Elevated circulating follistatin associates with increased risk of mortality and cardiometabolic disorders.

BACKGROUND AND AIMS: Previous study showed that elevated circulating hepatokine follistatin (FST) associates with an increased risk of type 2 diabetes by inducing adipose tissue insulin resistance. Here we explore further the relationships between plasma FST levels with mortality and health outcomes. METHODS AND RESULTS: The population-based Malmö Diet Cancer cardiovascular cohort (n = 4733, age 45-68 years) was used to study plasma FST in relation to incidence of health outcomes, by linkage with national patient registers. Cox regression analysis was used to assess the associations of plasma FST and outcomes, with adjustments for multiple potential confounding factors. During the mean follow-up time of 22.64 ± 5.84 years in 4,733 individuals, 526 had incident stroke, 432 had ischemic stroke, 530 had incident coronary events (CE), 339 had incident heart failure (HF), 320 had incident chronic kidney disease (CKD) and 1,843 individuals died. Hazard ratio (HR) per standard deviation increase in FST levels adjusted for multiple risk factors was 1.05 (95%CI: 1.00-1.11, p = 0.036) for mortality; 1.10 (95%CI: 1.00-1.20, p = 0.042) for stroke; 1.13 (95%CI: 1.03-1.25, p = 0.014) for ischemic stroke; 1.16 (95%CI: 1.03-1.30, p = 0.015) for HF; and 1.38 (95%CI: 1.12-1.70, p = 0.003) for a diagnosis of CKD. In MDC-CC individuals without prevalent or incident diabetes, the association between FST and stroke, CE and CKD remained significant; but not with mortality or HF. CONCLUSIONS: Elevated circulating FST associates with an increased risk of mortality and HF, which partly may be mediated by diabetes. FST also associated with stroke, ischemic stroke, CE and CKD, independently of established risk factors including diabetes.

Intracellular Reverse Transcription of Pfizer BioNTech COVID-19 mRNA Vaccine BNT162b2 In Vitro in Human Liver Cell Line.

Preclinical studies of COVID-19 mRNA vaccine BNT162b2, developed by Pfizer and BioNTech, showed reversible hepatic effects in animals that received the BNT162b2 injection. Furthermore, a recent study showed that SARS-CoV-2 RNA can be reverse-transcribed and integrated into the genome of human cells. In this study, we investigated the effect of BNT162b2 on the human liver cell line Huh7 in vitro. Huh7 cells were exposed to BNT162b2, and quantitative PCR was performed on RNA extracted from the cells. We detected high levels of BNT162b2 in Huh7 cells and changes in gene expression of long interspersed nuclear element-1 (LINE-1), which is an endogenous reverse transcriptase. Immunohistochemistry using antibody binding to LINE-1 open reading frame-1 RNA-binding protein (ORFp1) on Huh7 cells treated with BNT162b2 indicated increased nucleus distribution of LINE-1. PCR on genomic DNA of Huh7 cells exposed to BNT162b2 amplified the DNA sequence unique to BNT162b2. Our results indicate a fast up-take of BNT162b2 into human liver cell line Huh7, leading to changes in LINE-1 expression and distribution. We also show that BNT162b2 mRNA is reverse transcribed intracellularly into DNA in as fast as 6 h upon BNT162b2 exposure.

Epigenome-Wide Histone Acetylation Changes in Peripheral Blood Mononuclear Cells in Patients with Type 2 Diabetes and Atherosclerotic Disease.

There is emerging evidence of an association between epigenetic modifications, glycemic control and atherosclerosis risk. In this study, we mapped genome-wide epigenetic changes in patients with type 2 diabetes (T2D) and advanced atherosclerotic disease. We performed chromatin immunoprecipitation sequencing (ChIP-seq) using a histone 3 lysine 9 acetylation (H3K9ac) mark in peripheral blood mononuclear cells from patients with atherosclerosis with T2D (n = 8) or without T2D (ND, n = 10). We mapped epigenome changes and identified 23,394 and 13,133 peaks in ND and T2D individuals, respectively. Out of all the peaks, 753 domains near the transcription start site (TSS) were unique to T2D. We found that T2D in atherosclerosis leads to an H3K9ac increase in 118, and loss in 63 genomic regions. Furthermore, we discovered an association between the genomic locations of significant H3K9ac changes with genetic variants identified in previous T2D GWAS. The transcription factor 7-like 2 (TCF7L2) rs7903146, together with several human leukocyte antigen (HLA) variants, were among the domains with the most dramatic changes of H3K9ac enrichments. Pathway analysis revealed multiple activated pathways involved in immunity, including type 1 diabetes. Our results present novel evidence on the interaction between genetics and epigenetics, as well as epigenetic changes related to immunity in patients with T2D and advanced atherosclerotic disease.

Elevated circulating follistatin associates with an increased risk of type 2 diabetes.

The hepatokine follistatin is elevated in patients with type 2 diabetes (T2D) and promotes hyperglycemia in mice. Here we explore the relationship of plasma follistatin levels with incident T2D and mechanisms involved. Adjusted hazard ratio (HR) per standard deviation (SD) increase in follistatin levels for T2D is 1.24 (CI: 1.04-1.47, p < 0.05) during 19-year follow-up (n = 4060, Sweden); and 1.31 (CI: 1.09-1.58, p < 0.01) during 4-year follow-up (n = 883, Finland). High circulating follistatin associates with adipose tissue insulin resistance and non-alcoholic fatty liver disease (n = 210, Germany). In human adipocytes, follistatin dose-dependently increases free fatty acid release. In genome-wide association study (GWAS), variation in the glucokinase regulatory protein gene (GCKR) associates with plasma follistatin levels (n = 4239, Sweden; n = 885, UK, Italy and Sweden) and GCKR regulates follistatin secretion in hepatocytes in vitro. Our findings suggest that GCKR regulates follistatin secretion and that elevated circulating follistatin associates with an increased risk of T2D by inducing adipose tissue insulin resistance.

Detection of SARS-CoV-2 by rapid antigen tests on saliva in hospitalized patients with COVID-19.

BACKGROUND: The COVID-19 pandemic presents great challenges on transmission prevention, and rapid diagnosis is essential to reduce the disease spread. Various diagnostic methods are available to identify an ongoing infection by nasopharyngeal (NPH) swab sampling. However, the procedure requires handling by health care professionals, and therefore limits the application in household and community settings. OBJECTIVES: In this study, we aimed to determine if the detection of SARS-CoV-2 can be performed alternatively on saliva specimens by rapid antigen test. STUDY DESIGN: Saliva and NPH specimens were collected from 44 patients with confirmed COVID-19. To assess the diagnostic accuracy of point-of-care SARS-CoV-2 rapid antigen test on saliva specimens, we compared the performance of four test products. RESULTS: RT-qPCR was performed and NPH and saliva sampling had similar Ct values, which associated with disease duration. All four antigen tests showed similar trend in detecting SARS-CoV-2 in saliva, but with variation in the ability to detect positive cases. The rapid antigen test with the best performance could detect up to 67% of the positive cases with Ct values lower than 25, and disease duration shorter than 10 days. CONCLUSION: Our study therefore supports saliva testing as an alternative diagnostic procedure to NPH testing, and that rapid antigen test on saliva provides a potential complement to PCR test to meet increasing screening demand.

FS-GBDT: identification multicancer-risk module via a feature selection algorithm by integrating Fisher score and GBDT.

Cancer is a highly heterogeneous disease caused by dysregulation in different cell types and tissues. However, different cancers may share common mechanisms. It is critical to identify decisive genes involved in the development and progression of cancer, and joint analysis of multiple cancers may help to discover overlapping mechanisms among different cancers. In this study, we proposed a fusion feature selection framework attributed to ensemble method named Fisher score and Gradient Boosting Decision Tree (FS-GBDT) to select robust and decisive feature genes in high-dimensional gene expression datasets. Joint analysis of 11 human cancers types was conducted to explore the key feature genes subset of cancer. To verify the efficacy of FS-GBDT, we compared it with four other common feature selection algorithms by Support Vector Machine (SVM) classifier. The algorithm achieved highest indicators, outperforms other four methods. In addition, we performed gene ontology analysis and literature validation of the key gene subset, and this subset were classified into several functional modules. Functional modules can be used as markers of disease to replace single gene which is difficult to be found repeatedly in applications of gene chip, and to study the core mechanisms of cancer.

Post-outbreak serological screening for SARS-CoV-2 infection in healthcare workers at a Swedish University Hospital.

BACKGROUND: Nosocomial outbreaks of coronavirus disease 2019 (COVID-19) can have devastating consequences from both a resource cost and patient healthcare perspective. Relying on reverse transcription-polymerase chain reaction (RT-PCR) for identifying infected individuals may result in missed cases. Screening for antibodies after an outbreak can help to find missed cases and better illuminate routes of transmission. METHODS: In this study, we present the results of a serological screening of the healthcare workers (HCWs) on a ward for infectious diseases in Sweden with a point-of-care antibody test 8 weeks after an outbreak of COVID-19. In all, 107/123 (87%) of HCWs who were tested with RT-PCR in the outbreak investigation participated in this study on seroprevalence. Participants were also asked to fill out a questionnaire entailing epidemiological data. The cohort was stratified by RT-PCR result and the resulting groups were compared to each other. RESULTS: Six (8%) HCWs who were tested RT-PCR negative during the outbreak investigation had developed specific IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These HCWs had all worked shifts with colleagues who later were tested RT-PCR positive during the outbreak. CONCLUSIONS: Our results indicate that a serological follow-up screening after an outbreak may be used as a complement to virus detection in an outbreak situation. However, immunoglobulin (Ig) G-detection should also be performed at the start of an outbreak, to facilitate interpretation of the results.

Association between SARS-CoV-2 and exposure risks in health care workers and university employees - a cross-sectional study.

BACKGROUND: In health care workers SARS-CoV-2 has been shown to be an occupational health risk, often associated with transmission between health care workers. Yet, insufficient information on transmission dynamics has been presented to elucidate the precise risk factors for contracting SARS-CoV-2 in this group. METHODS: In this cross-sectional study, we investigated association between questionnaire answers on potential exposure situations and SARS-CoV-2-positivity. Health care workers with and without COVID-19-patient contact at nine units at Skåne University Hospitals in Malmö and Lund, Sweden and university employees from Lund University, Sweden were enrolled. To limit impact of health care worker to health care worker transmission, units with known outbreaks were excluded. A SARS-CoV-2-positive case was defined by a previous positive PCR or anti-SARS-CoV-2 IgG in the ZetaGene COVID-19 Antibody Test. RESULTS: SARS-CoV-2-positivity was detected in 11/51 (22%) health care workers in COVID-19-units, 10/220 (5%) in non-COVID-19-units and 11/192 (6%) University employees (p = .001, Fischer's exact). In health care workers, SARS-CoV-2-positivity was associated with work in a designated COVID-19-unit (OR 5.7 (95CI 2.1-16)) and caring for COVID-19-patients during the majority of shifts (OR 5.4 (95CI 2.0-15)). In all participants, SARS-CoV-2-positivity was associated with a confirmed COVID-19 case (OR 10 (95CI 2.0-45)) in the household. CONCLUSION: Our study confirmed previous findings of elevated risk of acquiring SARS-CoV-2 in health care workers in COVID-19-units, despite exclusion of units with known outbreaks. Interestingly, health care workers in non-COVID-19-units had similar risk as University employees. Further measures to improve the safety of health care workers might be needed.KEY POINTSPrevious findings of elevated risk of contracting SARS-CoV-2 in health care workers with COVID-19 patient contact was confirmed, despite exclusion of wards with known SARS-CoV-2 outbreaks. Further measures to improve the safety of health care workers might be needed.

Serology assessment of antibody response to SARS-CoV-2 in patients with COVID-19 by rapid IgM/IgG antibody test.

The coronavirus disease 2019 (COVID-19) pandemic has created a global health- and economic crisis. Detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which causes COVID-19 by serological methods is important to diagnose a current or resolved infection. In this study, we applied a rapid COVID-19 IgM/IgG antibody test and performed serology assessment of antibody response to SARS-CoV-2. In PCR-confirmed COVID-19 patients (n = 45), the total antibody detection rate is 92% in hospitalized patients and 79% in non-hospitalized patients. The total IgM and IgG detection is 63% in patients with <2 weeks from disease onset; 85% in non-hospitalized patients with >2 weeks disease duration; and 91% in hospitalized patients with >2 weeks disease duration. We also compared different blood sample types and suggest a higher sensitivity by serum/plasma over whole blood. Test specificity was determined to be 97% on 69 sera/plasma samples collected between 2016-2018. Our study provides a comprehensive validation of the rapid COVID-19 IgM/IgG serology test, and mapped antibody detection patterns in association with disease progress and hospitalization. Our results support that the rapid COVID-19 IgM/IgG test may be applied to assess the COVID-19 status both at the individual and at a population level.

Peptide YY (1-36) peptides from phylogenetically ancient fish targeting mammalian neuropeptide Y1 receptors demonstrate potent effects on pancreatic ß-cell function, growth and survival.

AIM: To investigate the antidiabetic efficacy of enzymatically stable Peptide YY (PYY) peptides from phylogenetically ancient fish. MATERIALS AND METHODS: N-terminally stabilized, PYY (1-36) sequences from Amia calva (bowfin), Oncorhynchus mykiss (trout), Petromyzon marinus (sea lamprey) and Scaphirhynchus albus (sturgeon), were synthesized, and both biological actions and antidiabetic therapeutic efficacy were assessed. RESULTS: All fish PYY (1-36) peptides were resistant to dipeptidyl peptidase-4 (DPP-4) degradation and inhibited glucose- and alanine-induced (P < 0.05 to P < 0.001) insulin secretion. In addition, PYY (1-36) peptides imparted significant (P < 0.05 to P < 0.001) ß-cell proliferative and anti-apoptotic benefits. Proliferative effects were almost entirely absent in ß cells with CRISPR-Cas9-induced knockout of Npyr1. In contrast to human PYY (1-36), the piscine-derived peptides lacked appetite-suppressive actions. Twice-daily administration of sea lamprey PYY (1-36), the superior bioactive peptide, for 21 days significantly (P < 0.05 to P < 0.001) decreased fluid intake, non-fasting glucose and glucagon in streptozotocin (STZ)-induced diabetic mice. In addition, glucose tolerance, insulin sensitivity, pancreatic insulin and glucagon content were significantly improved. Metabolic benefits were linked to positive changes in pancreatic islet morphology as a result of augmented (P < 0.001) proliferation and decreased apoptosis of ß cells. Sturgeon PYY (1-36) exerted similar but less impressive effects in STZ mice. CONCLUSION: These observations reveal, for the first time, that PYY (1-36) peptide sequences from phylogenetically ancient fish replicate the pancreatic ß-cell benefits of human PYY (1-36) and have clear potential for the treatment of type 2 diabetes.

PTPD: predicting therapeutic peptides by deep learning and word2vec.

*: Background In the search for therapeutic peptides for disease treatments, many efforts have been made to identify various functional peptides from large numbers of peptide sequence databases. In this paper, we propose an effective computational model that uses deep learning and word2vec to predict therapeutic peptides (PTPD). *: Results Representation vectors of all k-mers were obtained through word2vec based on k-mer co-existence information. The original peptide sequences were then divided into k-mers using the windowing method. The peptide sequences were mapped to the input layer by the embedding vector obtained by word2vec. Three types of filters in the convolutional layers, as well as dropout and max-pooling operations, were applied to construct feature maps. These feature maps were concatenated into a fully connected dense layer, and rectified linear units (ReLU) and dropout operations were included to avoid over-fitting of PTPD. The classification probabilities were generated by a sigmoid function. PTPD was then validated using two datasets: an independent anticancer peptide dataset and a virulent protein dataset, on which it achieved accuracies of 96% and 94%, respectively. *: Conclusions PTPD identified novel therapeutic peptides efficiently, and it is suitable for application as a useful tool in therapeutic peptide design.

Interaction of Serum-Derived and Internalized C3 With DNA in Human B Cells-A Potential Involvement in Regulation of Gene Transcription.

Beside its classical role as a serum effector system of innate immunity, evidence is accumulating that complement has an intracellular repertoire of components that provides not only immune defense, but also functions to maintain cellular homeostasis. While complement proteins, mainly the central component C3, have been detected in B cells, their exact function and source remain largely unexplored. In this study, we investigated the expression and origin of intracellular C3 in human B cells together with its role in B cell homeostasis. Our data provide evidence that endogenous expression of C3 is very low in human B cells and, in accordance with the recent publication, the main origin of intracellular C3 is the serum. Interestingly, we found that both serum-derived and purified C3 are able to enter the nucleus of viable B cells, suggesting its potential involvement in regulation of gene transcription. ELISA, gel shift assay, confocal microscopy, and chromatin immunoprecipitation proved that C3 and C3a strongly bind to nuclear DNA, and among the interacting genes there are key factors of lymphocyte development and differentiation. The strong interaction of C3 with histone proteins and its potential ability to induce chromatin rearrangement suggest that C3/C3a might regulate DNA transcription via chromatin remodeling. Our data reveal a novel, hitherto undescribed role of C3 in immune cell homeostasis, which further extends the repertoire how complement links innate and adaptive immunity and regulates basic processes of the cells.

Preserving Insulin Secretion in Diabetes by Inhibiting VDAC1 Overexpression and Surface Translocation in ß Cells.

Type 2 diabetes (T2D) develops after years of prediabetes during which high glucose (glucotoxicity) impairs insulin secretion. We report that the ATP-conducting mitochondrial outer membrane voltage-dependent anion channel-1 (VDAC1) is upregulated in islets from T2D and non-diabetic organ donors under glucotoxic conditions. This is caused by a glucotoxicity-induced transcriptional program, triggered during years of prediabetes with suboptimal blood glucose control. Metformin counteracts VDAC1 induction. VDAC1 overexpression causes its mistargeting to the plasma membrane of the insulin-secreting ß cells with loss of the crucial metabolic coupling factor ATP. VDAC1 antibodies and inhibitors prevent ATP loss. Through direct inhibition of VDAC1 conductance, metformin, like specific VDAC1 inhibitors and antibodies, restores the impaired generation of ATP and glucose-stimulated insulin secretion in T2D islets. Treatment of db/db mice with VDAC1 inhibitor prevents hyperglycemia, and maintains normal glucose tolerance and physiological regulation of insulin secretion. Thus, ß cell function is preserved by targeting the novel diabetes executer protein VDAC1.

A novel model for protein sequence similarity analysis based on spectral radius.

Advances in sequencing technologies led to rapid increase in the number and diversity of biological sequences, which facilitated development in the sequence research. In this paper, we present a new method for analyzing protein sequence similarity. We calculated the spectral radii of 20 amino acids (AAs) and put forward a novel 2-D graphical representation of protein sequences. To characterize protein sequences numerically, three groups of features were extracted and related to statistical, dynamics measurements and fluctuation complexity of the sequences. With the obtained feature vector, two models utilizing Gaussian Kernel similarity and Cosine similarity were built to measure the similarity between sequences. We applied our method to analyze the similarities/dissimilarities of four data sets. Both proposed models received consistent results with improvements when compared to that obtained by the ClustalW analysis. The novel approach we present in this study may therefore benefit protein research in medical and scientific fields.

Role of osteopontin and its regulation in pancreatic islet.

Osteopontin (OPN) is involved in various physiological processes and also implicated in multiple pathological states. It has been suggested that OPN may have a role in type 2 diabetes (T2D) by protecting pancreatic islets and interaction with incretins. However, the regulation and function of OPN in islets, especially in humans, remains largely unexplored. In this study, we performed our investigations on both diabetic mouse model SUR1-E1506K+/+ and islets from human donors. We demonstrated that OPN protein, secretion and gene expression was elevated in the diabetic SUR1-E1506K+/+ islets. We also showed that high glucose and incretins simultaneously stimulated islet OPN secretion. In islets from human cadaver donors, OPN gene expression was elevated in diabetic islets, and externally added OPN significantly increased glucose-stimulated insulin secretion (GSIS) from diabetic but not normal glycemic donors. The increase in GSIS by OPN in diabetic human islets was Ca2+ dependent, which was abolished by Ca2+-channel inhibitor isradipine. Furthermore, we also confirmed that OPN promoted cell metabolic activity when challenged by high glucose. These observations provided evidence on the protective role of OPN in pancreatic islets under diabetic condition, and may point to novel therapeutic targets for islet protection in T2D.

Regulation of Nuclear Receptor Interacting Protein 1 (NRIP1) Gene Expression in Response to Weight Loss and Exercise in Humans.

OBJECTIVE: Nuclear receptor interacting protein 1 (NRIP1) is an important energy regulator, but few studies have addressed its role in humans. This study investigated adipose tissue and skeletal muscle NRIP1 gene expression and serum levels in response to weight loss and exercise in humans. METHODS: NRIP1 expression was measured by microarray and serum NRIP1 by ELISA and Western blotting. Skeletal muscle transcriptomes were analyzed from Gene Expression Omnibus databases. Network-based proximity analysis was performed on the proximity of NRIP1 interacting genes in the human interactome. RESULTS: In patients with obesity, adipose tissue NRIP1 mRNA expression increased during weight loss and weight maintenance and showed strong associations with metabolic markers and anthropometric parameters. Serum NRIP1 protein levels also increased after weight loss. In skeletal muscle, imposed rest increased NRIP1 expression by 80%, and strength training increased expression by ∼25% compared to baseline. Following rest, NRIP1 expression became sensitive to insulin stimulation. After re-training, NRIP1 expression decreased. Interactome analysis showed significant proximity of NRIP1 interacting partners to the obesity network/module. CONCLUSIONS: NRIP1 gene expression and serum levels are strongly associated with metabolic states such as obesity, weight loss, different types of exercise, and peripheral tissue insulin resistance, potentially as a mediator of sedentary effects.

Histone acetylation of glucose-induced thioredoxin-interacting protein gene expression in pancreatic islets.

Thioredoxin-interacting protein (TXNIP) has been shown to be associated with glucose-induced deterioration of pancreatic beta cell function in diabetes. However, whether epigenetic mechanisms contribute to the regulation of TXNIP gene expression by glucose is not clear. Here we studied how glucose exerts its effect on TXNIP gene expression via modulation of histone acetylation marks. To achieve this, we applied clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) to knock out histone acetyltransferase (HAT) p300 in a rat pancreatic beta cell line INS1 832/13. We also treated the cells and human islets with chemical inhibitors of HAT p300 and histone deacetylase (HDAC). In human islets, diabetes and high glucose resulted in elevated TXNIP and EP300 expression, and glucose-induced TXNIP expression could be reversed by p300 inhibitor C646. In INS1 832/13 cells, Ep300 knock-out by CRISPR/Cas9 elevated glucose-induced insulin secretion and greatly reduced glucose-stimulated Txnip expression and cell apoptosis. This effect could be ascribed to decrease in histone marks H3K9ac and H4ac at the promoter and first coding region of the Txnip gene. Histone marks H3K9ac and H4ac in the Txnip gene in the wild-type cells was inhibited by HDAC inhibitor at high glucose, which most likely was due to enhanced acetylation levels of p300 after HDAC inhibition; and thereby reduced p300 binding to the Txnip gene promoter region. Such inhibition was absent in the Ep300 knock-out cells. Our study provides evidence that histone acetylation serves as a key regulator of glucose-induced increase in TXNIP gene expression and thereby glucotoxicity-induced apoptosis.

Discriminative Prediction of A-To-I RNA Editing Events from DNA Sequence.

RNA editing is a post-transcriptional alteration of RNA sequences that, via insertions, deletions or base substitutions, can affect protein structure as well as RNA and protein expression. Recently, it has been suggested that RNA editing may be more frequent than previously thought. A great impediment, however, to a deeper understanding of this process is the paramount sequencing effort that needs to be undertaken to identify RNA editing events. Here, we describe an in silico approach, based on machine learning, that ameliorates this problem. Using 41 nucleotide long DNA sequences, we show that novel A-to-I RNA editing events can be predicted from known A-to-I RNA editing events intra- and interspecies. The validity of the proposed method was verified in an independent experimental dataset. Using our approach, 203 202 putative A-to-I RNA editing events were predicted in the whole human genome. Out of these, 9% were previously reported. The remaining sites require further validation, e.g., by targeted deep sequencing. In conclusion, the approach described here is a useful tool to identify potential A-to-I RNA editing events without the requirement of extensive RNA sequencing.

Epigenetic regulation of the thioredoxin-interacting protein (TXNIP) gene by hyperglycemia in kidney.

Diabetic kidney disease is the leading cause of end-stage renal disease. Genetic factors have been suggested to contribute to its susceptibility. However, results from genetic studies are disappointing possibly because the role of glucose in diabetic kidney disease predisposed by epigenetic mechanisms has not been taken into account. Since thioredoxin-interacting protein (TXNIP) has been shown to play an important role in the pathogenesis of diabetic kidney disease, we tested whether glucose could induce expression of TXNIP in the kidney by epigenetic mechanisms. In kidneys from diabetic Sur1-E1506K(+/+) mice, hyperglycemia-induced Txnip expression was associated with stimulation of activating histone marks H3K9ac, H3K4me3, and H3K4me1, as well as decrease in the repressive histone mark H3K27me3 at the promoter region of the gene. Glucose also coordinated changes in histone marks and TXNIP gene expression in mouse SV40 MES13 mesangial cells and the normal human mesangial cell line NHMC. The involvement of histone acetylation in glucose-stimulated TXNIP expression was confirmed by reversing or enhancing acetylation using the histone acetyltransferase p300 inhibitor C646 or the histone deacetylase inhibitor trichostatin A. Thus, glucose is a potent inducer of histone modifications, which could drive expression of proinflammatory genes and thereby predispose to diabetic kidney disease.

Epigenetic regulation of glucose-stimulated osteopontin (OPN) expression in diabetic kidney.

Diabetes nephropathy (DN) is the leading cause of end stage renal disease and it affects up to 40% of diabetic patients. In addition to hyperglycemia, genetic factors are thought to contribute to the development of DN, but few if any genetic factors have been convincingly linked to DN. Other possible mechanisms may involve epigenetic regulation of glucose-stimulated gene activity which was suggested to explain long-term effects of poor glycemic control on risk of diabetic complications, often referred to as metabolic memory. Osteopontin (OPN) is one of the genes upregulated in kidneys from diabetic mouse models as well as humans with DN, and suggested to play an important role in the pathogenesis of DN. In this study, we demonstrated that OPN gene expression is upregulated in the kidneys of a hyperglycemia diabetes mouse model SUR1-E1506K, and glucose-stimulated OPN gene expression is strongly associated with increases in activating histone marks H3K9ac, H3K4me1 and H3K4me3 and decrease in inactivating mark H3K27me3 in the promoter region of OPN gene. These findings were replicated in human mesangial cells treated with high glucose. Further proof for the involvement of histone acetylation and methylation in glucose-induced changes in OPN gene expression was obtained by manipulating histone modifications thereby OPN gene expression by histone deacetylase (HDAC) inhibitor trichostatin A and histone methyltransferase (HMT) inhibitor MM-102. We conclude that glucose is a potent inducer of histone acetylation and methylation, which in turn leads to upregulation of OPN gene expression. Treatment targeting histone marks may therefore represent an alternative method to protect kidneys from deleterious effects of glucose.