Long Noncoding RNA and Epigenomics

Prognostic Value of Drug Targets Predicted Using Deep Bioinformatic Analysis of m6A-Associated lncRNA-Based Pancreatic Cancer Model Characteristics and Its Tumour Microenvironment

The role of N6-methyladenosine (m6A)-associated long-stranded non-coding RNA (lncRNA) in pancreatic cancer is unclear. Therefore, we analysed the characteristics and tumour microenvironment in pancreatic cancer and determined the value of m6A-related lncRNAs for prognosis and drug target prediction. An m6A-lncRNA co-expression network was constructed using The Cancer Genome Atlas database to screen m6A-related lncRNAs. Prognosis-related lncRNAs were screened using univariate Cox regression; patients were divided into high- and low-risk groups and randomised into training and test groups. In the training group, least absolute shrinkage and selection operator (LASSO) was used for regression analysis and to construct a prognostic model, which was validated in the test group. Tumor mutational burden (TMB), immune evasion, and immune function of risk genes were analysed using R; drug sensitivity and potential drugs were examined using the Genomics of Drug Sensitivity in Cancer database. We screened 129 m6A-related lncRNAs; 17 prognosis-related m6A-related lncRNAs were obtained using multivariate analysis and three m6A-related lncRNAs (AC092171.5, MEG9, and AC002091.1) were screened using LASSO regression. Survival rates were significantly higher (p < 0.05) in the low-risk than in the high-risk group. Risk score was an independent predictor affecting survival (p < 0.001), with the highest risk score being obtained by calculating the c-index. The TMB significantly differed between the high- and low-risk groups (p < 0.05). In the high- and low-risk groups, mutations were detected in 61 of 70 samples and 49 of 71 samples, respectively, with KRAS, TP53, and SMAD4 showing the highest mutation frequencies in both groups. A lower survival rate was observed in patients with a high versus low TMB. Immune function HLA, Cytolytic activity, and Inflammation-promoting, T cell co-inhibition, Check-point, and T cell co-stimulation significantly differed in different subgroups (p < 0.05). Immune evasion scores were significantly higher in the high-risk group than in the low-risk group. Eight sensitive drugs were screened: ABT.888, ATRA, AP.24534, AG.014699, ABT.263, axitinib, A.443654, and A.770041. We screened m6A-related lncRNAs using bioinformatics, constructed a prognosis-related model, explored TMB and immune function differences in pancreatic cancer, and identified potential therapeutic agents, providing a foundation for further studies of pancreatic cancer diagnosis and treatment.

The long noncoding RNA TUNAR modulates Wnt signaling and regulates human β-cell proliferation

Many long noncoding RNAs (lncRNAs) are enriched in pancreatic islets and several lncRNAs are linked to type 2 diabetes (T2D). Although they have emerged as potential players in β-cell biology and T2D, little is known about their functions and mechanisms in human β-cells. We identified an islet-enriched lncRNA, TUNAR (TCL1 upstream neural differentiation-associated RNA), which was upregulated in β-cells of patients with T2D and promoted human β-cell proliferation via fine-tuning of the Wnt pathway. TUNAR was upregulated following Wnt agonism by a glycogen synthase kinase-3 (GSK3) inhibitor in human β-cells. Reciprocally, TUNAR repressed a Wnt antagonist Dickkopf-related protein 3 (DKK3) and stimulated Wnt pathway signaling. DKK3 was aberrantly expressed in β-cells of patients with T2D and displayed a synchronized regulatory pattern with TUNAR at the single cell level. Mechanistically, DKK3 expression was suppressed by the repressive histone modifier enhancer of zeste homolog 2 (EZH2). TUNAR interacted with EZH2 in β-cells and facilitated EZH2-mediated suppression of DKK3. These findings reveal a novel cell-specific epigenetic mechanism via islet-enriched lncRNA that fine-tunes the Wnt pathway and subsequently human β-cell proliferation.NEW & NOTEWORTHY The discovery that long noncoding RNA TUNAR regulates β-cell proliferation may be important in designing new treatments for diabetes.

Effect of silencing lncRNATUG1 on rapamycin-induced inhibition of endothelial cell proliferation and migration

Angiogenesis refers to the formation of new blood vessels from existing blood vessels. The proliferation and migration of endothelial cells serves a key function in this process. Previous research has demonstrated that rapamycin suppresses endothelial cell proliferation and migration, as well as angiogenesis. However, the mechanism by which rapamycin inhibits the proliferation and migration of endothelial cells remains unclear. Long noncoding RNAs (lncRNAs) serve a key function in the regulation of endothelial cell function. The aim of the current study was to investigate whether lncRNA taurine upregulated 1 (lncRNATUG1) is involved in rapamycin-induced inhibition of proliferation and migration in human umbilical vein endothelial cells (HUVECs). Reverse transcription quantitative polymerase chain reaction results indicated that the expression of lncRNATUG1 was upregulated in HUVECs that had been cultured with rapamycin. Subsequently, HUVECs were transfected with siRNAs and CCK-8 assays were performed to detect cell proliferation; additionally, flow cytometry was employed to detect cell apoptosis, and wound healing assays were performed to investigate cell migration. The results demonstrated that rapamycin suppressed the proliferation and migration of HUVECs, and promoted the apoptosis of HUVECs. In addition, rapamycin downregulated the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2 and MMP-9 in HUVECs. However, silencing of lncRNATUG1 was revealed to attenuate rapamycin-induced inhibition of cellular proliferation and migration of HUVECs, as well as upregulating the expression of VEGF, MMP2 and MMP-9. These results suggested that lncRNATUG1 regulates rapamycin-induced inhibition of endothelial cell proliferation and migration. Therefore, lncRNATUG1 may serve a key function in rapamycin-induced inhibition of endothelial cell proliferation and migration.

KDM1A microenvironment, its oncogenic potential, and therapeutic significance

The lysine-specific histone demethylase 1A (KDM1A) was the first demethylase to challenge the concept of the irreversible nature of methylation marks. KDM1A, containing a flavin adenine dinucleotide (FAD)-dependent amine oxidase domain, demethylates histone 3 lysine 4 and histone 3 lysine 9 (H3K4me1/2 and H3K9me1/2). It has emerged as an epigenetic developmental regulator and was shown to be involved in carcinogenesis. The functional diversity of KDM1A originates from its complex structure and interactions with transcription factors, promoters, enhancers, oncoproteins, and tumor-associated genes (tumor suppressors and activators). In this review, we discuss the microenvironment of KDM1A in cancer progression that enables this protein to activate or repress target gene expression, thus making it an important epigenetic modifier that regulates the growth and differentiation potential of cells. A detailed analysis of the mechanisms underlying the interactions between KDM1A and the associated complexes will help to improve our understanding of epigenetic regulation, which may enable the discovery of more effective anticancer drugs.

Differential expression profile of long non-coding RNA in the stenosis tissue of arteriovenous fistula

OBJECTIVE

To analyze and preliminarily validate the lncRNA expression profiles in the stenosis tissue of arteriovenous fistula (AVF).

METHODS

A total of 54 uremic patients administered in the department of nephrology in the First Affiliated Hospital of Nanchang University between February 2017 and March 2017 were included in the study and subsequently categorized as experimental group, which included 12 patients with confirmed diagnosis of AVF, and control group which included 42 patients with no vascular stenosis. The experimental group inclusion criteria include: AVF used >3 months; The blood flow of AVF <200 mL/min; the degree of the stenosis was >50%, excluded obvious thrombosis; The ultrasonographic data of AVF stenosis is complete. The controls were randomly selected from uremic patients who were primary AVF operation, excluded obvious vascular stenosis and vascular diseases. Among them, 4 sample in the experimental group and 4 controls were used in LncRNA sequencing. RNA in vascular tissue was extracted by Trizol and IncRNA sequencing was used to establish the expression profiles of lncRNA in the stenosis tissue of AVF.9 difference expression lncRNA were collected for validating in AVF stenosis cases by using quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, Cluster analysis, gene functional analysis and pathway analysis were used to explore the function of difference expression lncRNA.

RESULTS

Among the 27,692 lncRNA transcripts examined, 247 lncRNAs were found to be significantly differentially expressed (P < 0.05, fold change ≥2) in the experimental group and control group, with 141 being up-regulated and 106 down-regulated. The expression levels of 9 lncRNAs validated by subsequent qRT-PCR were shown to be highly consistent with the sequencing data.

CONCLUSION

Our study revealed lncRNAs expression profiles in the stenosis tissue of AVF by LncRNA sequencing. These lncRNAs and its related signaling pathways may play a key role in the occurrence and progression of AVF stenosis.

ZBTB7A Enhances Osteosarcoma Chemoresistance by Transcriptionally Repressing lncRNALINC00473-IL24 Activity

Chemoresistance remains a major drawback to osteosarcoma treatment. ZBTB7A, a member of the POK transcription repressor family, was shown to play an important role in tumorigenesis. However, the effect of ZBTB7A on osteosarcoma chemoresistance is completely unknown. In this study, we found that ZBTB7A is increased in cisplatin-resistant osteosarcoma cells and that elevated ZBTB7A inhibits cisplatin-induced apoptosis by repressing LINC00473 expression. Further mechanistic studies revealed that ZBTB7A directly binds to the promoter and suppresses the transcription of LINC00473. Additionally, our data indicate that LINC00473 interacts with the transcript factor C/EBPβ, facilitating its binding to the promoter of IL24, leading to decrease chemoresistance. Thus, these findings indicate that the ZBTB7A-mediated LINC00473-C/EBPβ-IL24 pathway is a promising novel target for overcoming cisplatin resistance in osteosarcoma.

Long noncoding RNA HULC modulates the phosphorylation of YB-1 through serving as a scaffold of extracellular signal-regulated kinase and YB-1 to enhance hepatocarcinogenesis

Dysregulated expression of long noncoding RNAs has been reported in many types of cancers, indicating that it may play a critical role in tumorigenesis. The long noncoding RNA highly up-regulated in liver cancer (HULC) was first characterized in hepatocellular carcinoma. However, the detailed mechanisms of HULC remain unclear. Here, we demonstrate a novel mechanism by which long noncoding RNA plays oncogenic roles through modulating the phosphorylation status of its interaction protein. First, we validated the markedly increased expression levels of HULC in hepatocellular carcinoma tissues compared to their adjacent noncancerous tissues. Furthermore, up-regulation of HULC was correlated with grading and overall survival. Meanwhile, HULC could promote cell proliferation, migration, and invasion in vitro and inhibit cisplatin-induced apoptosis. Moreover, we show that HULC specifically binds to Y-box binding protein 1 (YB-1) protein both in vitro and in vivo. YB-1 is a major component of translationally inactive messenger ribonucleoprotein particles which keeps mRNA in a silent state. Our study further demonstrated that HULC could promote the phosphorylation of YB-1 protein, which leads to the release of YB-1 from its bound mRNA. As a consequence, translation of silenced oncogenic mRNAs would be activated, including cyclin D1, cyclin E1, and matrix metalloproteinase 3. In addition, we found that HULC promotes the phosphorylation of YB-1 protein mainly through extracellular signal-regulated kinase.

CONCLUSION

We demonstrate that HULC promotes the phosphorylation of YB-1 through the extracellular signal-regulated kinase pathway, in turn regulates the interaction of YB-1 with certain oncogenic mRNAs, and consequently accelerates the translation of these mRNAs in the process of tumorigenesis. (Hepatology 2017;65:1612-1627).

H19 mediates methotrexate resistance in colorectal cancer through activating Wnt/β-catenin pathway

Colorectal cancer (CRC) is a common malignancy, most of which remain unresponsive to chemotherapy. As one of the earliest cytotoxic drugs, methotrexate (MTX) serves as an anti-metabolite and anti-folate chemotherapy for various cancers. Unfortunately, MTX resistance prevents its clinical application in cancer therapy. Thereby, overcoming the drug resistance is an alternative strategy to maximize the therapeutic efficacy of MTX in clinics. Long noncoding RNAs (lncRNAs) have gained widespread attention in recent years. More and more emerging evidences have demonstrated that they play important regulatory roles in various biological activities and disease progression including drug resistance. In the present study, a MTX-resistant colorectal cell line HT-29 (HT-29-R) was developed, which displayed the active proliferation and shortened cell cycle. LncRNA H19 was found to be significantly upregulated in this resistant cell line. Further investigation showed that H19 knockdown sensitized the MTX resistance in HT-29-R cells while its overexpression improved the MTX resistance in the parental cells, suggesting that H19 mediate MTX resistance. The Wnt/β-catenin signaling was activated in HT-29-R cells, and H19 knockdown suppressed this signaling in the parental cells. In conclusion, H19 mediated MTX resistance via activating Wnt/β-catenin signaling, which help to develop H19 as a promising therapeutic target for MTX resistant CRC.

Infantile Hemangioma Originates From A Dysregulated But Not Fully Transformed Multipotent Stem Cell

Infantile hemangioma (IH) is the most common tumor of infancy. Its cellular origin and biological signals for uncontrolled growth are poorly understood, and specific pharmacological treatment is unavailable. To understand the process of hemangioma-genesis we characterized the progenitor hemangioma-derived stem cell (HemSC) and its lineage and non-lineage derivatives. For this purpose we performed a high-throughput (HT) phenotypic and gene expression analysis of HemSCs, and analyzed HemSC-derived tumorspheres. We found that IH is characterized by high expression of genes involved in vasculogenesis, angiogenesis, tumorigenesis and associated signaling pathways. These results show that IH derives from a dysregulated stem cell that remains in an immature, arrested stage of development. The potential biomarkers we identified can afford the development of diagnostic tools and precision-medicine therapies to "rewire" or redirect cellular transitions at an early stage, such as signaling pathways or immune response modifiers.

Long non-coding RNAs in the regulation of myeloid cells

Long non-coding RNAs (lncRNAs) have been attracting immense research interests. The relevance of lncRNAs in biological and physiological as well as in pathological processes has increased along with the understanding of their various regulatory mechanisms. Abundant studies have indicated that lncRNAs are involved in the differentiation, proliferation, activation, and initiation of apoptosis in different cell types. However, most studies about the regulating biology of lncRNAs are currently focused on cancer cells. This review is focused on the widely unexplored role of lncRNAs in the cell fate of myeloid cells. In this review, we summarize recent studies that have confirmed lncRNAs to be essential in the development of myeloid cells under normal and pathological conditions.

Long noncoding RNAs and neuroblastoma

Neuroblastoma is a disease that affects infants and despite intense multimodal therapy, high-risk patients have low survival rates (<50%). In recent years long noncoding RNAs (lncRNAs) have become the cutting edge of cancer research with inroads made in understanding their roles in multiple cancer types, including prostate and breast cancers. The roles of lncRNAs in neuroblastoma have just begun to be elucidated. This review summarises where we are with regards to lncRNAs in neuroblastoma. The known mechanistic roles of lncRNAs during neuroblastoma pathogenesis are discussed, as well as the relationship between lncRNA expression and the differentiation capacity of neuroblastoma cells. We speculate about the use of some of these lncRNAs, such as those mapping to the 6p22 hotspot, as biomarkers for neuroblastoma prognosis and treatment. This novel way of thinking about both neuroblastoma and lncRNAs brings a new perspective to the prognosis and treatment of high-risk patients.

Characters, functions and clinical perspectives of long non-coding RNAs

It is well established that most of the human genome and those of other mammals and plants are transcribed into RNA without protein-coding capacity, which we define as non-coding RNA. From siRNA to microRNA, whose functions and features have been well characterized, non-coding RNAs have been a popular topic in life science research over the last decade. Long non-coding RNAs (lncRNAs), however, as a novel class of transcripts, are distinguished from these other small RNAs. Recent studies have revealed a diverse population of lncRNAs with different sizes and functions across different species. These populations are expressed dynamically and act as important regulators in a variety of biological processes, especially in gene expression. Nevertheless, the functions and mechanisms of most lncRNAs remain unclear. In this review, we present recent progress in the identification of lncRNAs, their functions and molecular mechanisms, their roles in human diseases, their potential diagnostic and therapeutic applications as well as newer technologies for identifying deregulated lncRNAs in disease tissues.

Familiar Stranger: Ecological Genomics of the Model Saprotroph and Industrial Enzyme Producer Trichoderma reesei Breaks the Stereotypes

The filamentous fungus Trichoderma reesei (Hypocreales, Ascomycota) has properties of an efficient cell factory for protein production that is exploited by the enzyme industry, particularly with respect to cellulase and hemicellulase formation. Under conditions of industrial fermentations it yields more than 100g secreted protein L(-1). Consequently, T. reesei has been intensively studied in the 20th century. Most of these investigations focused on the biochemical characteristics of its cellulases and hemicellulases, on the improvement of their properties by protein engineering, and on enhanced enzyme production by recombinant strategies. However, as the fungus is rare in nature, its ecology remained unknown. The breakthrough in the understanding of the fundamental biology of T. reesei only happened during 2000s-2010s. In this review, we compile the current knowledge on T. reesei ecology, physiology, and genomics to present a holistic view on the natural behavior of the organism. This is not only critical for science-driven further improvement of the biotechnological applications of this fungus, but also renders T. reesei as an attractive model of filamentous fungi with superior saprotrophic abilities.

Epigenetics as an emerging tool for improvement of fungal strains used in biotechnology

Filamentous fungi are today a major source of industrial biotechnology for the production of primary and secondary metabolites, as well as enzymes and recombinant proteins. All of them have undergone extensive improvement strain programs, initially by classical mutagenesis and later on by genetic manipulation. Thereby, strategies to overcome rate-limiting or yield-reducing reactions included manipulating the expression of individual genes, their regulatory genes, and also their function. Yet, research of the last decade clearly showed that cells can also undergo heritable changes in gene expression that do not involve changes in the underlying DNA sequences (=epigenetics). This involves three levels of regulation: (i) DNA methylation, (ii) chromatin remodeling by histone modification, and (iii) RNA interference. The demonstration of the occurrence of these processes in fungal model organisms such as Aspergillus nidulans and Neurospora crassa has stimulated its recent investigation as a tool for strain improvement in industrially used fungi. This review describes the progress that has thereby been obtained.

Long noncoding RNAs: Lessons from genomic imprinting

Genomic imprinting has been a great resource for studying transcriptional and post-transcriptional-based gene regulation by long noncoding RNAs (lncRNAs). In this article, I overview the functional role of intergenic lncRNAs (H19, IPW, and MEG3), antisense lncRNAs (Kcnq1ot1, Airn, Nespas, Ube3a-ATS), and enhancer lncRNAs (IG-DMR eRNAs) to understand the diverse mechanisms being employed by them in cis and/or trans to regulate the parent-of-origin-specific expression of target genes. Recent evidence suggests that some of the lncRNAs regulate imprinting by promoting intra-chromosomal higher-order chromatin compartmentalization, affecting replication timing and subnuclear positioning. Whereas others act via transcriptional occlusion or transcriptional collision-based mechanisms. By establishing genomic imprinting of target genes, the lncRNAs play a critical role in important biological functions, such as placental and embryonic growth, pluripotency maintenance, cell differentiation, and neural-related functions such as synaptic development and plasticity. An emerging consensus from the recent evidence is that the imprinted lncRNAs fine-tune gene expression of the protein-coding genes to maintain their dosage in cell. Hence, lncRNAs from imprinted clusters offer insights into their mode of action, and these mechanisms have been the basis for uncovering the mode of action of lncRNAs in several other biological contexts. This article is part of a Special Issue entitled: Clues to long noncoding RNA taxonomy, edited by Dr. Tetsuro Hirose and Dr. Shinichi Nakagawa.

The risk-associated long noncoding RNA NBAT-1 controls neuroblastoma progression by regulating cell proliferation and neuronal differentiation

Neuroblastoma is an embryonal tumor of the sympathetic nervous system and the most common extracranial tumor of childhood. By sequencing transcriptomes of low- and high-risk neuroblastomas, we detected differentially expressed annotated and nonannotated long noncoding RNAs (lncRNAs). We identified a lncRNA neuroblastoma associated transcript-1 (NBAT-1) as a biomarker significantly predicting clinical outcome of neuroblastoma. CpG methylation and a high-risk neuroblastoma associated SNP on chromosome 6p22 functionally contribute to NBAT-1 differential expression. Loss of NBAT-1 increases cellular proliferation and invasion. It controls these processes via epigenetic silencing of target genes. NBAT-1 loss affects neuronal differentiation through activation of the neuronal-specific transcription factor NRSF/REST. Thus, loss of NBAT-1 contributes to aggressive neuroblastoma by increasing proliferation and impairing differentiation of neuronal precursors.

Epigenetic modifications and potential new treatment targets in diabetic retinopathy

Retinopathy is a debilitating vascular complication of diabetes. As with other diabetic complications, diabetic retinopathy (DR) is characterized by the metabolic memory, which has been observed both in DR patients and in DR animal models. Evidences have provided that after a period of poor glucose control insulin or diabetes drug treatment fails to prevent the development and progression of DR even when good glycemic control is reinstituted (glucose normalization), suggesting a metabolic memory phenomenon. Recent studies also underline the role of epigenetic chromatin modifications as mediators of the metabolic memory. Indeed, epigenetic changes may lead to stable modification of gene expression, participating in DR pathogenesis. Moreover, increasing evidences suggest that environmental factors such as chronic hyperglycemia are implicated DR progression and may also affect the epigenetic state. Here we review recent findings demonstrating the key role of epigenetics in the progression of DR. Further elucidation of epigenetic mechanisms, acting both at the cis- and trans-chromatin structural elements, will yield new insights into the pathogenesis of DR and will open the way for the discovery of novel therapeutic targets to prevent DR progression.

Long noncoding RNAs in imprinting and X chromosome inactivation

The field of long noncoding RNA (lncRNA) research has been rapidly advancing in recent years. Technological advancements and deep-sequencing of the transcriptome have facilitated the identification of numerous new lncRNAs, many with unusual properties, however, the function of most of these molecules is still largely unknown. Some evidence suggests that several of these lncRNAs may regulate their own transcription in cis, and that of nearby genes, by recruiting remodeling factors to local chromatin. Notably, lncRNAs are known to exist at many imprinted gene clusters. Genomic imprinting is a complex and highly regulated process resulting in the monoallelic silencing of certain genes, based on the parent-of-origin of the allele. It is thought that lncRNAs may regulate many imprinted loci, however, the mechanism by which they exert such influence is poorly understood. This review will discuss what is known about the lncRNAs of major imprinted loci, and the roles they play in the regulation of imprinting.

What's wrong with epigenetics in Huntington's disease?

Huntington's disease (HD) can be considered the paradigm of epigenetic dysregulation in neurodegenerative disorders. In this review, we attempted to compile the evidence that indicates, on the one hand, that several epigenetic marks (histone acetylation, methylation, ubiquitylation, phosphorylation and DNA modifications) are altered in multiple models and in postmortem patient samples, and on the other hand, that pharmacological treatments aimed to reverse such alterations have beneficial effects on HD phenotypic and biochemical traits. However, the working hypotheses regarding the biological significance of epigenetic dysregulation in this disease and the mechanisms of action of the tested ameliorative strategies need to be refined. Understanding the complexity of the epigenetics in HD will provide useful insights to examine the role of epigenetic dysregulation in other neuropathologies, such as Alzheimer's or Parkinson's diseases.

Thioredoxin Interacting Protein (TXNIP) and Pathogenesis of Diabetic Retinopathy

Chronic hyperglycemia (HG)-associated reactive oxygen/nitrogen species (ROS/RNS) stress and low grade inflammation are considered to play critical roles in the development of diabetic retinopathy (DR). Excess glucose metabolic flux through the aldose reductase/polyol pathway, advanced glycation end product (AGE) formation, elevated hexosamine biosynthesis pathway (HBP), diacyl glycerol/PKC activation, and mitochondrial ROS generation are all implicated in DR. In addition, endoplasmic reticulum stress/unfolded protein response (er-UPR) and deregulation of mitochondrial quality control by autophagy/mitophagy are observed causing cellular bioenergetic deficiency and injury. Recently, a pro-oxidant and pro-apoptotic thioredoxin interacting protein (TXNIP) was shown to be highly upregulated in DR and by HG in retinal cells in culture. TXNIP binds to thioredoxin (Trx) inhibiting its oxidant scavenging and thiolreducing capacity. Hence, prolonged overexpression of TXNIP causes ROS/RNS stress, mitochondrial dysfunction, inflammation and premature cell death in DR. Initially, DR was considered as microvascular complications of endothelial dysfunction and pericyte loss characterized by capillary basement membrane thickening, pericyte ghost, blood retinal barrier leakage, acellular capillary and neovascularization. However, it is currently acknowledged that neuro-glia are also affected by HG in diabetes and that neuronal injury, glial activation, innate immunity/sterile inflammation, and ganglion apoptosis occur early in DR. In addition, retinal pigment epithelium (RPE) becomes dysfunctional in DR. Since TXNIP is induced by HG in most cells, its effects are not restricted to a particular cell type in DR. However, depending on the metabolic activity and anti-oxidant capacity, some cells may be affected earlier by TXNIP than others. Identification of TXNIP sensitive cells and elucidating the underlying mechanism(s) will be critical for preventing pre-mature cell death and progression of DR.