4/5. Failure to form a heterotrimer due to mutation leads to the dysfunction of the glomerular basement membrane, and end-stage renal disease. Previous reports have suggested the involvement of the receptor tyrosine kinase discoidin domain receptor (DDR) 1 in the progression of AS pathology. However, due to the similarity between DDR1 and DDR2, the role of DDR2 in AS pathology is unclear. Here, we investigated the involvement of DDR2 in AS using the X-linked AS mouse model. Mice were treated subcutaneously with saline or antisense oligonucleotide (ASO; 5 mg/kg or 15 mg/kg per week) for 8 weeks. Renal function parameters and renal histology were analyzed, and the gene expressions of inflammatory cytokines were determined in renal tissues. The expression level of DDR2 was highly elevated in kidney tissues of AS mice. Knockdown of Ddr2 using Ddr2-specific ASO decreased the Ddr2 expression. However, the DDR2 ASO treatment did not improve the proteinuria or decrease the BUN level. DDR2 ASO also did not significantly ameliorate the renal injury, inflammation and fibrosis in AS mice. These results showed that Ddr2 knockdown by ASO had no notable effect on the progression of AS indicating that DDR2 may not be critically involved in AS pathology. This finding may provide useful information and further understanding of the role of DDRs in AS.

Activation of heat shock response improves biomarkers of NAFLD in patients with metabolic diseases

Nonalcoholic fatty liver disease (NAFLD) is often accompanied by metabolic disorders such as metabolic syndrome and type 2 diabetes (T2DM). Heat shock response (HSR) is one of the most important homeostatic abilities but is deteriorated by chronic metabolic insults. Heat shock (HS) with an appropriate mild electrical stimulation (MES) activates HSR and improves metabolic abnormalities including insulin resistance, hyperglycemia and inflammation in metabolic disorders. To analyze the effects of HS + MES treatment on NAFLD biomarkers, three cohorts including healthy men (two times/week, n = 10), patients with metabolic syndrome (four times/week, n = 40), and patients with T2DM (n = 100; four times/week (n = 40) and two, four, seven times/week (n = 20 each)) treated with HS + MES were retrospectively analyzed. The healthy subjects showed no significant alterations in NAFLD biomarkers after the treatment. In patients with metabolic syndrome, many of the NAFLD steatosis markers, including fatty liver index, NAFLD-liver fat score, liver/spleen ratio and hepatic steatosis index and NAFLD fibrosis marker, aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, were improved upon the treatment. In patients with T2DM, all investigated NAFLD steatosis markers were improved and NAFLD fibrosis markers such as the AST/ALT ratio, fibrosis-4 index and NAFLD-fibrosis score were improved upon the treatment. Thus, HS + MES, a physical intervention, may become a novel treatment strategy for NAFLD as well as metabolic disorders.

Type IV Collagen Variants in CKD: Performance of Computational Predictions for Identifying Pathogenic Variants

Rationale & Objective

Pathogenic variants in type IV collagen have been reported to account for a significant proportion of chronic kidney disease. Accordingly, genetic testing is increasingly used to diagnose kidney diseases, but testing also may reveal rare missense variants that are of uncertain clinical significance. To aid in interpretation, computational prediction (called in silico) programs may be used to predict whether a variant is clinically important. We evaluate the performance of in silico programs for COL4A3/A4/A5 variants.

Study Design, Setting, & Participants

Rare missense variants in COL4A3/A4/A5 were identified in disease cohorts, including a local focal segmental glomerulosclerosis (FSGS) cohort and publicly available disease databases, in which they are categorized as pathogenic or benign based on clinical criteria.

Tests Compared & Outcomes

All rare missense variants identified in the 4 disease cohorts were subjected to in silico predictions using 12 different programs. Comparisons between the predictions were compared with: (1) variant classification (pathogenic or benign) in the cohorts and (2) functional characterization in a randomly selected smaller number (17) of pathogenic or uncertain significance variants obtained from the local FSGS cohort.

Results

In silico predictions correctly classified 75% to 97% of pathogenic and 57% to 100% of benign COL4A3/A4/A5 variants in public disease databases. The congruency of in silico predictions was similar for variants categorized as pathogenic and benign, with the exception of benign COL4A5 variants, in which disease effects were overestimated. By contrast, in silico predictions and functional characterization classified all 9 pathogenic COL4A3/A4/A5 variants correctly that were obtained from a local FSGS cohort. However, these programs also overestimated the effects of genomic variants of uncertain significance when compared with functional characterization. Each of the 12 in silico programs used yielded similar results.

Limitations

Overestimation of in silico program sensitivity given that they may have been used in the categorization of variants labeled as pathogenic in disease repositories.

Conclusions

Our results suggest that in silico predictions are sensitive but not specific to assign COL4A3/A4/A5 variant pathogenicity, with misclassification of benign variants and variants of uncertain significance. Thus, we do not recommend in silico programs but instead recommend pursuing more objective levels of evidence suggested by medical genetics guidelines.

Intrapopulation analysis of longitudinal lifespan in Caenorhabditis elegans identifies W09D10.4 as a novel AMPK-associated healthspan shortening factor

Caenorhabditis elegans is a model organism widely used for longevity studies. Current advances have been made in the methods that allow automated monitoring of C. elegans behavior. However, ordinary manual assays as well as automated methods have yet to achieve qualitative whole-life analysis of C. elegans longevity based on intrapopulation variation. Here, we utilized live-cell analysis system to determine the parameters of nematode lifespans. Image-based superposition method enabled to determine not only frailty in worms, but also to measure individual and longitudinal lifespan, healthspan, and frailspan. Notably, k-means clustering via principal component analysis revealed four clusters with distinct longevity patterns in wild-type C. elegans. Physiological relevance of clustering was confirmed by assays with pharmacological and/or genetic manipulation of AMP-activated protein kinase (AMPK), a crucial regulator of healthspan. Finally, we focused on W09D10.4 among the possible regulators extracted by integrative expression analysis with existing data sets. Importantly, W09D10.4 knockdown increased the high-healthspan populations only in the presence of AMPK, suggesting that W09D10.4 is a novel AMPK-associated healthspan shortening factor in C. elegans. Overall, the study establishes a novel platform of longitudinal lifespan in C. elegans, which is user-friendly, and may be a useful pharmacological tool to identify healthspan modulatory factors.

Higher Blood Uric Acid in Female Humans and Mice as a Protective Factor against Pathophysiological Decline of Lung Function

The oxidant/antioxidant imbalance plays a pivotal role in the lung. Uric acid (UA), an endogenous antioxidant, is highly present in lung tissue, however, its impact on lung function under pathophysiological conditions remains unknown. In this work, pharmacological and genetic inhibition of UA metabolism in experimental mouse models of acute and chronic obstructive pulmonary disease (COPD) revealed that increased plasma UA levels improved emphysematous phenotype and lung dysfunction in accordance with reduced oxidative stress specifically in female but not in male mice, despite no impact of plasma UA induction on the pulmonary phenotypes in nondiseased mice. In vitro experiments determined that UA significantly suppressed hydrogen peroxide (H₂O₂)-induced oxidative stress in female donor-derived primary human bronchial epithelial (NHBE) cells in the absence of estrogen, implying that the benefit of UA is limited to the female airway in postmenopausal conditions. Consistently, our clinical observational analyses confirmed that higher blood UA levels, as well as the SLC2A9/GLUT9 rs11722228 T/T genotype, were associated with higher lung function in elderly human females. Together, our findings provide the first unique evidence that higher blood UA is a protective factor against the pathological decline of lung function in female mice, and possibly against aging-associated physiological decline in human females.

Melinjo seed extract increases adiponectin multimerization in physiological and pathological conditions

Melinjo seed extract (MSE) contains large amounts of polyphenols, including dimers of trans-resveratrol (e.g. gnetin C, L, gnemonoside A, B and D), and has been shown to potentially improve obesity. However, there is no clinical evidence regarding the anti-obesity effects of MSE, and its mechanisms are also unclear. We investigated the hypothesis that MSE supplementation increases the adiponectin (APN) multimerization via the up-regulation of disulfide bond A oxidoreductase-like protein (DsbA-L) under either or both physiological and obese conditions. To investigate the effect of MSE on the physiological condition, 42 healthy young volunteers were enrolled in a randomized, double-blind placebo-controlled clinical trial for 14 days. The participants were randomly assigned to the MSE 150 mg/day, MSE 300 mg/day or placebo groups. Furthermore, in order to investigate the effect of MSE on APN levels under obese conditions, we administered MSE powder (500 or 1000 mg/kg/day) to control-diet- or high-fat-diet (HFD)-fed C57BL/6 mice for 4 weeks. All participants completed the clinical trial. The administration of MSE 300 mg/day was associated with an increase in the ratio of HMW/total APN in relation to the genes regulating APN multimerization, including DsbA-L. Furthermore, this effect of MSE was more pronounced in carriers of the DsbA-L rs191776 G/T or T/T genotype than in others. In addition, the administration of MSE to HFD mice suppressed their metabolic abnormalities (i.e. weight gain, increased blood glucose level and fat mass accumulation) and increased the levels of total and HMW APN in serum and the mRNA levels of ADIPOQ and DsbA-L in adipose tissue. The present study suggests that MSE may exert beneficial effects via APN multimerization in relation to the induction of DsbA-L under both physiological and obese conditions.

Azithromycin Inhibits Constitutive Airway Epithelial Sodium Channel Activation in Vitro and Modulates Downstream Pathogenesis in Vivo

Epithelial sodium channel (ENaC) is an amiloride-sensitive sodium ion channel that is expressed in epithelial tissues. ENaC overexpression and/or hyperactivation in airway epithelial cells cause sodium over-absorption and dysregulated ciliary movement for mucus clearance; however, the agents that suppress constitutive airway ENaC activation are yet to be clinically available. Here, we focused on macrolides, which are widely used antibiotics that have many potential immunomodulatory effects. We examined whether macrolides could modulate constitutive ENaC activity and downstream events that typify cystic fibrosis (CF) and chronic obstructive pulmonary diseases (COPD) in in vitro and in vivo models of ENaC overexpression. Treatment of ENaC-overexpressing human bronchial epithelial cells (β/γENaC-16HBE14o- cells) with three macrolides (erythromycin, clarithromycin, azithromycin) confirmed dose-dependent suppression of ENaC function. For in vivo studies, mice harboring airway specific βENaC overexpression (C57BL/6J-βENaC-transgenic mice) were treated orally with azithromycin, a well-established antimicrobial agent that has been widely prescribed. Azithromycin treatment modulated pulmonary mechanics, emphysematous phenotype and pulmonary dysfunction. Notably, a lower dose (3 mg kg^-1) of azithromycin significantly increased forced expiratory volume in 0.1 s (FEV0.1), an inverse indicator of bronchoconstriction. Although not statistically significant, improvement of pulmonary obstructive parameters such as emphysema and lung dysfunction (FEV0.1%) was observed. Our results demonstrate that macrolides directly attenuate constitutive ENaC function in vitro and may be promising for the treatment of obstructive lung diseases with defective mucociliary clearance, possibly by targeting ENaC hyperactivation.

Intratracheal GLP-1 receptor agonist treatment up-regulates mucin via p38 and exacerbates emphysematous phenotype in mucus hypersecretory obstructive lung diseases

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone that stimulates glucose-mediated insulin production by pancreatic beta cells. It is also associated with protective effects in multiple tissues. GLP-1 receptor is highly expressed in pulmonary tissue, hinting possible pulmonary delivery of GLP-1 drugs. However, little is known about the role of GLP-1 signaling in the lung, especially in mucus hypersecretory obstructive lung diseases. Here, we showed that treatment with exendin-4, a clinically available GLP-1 receptor agonist, up-regulates mucin expression in normal airway epithelial cells and in the lung of normal mice, indicating mucus stimulatory effect of GLP-1 under physiological condition. Exendin-4 also increased mucin expression in in vitro cellular and in vivo murine models of obstructive lung diseases via the activation of p38 MAP kinase. Notably, mucin induction in vivo exacerbated key pulmonary abnormalities including emphysematous phenotypes, implying that GLP-1 signaling in the lung is detrimental under pulmonary obstructive condition. Another GLP-1 receptor agonist liraglutide had similar induction of mucin. Together, our studies not only demonstrate novel physiological and pathological roles of GLP-1 in the lung but may also caution against the clinical use of inhaled GLP-1 receptor agonists in the patients with obstructive lung diseases.

Auto-measure emphysematous parameters and pathophysiological gene expression profiles in experimental mouse models of acute and chronic obstructive pulmonary diseases

Pulmonary emphysema, inflammation and senescence-like phenotype are pathophysiological characteristics of chronic obstructive pulmonary disease (COPD). Recently, a murine model of COPD has been established by inducing airway-specific overexpression of epithelial Na⁺ channel β subunit (βENaC-Tg mice). However, little is known about the histological and biochemical differences between βENaC-Tg mice and an existing acute emphysematous mouse model (elastase-induced model). Here, we first utilized whole lung image-based quantification method for histological analysis to determine auto-measure parameters, including alveolar area, alveolar perimeter, (major axis + minor axis)/2 and Feret diameter. Even though the extent of emphysema was similar in both models, the coefficient of variation (CV) of all histological parameters was smaller in βENaC-Tg mice, indicating that βENaC-Tg mice show homogeneous emphysema as compared with elastase-induced acute model. Expression analysis of lung tissue RNAs further revealed that elastase-induced model exhibits transient changes of inflammation markers (Kc, Il-6, Lcn2) and senescence-related markers (Sirt1, p21) at emphysema-initiation stage (1 day), which does not last until emphysema-manifestation stage (3 weeks); while the up-regulation is stable at emphysema-manifestation stage in βENaC-Tg mice (14-week old). Thus, these studies demonstrate that βENaC-Tg mice exhibit diffuse-type emphysema with stable expression of inflammatory and senescence-like markers.

Transthyretin Amyloid Fibril Disrupting Activities of Extracts and Fractions from Juglans mandshurica Maxim. var. cordiformis (Makino) Kitam

Transthyretin-related amyloidosis is a slowly progressive disorder caused by deposition of insoluble amyloid plaques formed by fibrillization of mutant or defective transthyretin (TTR) monomers that leads to neurodegeneration and organ failure. Thus, any compound exhibiting TTR amyloid formation inhibitory activity or TTR amyloid fibril disrupting activity might be a potential candidate for the development of therapies for these disorders. Our aim in this study was the evaluation of the TTR amyloid fibril disrupting potential of extracts of leaves and immature fruits of two Juglans plants, i.e., Juglans mandshurica var. sachalinensis and Juglans mandshurica var. cordiformis. The TTR amyloid fibril disrupting activity was measured by Thioflavin-T (ThT) assay and PROTEOSTAT^® Protein aggregation assay methods. A fifty percent acetone extract of the fruits of Juglans mandshurica var. cordiformis showed strong amyloid fibril disrupting activity, and was further fractionated using different solvents. Ethyl acetate and n-butanol fractions showed significant activity in both assays. Syringic acid was isolated and identified as main compound in both of these fractions; however, it did not show any activity. Furthermore, some of the previously reported compounds from Juglans plants including naphthoquinone derivatives and phenolic compounds were evaluated to identify the potential bioactive compounds. Among them, juglone, a naphthoquinone derivative showed promising activity. However, juglone also showed strong cytotoxicity in HEK293 cells. Thus, future studies should focus on the isolation and identification of naphthoquinone derivatives or other compounds from Juglans plan ts with potent bioactivity and low cytotoxicity.

Curcumin Down-Regulates Toll-Like Receptor-2 Gene Expression and Function in Human Cystic Fibrosis Bronchial Epithelial Cells

Cystic fibrosis (CF), the most common lethal inherited disorder caused by mutation in the gene encoding the CF transmembrane regulator (CFTR), is characterized by chronic inflammation that ultimately leads to death from respiratory failure. In CF patients, up-regulation of toll-like receptor-2 (TLR2), a pattern recognition receptor that senses CF-pathogenic bacteria Staphylococcus aureus peptidoglycan (PGN), in airway epithelial cells is observed, and enhanced proinflammatory responses towards PGN may result in detrimental effects in CF patients. Here, we showed that curcumin, a well known anti-inflammatory agent derived from the curry spice turmeric, inhibits TLR2 expression in CF bronchial epithelial cell line, CFBE41o- cells. Strong suppression of TLR2 gene and protein expression was observed at more than 40 µM of curcumin treatment in CFBE41o- cells. Consistent with decreased expression of TLR2, PGN-dependent interleukin-8 (IL-8) gene up-regulation was markedly reduced by 40 µM of curcumin treatment. Strong reductions of TLR2 gene expression and function were also observed in primary human CF bronchial epithelial cells, but not in human non-CF primary cells. Interestingly, curcumin treatment decreased nuclear expression of transcription factor specificity protein 1 (SP1), a factor that is critical for increased basal TLR2 expression in CF cell line and primary cells. Finally, curcumin-dependent SP1 reduction was diminished by anti-oxidant N-acetylcystein (NAC) and proteasomal inhibitor MG-132, suggesting the crucial roles of oxidative and proteasomal degradation pathways. Taken together, our study shows that curcumin down-regulates TLR2 gene expression and function in CF bronchial epithelial cells possibly by accelerating SP1 degradation via an oxidative process.

Integrative expression analysis identifies a novel interplay between CFTR and linc-SUMF1-2 that involves CF-associated gene dysregulation

Cystic fibrosis transmembrane regulator (CFTR) is a cyclic AMP-dependent Cl^- channel, and its dysfunction, due to CFTR gene mutations, causes the lethal inherited disorder cystic fibrosis (CF). To date, widespread dysregulation of certain coding genes in CF airway epithelial cells is well studied and considered as the driver of pulmonary abnormality. However, the involvement of non-coding genes, novel classes of functional RNAs with little or no protein-coding capacity, in the regulation of CF-associated gene dysregulation is poorly understood. Here, we utilized integrative analyses of human transcriptome array (HTA) and characterized 99 coding and 91 non-coding RNAs that are dysregulated in CFTR-defective CF bronchial epithelial cell line CFBE41o-. Among these genes, the expression level of linc-SUMF1-2, an intergenic non-coding RNA (lincRNA) whose function is unknown, was inversely correlated with that of WT-CFTR and consistently higher in primary human CF airway epithelial cells (DHBE-CF). Further integrative analyses under linc-SUMF1-knockdown condition determined MXRA5, SEMA5A, CXCL10, AK022877, CTGF, MYC, AREG and LAMB3 as both CFTR- and linc-SUMF1-2-dependent dysregulated gene sets in CF airway epithelial cells. Overall, our analyses reveal linc-SUMF1-2 as a dysregulated non-coding gene in CF as well as CFTR-linc-SUMF1-2 axis as a novel regulatory pathway involved in CF-associated gene dysregulation.

Mild electrical stimulation with heat shock reduces inflammatory symptoms in the imiquimod-induced psoriasis mouse model

Psoriasis is a chronic skin disease caused by immune disorder. The chronic skin inflammation involves inflammatory molecules that are released from T lymphocytes and keratinocytes. Therefore, developing an anti-inflammatory therapy that is suitable for long-term treatment is needed. Electrical stimulation induces biological responses by modulating intracellular signaling pathways. Our previous studies showed that the optimized combination treatment of mild electrical stimulation (MES, 0.1-millisecond; ms, 55-pulses per second; pps) and heat shock (HS, 42°C) modulates inflammatory symptoms of metabolic disorders and chronic kidney disease in mice models and clinical trials. Here, we investigated the effect of MES+HS treatment on imiquimod-induced psoriasis mouse model. Topical application of imiquimod cream (15 mg) to mice ear induced keratinocyte hyperproliferation and psoriasis-like inflammation. In MES+HS-treated mice, imiquimod-induced skin hyperplasia was significantly decreased. MES+HS treatment reduced the protein expression of IL-17A and the infiltration of CD3-positive cells in lesioned skin. In addition, MES+HS-treated mice had decreased mRNA expression level of antimicrobial molecules (S100A8 and Reg3γ) which aggravate psoriasis. In IL-17A-stimulated HaCaT cells, MES+HS treatment significantly lowered the mRNA expression of aggravation markers (S100A8, S100A9 and β-defensin2). Taken together, our study suggested that MES+HS treatment improves the pathology of psoriasis via decreasing the expression of inflammatory molecules.

Roles and regulations of the ETS transcription factor ELF4/MEF

Most E26 transformation-specific (ETS) transcription factors are involved in the pathogenesis and progression of cancer. This is in part due to the roles of ETS transcription factors in basic biological processes such as growth, proliferation, and differentiation, and also because of their regulatory functions that have physiological relevance in tumorigenesis, immunity, and basal cellular homoeostasis. A member of the E74-like factor (ELF) subfamily of the ETS transcription factor family—myeloid elf-1-like factor (MEF), designated as ELF4—has been shown to be critically involved in immune response and signalling, osteogenesis, adipogenesis, cancer, and stem cell quiescence. ELF4 carries out these functions as a transcriptional activator or through interactions with its partner proteins. Mutations in ELF4 cause aberrant interactions and induce downstream processes that may lead to diseased cells. Knowing how ELF4 impinges on certain cellular processes and how it is regulated in the cells can lead to a better understanding of the physiological and pathological consequences of modulated ELF4 activity.

Transcriptional regulation of HIV-1 host factor COMMD1 by the Sp family

Copper metabolism Murr1 domain containing 1 (COMMD1) has multiple functions in the regulation of protein stability at the plasma membrane and in the cytoplasm. However, the regulation of COMMD1 transcriptional has remained to be elucidated. In the present study, the 5'‑flanking region (‑1,192/+83 bp) of the human COMMD1 gene was cloned. It was observed that the COMMD1 promoter region contains GC‑rich region that has 7 putative Sp1‑binding sites via in silico analysis. The proximal promoter region at ‑289/+83 bp was required for COMMD1 basal promoter activity by deletion constructs of COMMD1 promoter. Moreover, Sp1 inhibitor, mithramycin A, suppressed basal COMMD1 promoter activity. The Sp1‑binding site (‑11/‑1 bp) in the proximal promoter region was a critical site for COMMD1 gene regulation by Sp1 and Sp3. Sp1 upregulated COMMD1 promoter activity, whereas Sp3 suppressed it. Endogenous Sp1 and Sp3 bound to the proximal promoter region of COMMD1. Taken together, Sp1 constitutively regulates the basal expression of the COMMD1 gene in human epithelial cell lines.

A Split-Luciferase-Based Trimer Formation Assay as a High-throughput Screening Platform for Therapeutics in Alport Syndrome

Alport syndrome is a hereditary glomerular disease caused by mutation in type IV collagen α3-α5 chains (α3-α5(IV)), which disrupts trimerization, leading to glomerular basement membrane degeneration. Correcting the trimerization of α3/α4/α5 chain is a feasible therapeutic approach, but is hindered by lack of information on the regulation of intracellular α(IV) chain and the absence of high-throughput screening (HTS) platforms to assess α345(IV) trimer formation. Here, we developed sets of split NanoLuc-fusion α345(IV) proteins to monitor α345(IV) trimerization of wild-type and clinically associated mutant α5(IV). The α345(IV) trimer assay, which satisfied the acceptance criteria for HTS, enabled the characterization of intracellular- and secretion-dependent defects of mutant α5(IV). Small interfering RNA-based and chemical screening targeting the ER identified several chemical chaperones that have potential to promote α345(IV) trimer formation. This split luciferase-based trimer formation assay is a functional HTS platform that realizes the feasibility of targeting α345(IV) trimers to treat Alport syndrome.

Zinc Deficiency via a Splice Switch in Zinc Importer ZIP2/SLC39A2 Causes Cystic Fibrosis-Associated MUC5AC Hypersecretion in Airway Epithelial Cells

Airway mucus hyperproduction and fluid imbalance are important hallmarks of cystic fibrosis (CF), the most common life-shortening genetic disorder in Caucasians. Dysregulated expression and/or function of airway ion transporters, including cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC), have been implicated as causes of CF-associated mucus hypersecretory phenotype. However, the contributory roles of other substances and transporters in the regulation of CF airway pathogenesis remain unelucidated. Here, we identified a novel connection between CFTR/ENaC expression and the intracellular Zn^2 + concentration in the regulation of MUC5AC, a major secreted mucin that is highly expressed in CF airway. CFTR-defective and ENaC-hyperactive airway epithelial cells specifically and highly expressed a unique, alternative splice isoform of the zinc importer ZIP2/SLC39A2 (ΔC-ZIP2), which lacks the C-terminal domain. Importantly, ΔC-ZIP2 levels correlated inversely with wild-type ZIP2 and intracellular Zn^2 + levels. Moreover, the splice switch to ΔC-ZIP2 as well as decreased expression of other ZIPs caused zinc deficiency, which is sufficient for induction of MUC5AC; while ΔC-ZIP2 expression per se induced ENaC expression and function. Thus, our findings demonstrate that the novel splicing switch contributes to CF lung pathology via the novel interplay of CFTR, ENaC, and ZIP2 transporters.

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Zinc deficiency is a common feature in both CFTR-defective (CF) and ENaC-hyperactive (CF-like) airway epithelial cells.

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A splice switch from WT-ZIP2 to ΔC-ZIP2 as well as other ZIPs down-regulation caused zinc deficiency in CF and CF-like cells.

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Lower intracellular Zn^2 + levels contributed to CF-associated MUC5AC hypersecretion in airway epithelial cells.

The role of zinc in the pathogenesis of CF lung disease is not well understood. We utilized human CF patient-derived cell lines and primary cells as well as murine CF model, and identified zinc deficiency as a common characteristic in CF models. Down-regulation of several zinc importers (ZIPs) in CF cells caused zinc deficiency, which is sufficient for induction of MUC5AC, a major secreted mucin that exacerbates CF pathogenesis. Especially, strong contribution of ΔC-ZIP2, a novel ZIP2 splice isoform, in the regulation of CF-associated MUC5AC hypersecretion was clearly demonstrated. The study refined the importance of zinc in airway homeostasis.

Bromide supplementation exacerbated the renal dysfunction, injury and fibrosis in a mouse model of Alport syndrome

A seminal study recently demonstrated that bromide (Br-) has a critical function in the assembly of type IV collagen in basement membrane (BM), and suggested that Br- supplementation has therapeutic potential for BM diseases. Because salts of bromide (KBr and NaBr) have been used as antiepileptic drugs for several decades, repositioning of Br- for BM diseases is probable. However, the effects of Br- on glomerular basement membrane (GBM) disease such as Alport syndrome (AS) and its impact on the kidney are still unknown. In this study, we administered daily for 16 weeks 75 mg/kg or 250 mg/kg (within clinical dosage) NaBr or NaCl (control) via drinking water to 6-week-old AS mice (mouse model of X-linked AS). Treatment with 75 mg/kg NaBr had no effect on AS progression. Surprisingly, compared with 250 mg/kg NaCl, 250 mg/kg NaBr exacerbated the progressive proteinuria and increased the serum creatinine and blood urea nitrogen in AS mice. Histological analysis revealed that glomerular injury, renal inflammation and fibrosis were exacerbated in mice treated with 250 mg/kg NaBr compared with NaCl. The expressions of renal injury markers (Lcn2, Lysozyme), matrix metalloproteinase (Mmp-12), pro-inflammatory cytokines (Il-6, Il-8, Tnf-α, Il-1β) and pro-fibrotic genes (Tgf-β, Col1a1, α-Sma) were also exacerbated by 250 mg/kg NaBr treatment. Notably, the exacerbating effects of Br- were not observed in wild-type mice. These findings suggest that Br- supplementation needs to be carefully evaluated for real positive health benefits and for the absence of adverse side effects especially in GBM diseases such as AS.

6-Formylindolo[3,2-b]Carbazole Accelerates Skin Wound Healing via Activation of ERK, but Not Aryl Hydrocarbon Receptor

Wound healing is an elaborate process composed of overlapping phases, such as proliferation and remodeling, and is delayed in several circumstances, including diabetes. Although several treatment strategies for chronic wounds, such as growth factors, have been applied, further alternatives are required. The skin, especially keratinocytes, is continually exposed to UV rays, which impairs wound healing. 6-Formylindolo[3,2-b]carbazole (FICZ) is a tryptophan photoproduct formed by UV exposure, indicating that FICZ might be one of the effectors of UV radiation. In contrast, treatment with tryptophan, the precursor for FICZ, promoted wound closure in keratinocytes. Therefore, the aim of our study was to determine the role of FICZ in wound healing. Here we showed that FICZ enhanced keratinocyte migration through mitogen-activated protein kinase/extracellular signal-regulated kinase activation, and promoted wound healing in various mouse models, including db/db mice, which exhibit wound healing impairments because of type 2 diabetes. Moreover, FICZ, the endogenous ligand of an aryl hydrocarbon receptor, accelerated migration even in the aryl hydrocarbon receptor knockdown condition and also promoted wound healing in DBA/2 mice, bearing a low-affinity aryl hydrocarbon receptor, suggesting that FICZ enhanced keratinocyte migration in a mitogen-activated protein kinase/extracellular signal-regulated kinase-dependent, but aryl hydrocarbon receptor-independent, manner. The function of FICZ might indicate the possibility of its clinical use for intractable chronic wounds.

Mild electrical stimulation with heat shock guides differentiation of embryonic stem cells into Pdx1-expressing cells within the definitive endoderm

Background

Because of the increasing number of diabetic patients, it is important to generate pancreatic and duodenal homeobox gene 1 (Pdx1)-expressing cells, which are capable of differentiating into pancreatic endocrine β cells. Mild electrical stimulation was reported to modulate the differentiation of ES cells into ectoderm-derived neuronal cells or mesoderm-derived cardiac cells.

Results

In this study, we report that mild electrical stimulation with heat shock (MET) potentiates the differentiation of ES cells into definitive endoderm-derived Pdx1-expressing cells. MET has no effect when applied to early definitive endoderm on differentiation day 5. A 1.87-fold increase in the proportion of Pdx1-expressing cells was observed when stimulation was applied to the late definitive endoderm one day prior to the immergence of Pdx1/GFP-expressing cells on differentiation day 7. Pdx1 mRNA was also up-regulated by MET. The potentiating effect of MET synergized with activin and basic fibroblast growth factor into Pdx1-expressing cells. Moreover, MET stimulation on late definitive endoderm up-regulated heat shock protein 72 and activated various kinases including Akt, extracellular signal-regulated kinase, p38, and c-jun NH₂-terminal kinase in ES cells.

Conclusions

Our findings indicate that MET induces the differentiation of Pdx1-expressing cells within the definitive endoderm in a time-dependent manner, and suggest useful application for regenerative medicine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-017-0331-z) contains supplementary material, which is available to authorized users.

Activation of heat shock response to treat obese subjects with type 2 diabetes: a prospective, frequency-escalating, randomized, open-label, triple-arm trial

Activation of heat shock response (HSR) improves accumulated visceral adiposity and metabolic abnormalities in type 2 diabetes. To identify the optimal intervention strategy of the activation of the HSR provided by mild electrical stimulation (MES) with heat shock (HS) in type 2 diabetes. This study was a prospective, frequency-escalating, randomized, open-label, triple-arm trial in Japan. A total of 60 obese type 2 diabetes patients were randomized into three groups receiving two, four, or seven treatments per week for 12 weeks. No adverse events were identified. MES + HS treatment (when all three groups were combined), significantly improved visceral adiposity, glycemic control, insulin resistance, systemic inflammation, renal function, hepatic steatosis and lipid profile compared to baseline. The reduction in HbA1c was significantly greater among those treated four times per week (−0.36%) or seven times per week (−0.65%) than among those treated two times per week (−0.10%). The relative HbA1c levels in seven times per week group was significantly decreased when adjusted by two times per week group (−0.55%. p = 0.001). This research provides the positive impact of MES + HS to treat obese patients with type 2 diabetes mellitus.

Structural stabilization of transthyretin by a new compound, 6-benzoyl-2-hydroxy-1H-benzo[de]isoquinoline-1,3(2H)-dione

Familial amyloid polyneuropathy (FAP) is a genetic, adult-onset, neurodegenerative disorder caused by amyloid formation of transthyretin (TTR), a thyroxine-binding protein. Mutation in TTR causes a propensity of TTR tetramer to dissociate to monomer, which is the first step to amyloidosis. Thus, a drug that can stabilize the tetramer structure will have therapeutic benefit. Here, by virtual screening and biochemical assays, we identified small molecule 6-benzoyl-2-hydroxy-1H-benzo[de]isoquinoline-1,3(2H)-dione (L6) that can prevent the dissociation of TTR to monomer. X-ray crystallography reveals that L6 binds to the T4 binding pocket of TTR. These findings show that L6 is a candidate TTR stabilizer.

Endoplasmic Reticulum (ER) Stress Induces Sirtuin 1 (SIRT1) Expression via the PI3K-Akt-GSK3β Signaling Pathway and Promotes Hepatocellular Injury

Sirtuin 1 (SIRT1), an NAD(+)-dependent histone deacetylase, plays crucial roles in various biological processes including longevity, stress response, and cell survival. Endoplasmic reticulum (ER) stress is caused by dysfunction of ER homeostasis and exacerbates various diseases including diabetes, fatty liver, and chronic obstructive pulmonary disease. Although several reports have shown that SIRT1 negatively regulates ER stress and ER stress-induced responses in vitro and in vivo, the effect of ER stress on SIRT1 is less explored. In this study, we showed that ER stress induced SIRT1 expression in vitro and in vivo. We further determined the molecular mechanisms of how ER stress induces SIRT1 expression. Surprisingly, the conventional ER stress-activated transcription factors XBP1, ATF4, and ATF6 seem to be dispensable for SIRT1 induction. Based on inhibitor screening experiments with SIRT1 promoter, we found that the PI3K-Akt-GSK3β signaling pathway is required for SIRT1 induction by ER stress. Moreover, we showed that pharmacological inhibition of SIRT1 by EX527 inhibited the ER stress-induced cellular death in vitro and severe hepatocellular injury in vivo, indicating a detrimental role of SIRT1 in ER stress-induced damage responses. Collectively, these data suggest that SIRT1 expression is up-regulated by ER stress and contributes to ER stress-induced cellular damage.

Podocyte p53 Limits the Severity of Experimental Alport Syndrome

Alport syndrome (AS) is one of the most common types of inherited nephritis caused by mutation in one of the glomerular basement membrane components. AS is characterized by proteinuria at early stage of the disease and glomerular hyperplastic phenotype and renal fibrosis at late stage. Here, we show that global deficiency of tumor suppressor p53 significantly accelerated AS progression in X-linked AS mice and decreased the lifespan of these mice. p53 protein expression was detected in 21-week-old wild-type mice but not in age-matched AS mice. Expression of proinflammatory cytokines and profibrotic genes was higher in p53(+/-) AS mice than in p53(+/+) AS mice. In vitro experiments revealed that p53 modulates podocyte migration and positively regulates the expression of podocyte-specific genes. We established podocyte-specific p53 (pod-p53)-deficient AS mice, and determined that pod-p53 deficiency enhanced the AS-induced renal dysfunction, foot process effacement, and alteration of gene-expression pattern in glomeruli. These results reveal a protective role of p53 in the progression of AS and in maintaining glomerular homeostasis by modulating the hyperplastic phenotype of podocytes in AS.

Mild electrical stimulation increases stress resistance and suppresses fat accumulation via activation of LKB1-AMPK signaling pathway in C. elegans

Electrical current at physiological strength has been applied as a therapeutic approach for various diseases. Several of our works showed that mild electrical stimulation (MES) at 0.1-ms pulse width has positive impact on organisms. But despite the growing evidence of the beneficial effects of MES, its effects on individual animals and the molecular underpinnings are poorly understood and rarely studied. Here, we examined the effects of MES on individual animal and its mechanisms by mainly using Caenorhabditis elegans, a powerful genetic model organism. Interestingly, MES increased stress resistance and suppressed excess fat accumulation in wild-type N2 worms but not in AMPK/AAK-2 and LKB1/PAR-4 mutant worms. MES promoted the nuclear localization of transcription factors DAF-16 and SKN-1 and consequently increased the expression of anti-stress genes, whereas MES inhibited the nuclear localization of SBP-1 and suppressed the expression of lipogenic genes. Moreover, we found that MES induced the activation of LKB1/PAR4-AMPK/AAK2 pathway in C. elegans and in several mammalian cell lines. The mitochondrial membrane potential and cellular ATP level were slightly and transiently decreased by MES leading to the activation of LKB1-AMPK signaling pathway. Together, we firstly and genetically demonstrated that MES exerts beneficial effects such as stress resistance and suppression of excess fat accumulation, via activation of LKB1-AMPK signaling pathway.

Mild Electrical Stimulation with Heat Shock Reduces Visceral Adiposity and Improves Metabolic Abnormalities in Subjects with Metabolic Syndrome or Type 2 Diabetes: Randomized Crossover Trials

Background

The induction of heat shock protein (HSP) 72 by mild electrical stimulation with heat shock (MES + HS), which improves visceral adiposity and insulin resistance in mice, may be beneficial in treating metabolic syndrome (MS) or type 2 diabetes mellitus (T2DM).

Methods

Using open-label crossover trials, 40 subjects with MS or T2DM were randomly assigned using computer-generated random numbers to 12 weeks of therapeutic MES + HS followed by 12 weeks of no treatment, or vice versa. During the intervention period, physical and biochemical markers were measured.

Findings

Compared to no treatment, MES + HS treatment was associated with a significant decrease in visceral adiposity (− 7.54 cm² (− 8.61%), 95% CI − 8.55 to − 6.53 (p = 0.037) in MS, − 19.73 cm² (− 10.89%), 95% CI − 20.97 to − 18.49 (p = 0.003) in T2DM). Fasting plasma glucose levels were decreased by 3.74 mg/dL (− 5.28%: 95% CI − 4.37 to − 3.09 mg/dL, p = 0.029) in MS and by 14.97 mg/dL (10.40%: 95% CI − 15.79 to 14.15 mg/dL, p < 0.001) in T2DM, and insulin levels were also reduced by 10.39% and 25.93%, respectively. HbA1c levels showed a trend toward reduction (− 0.06%) in MS, and was significantly declined by − 0.43% (95% CI − 0.55 to − 0.31%, p = 0.009) in T2DM. HbA1c level of less than 7.0% was achieved in 52.5% of the MES + HS-treated T2DM patients in contrast to 15% of the non-treated period. Several insulin resistance indices, inflammatory cytokines or adipokines, including C-reactive protein, adiponectin, and tumor necrosis factor-α, were all improved in both groups. In isolated monocytes, HSP72 expression was increased and cytokine expression was reduced following MES + HS treatment. Glucose excursions on meal tolerance test were lower after using MES + HS in T2DM.

Interpretation

This combination therapy has beneficial impacts on body composition, metabolic abnormalities, and inflammation in subjects with MS or T2DM. Activation of the heat shock response by MES + HS may provide a novel approach for the treatment of lifestyle-related diseases.

Funding

Funding for this research was provided by MEXT KAKENHI (Grants-in-Aid for Scientific Research from Ministry of Education, Culture, Sports, Science and Technology, Japan).

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We report the use of mild electrical stimulation with heat shock (MES + HS) in treating metabolic syndrome or type 2 diabetes.

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The treatment improves visceral adiposity, glucose homeostasis, insulin resistance and chronic inflammatory status.

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Our findings suggest that MES + HS might be a valuable therapeutic option for patients with these lifestyle-related diseases.

The transcription factor MEF/Elf4 is dually modulated by p53-MDM2 axis and MEF-MDM2 autoregulatory mechanism

Myeloid Elf-1-like factor (MEF) or Elf4 is an ETS transcription factor that activates innate immunity-associated genes such as lysozyme (LYZ), human β-defensin 2 (HβD2), and interleukin-8 (IL-8) in epithelial cells and is also known to influence cell cycle progression. MEF is transcriptionally activated by E2F1, but the E2F1-mediated transcriptional activation is inhibited by p53 through E2F1-p53 protein interaction. Although the transcriptional activation of MEF has been investigated in depth, its post-translational regulation is not well explored. By overexpressing MEF cDNA in human cell lines, here we show that MEF protein expression is suppressed by p53. By screening a number of E3 ligases regulated by p53, we found that MDM2 is involved in the effect of p53 on MEF. MDM2 is transcriptionally activated by p53 and interacts with MEF protein to enhance MEF degradation. MDM2 reduces MEF protein expression, as well as stability and function of MEF as transcriptional activator. Furthermore, MDM2 was able to down-regulate MEF in the absence of p53, indicating a p53-independent effect on MEF. Notably, MEF transcriptionally activates MDM2, which was previously demonstrated to be the mechanism by which MEF suppresses the p53 protein. These results reveal that in addition to the potential of MEF to down-regulate p53 by transcriptionally activating E3 ligase MDM2, MEF participates with MDM2 in a novel autoregulatory feedback loop to regulate itself. Taken together with the findings on the effect of p53 on MEF, these data provide evidence that the p53-MDM2-MEF axis is a feedback mechanism that exquisitely controls the balance of these transcriptional regulators.

Lipopolysaccharide decreases single immunoglobulin interleukin-1 receptor-related molecule (SIGIRR) expression by suppressing specificity protein 1 (Sp1) via the Toll-like receptor 4 (TLR4)-p38 pathway in monocytes and neutrophils

Single immunoglobulin interleukin-1 receptor-related molecule (SIGIRR) is one of the immunoglobulin-like membrane proteins that is crucial for negative regulation of toll-like receptor 4 (TLR4) and interleukin-1 receptor. Despite the importance of understanding its expression and function, knowledge is limited on the regulatory mechanism in the epithelial tissues, such as the liver, lung, and gut, where its predominant expression is originally described. Here, we found expression of SIGIRR in non-epithelial innate immune cells, including primary peripheral blood monocytes, polymorphonuclear neutrophils, monocytic RAW264 cells, and neutrophilic-differentiated HL-60 cells. Consistent with previous findings in epithelial tissues, SIGIRR gene and protein expression were also down-regulated by LPS treatment in a time-dependent manner in primary blood monocytes and polymorphonuclear neutrophils. A reduction was also observed in RAW264 and differentiated HL-60 cells. Notably, exogenous introduction of the dominant negative form of TLR4 and siRNA of p38 resulted in inhibition of LPS-induced SIGIRR down-regulation, whereas treatment with p38 activator anisomycin showed a dose-dependent decrease in SIGIRR expression, suggesting TLR4-p38 signal as a critical pathway for LPS-induced SIGIRR down-regulation. Finally, reporter gene and chromatin immunoprecipitation assays demonstrated that Sp1 is a key factor that directly binds to the proximal promoter of SIGIRR gene and consequently regulates basal SIGIRR expression, which is negatively regulated by the LPS-dependent TLR4-p38 pathway. In summary, the data precisely demonstrate how LPS down-regulates SIGIRR expression and provide a role of LPS signal that counteracts Sp1-dependent basal promoter activation of SIGIRR gene via TLR4-p38 pathway in non-epithelial innate immune cells.

Comparative analysis of ER stress response into HIV protease inhibitors: lopinavir but not darunavir induces potent ER stress response via ROS/JNK pathway

HIV protease inhibitor (PI)-induced ER stress has been associated with adverse effects. Although it is a serious clinical problem for HIV/AIDS patients, comparative analyses of ER stress induction by clinically used PIs have rarely been done. Especially, there is no report on the differential ER stress response between lopinavir (LPV) and darunavir (DRV), although these PIs are the most clinically used PIs. We show here that LPV induces the most potent CHOP expression, ER stress marker, among the 9 Food and Drug Administration (FDA)-approved PIs in human peripheral blood mononuclear cells, several human epithelial cells, and mouse embryonic fibroblasts. LPV induced the most potent ROS production and JNK activation in 9 PIs. A comparison among the most clinically used PIs, ritonavir (RTV), LPV, and DRV, revealed that LPV potently and RTV moderately but not DRV induced ER stress via ROS-dependent JNK activation rather than proteasome inhibition. Finally, we analyzed ER stress induction in tissues of mice intraperitoneally injected with RTV, LPV, and DRV. RTV and LPV but not DRV showed ER stress induction in several mice tissues. In conclusion, we first identify LPV as the most potent ER stress inducing PI among 9 FDA-approved PIs in human cells, and although clinical verification is necessary, we show here that DRV has the advantage of less ROS and ER stress induction potential compared with LPV in vitro and in vivo.

Mild electrical stimulation with heat stimulation increase heat shock protein 70 in articular chondrocyte

The objective of this study is to investigate the effects of mild electrical stimulation (MES) and heat stress (HS) on heat shock protein 70 (HSP70), that protects chondrocytes and enhances cartilage matrix metabolism, in chondrocyte and articular cartilage. Rabbit articular chondrocytes were treated with MES and/or HS. The safeness was assessed by LDH assay and morphology. HSP70 protein, ubiquitinated proteins and HSP70 mRNA were examined by Western blotting and real-time PCR. Rat knee joints were treated with MES and/or HS. HSP70 protein, ubiquitinated proteins, HSP70 mRNA and proteoglycan core protein (PG) mRNA in articular cartilage were investigated. In vitro, HS increased HSP70 mRNA and HSP70 protein. MES augmented ubiquitinated protein and HSP70 protein, but not HSP70 mRNA. MES + HS raised HSP70 mRNA and ubiquitinated protein, and significantly increased HSP70 protein. In vivo, HS and MES + HS treatment augmented HSP70 mRNA. HS modestly augmented HSP70 protein. MES + HS significantly increased HSP70 protein and ubiquitinated proteins. PG mRNA was markedly raised by MES + HS. This study demonstrated that MES, in combination with HS, increases HSP70 protein in chondrocytes and articular cartilage, and promotes cartilage matrix metabolism in articular cartilage. MES in combination with HS can be a novel physical therapy for osteoarthritis by inducing HSP70 in articular cartilage.

Mild electrical stimulation at 0.1-ms pulse width induces p53 protein phosphorylation and G2 arrest in human epithelial cells

Exogenous low-intensity electrical stimulation has been used for treatment of various intractable diseases despite the dearth of information on the molecular underpinnings of its effects. Our work and that of others have demonstrated that applied electrical stimulation at physiological strength or mild electrical stimulation (MES) activates the PI3K-Akt pathway, but whether MES activates other molecules remains unknown. Considering that MES is a form of physiological stress, we hypothesized that it can activate the tumor suppressor p53, which is a key modulator of the cell cycle and apoptosis in response to cell stresses. The potential response of p53 to an applied electrical current of low intensity has not been investigated. Here, we show that p53 was transiently phosphorylated at Ser-15 in epithelial cells treated with an imperceptible voltage (1 V/cm) and a 0.1-ms pulse width. MES-induced p53 phosphorylation was inhibited by pretreatment with a p38 MAPK inhibitor and transfection of dominant-negative mutants of p38, MKK3b, and MKK6b, implying the involvement of the p38 MAPK signaling pathway. Furthermore, MES treatment enhanced p53 transcriptional function and increased the expression of p53 target genes p21, BAX, PUMA, NOXA, and IRF9. Importantly, MES treatment triggered G2 cell cycle arrest, but not cell apoptosis. MES treatment had no effect on the cell cycle in HCT116 p53(-/-) cells, suggesting a dependence on p53. These findings identify some molecular targets of electrical stimulation and incorporate the p38-p53 signaling pathway among the transduction pathways that MES affects.

Insulin receptor activation through its accumulation in lipid rafts by mild electrical stress

Insulin resistance is due to the reduced cellular response to insulin in peripheral tissues. The interaction of insulin with its receptor is the first step in insulin action and thus the identified target of insulin resistance. It has been well established that defects or mutations in the insulin receptor (IR) cause insulin resistance. Therefore, an IR activator might be a novel therapeutic approach for insulin resistance. Our previous report showed that mild electrical stress (MES) enhanced the insulin-induced signaling pathway. However, the molecular mechanism of the effect of MES remains unclear. We assessed the effect of MES, which is characterized by low-intensity direct current, on insulin signaling in vitro and in vivo. Here, we showed that MES activated the insulin signaling in an insulin-independent manner and improved insulin resistance in peripheral tissues of high fat-fed mice. Moreover, we found that MES increased the localization of IR in lipid rafts and enhanced the level of phosphorylated Akt in insulin-resistant hepatic cells. Ablation of lipid rafts disrupted the effect of MES on Akt activation. Our findings indicate that MES has potential as an activator of IR in an insulin-independent manner, and might be beneficial for insulin resistance in type 2 diabetes.

Hyperthermia with mild electrical stimulation protects pancreatic β-cells from cell stresses and apoptosis

Induction of heat shock protein (HSP) 72 improves metabolic profiles in diabetic model mice. However, its effect on pancreatic β-cells is not known. The current study investigated whether HSP72 induction can reduce β-cell stress signaling and apoptosis and preserve β-cell mass. MIN6 cells and db/db mice were sham-treated or treated with heat shock (HS) and mild electrical stimulation (MES) (HS+MES) to induce HSP72. Several cellular markers, metabolic parameters, and β-cell mass were evaluated. HS+MES treatment or HSP72 overexpression increased HSP72 protein levels and decreased tumor necrosis factor (TNF)-α-induced Jun NH(2)-terminal kinase (JNK) phosphorylation, endoplasmic reticulum (ER) stress, and proapoptotic signal in MIN6 cells. In db/db mice, HS+MES treatment for 12 weeks significantly improved insulin sensitivity and glucose homeostasis. Upon glucose challenge, a significant increase in insulin secretion was observed in vivo. Compared with sham treatment, levels of HSP72, insulin, pancreatic duodenal homeobox-1, GLUT2, and insulin receptor substrate-2 were upregulated in the pancreatic islets of HS+MES-treated mice, whereas JNK phosphorylation, nuclear translocation of forkhead box class O-1, and nuclear factor-κB p65 were reduced. Apoptotic signals, ER stress, and oxidative stress markers were attenuated. Thus, HSP72 induction by HS+MES treatment protects β-cells from apoptosis by attenuating JNK activation and cell stresses. HS+MES combination therapy may preserve pancreatic β-cell volume to ameliorate glucose homeostasis in diabetes.

Synergism between interleukin (IL)-17 and Toll-like receptor 2 and 4 signals to induce IL-8 expression in cystic fibrosis airway epithelial cells

Cystic fibrosis (CF) is the most common lethal inherited disorder and is caused by mutations in the gene encoding the CF transmembrane regulator (CFTR). The CF lung expresses a profound proinflammatory phenotype that appears to be related to a constitutive hypersecretion of interleukin (IL)-8 from airway epithelial cells in response to microbial infection. Since overproduction of IL-8 in CF contributes to massive bronchial infiltrates of neutrophils, identification of the pathways underlying IL-8 induction could provide novel drug targets for treatment of neutrophil-dominated inflammatory diseases such as CF. Here, we show that IL-17A synergistically increases IL-8 production induced by a toll-like receptor (TLR) 2 agonist, peptidoglycan (PGN), or TLR4 agonist, lipopolysaccharide (LPS), in a human CF bronchial epithelial cell line (CFBE41o-). A strong synergism was also observed in primary human CF bronchial epithelial cells, but not in human non-CF cell lines and primary cells. Notably, despite the induction of nuclear factor-κB and MAP kinases during TLR2 or TLR4 activation in CFBE41o-, IL-17A-dependent synergism appears to be the result of enhanced PGN- or LPS-induced phosphorylation of p38. Taken together, these studies provide evidence that IL-17A is a critical factor in increasing IL-8 expression in bacteria-infected CF airways via a pathway that regulates p38 phosphorylation.

Diethyldithiocarbamate induces apoptosis in HHV-8-infected primary effusion lymphoma cells via inhibition of the NF-κB pathway

Primary effusion lymphoma (PEL) is a subtype of B-cell lymphoma caused by human herpes virus 8/Kaposi sarcoma-associated herpes virus (HHV-8/KSHV), which is mostly found in patients with AIDS and has poor prognosis. Nuclear factor (NF)-κB pathway is constitutively activated in HHV-8-infected PEL cells and plays a crucial role in tumorigenesis. Recently, it has been shown that diethyldithiocarbamate (DDTC), an active metabolite of disulfiram, has apoptotic activity in cancer cells. Here, we investigated the effect of DDTC on PEL using a PEL mouse model generated by intraperitoneal injection of BC-3 cells, a PEL cell line. DDTC ameliorated the symptoms of PEL in these mice, such as development of ascites, splenomegaly and increase of body weight, in comparison with PBS-treated controls. Moreover, we determined in vitro that DDTC suppressed the constitutively activated NF-κB pathway in BC-3 cells. Methylthiotetrazole assay revealed that the cell proliferation of various PEL cell lines was significantly suppressed by the treatment of DDTC. DDTC also induced the expression of cleaved caspase-3, an apoptosis marker, whereas the addition of Q-VD-OPh, a pan-caspase inhibitor, inhibited cell apoptosis induced by DDTC treatment. Together, our results indicated that DDTC induces apoptosis via inhibition of the NF-κB signaling pathway in HHV-8-infected PEL cells. This study suggests the potential use of DDTC as a therapeutic approach for PEL.