Guidelines of care for the management of acne vulgaris

BACKGROUND

Acne vulgaris commonly affects adults, adolescents, and preadolescents aged 9 years or older.

OBJECTIVE

The objective of this study was to provide evidence-based recommendations for the management of acne.

METHODS

A work group conducted a systematic review and applied the Grading of Recommendations, Assessment, Development, and Evaluation approach for assessing the certainty of evidence and formulating and grading recommendations.

RESULTS

This guideline presents 18 evidence-based recommendations and 5 good practice statements. Strong recommendations are made for benzoyl peroxide, topical retinoids, topical antibiotics, and oral doxycycline. Oral isotretinoin is strongly recommended for acne that is severe, causing psychosocial burden or scarring, or failing standard oral or topical therapy. Conditional recommendations are made for topical clascoterone, salicylic acid, and azelaic acid, as well as for oral minocycline, sarecycline, combined oral contraceptive pills, and spironolactone. Combining topical therapies with multiple mechanisms of action, limiting systemic antibiotic use, combining systemic antibiotics with topical therapies, and adding intralesional corticosteroid injections for larger acne lesions are recommended as good practice statements.

LIMITATIONS

Analysis is based on the best available evidence at the time of the systematic review.

CONCLUSIONS

These guidelines provide evidence-based recommendations for the management of acne vulgaris.

Correction: Entamoeba lysyl-tRNA Synthetase Contains a Cytokine-Like Domain with Chemokine Activity towards Human Endothelial Cells

[This corrects the article DOI: 10.1371/journal.pntd.0001398.].

Nutrient sensors and their crosstalk

The macronutrients glucose, lipids, and amino acids are the major components that maintain life. The ability of cells to sense and respond to fluctuations in these nutrients is a crucial feature for survival. Nutrient-sensing pathways are thus developed to govern cellular energy and metabolic homeostasis and regulate diverse biological processes. Accordingly, perturbations in these sensing pathways are associated with a wide variety of pathologies, especially metabolic diseases. Molecular sensors are the core within these sensing pathways and have a certain degree of specificity and affinity to sense the intracellular fluctuation of each nutrient either by directly binding to that nutrient or indirectly binding to its surrogate molecules. Once the changes in nutrient levels are detected, sensors trigger signaling cascades to fine-tune cellular processes for energy and metabolic homeostasis, for example, by controlling uptake, de novo synthesis or catabolism of that nutrient. In this review, we summarize the major discoveries on nutrient-sensing pathways and explain how those sensors associated with each pathway respond to intracellular nutrient availability and how these mechanisms control metabolic processes. Later, we further discuss the crosstalk between these sensing pathways for each nutrient, which are intertwined to regulate overall intracellular nutrient/metabolic homeostasis.

Combination of the LARS1 Inhibitor, BC-LI-0186 with a MEK1/2 Inhibitor Enhances the Anti-Tumor Effect in Non-Small Cell Lung Cancer

Purpose

The mammalian target of rapamycin complex 1 (mTORC1) regulates cell growth and proliferation by growth factor coordination and amino acid availability. Leucyl-tRNA synthetase 1 (LARS1) senses the intracellular leucine concentration and mediates amino acid-induced activation of mTORC1. Thus, LARS1 inhibition could be useful in cancer treatment. However, the fact that mTORC1 can be stimulated by various growth factors and amino acids suggests that LARS1 inhibition alone has limitations in inhibiting cell growth and proliferation. We investigated the combined effects of BC-LI-0186, a LARS1 inhibitor, and trametinib, an MEK inhibitor, on non-small cell lung cancer (NSCLC).

Materials and Methods

Protein expression and phosphorylation were observed by immunoblotting, and genes differentially expressed between BC-LI-0186-sensitive and -resistant cells were identified by RNA sequencing. The combined effect of the two drugs was inferred from the combination index values and a xenograft model.

Results

LARS1 expression was positively correlated with mTORC1 in NSCLC cell lines. BC-LI-0186 treatment of A549 and H460 cells maintained in media supplemented with foetal bovine serum revealed paradoxical phosphorylation of S6 and activation of mitogen-activated protein kinase (MAPK) signalling. Compared with BC-LI-0186-sensitive cells, -resistant cells showed enrichment of the MAPK gene set. The combination of trametinib and BC-LI-0186 inhibited the phosphorylation of S6, MEK, and extracellular signal-regulated kinase and their synergistic effects were confirmed in a mouse xenograft model.

Conclusion

The combination of BC-LI-0186 and trametinib inhibited the non-canonical mTORC1-activating function of LARS1. Our study demonstrated a new therapeutic approach for NSCLC without targetable driver mutations.

Enhanced Glutaminolysis Drives Hypoxia-Induced Chemoresistance in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) exhibits severe hypoxia, which is associated with chemoresistance and worse patient outcome. It has been reported that hypoxia induces metabolic reprogramming in cancer cells. However, it is not well known whether metabolic reprogramming contributes to hypoxia. Here, we established that increased glutamine catabolism is a fundamental mechanism inducing hypoxia, and thus chemoresistance, in PDAC cells. An extracellular matrix component-based in vitro three-dimensional cell printing model with patient-derived PDAC cells that recapitulate the hypoxic status in PDAC tumors showed that chemoresistant PDAC cells exhibit markedly enhanced glutamine catabolism compared with chemoresponsive PDAC cells. The augmented glutamine metabolic flux increased the oxygen consumption rate via mitochondrial oxidative phosphorylation (OXPHOS), promoting hypoxia and hypoxia-induced chemoresistance. Targeting glutaminolysis relieved hypoxia and improved chemotherapy efficacy in vitro and in vivo. This work suggests that targeting the glutaminolysis-OXPHOS-hypoxia axis is a novel therapeutic target for treating patients with chemoresistant PDAC.

SIGNIFICANCE

Increased glutaminolysis induces hypoxia via oxidative phosphorylation-mediated oxygen consumption and drives chemoresistance in pancreatic cancer, revealing a potential therapeutic strategy of combining glutaminolysis inhibition and chemotherapy to overcome resistance.

Longitudinal multi-omics analyses of the gut-liver axis reveals metabolic dysregulation in hepatitis C infection and cirrhosis

The gut and liver are connected via the portal vein, and this relationship, which includes the gut microbiome, is described as the gut-liver axis. Hepatitis C virus (HCV) can infect the liver and cause fibrosis with chronic infection. HCV has been associated with an altered gut microbiome; however, how these changes impact metabolism across the gut-liver axis and how this varies with disease severity and time is unclear. Here we used multi-omics analysis of portal and peripheral blood, faeces and liver tissue to characterize the gut-liver axis of patients with HCV across a fibrosis severity gradient before (n = 29) and 6 months after (n = 23) sustained virologic response, that is, no detection of the virus. Fatty acids were the major metabolites perturbed across the liver, portal vein and gut microbiome in HCV, especially in patients with cirrhosis. Decreased fatty acid degradation by hepatic peroxisomes and mitochondria was coupled with increased free fatty acid (FFA) influx to the liver via the portal vein. Metatranscriptomics indicated that Anaerostipes hadrus-mediated fatty acid synthesis influences portal FFAs. Both microbial fatty acid synthesis and portal FFAs were associated with enhanced hepatic fibrosis. Bacteroides vulgatus-mediated intestinal glycan breakdown was linked to portal glycan products, which in turn correlated with enhanced portal inflammation in HCV. Paired comparison of patient samples at both timepoints showed that hepatic metabolism, especially in peroxisomes, is persistently dysregulated in cirrhosis independently of the virus. Sustained virologic response was associated with a potential beneficial role for Methanobrevibacter smithii, which correlated with liver disease severity markers. These results develop our understanding of the gut-liver axis in HCV and non-HCV liver disease aetiologies and provide a foundation for future therapies.

Effects of colchicine on lipolysis and adipose tissue inflammation in adults with obesity and metabolic syndrome

OBJECTIVE

The aim of this study was to examine whether colchicine's anti-inflammatory effects would improve measures of lipolysis and distribution of leukocyte populations in subcutaneous adipose tissue (SAT).

METHODS

A secondary analysis was conducted for a double-blind, randomized, placebo-controlled pilot study in which 40 adults with obesity and metabolic syndrome (MetS) were randomized to colchicine 0.6 mg or placebo twice daily for 3 months. Non-insulin-suppressible (l₀ ), insulin-suppressible (l₂ ), and maximal (l₀ +l₂ ) lipolysis rates were calculated by minimal model analysis. Body composition was determined by dual-energy x-ray absorptiometry. SAT leukocyte populations were characterized by flow cytometry analysis from biopsied samples obtained before and after the intervention.

RESULTS

Colchicine treatment significantly decreased l₂ and l₀ +l₂ versus placebo (p < 0.05). These changes were associated with a significant reduction in markers of systemic inflammation, including high-sensitivity C-reactive protein, resistin, and circulating monocytes and neutrophils (p < 0.01). Colchicine did not significantly alter SAT leukocyte population distributions (p > 0.05).

CONCLUSIONS

In adults with obesity and MetS, colchicine appears to improve insulin regulation of lipolysis and reduce markers of systemic inflammation independent of an effect on local leukocyte distributions in SAT. Further studies are needed to better understand the mechanisms by which colchicine affects adipose tissue metabolic pathways in adults with obesity and MetS.

The Mitochondrial Ca2+ uniporter is a central regulator of interorganellar Ca2+ transfer and NFAT activation

Mitochondrial Ca²⁺ uptake tailors the strength of stimulation of plasma membrane phospholipase C–coupled receptors to that of cellular bioenergetics. However, how Ca²⁺ uptake by the mitochondrial Ca²⁺ uniporter (MCU) shapes receptor-evoked interorganellar Ca²⁺ signaling is unknown. Here, we used CRISPR/Cas9 gene knockout, subcellular Ca²⁺ imaging, and mathematical modeling to show that MCU is a universal regulator of intracellular Ca²⁺ signaling across mammalian cell types. MCU activity sustains cytosolic Ca²⁺ signaling by preventing Ca²⁺-dependent inactivation of store-operated Ca²⁺ release–activated Ca²⁺ channels and by inhibiting Ca²⁺ extrusion. Paradoxically, MCU knockout (MCU-KO) enhanced cytosolic Ca²⁺ responses to store depletion. Physiological agonist stimulation in MCU-KO cells led to enhanced frequency of cytosolic Ca²⁺ oscillations, endoplasmic reticulum Ca²⁺ refilling, nuclear translocation of nuclear factor for activated T cells transcription factors, and cell proliferation, without altering inositol-1,4,5-trisphosphate receptor activity. Our data show that MCU has dual counterbalancing functions at the cytosol–mitochondria interface, whereby the cell-specific MCU-dependent cytosolic Ca²⁺ clearance and buffering capacity of mitochondria reciprocally regulate interorganellar Ca²⁺ transfer and nuclear factor for activated T cells nuclear translocation during receptor-evoked signaling. These findings highlight the critical dual function of the MCU not only in the acute Ca²⁺ buffering by mitochondria but also in shaping endoplasmic reticulum and cytosolic Ca²⁺ signals that regulate cellular transcription and function.

Effects of Colchicine on Measures of Lipolysis in Adults With Obesity

Background: Obesity-associated inflammation promotes adipose tissue (AT) dysfunction and contributes to the progression of type 2 diabetes and cardiovascular disease. Recent clinical studies have demonstrated that colchicine may improve metabolic and cardiovascular outcomes; however, colchicine’s effects on metabolic and inflammatory measures within AT remain unclear. Methods: The aim of this study was to examine if colchicine’s anti-inflammatory effects would improve measures of lipolysis and immune cell populations in subcutaneous AT (SAT). This is a secondary analysis of a double-blind, randomized, placebo-controlled pilot study in which 40 nondiabetic adults with obesity and metabolic syndrome (MetS) were randomized to colchicine 0.6mg or placebo twice daily for 3 months. Blood samples for insulin, glucose, and free fatty acids were collected in the fasted state and during a frequently-sampled intravenous glucose tolerance test. Noninsulin-suppressible (l₀), insulin-suppressible (l₂), and maximal (l₀+l₂) lipolysis rates were calculated by minimal model analysis. Body composition was determined by DXA. SAT immune cell populations were characterized by flow cytometry fluorescence-activated single cell sorting of the stromovascular fractions obtained after collagenase digestion of SAT samples obtained using a mini-liposuction technique pre- and post-intervention. Results: Data from 18 subjects in the colchicine group (Mean ± SD: age 48.4 ± 13.5 y; BMI 39.3 ± 6.3 kg/m2; sex: female 72.2%) and 18 subjects in the placebo group (age 44.7 ± 10.2 y; BMI 41.8 ± 8.2 kg/m2; sex: female 77.8%) were available for this study. Colchicine treatment significantly reduced l₂ (p = 0.04) and l₀+l₂ (p = 0.04) versus placebo. These changes were significantly associated with reductions in systemic inflammation, including the changes in high-sensitivity C-reactive protein concentrations, white blood cell count, circulating monocyte and neutrophil populations, and the neutrophil-lymphocyte ratio (p’s < 0.015). Colchicine did not significantly alter SAT immune cell population distributions (p’s > 0.05). Conclusions: In adults with obesity and MetS, colchicine may improve insulin action at the level of AT. These improvements were positively associated with the suppression of systemic inflammation. However, no local AT inflammatory cell populations were significantly affected by colchicine use in our study, suggesting that colchicine’s systemic, rather than local, anti-inflammatory effects may be more consequential in ameliorating AT metabolic pathways in MetS. Further studies are warranted to elucidate the biological mechanisms underlying colchicine’s effects in AT, as these investigations could potentially shed light on treatments to improve metabolic outcomes in human obesity.

Leucine-sensing mechanism of leucyl-tRNA synthetase 1 for mTORC1 activation

Leucyl-tRNA synthetase 1 (LARS1) mediates activation of leucine-dependent mechanistic target of rapamycin complex 1 (mTORC1) as well as ligation of leucine to its cognate tRNAs, yet its mechanism of leucine sensing is poorly understood. Here we describe leucine binding-induced conformational changes of LARS1. We determine different crystal structures of LARS1 complexed with leucine, ATP, and a reaction intermediate analog, leucyl-sulfamoyl-adenylate (Leu-AMS), and find two distinct functional states of LARS1 for mTORC1 activation. Upon leucine binding to the synthetic site, H251 and R517 in the connective polypeptide and ⁵⁰FPYPY⁵⁴ in the catalytic domain change the hydrogen bond network, leading to conformational change in the C-terminal domain, correlating with RagD association. Leucine binding to LARS1 is increased in the presence of ATP, further augmenting leucine-dependent interaction of LARS1 and RagD. Thus, this work unveils the structural basis for leucine-dependent long-range communication between the catalytic and RagD-binding domains of LARS1 for mTORC1 activation.

Aminoacyl-tRNA synthetases and amino acid signaling

Aminoacyl-tRNA synthetases (ARSs) are a family of evolutionarily conserved housekeeping enzymes used for protein synthesis that have pivotal roles in the ligation of tRNA with their cognate amino acids. Recent advances in the structural and functional studies of ARSs have revealed many previously unknown biological functions beyond the classical catalytic roles. Sensing the sufficiency of intracellular nutrients such as amino acids, ATP, and fatty acids is a crucial aspect for every living organism, and it is closely connected to the regulation of diverse cellular physiologies. Notably, among ARSs, leucyl-tRNA synthetase 1 (LARS1) has been identified to perform specifically as a leucine sensor upstream of the amino acid-sensing pathway and thus participates in the coordinated control of protein synthesis and autophagy for cell growth. In addition to LARS1, other types of ARSs are also likely involved in the sensing and signaling of their cognate amino acids inside cells. Collectively, this review focuses on the mechanisms of ARSs interacting within amino acid signaling and proposes the possible role of ARSs as general intracellular amino acid sensors.

Glutamine reliance in cell metabolism

As knowledge of cell metabolism has advanced, glutamine has been considered an important amino acid that supplies carbon and nitrogen to fuel biosynthesis. A recent study provided a new perspective on mitochondrial glutamine metabolism, offering mechanistic insights into metabolic adaptation during tumor hypoxia, the emergence of drug resistance, and glutaminolysis-induced metabolic reprogramming and presenting metabolic strategies to target glutamine metabolism in cancer cells. In this review, we introduce the various biosynthetic and bioenergetic roles of glutamine based on the compartmentalization of glutamine metabolism to explain why cells exhibit metabolic reliance on glutamine. Additionally, we examined whether glutamine derivatives contribute to epigenetic regulation associated with tumorigenesis. In addition, in discussing glutamine transporters, we propose a metabolic target for therapeutic intervention in cancer.

Glucose-dependent control of leucine metabolism by leucyl-tRNA synthetase 1

Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 (LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine binding. The phosphorylated LARS1 showed decreased leucine binding, which may inhibit protein synthesis and help save energy. Leucine that is not used for anabolic processes may be available for catabolic pathway energy generation. The LARS1-mediated changes in leucine utilization might help support cell survival under glucose deprivation. Thus, depending on glucose availability, LARS1 may help regulate whether leucine is used for protein synthesis or energy production.

Fluorescent 1,4-Naphthoquinones To Visualize Diffuse and Dense-Core Amyloid Plaques in APP/PS1 Transgenic Mouse Brains

Recent clinical approvals of brain imaging radiotracers targeting amyloid-β provided clinicians the tools to detect and confirm Alzheimer's disease pathology without autopsy or biopsy. While current imaging agents are effective in postsymptomatic Alzheimer's patients, there is much room for improvement in earlier diagnosis, hence prompting a need for new and improved amyloid imaging agents. Here we synthesized 41 novel 1,4-naphthoquinone derivatives and initially discovered 14 antiamyloidogenic compounds via in vitro amyloid-β aggregation assay; however, qualitative analyses of these compounds produced conflicting results and required further investigation. Follow-up docking and biophysical studies revealed that four of these compounds penetrate the blood-brain barrier, directly bind to amyloid-β aggregates, and enhance fluorescence properties upon interaction. These compounds specifically stain both diffuse and dense-core amyloid-β plaques in brain sections of APP/PS1 double transgenic Alzheimer's mouse models. Our findings suggest 1,4-naphthoquinones as a new scaffold for amyloid-β imaging agents for early stage Alzheimer's.

Therapeutic effects of the novel Leucyl-tRNA synthetase inhibitor BC-LI-0186 in non-small cell lung cancer

Objective:

Leucyl-tRNA synthetase (LRS) is an aminoacyl-tRNA synthetase catalyzing ligation of leucine to its cognate tRNA and is involved in the activation of mTORC1 by sensing cytoplasmic leucine. In this study, the usefulness of LRS as a therapeutic target of non-small cell lung cancer (NSCLC) and the anticancer effect of the LRS inhibitor, BC-LI-0186, was evaluated.

Methods:

LRS expression and the antitumor effect of BC-LI-0186 were evaluated by immunohistochemical staining, immunoblotting, and live cell imaging. The in vivo antitumor effect of BC-LI-0186 was evaluated using Lox-Stop-Lox (LSL) K-ras G12D mice.

Results:

LRS was frequently overexpressed in NSCLC tissues, and its expression was positively correlated with mTORC1 activity. The guanosine-5’-triphosphate (GTP) binding status of RagB was related to the expression of LRS and the S6K phosphorylation. siRNA against LRS inhibited leucine-mediated mTORC1 activation and cell growth. BC-LI-0186 selectively inhibited phosphorylation of S6K without affecting phosphorylation of AKT and leucine-mediated co-localization of Raptor and LAMP2 in the lysosome. BC-LI-0186 induced cleaved poly (ADP-ribose) polymerase (PARP) and caspase-3 and increase of p62 expression, showing that it has the autophagy-inducing property. BC-LI-0186 has the cytotoxic effect at nanomolar concentration and its GI₅₀ value was negatively correlated with the degree of LRS expression. BC-LI-0186 showed the antitumor effect, which was comparable with that of cisplatin, and mTORC1 inhibitory effect in a lung cancer model.

Conclusions:

BC-LI-0186 inhibits the noncanonical mTORC1-activating function of LRS. These results provide a new therapeutic strategy for NSCLC and warrant future clinical development by targeting LRS.

Pilot Study: An Ocular Biomarker for Diagnosis of Attention Deficit Hyperactivity Disorder

OBJECTIVE

Biomarkers of attention deficit hyperactivity disorder (ADHD) are crucial for early diagnosis and intervention, in which the identification of biomarkers in other areas of the body that represent the immature brain of children with ADHD is necessary. The present study aimed to find biomarkers of ADHD in the retina and assessed the relationship between macular thickness of the retina and cortical thickness of the brain in children with ADHD.

METHODS

Twelve children with ADHD and 13 control children were recruited for the study. To find ocular markers of ADHD, we investigated the correlation between clinical symptoms of ADHD assessed with the Korean ADHD Rating Scale (K-ARS), cortical thickness of the brain, and macular thickness measured with the mean thickness from the Early Treatment Diabetic Retinopathy Study (ETDRS).

RESULTS

Children with ADHD showed increased macular thicknesses quantified as an ETDRS ring in both eyes, compared to control subjects. Moreover, the right inner ETDRS ring had a positive correlation with K-ARS scores. The ADHD group had an increased ratio of thickness of the right frontal lobe to that of the parietal cortex, compared with the control group. There were positive correlations between the means of the inner ETDRS ring (right) and the left paracentral/right isthmus cingulate thicknesses in the control group. However, there were negative correlations between the means of the inner ETDRS ring (right) and the left frontal pole/right pars triangularis thicknesses in the ADHD group. The results of both groups were at the uncorrected level.

CONCLUSION

The different patterns of macular thickness might represent the immature cortical thickness of the brain in children with ADHD.

Nontranslational function of leucyl-tRNA synthetase regulates myogenic differentiation and skeletal muscle regeneration

Aside from its catalytic function in protein synthesis, leucyl-tRNA synthetase (LRS) has a nontranslational function in regulating cell growth via the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) pathway by sensing amino acid availability. mTOR also regulates skeletal myogenesis, but the signaling mechanism is distinct from that in cell growth regulation. A role of LRS in myogenesis has not been reported. Here we report that LRS negatively regulated myoblast differentiation in vitro. This function of LRS was independent of its regulation of protein synthesis, and it required leucine-binding but not tRNA charging activity of LRS. Local knock down of LRS accelerated muscle regeneration in a mouse injury model, and so did the knock down of Rag or Raptor. Further in vitro studies established a Rag-mTORC1 pathway, which inhibits the IRS1-PI3K-Akt pathway, to be the mediator of the nontranslational function of LRS in myogenesis. BC-LI-0186, an inhibitor reported to disrupt LRS-Rag interaction, promoted robust muscle regeneration with enhanced functional recovery, and this effect was abolished by cotreatment with an Akt inhibitor. Taken together, our findings revealed what we believe is a novel function for LRS in controlling the homeostasis of myogenesis, and suggested a potential therapeutic strategy to target a noncanonical function of a housekeeping protein.

MON-161 Lipolytic Rate in Relation to Skeletal Muscle and Hepatic Insulin Resistance

Introduction: Increased circulating free fatty acid (FFA) due to impaired control of adipocyte triglyceride lipolysis contributes to the development of obesity-related insulin resistance (IR). However, it is less clear whether there are differences in the relationship between lipolysis and skeletal muscle vs hepatic IR, or how these relationships are influenced by age, race, sex, body composition, or inflammation. We investigated the associations of lipolytic rate (LR) with skeletal muscle insulin sensitivity, as evidenced by insulin sensitivity index (SI), and hepatic IR, as measured by HOMA-IR. Methods: 46 healthy, non-diabetic adults with obesity (BMI 39.8±6.9 kg/m²) and 11 lean (BMI 25.6±2.1 kg/m²) adults (40% NHB, 20% HISP, 37% NHW, 3% Asian; 65% female; age 45.8±12.6y) underwent fasting blood draws and an insulin-modified frequently sampled intravenous glucose tolerance test (FSIVGTT). LR was calculated by a mathematical minimal model that estimated basal lipolysis and insulin-mediated lipolysis stimulated by insulin modulation of FFA during the FSIVGTT; SI was derived from Bergman’s minimal model. Body composition was determined by DXA. Using ANCOVA, we examined how LR was related to SI and HOMA-IR, controlling for age, race, and sex. Secondary analyses examined if the differences seen could be accounted for by differences in total fat mass or hsCRP. Results: As expected, LR was significantly elevated in adults with obesity (Mean±SD: 0.069±0.047 vs. 0.0052±0.00084 mEq/L*min, p<.001) and was positively correlated with total fat mass (r= +.64, p<.001). LR was also correlated with fasting insulin (r=.+56, p<.001), HOMA-IR (r= +.57, p<.001), SI (r= -.39, p<.01), and hsCRP (r= +.70, p<.001). Controlling for age, race, and sex (all ps>.05), LR remained correlated with SI (B= -.24, p<.01) and with HOMA-IR (B= +.33, p<.001). However, for SI, after including total fat mass and hsCRP in the model, the effect of LR on SI was no longer observed (p>.05). By contrast, for HOMA-IR, even after including total fat mass and hsCRP in the model, the effect of LR was still observed (B= +.30, p<.05). Conclusions: Previous studies have shown that excessive lipolysis plays a significant role in the pathogenesis of IR. By minimal model analysis of an insulin-modified FSIVGTT, we confirmed the well-described association of increased LR with skeletal muscle and hepatic IR. We found that differences in total fat mass fully explained the LR effect in skeletal muscle IR. However, even after controlling for total fat mass and hsCRP, our model revealed a significant association of LR with HOMA-IR. Our data suggest that LR is likely a strong predictor of hepatic IR across age, race, and sex in human obesity. Further studies are warranted to investigate how adiposity and inflammation mediate this relationship between lipolysis and IR.

Glycoprotein 96 polymorphisms are associated with the risk of systemic lupus erythematosus: A case-control study

AIM

To investigate the clinical implications of a genetic polymorphism in glycoprotein 96 (GP96), by analyzing the association between the genotype and haplotype of GP96 with systemic lupus erythematosus (SLE).

METHOD

We analyzed cell-surface expression of GP96 in peripheral blood mononuclear cells (PBMCs) and serum titer of anti-GP96 antibody of SLE patients. Single nucleotide polymorphisms and deletion mutants of GP96 were detected by two-dimensional gene scanning (TDGS). Odds ratios with 95% confidence intervals (CI) were determined for each genotype and haplotype through the chi-square test.

RESULTS

In total, 216 Korean SLE patients and 215 age- and sex-matched healthy controls were enrolled. In SLE patients, as opposed to healthy controls, cell-surface expression of GP96 among human leukocyte antigen-DR+ PBMCs (76.4% vs 45.5%, respectively, P < 0.001) and serum anti-GP96 antibody titers (0.98 vs 0.50, respectively, P = 0.012) increased. TDGS revealed six polymorphic sites in GP96, two of which were significantly associated with SLE (exon 1, g.-7C>G, odds ratio [OR] 1.78, 95% CI 1.16-2.75, P = 0.009; exon 17, g.17009_17011del, OR 1.76, 95% CI 1.18-2.64, P = 0.006). Two haplotypes (121111, 211212) were strongly associated with SLE (OR 8.92, 95% CI 1.10-72.6, P = 0.041; OR 3.03, 95% CI 1.22-7.50, P = 0.017, respectively) and specific clinical manifestations (discoid rash, arthritis, renal disorder, neurologic disorder, and hematologic disorder). Haplotype-based analysis revealed a stronger association between GP96 and SLE than did genotype-based analysis.

CONCLUSION

The two polymorphisms, each in exons 1 and 17 of GP96 are potential genetic risk factors of SLE. Two haplotypes 121111 and 211212 are related to not only SLE but also specific clinical manifestations.

The HDAC6 inhibitor ACY‑1215 enhances the anticancer activity of oxaliplatin in colorectal cancer cells

ACY‑1215, also known as ricolinostat, is a leading histone deacetylase 6 inhibitor, which is currently being tested in clinical trials for hematological malignancies. Previous studies have reported that ACY‑1215 is not potent enough as a monotherapy for the treatment of colorectal cancer (CRC), which generally requires combination therapy for successful treatment. Therefore, the present study aimed to determine whether the synergistic interaction detected between ACY‑1215 and anticancer agents in hematological cancers could occur in solid tumors. The results of the present study indicated that ACY‑1215 exerted a potent synergistic anti-proliferative effect when used in combination with anticancer agents in CRC cells. The combination of ACY‑1215 and oxaliplatin was more potent than either drug alone, as indicated by an increase in apoptotic cells and their effects on the apoptotic pathway; ACY‑1215 and oxaliplatin cotreatment activated caspase‑3 and poly (ADP ribose) polymerase, increased B‑cell lymphoma (Bcl)‑2 homologous antagonist/killer expression, and decreased Bcl‑extra large protein, phosphorylated-extracellular signal-regulated kinase and phosphorylated-protein kinase B expression. In addition, combined treatment of ACY‑1215 and anticancer agents induced synergistic upregulation of programmed death‑ligand 1. These findings suggested that a therapeutic strategy that combines ACY‑1215 and oxaliplatin warrants attention for the treatment of solid tumors, including CRC.

[Effects of zirconia micron coating on the proliferation and differentiation of osteoblasts]

Objective: To investigate the effects of zirconia micro coating on the proliferation and differentiation of osteoblasts on the surface of zirconia ceramic, and to provide a strategy for zirconia implant surface treatment. Methods: Forty tablets of zirconia ceramic, with the diameter of 15 mm and the thickness of 1.5 mm, were prepared. Then, twenty tablets polished by water sandpaper were taken as the control group, and 20 pieces of the zirconia coating after sintering micron were taken as the experimental group. The micromorphology of the surface of the two groups were observed by scanning electron microscope. The cell morphology after inoculation with MC3T3-E1 of osteoblasts on the surface of the material was investigated for 1, 3, and 5 days by scanning electron microscope. The cell proliferation was detected at 1 and 3 days by methyl thiazolyl tetrazolium. The cell differentiation ability was detected at 3 and 7 days by real-time quantitative PCR. Statistical analysis was conducted by independent sample t test. Results: After coating with zirconia micron particles, pores with the diameter of 1-20 μm could be observed on the surface of the test group of tiles through high temperature sintering. The growth of osteoblasts on the surface of the ceramic chip in the test group and control group exhibited the similar cell morphology. As they were cultured for 1 day, the experimental group exhibited a similar quality of cells as those in the test group (P>0.05). After 3 days' incubation, comparing with the cell quality of the test group (1.067 ± 0.077) (P<0.05), the quality of osteoblasts on the surface of zirconia ceramics coating increased to 1.763±0.165, and the expression of mRNA in alkaline phosphatase (ALP), osteopotin (OPN) and osteocalcin (OCN) also increased with the amount of 1.63±0.28, 1.99±0.41 and 1.60±0.30, respectively, compared with the test group (1.00± 0.00) (P<0.05). Seven days later, the expression of mRNA in Runt-related transcription factor-2 (RNUX2) (1.33±0.19), special AT-rich sequence binding protein-2 (SATB2) (1.64 ± 0.36), as well as alkaline phosphatase (ALP) (1.78±0.40), OPN (2.25±0.36), and OCN (1.88±0.21), showed a remarkably increase compared with the test group (1.00±0.00) (P<0.05). Conclusions: Zirconia micro coating on the surface of zirconia ceramics promoted the proliferation and differentiation of osteoblasts adhered.

A Human Antibody That Binds to the Sixth Ig-Like Domain of VCAM-1 Blocks Lung Cancer Cell Migration In Vitro

Vascular cell adhesion molecule-1 (VCAM-1) is closely associated with tumor progression and metastasis. However, the relevance and role of VCAM-1 in lung cancer have not been clearly elucidated. In this study, we found that VCAM-1 was highly overexpressed in lung cancer tissue compared with that of normal lung tissue, and high VCAM-1 expression correlated with poor survival in lung cancer patients. VCAM-1 knockdown reduced migration of A549 human lung cancer cells into Matrigel, and competitive blocking experiments targeting the Ig-like domain 6 of VCAM-1 (VCAM-1-D6) demonstrated that the VCAM-1-D6 domain was critical for VCAM-1 mediated A549 cell migration into Matrigel. Next, we developed a human monoclonal antibody specific to human and mouse VCAM-1-D6 (VCAM-1-D6 huMab), which was isolated from a human synthetic antibody library using phage display technology. Finally, we showed that VCAM-1-D6 huMab had a nanomolar affinity for VCAM-1-D6 and that it potently suppressed the migration of A549 and NCI-H1299 lung cancer cell lines into Matrigel. Taken together, these results suggest that VCAM-1-D6 is a key domain for regulating VCAM-1-mediated lung cancer invasion and that our newly developed VCAM-1-D6 huMab will be a useful tool for inhibiting VCAM-1-expressing lung cancer cell invasion.

A mathematical model of calcium dynamics in HSY cells

Saliva is an essential part of activities such as speaking, masticating and swallowing. Enzymes in salivary fluid protect teeth and gums from infectious diseases, and also initiate the digestion process. Intracellular calcium (Ca2+) plays a critical role in saliva secretion and regulation. Experimental measurements of Ca2+ and inositol trisphosphate (IP3) concentrations in HSY cells, a human salivary duct cell line, show that when the cells are stimulated with adenosine triphosphate (ATP) or carbachol (CCh), they exhibit coupled oscillations with Ca2+ spike peaks preceding IP3 spike peaks. Based on these data, we construct a mathematical model of coupled Ca2+ and IP3 oscillations in HSY cells and perform model simulations of three different experimental settings to forecast Ca2+ responses. The model predicts that when Ca2+ influx from the extracellular space is removed, oscillations gradually slow down until they stop. The model simulation of applying a pulse of IP3 predicts that photolysis of caged IP3 causes a transient increase in the frequency of the Ca2+ oscillations. Lastly, when Ca2+-dependent activation of PLC is inhibited, we see an increase in the oscillation frequency and a decrease in the amplitude. These model predictions are confirmed by experimental data. We conclude that, although concentrations of Ca2+ and IP3 oscillate, Ca2+ oscillations in HSY cells are the result of modulation of the IP3 receptor by intracellular Ca2+, and that the period is modulated by the accompanying IP3 oscillations.

Leucyl-tRNA Synthetase Activates Vps34 in Amino Acid-Sensing mTORC1 Signaling

Amino acid availability activates signaling by the mammalian target of rapamycin (mTOR) complex 1, mTORC1, a master regulator of cell growth. The class III PI-3-kinase Vps34 mediates amino acid signaling to mTORC1 by regulating lysosomal translocation and activation of the phospholipase PLD1. Here, we identify leucyl-tRNA synthetase (LRS) as a leucine sensor for the activation of Vps34-PLD1 upstream of mTORC1. LRS is necessary for amino acid-induced Vps34 activation, cellular PI(3)P level increase, PLD1 activation, and PLD1 lysosomal translocation. Leucine binding, but not tRNA charging activity of LRS, is required for this regulation. Moreover, LRS physically interacts with Vps34 in amino acid-stimulatable non-autophagic complexes. Finally, purified LRS protein activates Vps34 kinase in vitro in a leucine-dependent manner. Collectively, our findings provide compelling evidence for a direct role of LRS in amino acid activation of Vps34 via a non-canonical mechanism and fill a gap in the amino acid-sensing mTORC1 signaling network.

AIMP2 Controls Intestinal Stem Cell Compartments and Tumorigenesis by Modulating Wnt/β-Catenin Signaling

Wnt/β-catenin (CTNNB1) signaling is crucial for the proliferation and maintenance of intestinal stem cells (ISC), but excessive activation leads to ISC expansion and eventually colorectal cancer. Thus, negative regulators are required to maintain optimal levels of Wnt/β-catenin signaling. Aminoacyl-tRNA synthetase-interacting multifunctional proteins (AIMP) function in protein synthesis, but have also been implicated in signaling cascades affecting angiogenesis, immunity, and apoptosis. In this study, we investigated the relationship between AIMP2 and Wnt/β-catenin signaling in a murine model of intestinal homeostasis and tumorigenesis. Hemizygous deletion of Aimp2 resulted in enhanced Wnt/β-catenin signaling, increased proliferation of cryptic epithelial cells, and expansion of ISC compartments. In an Apc(Min/+) background, Aimp2 hemizygosity increased adenoma formation. Mechanistically, AIMP2 disrupted the interaction between AXIN and Dishevelled-1 (DVL1) to inhibit Wnt/β-catenin signaling by competing with AXIN. Furthermore, AIMP2 inhibited intestinal organoid formation and growth by suppressing Wnt/β-catenin signaling in an Aimp2 gene dosage-dependent manner. Collectively, our results showed that AIMP2 acts as a haploinsufficient tumor suppressor that fine-tunes Wnt/β-catenin signaling in the intestine, illuminating the regulation of ISC abundance and activity. Cancer Res; 76(15); 4559-68. ©2016 AACR.

Transcriptome analysis and anthocyanin-related genes in red leaf lettuce

This study aimed to analyze the transcriptome profile of red lettuce and identify the genes involved in anthocyanin accumulation. Red leaf lettuce is a popular vegetable and popular due to its high anthocyanin content. However, there is limited information available about the genes involved in anthocyanin biosynthesis in this species. In this study, transcriptomes of 15-day-old seedlings and 40-day-old red lettuce leaves were analyzed using an Illuminia HiseqTM 2500 platform. A total of 10.6 GB clean data were obtained and de novo assembled into 83,333 unigenes with an N50 of 1067. After annotation against public databases, 51,850 unigene sequences were identified, among which 46,087 were annotated in the NCBI non-redundant protein database, and 41,752 were annotated in the Swiss-Prot database. A total of 9125 unigenes were mapped into 163 pathways using the Kyoto Encyclopedia of Genes and Genomes database. Thirty-four structural genes were found to cover the main steps of the anthocyanin pathway, including chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, flavonoid 3'-hydroxylase, flavonoid 3',5'-hydroxylase, dihydroflavonol 4-reductase, and anthocyanidin synthase. Seven MYB, three bHLH, and two WD40 genes, considered anthocyanin regulatory genes, were also identified. In addition, 3607 simple sequence repeat (SSR) markers were identified from 2916 unigenes. This research uncovered the transcriptomic characteristics of red leaf lettuce seedlings and mature plants. The identified candidate genes related to anthocyanin biosynthesis and the detected SSRs provide useful tools for future molecular breeding studies.

Direct Regulation of TLR5 Expression by Caveolin-1

Toll-like receptor 5 (TLR5) is a specific receptor for microbial flagellin and is one of the most well-known receptors in the TLR family. We reported previously that TLR5 signaling is well maintained during aging and that caveolin-1 may be involved in TLR5 signaling in aged macrophages through direct interactions. Therefore, it is important to clarify whether caveolin-1/TLR5 interactions affect TLR5 expression during aging. To assess the effect of caveolin-1 on TLR5, we analyzed TLR5 expression in senescent fibroblasts and aged tissues expressing high levels of caveolin-1. As expected, TLR5 mRNA and protein expression was well maintained in senescent fibroblasts and aged tissues, whereas TLR4 mRNA and protein were diminished in those cells and tissues. To determine the mechanism of caveolin-1-dependent TLR5 expression, we examined TLR5 expression in caveolin-1 deficient mice. Interestingly, TLR5 mRNA and protein levels were decreased dramatically in tissues from caveolin-1 knockout mice. Moreover, overexpressed caveolin-1 in vitro enhanced TLR5 mRNA through the MAPK pathway and prolonged TLR5 protein half-life through direct interaction. These results suggest that caveolin-1 may play a crucial role in maintaining of TLR5 by regulating transcription systems and increasing protein half-life.

Flagellin-dependent TLR5/caveolin-1 as a promising immune activator in immunosenescence

The age-associated decline of immune responses causes high susceptibility to infections and reduced vaccine efficacy in the elderly. However, the mechanisms underlying age-related deficits are unclear. Here, we found that the expression and signaling of flagellin (FlaB)-dependent Toll-like receptor 5 (TLR5), unlike the other TLRs, were well maintained in old macrophages, similar to young macrophages. The expression and activation of TLR5/MyD88, but not TLR4, were sensitively regulated by the upregulation of caveolin-1 in old macrophages through direct interaction. This interaction was also confirmed using macrophages from caveolin-1 or MyD88 knockout mice. Because TLR5 and caveolin-1 were well expressed in major old tissues including lung, skin, intestine, and spleen, we analyzed in vivo immune responses via a vaccine platform with FlaB as a mucosal adjuvant for the pneumococcal surface protein A (PspA) against Streptococcus pneumoniae infection in young and aged mice. The FlaB-PspA fusion protein induced a significantly higher level of PspA-specific IgG and IgA responses and demonstrated a high protective efficacy against a lethal challenge with live S. pneumoniae in aged mice. These results suggest that caveolin-1/TLR5 signaling plays a key role in age-associated innate immune responses and that FlaB-PspA stimulation of TLR5 may be a new strategy for a mucosal vaccine adjuvant against pneumococcal infection in the elderly.

Incidence, risk factors, and prognosis of acute kidney injury following transarterial chemoembolization in patients with hepatocellular carcinoma: a prospective cohort study

BACKGROUND

Transcatheter arterial chemoembolization (TACE) is an effective first-line therapy for intermediate stage hepatocellular carcinoma (HCC). Acute renal injury may be induced after transarterial chemoembolization because of iodinated radiocontrast medium, but its incidence, risk factors, and prognosis remain unclear.

PATIENTS AND METHODS

This prospective study enrolled 166 HCC patients with a total of 316 TACE treatments. The incidence, risk factors, and prognosis of acute kidney injury (AKI) were examined.

RESULTS

The incidence of post-TACE AKI was 21.84% (69/316) according to Barrett and Parfrey criteria, whereas 7.59% (24/316) according to acute kidney injury network (AKIN) criteria. Multivariate logistic regression analysis showed that serum total bilirubin (TB) (>13.5 μmol/L; odds ratio [OR]: 1.871 95% confidence interval [CI]: 1.044-3.352; P = 0.035) and hemoglobin (HGB) level (<120 g/L; OR: 1.823, 95% CI: 1.019-3.264; P = 0.043) were associated with the development of AKI after TACE procedure in accordance to Barrett and Parfrey criteria. Meanwhile, age (>55 years; OR: 3.456, 95% CI: 1.107-10.790; P = 0.033), post-TACE AKI history (OR: 7.108, 95% CI: 1.387-36.434, P = 0.019), and serum aminotransferase level (>55 U/L; OR: 4.420, 95% CI: 1.792-10.906; P = 0.001) were associated with the development of AKI after TACE procedure in accordance to AKIN criteria. Total hospitalization cost was significantly higher (P = 0.034) in the patients with AKI after TACE procedure according to Barrett and Parfrey criteria. A post-TACE AKI diagnosis was associated with mortality in any definition used (P = 0.034 and P = 0.001 for Barrett and Parfrey and AKIN criteria, respectively).

CONCLUSION

The present study showed that the incidence of post-TACE AKI was high in HCC patients (i.e., 7.59-21.84%) depending on criteria used. HGB (<120 g/L), serum TB (>13.5), and aminotransferase level (>55 U/L), age (>55 years) and post-TACE AKI history may be predictors of post-TACE AKI in HCC patients. The development of post-TACE AKI was associated with the risk of renal replacement treatment, prolonged renal insufficiency, or mortality according to AKIN criteria.

Identification of heat shock proteins via transcriptome profiling of tree peony leaf exposed to high temperature

The tree peony leaf is an important vegetative organ that is sensitive to abiotic stress and particularly to high temperature. This sensitivity affects plant growth and restricts tree peony distribution. However, the transcriptomic information currently available on the peony leaf in public databases is limited. In this study, we sequenced the transcriptomes of peony leaves subjected to high temperature using the Illumina HiSeq TM 2000 platform. We performed de novo assembly of 93,714 unigenes (average length of 639.7 bp). By searching the public databases, 22,323 unigenes and 13,107 unigenes showed significant similarities with proteins in the NCBI non-redundant protein database and SWISS-PROT database (E-value < 1e-5), respectively. We assigned 17,340 unigenes to Gene Ontology categories, and we assigned 7618 unigenes to clusters of orthologous groups for eukaryotic complete genomes. By searching the Kyoto Encyclopedia of Genes and Genomes Pathway database, 8014 unigenes were assigned to 6 main categories, including 290 KEGG pathways. To advance research on improving thermotolerance, we identified 24 potential heat shock protein genes with complete open reading frames from the transcriptomic sequences. This is the first study to characterize the leaf transcriptome of tree peony leaf using high-throughput sequencing. The information obtained from the tree peony leaf is valuable for gene discovery, and the identified heat shock protein genes can be used to improve plant stress-tolerance.

A "mix-and-match" approach to designing Ca(2+) microdomains at membrane-contact sites

Ca²⁺ microdomains are critical for regulating cellular activity and often form at membrane contact sites. Such sites between lysosomes and the ER potentially provide a platform for signaling by the Ca²⁺ mobilizing messenger NAADP. However, at present we know little of how Ca²⁺ release events are coordinated at these experimentally intractable junctions. We therefore developed a computational model of lysosome-ER microdomains, which suggested that small leaks of Ca²⁺ from the lysosome couple to Ca²⁺-sensitive Ins(1,4,5)P₃ receptors on the ER to generate global, microdomain-dependent Ca²⁺ signals. Here we discuss how the “mix-and-match” arrangement of different Ca²⁺ signaling proteins on the “source” and “target” membranes might generate functionally heterogeneous Ca²⁺ microdomains.

A computational model of lysosome-ER Ca2+ microdomains

Acidic organelles form an important intracellular Ca(2+) pool that can drive global Ca(2+) signals through coupling with endoplasmic reticulum (ER) Ca(2+) stores. Recently identified lysosome-ER membrane contact sites might allow formation of Ca(2+) microdomains, although their size renders observation of Ca(2+) dynamics impractical. Here, we generated a computational model of lysosome-ER coupling that incorporated a previous model of the inositol trisphosphate (IP3) receptor as the ER Ca(2+) 'amplifier' and lysosomal leaks as the Ca(2+) 'trigger'. The model qualitatively described global Ca(2+) responses to the lysosomotropic agent GPN, which caused a controlled but substantial depletion of small solutes from the lysosome. Adapting this model to physiological lysosomal leaks induced by the Ca(2+) mobilising messenger NAADP demonstrated that lysosome-ER microdomains are capable of driving global Ca(2+) oscillations. Interestingly, our simulations suggest that the microdomain [Ca(2+)] need not be higher than that in the cytosol for responses to occur, thus matching the relatively high affinity of IP3 receptors for Ca(2+). The relative distribution and overall density of the lysosomal leaks dictated whether microdomains triggered or modulated global signals. Our data provide a computational framework for probing lysosome-ER Ca(2+) dynamics.

AIMP1/p43 negatively regulates adipogenesis by inhibiting peroxisome proliferator-activated receptor gamma

Adipogenesis is known to be controlled by the concerted actions of transcription factors and co-regulators. However, little is known about the regulation mechanism of transcription factors that control adipogenesis. In addition, the adipogenic roles of translational factors remain unclear. Here, we show that aminoacyl-tRNA synthetase-interacting multifunctional protein 1 (AIMP1), an auxiliary factor that is associated with a macromolecular tRNA synthetase complex, negatively regulates adipogenesis via a direct interaction with the DNA-binding domain of peroxisome proliferator-activated receptor γ (PPARγ). AIMP1 expression increased during adipocyte differentiation. Adipogenesis was augmented in AIMP1-deficient cells, as compared with control cells. AIMP1 exhibited high affinity for active PPARγ and interacted with the DNA-binding domain of PPARγ, thereby inhibiting its transcriptional activity. Thus, AIMP1 appears to function as a novel inhibitor of PPARγ that regulates adipocyte differentiation by preventing the transcriptional activation of PPARγ.

Chemical inhibition of prometastatic lysyl-tRNA synthetase-laminin receptor interaction

Lysyl-tRNA synthetase (KRS), a protein synthesis enzyme in the cytosol, relocates to the plasma membrane after a laminin signal and stabilizes a 67-kDa laminin receptor (67LR) that is implicated in cancer metastasis; however, its potential as an antimetastatic therapeutic target has not been explored. We found that the small compound BC-K-YH16899, which binds KRS, impinged on the interaction of KRS with 67LR and suppressed metastasis in three different mouse models. The compound inhibited the KRS-67LR interaction in two ways. First, it directly blocked the association between KRS and 67LR. Second, it suppressed the dynamic movement of the N-terminal extension of KRS and reduced membrane localization of KRS. However, it did not affect the catalytic activity of KRS. Our results suggest that specific modulation of a cancer-related KRS-67LR interaction may offer a way to control metastasis while avoiding the toxicities associated with inhibition of the normal functions of KRS.

Multiple reaction monitoring of multiple low-abundance transcription factors in whole lung cancer cell lysates

Lung cancer-related transcription factors (TFs) were identified by integrating previously reported genomic, transcriptomic, and proteomic data and were quantified by multiple reaction monitoring (MRM) in various cell lines. All experiments were performed without affinity depletion or subfractionation of cell lysates. Since the target proteins were expected to be present in low abundance, we experimentally optimized MRM transition parameters with chemically synthesized peptides. Quantitation was based on stable isotope-labeled standard peptides (SIS peptides). Out of 288 MRM measurements (36 peptides representing 28 TFs × 8 cell lines), 241 were successfully obtained within a quantitation limit of 15 amol, 221 measurements (91.7%) showed coefficients of variation (CVs) of ≤ 20%, and 149 (61.8%) showed CVs of ≤ 10%, quantifying as low as 19.4 amol/μg protein for STAT2 with a CV of 6.3% in an A549 cell. Comparisons between MRM measurements and levels of the corresponding mRNAs revealed linear, nonlinear, or no relationship between protein and mRNA levels, indicating the need for an MRM assay. An integrative analysis of MRM and gene expression profiles from doxorubicin-resistant H69AR and sensitive H69 cells further showed that 14 differentially expressed TFs, such as STAT1 and SMAD4, regulated genes associated with drug resistance and cell differentiation-related processes. Thus, the analytical performance of MRM for the quantitation of low abundance TFs suggests its usefulness for biological application.

Identification of CD23 as a functional receptor for the proinflammatory cytokine AIMP1/p43

ARS-interacting multifunctional protein 1 (AIMP1/p43) can be secreted to trigger proinflammatory molecules while it is predominantly bound to a cytoplasmic macromolecular protein complex that contains several different aminoacyl-tRNA synthetases. Although its activities as a secreted signaling factor have been well-characterized, the functional receptor for its proinflammatory activity has not yet identified. In this study, we have identified the receptor molecule for AIMP1 that mediates the secretion of TNF-α from THP-1 monocytic cells and primary human peripheral blood mononuclear cells (PBMCs). In a screen of 499 soluble receptors, we identified CD23, a known low-affinity receptor for IgE, as a high affinity binding partner of AIMP1. We found that down-regulation of CD23 attenuated AIMP1-induced TNF-α secretion and AIMP1 binding to THP-1 and PBMCs. We also observed that in THP-1 and PBMCs, AIMP1-induced TNF-α secretion mediated by CD23 involved activation of ERK1/2. Interestingly, endothelial monocyte activating polypeptide II (EMAP II), the C-terminal fragment of AIMP1 that is also known to work as a proinflammatory cytokine, was incapable of binding to CD23 and of activating ERK1/2. Therefore, identification of CD23 not only explains the inflammatory function of AIMP1 but also provides the first evidence by which the mode of action of AIMP1 can be distinguished from that of its C-terminal domain, EMAP II.

Entamoeba lysyl-tRNA synthetase contains a cytokine-like domain with chemokine activity towards human endothelial cells

Immunological pressure encountered by protozoan parasites drives the selection of strategies to modulate or avoid the immune responses of their hosts. Here we show that the parasite Entamoeba histolytica has evolved a chemokine that mimics the sequence, structure, and function of the human cytokine HsEMAPII (Homo sapiens endothelial monocyte activating polypeptide II). This Entamoeba EMAPII-like polypeptide (EELP) is translated as a domain attached to two different aminoacyl-tRNA synthetases (aaRS) that are overexpressed when parasites are exposed to inflammatory signals. EELP is dispensable for the tRNA aminoacylation activity of the enzymes that harbor it, and it is cleaved from them by Entamoeba proteases to generate a standalone cytokine. Isolated EELP acts as a chemoattractant for human cells, but its cell specificity is different from that of HsEMAPII. We show that cell specificity differences between HsEMAPII and EELP can be swapped by site directed mutagenesis of only two residues in the cytokines' signal sequence. Thus, Entamoeba has evolved a functional mimic of an aaRS-associated human cytokine with modified cell specificity.

Enhancement of toll-like receptor 2-mediated immune responses by AIMP1, a novel cytokine, in mouse dendritic cells

Aminoacyl tRNA synthetase-interacting protein 1 (AIMP1) is a novel pleiotropic cytokine that was identified initially from Meth A-induced fibrosarcoma. It is expressed in the salivary glands, small intestine and large intestine, and is associated with the innate immune system. Previously, we demonstrated that AIMP1 might function as a regulator of innate immune responses by inducing the maturation and activation of bone-marrow-derived dendritic cells (BM-DCs). Toll-like receptors (TLRs) are major pathogen-recognition receptors that are constitutively expressed on DCs. In this study, we attempted to determine whether AIMP1 is capable of regulating the expression of TLRs, and also capable of affecting the TLR-mediated activation of DCs. Expression of TLR1, -2, -3 and -7 was highly induced by AIMP1 treatment in BM-DCs, whereas the expression of other TLRs was either down-regulated or remained unchanged. In particular, the expression of the TLR2 protein was up-regulated by AIMP1 in a time-dependent and dose-dependent manner, and was suppressed upon the addition of BAY11-7082, an inhibitor of nuclear factor-κB. AIMP1 was also shown to increase nuclear factor-κB binding activity. Importantly, AIMP1 enhanced the production of interleukin-6 and interleukin-12, and the expression of co-stimulatory molecules on BM-DCs when combined with lipoteichoic acid or Pam3Cys, two well-known TLR2 agonists. Collectively, these results demonstrate that the AIMP1 protein enhances TLR2-mediated immune responses via the up-regulation of TLR2 expression.

Importin beta plays an essential role in the regulation of the LysRS-Ap(4)A pathway in immunologically activated mast cells

We recently reported that diadenosine tetraphosphate hydrolase (Ap(4)A hydrolase) plays a critical role in gene expression via regulation of intracellular Ap(4)A levels. This enzyme serves as a component of our newly described lysyl tRNA synthetase (LysRS)-Ap(4)A biochemical pathway that is triggered upon immunological challenge. Here we explored the mechanism of this enzyme's translocation into the nucleus and found its immunologically dependent association with importin beta. Silencing of importin beta prevented Ap(4)A hydrolase nuclear translocation and affected the local concentration of Ap(4)A, which led to an increase in microphthalmia transcription factor (MITF) transcriptional activity. Furthermore, immunological activation of mast cells resulted in dephosphorylation of Ap(4)A hydrolase, which changed the hydrolytic activity of the enzyme.

Cancer-associated splicing variant of tumor suppressor AIMP2/p38: pathological implication in tumorigenesis

Although ARS-interacting multifunctional protein 2 (AIMP2, also named as MSC p38) was first found as a component for a macromolecular tRNA synthetase complex, it was recently discovered to dissociate from the complex and work as a potent tumor suppressor. Upon DNA damage, AIMP2 promotes apoptosis through the protective interaction with p53. However, it was not demonstrated whether AIMP2 was indeed pathologically linked to human cancer. In this work, we found that a splicing variant of AIMP2 lacking exon 2 (AIMP2-DX2) is highly expressed by alternative splicing in human lung cancer cells and patient's tissues. AIMP2-DX2 compromised pro-apoptotic activity of normal AIMP2 through the competitive binding to p53. The cells with higher level of AIMP2-DX2 showed higher propensity to form anchorage-independent colonies and increased resistance to cell death. Mice constitutively expressing this variant showed increased susceptibility to carcinogen-induced lung tumorigenesis. The expression ratio of AIMP2-DX2 to normal AIMP2 was increased according to lung cancer stage and showed a positive correlation with the survival of patients. Thus, this work identified an oncogenic splicing variant of a tumor suppressor, AIMP2/p38, and suggests its potential for anti-cancer target.

Lung cancer is one of the most common cancers and a leading cause of death resulting from cancer. Despite intensive investigation, effective therapeutic targets and reliable biomarkers are still limited. Here we found that a tumor suppressor, AIMP2 (MSC p38), produces a variant lacking a part of its structure in cancer tissues. We designated it AIMP2-DX2. This smaller version of AIMP2 compromises the normal tumor suppressive activity of AIMP2 and induces tumor formation. We also found that the expression of AIMP2-DX2 was increased according to cancer progression. In addition, the patients with higher expression of AIMP2-DX2 showed lower survival than those with lower levels of this variant. Suppression of AIMP2-DX2 slowed tumor growth, suggesting it as a new therapeutic target. In summary, this work newly identified a tumor-inducing factor, AIMP2-DX2, that can be used as a therapeutic target and biomarker associated with lung cancer.

Caveolae-mediated entry of Salmonella typhimurium into senescent nonphagocytotic host cells

Elderly individuals have an increased susceptibility to microbial infections because of age-related anatomical, physiological, and environmental factors. However, the mechanism of aging-dependent susceptibility to infection is not fully understood. Here, we found that caveolae-dependent endocytosis is elevated in senescent cells. Thus, we focused on the implications of caveolae-dependent endocytosis using Salmonella typhimurium, which causes a variety of diseases in humans and animals by invading the eukaryotic host cell. Salmonella invasion increased in nonphagocytotic senescent host cells in which caveolin-1 was also increased. When caveolae structures were disrupted by methyl-β-cyclodextrin or siRNA of caveolin-1 in the senescent cells, Salmonellae invasion was reduced markedly compared to that in nonsenescent cells. In contrast, the over-expression of caveolin-1 led to increased Salmonellae invasion in nonsenescent cells. Moreover, in aged mice, caveolin-1 was found to be highly expressed in Peyer’s patch and spleen, which are targets for infection by Salmonellae. These results suggest that high levels of caveolae and caveolin-1 in senescent host cells might be related to the increased susceptibility of elderly individuals to microbial infections.

Identification of gp96 as a novel target for treatment of autoimmune disease in mice

Heat shock proteins have been implicated as endogenous activators for dendritic cells (DCs). Chronic expression of heat shock protein gp96 on cell surfaces induces significant DC activations and systemic lupus erythematosus (SLE)-like phenotypes in mice. However, its potential as a therapeutic target against SLE remains to be evaluated. In this work, we conducted chemical approach to determine whether SLE-like phenotypes can be compromised by controlling surface translocation of gp96. From screening of chemical library, we identified a compound that binds and suppresses surface presentation of gp96 by facilitating its oligomerization and retrograde transport to endoplasmic reticulum. In vivo administration of this compound reduced maturation of DCs, populations of antigen presenting cells, and activated B and T cells. The chemical treatment also alleviated the SLE-associated symptoms such as glomerulonephritis, proteinuria, and accumulation of anti-nuclear and -DNA antibodies in the SLE model mice resulting from chronic surface exposure of gp96. These results suggest that surface translocation of gp96 can be chemically controlled and gp96 as a potential therapeutic target to treat autoimmune disease like SLE.

Caveolae-mediated entry of Salmonella typhimurium in a human M-cell model

Intestinal M cells in Peyer's patches, the specialized antigen-sampling cells of the mucosal immune system, are exploited by Salmonella and other pathogens as a route of invasion. Thus, M cells have attracted lots of attention as a major target of the mucosal immune system. Here, we report that caveolin-1 plays a crucial role in the entry of Salmonella into M cells. We established an in vitro M-like cell model in which polarized enterocyte-like Caco-2 cells created after co-culturing with the Raji B cell line that underwent a phenotypic switch to a form that morphologically and functionally resembles the specialized antigen-transporting M cells. Caveolin-1 was highly expressed in the M-like cells, while not in Caco-2 cells, and a great number of Salmonella infected caveolin-1-expressing M-like cells. To elucidate the role of caveolin-1 in the entry of Salmonella, we downregulated caveolin-1 expression by siRNA and analyzed the level of Salmonella transcytosis across the M-like cells. Transcytosis of Salmonella was markedly reduced by downregulation of caveolin-1 in the M-like cells. These results suggest that caveolin-1 is implicated in the gateway of microbial pathogens through M cells, and, thus, provides a new target of mucosal immunity.

LysRS serves as a key signaling molecule in the immune response by regulating gene expression

Lysyl-tRNA synthetase (LysRS) was found to produce diadenosine tetraphosphate (Ap(4)A) in vitro more than two decades ago. Here, we used LysRS silencing in mast cells in combination with transfected normal and mutated LysRS to demonstrate in vivo the critical role played by LysRS in the production of Ap(4)A in response to immunological challenge. Upon such challenge, LysRS was phosphorylated on serine 207 in a MAPK-dependent manner, released from the multisynthetase complex, and translocated into the nucleus. We previously demonstrated that LysRS forms a complex with MITF and its repressor Hint-1, which is released from the complex by its binding to Ap(4)A, enabling MITF to transcribe its target genes. Here, silencing LysRS led to reduced Ap(4)A production in immunologically activated cells, which resulted in a lower level of MITF inducible genes. Our data demonstrate that specific LysRS serine 207 phosphorylation regulates Ap(4)A production in immunologically stimulated mast cells, thus implying that LysRS is a key mediator in gene regulation.

AIMP2 promotes TNFalpha-dependent apoptosis via ubiquitin-mediated degradation of TRAF2

AIMP2 (aminoacyl-tRNA synthetase interacting multifunctional protein 2; also known as JTV-1) was first identified as p38 in a macromolecular protein complex that consisted of nine different aminoacyl-tRNA synthetases and two other auxiliary factors. AIMP2 also plays pivotal roles in the regulation of cell proliferation and death. Although AIMP2 was previously shown to augment TNFalpha-induced cell death, its working mechanism in this signal pathway was not understood. Here, we investigate the functional significance and mode of action of AIMP2 in TNFalpha signaling. TNFalpha-induced cell death was compromised in AIMP2-deficient or -suppressed cells and exogenous supplementation of AIMP2 augmented apoptotic sensitivity to TNFalpha signaling. This activity was confirmed by the AIMP2-dependent increase of IkappaB and suppression of NFkappaB. We found binding of AIMP2 to TRAF2, a key player in the TNFalpha signaling pathway. AIMP2 augmented the association of an E3 ubiquitin ligase, c-IAP1, with TRAF2, causing ubiquitin-dependent degradation of TRAF2. These findings suggest that AIMP2 can mediate the pro-apoptotic activity of TNFalpha via the downregulation of TRAF2 expression.

MUC19 expression in human ocular surface and lacrimal gland and its alteration in Sjögren syndrome patients

This study investigated the expression of MUC19, a newly discovered gel-forming mucin gene, in normal human lacrimal functional unit components and its alteration in Sjögren syndrome patients. Real-time PCR and immunohistochemistry were performed to determine the expression of MUC19 and MUC5AC in human cornea, conjunctiva, and lacrimal gland tissues. Conjunctival impression cytology specimens were collected from normal control subjects and Sjögren syndrome patients for Real-time PCR, PAS staining, and immunohistochemistry assays. In addition, conjunctiva biopsy specimens from both groups were examined for the expression differences of MUC19 and MUC5AC at both mRNA and protein level. The MUC19 mRNA was found to be present in cornea, conjunctiva and lacrimal gland tissues. The immunohistochemical staining of mucins showed that MUC19 was expressed in epithelial cells from corneal, conjunctival, and lacrimal gland tissues. In contrast, MUC5AC mRNA was only present in conjunctiva and lacrimal gland tissues, but not in cornea. Immunostaining demonstrates the co-staining of MUC19 and MUC5AC in conjunctival goblet cells. Consistent with the significant decrease of mucous secretion, both MUC19 and MUC5AC were decreased in conjunctiva of Sjögren syndrome patients compared to normal subjects. Considering the contribution of gel-forming mucins to the homeostasis of the ocular surface, the decreased expression of MUC19 and MUC5AC in Sjögren syndrome patients suggested that these mucins may be involved in the disruption of the ocular surface homeostasis in this disease.