Genetic variants in long noncoding RNA H19 and MEG3 confer risk of type 2 diabetes in an Iranian population

Association of lncRNA MEG3 rs941576 polymorphism, expression profile, and its related targets with the risk of obesity-related colorectal cancer: potential clinical insights

The identification of novel screening tools is imperative to empower the early detection of colorectal cancer (CRC). The influence of the long non-coding RNA maternally expressed gene 3 (MEG3) rs941576 single nucleotide polymorphism on CRC susceptibility remains uninvestigated. This research appraised MEG3 rs941576 association with the risk and clinical features of CRC and obesity-related CRC and its impact on serum MEG3 expression and its targets miR-27a/insulin-like growth factor 1 (IGF1)/IGF binding protein 3 (IGFBP3) and miR-181a/sirtuin 1 (SIRT1), along with the potential of these markers in obesity-related CRC diagnosis. 130 CRC patients (60 non-obese and 70 obese) and 120 cancer-free controls (64 non-obese and 56 obese) were enrolled. MEG3 targets were selected using bioinformatics analysis. MEG3 rs941576 was associated with magnified CRC risk in overall (OR (95% CI) 4.69(1.51-14.57), P = 0.0018) and stratified age and gender groups, but not with obesity-related CRC risk or MEG3/downstream targets' expression. Escalated miR-27a and IGFBP3 and reduced IGF1 serum levels were concomitant with MEG3 downregulation in overall CRC patients versus controls and obese versus non-obese CRC patients. Serum miR-181a and SIRT1 were upregulated in CRC patients versus controls but weren't altered in the obese versus non-obese comparison. Serum miR-181a and miR-27a were superior in overall and obesity-related CRC diagnosis, respectively; meanwhile, IGF1 was superior in distinguishing obese from non-obese CRC patients. Only serum miR-27a was associated with obesity-related CRC risk in multivariate logistic analysis. Among overall CRC patients, MEG3 rs941576 was associated with lymph node (LN) metastasis and tumor stage, serum MEG3 was negatively correlated with tumor stage, while SIRT1 was correlated with the anatomical site. Significant correlations were recorded between MEG3 and anatomical site, SIRT1 and tumor stage, and miR-27a/IGFBP3 and LN metastasis among obese CRC patients, while IGF1 was correlated with tumor stage and LN metastasis among non-obese CRC patients. Conclusively, this study advocates MEG3 rs941576 as a novel genetic marker of CRC susceptibility and prognosis. Our findings accentuate circulating MEG3/miR-27a/IGF1/IGFBP3, especially miR-27a as valuable markers for the early detection of obesity-related CRC. This axis along with SIRT1 could benefit obesity-related CRC prognosis.

Association Between rs217727 and rs2839698 H19 Polymorphisms and Obesity

Obesity is a worldwide health problem with an increasing trend. This condition has a significant genetic background. H19 lncRNA has been shown to protect from dietary obesity through decreasing levels of monoallelic genes in brown fat. In the current study, we aimed to find the association between two possibly functional H19 polymorphisms, namely rs217727 and rs2839698 and obesity in Iranian population. These polymorphisms have been shown to affect risk of some obesity-related conditions in different populations. The study included 414 obese cases and 392 controls. Notably, both rs2839698 and rs217727 were associated with obesity in the allelic model as well as all supposed inheritance models. In addition, after adjustment for gender, all P values remained significant. For rs2839698, the OR (95% CI) for T allele vs. C allele was 3.29 (2.67-4.05) (P-value < 0.0001). In the co-dominant model, both TT and CT genotypes were found to confer risk of obesity compared with CC genotype (OR (95% CI)= 14.02 (8.39-23.43) and 9.45 (6.36-14.04), respectively). Similarly, combination of TT and CT genotypes had an OR (95% CI) = 10.32 (7.03-15.17) when compared with CC genotype. For rs217727, the T allele was found to exert a protective effect (OR (95% CI) = 0.6 (0.48-0.75)). Moreover, in the co-dominant model, OR (95% CI) values for TT and TC genotypes vs. CC genotype were 0.23 (0.11-0.46) and 0.65 (0.49-0.87), respectively. Taken together, H19 polymorphisms may affect risk of obesity in Iranian population. It is necessary to conduct functional studies to confirm a causal relationship between the rs217727 and rs2839698 polymorphisms and obesity.

Long noncoding RNA (lncRNA) H19: An essential developmental regulator with expanding roles in cancer, stem cell differentiation, and metabolic diseases

Recent advances in deep sequencing technologies have revealed that, while less than 2% of the human genome is transcribed into mRNA for protein synthesis, over 80% of the genome is transcribed, leading to the production of large amounts of noncoding RNAs (ncRNAs). It has been shown that ncRNAs, especially long non-coding RNAs (lncRNAs), may play crucial regulatory roles in gene expression. As one of the first isolated and reported lncRNAs, H19 has gained much attention due to its essential roles in regulating many physiological and/or pathological processes including embryogenesis, development, tumorigenesis, osteogenesis, and metabolism. Mechanistically, H19 mediates diverse regulatory functions by serving as competing endogenous RNAs (CeRNAs), Igf2/H19 imprinted tandem gene, modular scaffold, cooperating with H19 antisense, and acting directly with other mRNAs or lncRNAs. Here, we summarized the current understanding of H19 in embryogenesis and development, cancer development and progression, mesenchymal stem cell lineage-specific differentiation, and metabolic diseases. We discussed the potential regulatory mechanisms underlying H19's functions in those processes although more in-depth studies are warranted to delineate the exact molecular, cellular, epigenetic, and genomic regulatory mechanisms underlying the physiological and pathological roles of H19. Ultimately, these lines of investigation may lead to the development of novel therapeutics for human diseases by exploiting H19 functions.

Evaluation of the expression levels of lncRNAs H19 and MEG3 in patients with type 2 diabetes mellitus

BACKGROUND

LncRNAs may play a role in either suppressing or exacerbating diabetes-associated vascular complications.

AIMS

This study aimed to assess MEG3 and H19 expression levels in T2DM and pre-diabetes and their roles in diabetes-related microvascular complications.

SUBJECT AND METHODS

(RT-PCR) analysis of the MEG3 and H19 plasma levels was carried out in 180 participants of T2DM, pre-diabetes, and control.

RESULTS

The expression level of lncRNA H19 was significantly down-regulated and lncRNA MEG3 up-regulated in T2DM compared to pre-diabetes and control, also for pre-diabetes versus control. The (ROC) analysis of MEG3 and H19 relative expression levels showed that MEG3 has better sensitivity for distinguishing T2DM from pre-diabetes and control groups.In comparison, H19 offered superior sensitivity to distinguish pre-diabetic from controls. Additionally, H19 was reported as an independent risk factor for T2DM by multivariate analysis. Low expression of H19 and over-expressed MEG3 were significantly associated with retinopathy, nephropathy, and elevated renal indicators (urea, creatinine, and UACR.

CONCLUSION

Our results implicated the potential diagnostic and predictive roles of lncRNA MEG3 and H19 for T2DM and related microvascular complications. Additionally, H19 may serve as a potential biomarker for pre-diabetes prediction.

Non-coding RNAs and type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a worldwide disease with rapidly increasing prevalence. This complex disorder caused by interplay between genetic predisposition factors, early developmental elements, diet and inactive lifestyle. Several researches have shown impact of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in the pathogenesis of this disorder. Several miRNAs such as miR-126, miR-222-3p, miR-182, let-7b-5p, and miR-1-3p have been down-regulated in different biological sources of patients with T2DM. Some other miRNAs including miR-21, miR-30d, miR-148a-3p, miR-146b and miR-486 have the opposite trends. In addition, a number of lncRNAs such as LY86-AS, HCG27_201, VIM-AS1, CTBP1-AS2, CASC2, GAS5, LINC-PINT, and MALAT1 have been altered in the peripheral blood, serum samples or tissues obtained from patients with T2DM. Taken together, both miRNAs and lncRNAs contribute to the development of T2DM and might be applied as markers or therapeutic molecules for this disorder.

The Role of Genetic Variants in the Long Non-Coding RNA Genes MALAT1 and H19 in the Pathogenesis of Childhood Obesity

Long non-coding RNAs (lncRNAs) play important roles in the maintenance of metabolic homeostasis. Recently, many studies have suggested that lncRNAs, such as Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1) and Imprinted Maternally Expressed Transcript (H19), might participate in the pathogenesis of metabolic disorders such as obesity. We conducted a case-control study with 150 Russian children and adolescents aged between 5 and 17 years old in order to assess the statistical association between the single nucleotide polymorphisms (SNPs) rs3200401 in MALAT1 and rs217727 in H19, and the risk of developing obesity in this population. We further explored the possible association of rs3200401 and rs217727 with BMI Z-score and insulin resistance. The MALAT1 rs3200401 and H19 rs217727 SNPs were genotyped using Taqman SNP genotyping assay. The MALAT1 rs3200401 SNP was identified as a risk factor for childhood obesity (p < 0.05) under the dominant and allelic models, and the CT heterozygous genotype was associated with the risk of increased BMI and with insulin resistance. The H19 rs217727 SNP had no significant association with obesity risk (all p > 0.05). Our findings thus suggest that MALAT1 SNP rs3200401 is a potential indicator of obesity susceptibility and pathogenesis in children and adolescents.

The rs3931283/PVT1 and rs7158663/MEG3 polymorphisms are associated with diabetic kidney disease and markers of renal function in patients with type 2 diabetes mellitus

BACKGROUND

Long non-coding RNAs (lncRNAs) are key regulators of gene expression. Some studies have reported the association of polymorphisms in lncRNA genes with diabetes mellitus (DM) and its chronic complications, including diabetic kidney disease (DKD); however, the results are still inconclusive. Thus, we investigated the association of the rs3200401/MALAT1, rs1894720/MIAT, rs3931283/PVT1, rs11993333/PVT1, rs5749201/TUG1, and rs7158663/MEG3 polymorphisms with DKD in patients with type 2 DM (T2DM).

METHODS AND RESULTS

This study comprised 902 patients with T2DM and DKD (cases) and 394 patients with T2DM without DKD (controls). The six polymorphisms of interest were genotyped by real-time PCR using TaqMan probes. Frequency of the rs3931283/PVT1 G/G genotype was 36.2% in cases and 31.9% in controls (P = 0.331). After adjustment for gender, glycated hemoglobin, HDL cholesterol, ethnicity, hypertension, and diabetic retinopathy, the G/G genotype was associated with risk for DKD (OR = 1.625, 95% CI 1.020-2.588; P = 0.041). The rs3931283/PVT1 G/G genotype was also associated with higher urinary albumin excretion levels compared to A allele carriers (P = 0.017). No difference was found in rs7158663/MEG3 genotype frequencies between T2DM controls and DKD patients (OR = 1.087, 95% CI 0.686-1.724; P = 0.722). However, the rs7158663/MEG3 G/G genotype was associated with protection against severe DKD (OR = 0.694, 95% CI 0.488-0.989; P = 0.043, for patients with severe DKD vs. T2DM controls). The rs7158663/MEG3 G/G genotype was also associated with lower creatinine levels (P = 0.007) and higher estimated glomerular filtration rate (P = 0.010) compared to A allele carriers. No association was found between the rs11993333/PVT1, rs3200401/MALAT1, rs1894720/MIAT, and rs5749201/TUG1 polymorphisms and DKD or its laboratory markers.

CONCLUSION

The rs3931283/PVT1 G/G and rs7158663/MEG3 G/G are associated with DKD and markers of renal function in T2DM patients from a Brazilian population.

Novel genetic variants in long non-coding RNA MEG3 are associated with the risk of asthma

Background

Asthma is the most common chronic inflammatory airway disease worldwide. Asthma is a complex disease whose exact etiologic mechanisms remain elusive; however, it is increasingly evident that genetic factors play essential roles in the development of asthma. The purpose of this study is to identify novel genetic susceptibility loci for asthma in Taiwanese. We selected a well-studied long non-coding RNA (lncRNA), MEG3, which is involved in multiple cellular functions and whose expression has been associated with asthma. We hypothesize that genetic variants in MEG3 may influence the risk of asthma.

Methods

We genotyped four single nucleotide polymorphisms (SNPs) in MEG3, rs7158663, rs3087918, rs11160608, and rs4081134, in 198 patients with asthma and 453 healthy controls and measured serum MEG3 expression level in a subset of controls.

Results

The variant AG and AA genotypes of MEG3 rs7158663 were significantly over-represented in the patients compared to the controls (P = 0.0024). In logistic regression analyses, compared with the wild-type GG genotype, the heterozygous variant genotype (AG) was associated with a 1.62-fold [95% confidence interval (CI) [1.18-2.32], P = 0.0093] increased risk and the homozygous variant genotype (AA) conferred a 2.68-fold (95% CI [1.52-4.83], P = 0.003) increased risk of asthma. The allelic test showed the A allele was associated with a 1.63-fold increased risk of asthma (95% CI [1.25-2.07], P = 0.0004). The AG plus AA genotypes were also associated with severe symptoms (P = 0.0148). Furthermore, the AG and AA genotype carriers had lower serum MEG3 expression level than the GG genotype carriers, consistent with the reported downregulation of MEG3 in asthma patients.

Conclusion

MEG3 SNP rs7158663 is a genetic susceptibility locus for asthma in Taiwanese. Individuals carrying the variant genotypes have lower serum MEG3 level and are at increased risks of asthma and severe symptoms.

SNP rs322931 (C>T) in miR-181b and rs7158663 (G>A) in MEG3 aggravate the inflammatory response of anal abscess in patients with Crohn's disease

BACKGROUND

The MEG3/miR-181b signaling has been implicated in the pathogenesis of several diseases including Crohn's disease. This work aimed to study the correlation between SNPs in MEG3/miR-181b and the severity of anal abscess in patients with Crohn's disease.

METHODS

Quantitative real-time PCR was performed to analyze the expression of MEG3 and miR-181b. ELISA was carried out to examine the expression of TNF-α, IL-1β, IL-6, CRP, SSA, AAT, AAG and HPT in the peripheral blood of patients with Crohn's disease. Luciferase assay was performed to explore the role of miR-181b in the expression of MEG3 and TNF-α.

RESULTS

The expression of MEG3 and miR-181b in the peripheral blood of patients with Crohn's disease was remarkably associated with the rs322931 and rs7158663 polymorphisms. rs322931 (C>T) in miR-181b and rs7158663 (G>A) in MEG3 significantly promoted the expression of TNF-α, IL-1β, IL-6, CRP, SSA, AAT, AAG and HPT. Luciferase assay demonstrated that miR-181b was capable of repressing the expression of MEG3 and TNF-α through binding to their specific binding sites. Moreover, alteration of MEG3 and miR-181b expression also showed a remarkable impact on the MEG3/miR-181b/TNF-α signaling pathway in THP-1 cells.

CONCLUSIONS

In conclusion, our study demonstrated that two SNPs, rs322931 (C>T) in miR-181b and rs7158663 (G>A) in MEG3, could aggravate the inflammatory response of anal abscess in patients with Crohn's disease via modulating the MEG3/miR-181b/TNF-α signaling pathway.

Single-nucleotide polymorphisms as important risk factors of diabetes among Middle East population

Diabetes is a chronic metabolic disorder that leads to the dysfunction of various tissues and organs, including eyes, kidneys, and cardiovascular system. According to the World Health Organization, diabetes prevalence is 8.8% globally among whom about 90% of cases are type 2 diabetes. There are not any significant clinical manifestations in the primary stages of diabetes. Therefore, screening can be an efficient way to reduce the diabetic complications. Over the recent decades, the prevalence of diabetes has increased alarmingly among the Middle East population, which has imposed exorbitant costs on the health care system in this region. Given that the genetic changes are among the important risk factors associated with predisposing people to diabetes, we examined the role of single-nucleotide polymorphisms (SNPs) in the pathogenesis of diabetes among Middle East population. In the present review, we assessed the molecular pathology of diabetes in the Middle East population that paves the way for introducing an efficient SNP-based diagnostic panel for diabetes screening among the Middle East population. Since, the Middle East has a population of 370 million people; the current review can be a reliable model for the introduction of SNP-based diagnostic panels in other populations and countries around the world.

Recent Advances of LncRNA H19 in Diabetes LncRNA H19 in Diabetes

Diabetes mellitus (DM) causes damage to major organs, including the heart, liver, brain, kidneys, eyes, and blood vessels, threatening the health of the individuals. Emerging evidence has demonstrated that lncRNAs has important functions in the pathogenesis of human diseases, such as cancers, neurodegenerative diseases, cardiac fibroblast phenotypes, hypertension, heart failure, atherosclerosis and diabetes. Recently, H19, a lncRNA, has been reported to shown to participate in the regulatory process of muscle differentiation, glucose metabolism, and tumor metastasis, as well as endometrial development. However, the roles of H19 in DM were still not completely understood. This review was conducted to summarize the functions of H19 in diabetes and discuss the challenges and possible strategies of H19 in DM.

Association of Polymorphisms within HOX Transcript Antisense RNA (HOTAIR) with Type 2 Diabetes Mellitus and Laboratory Characteristics: A Preliminary Case-Control Study

Type 2 diabetes mellitus (T2DM) is a complex heterogeneous disease resulting from the environment and genetic interactions. Lately, genetic association studies have shown that polymorphisms in long noncoding RNAs (lncRNAs) are associated with T2DM susceptibility. This preliminary study is aimed at investigating if HOX transcript antisense RNA (HOTAIR) polymorphisms contribute to T2DM development. Five hundred clinically diagnosed T2DM cases and 500 healthy controls were recruited from the southeast Iranian population. Genomic DNA was isolated from nucleated blood cells and genotyped for MspI (C/T) (rs920778) and AluI (A/G) (rs4759314) polymorphisms using the PCR-RFLP technique. For genotyping rs12826786 C/T and rs1899663 G/T variants, ARMS-PCR method was applied. Our findings indicated that HOTAIR rs920778 C/T, rs12826786 C/T, and rs4759314 A/G polymorphisms have a significant positive association with T2DM, while a negative association was observed between rs1899663 G/T T2DM susceptibility. Significant associations were also observed between rs920778 C/T and HDL-C as well as s4759314 A/G and both FBS and LDL-C in T2DM patients. Haplotype analysis indicated that the CGCG, CTTG, TGTA, and TTTG haplotypes of rs920778/rs1899663/rs12826786/rs4759314 significantly enhanced T2DM risk by 1.47, 1.96, 2.81, and 4.80 folds, respectively. No strong linkage disequilibrium was found between the four HOTAIR SNPs. We firstly reported that HOTAIR rs1899663 G/T, rs12826786 C/T, rs4759314 A/G, and rs920778 C/T polymorphisms might influence T2DM susceptibility by modulating different signaling pathways and could be regarded as potential prognostic markers in T2DM patients.

LncRNA SERPINB9P1 expression and polymorphisms are associated with ischemic stroke in a Chinese Han population

Long noncoding RNAs (lncRNAs) were reported to play important roles in the pathogenesis of ischemic stroke (IS). Our study aimed to investigate the role of lncRNA SERPINB9P1 expression in ischemic stroke and the association between SERPINB9P1 polymorphisms and IS risk, as well as examine the correlation of SERPINB9P1 expression and variants with clinical parameters of IS. The SERPINB9P1 levels in human participants and oxygen-glucose deprivation (OGD)-treated human A172 cells were measured by qRT-PCR. The SERPINB9P1 polymorphisms (rs375556 and rs318429) were genotyped by the MassARRAY platform. We found that the SERPINB9P1 expression was significantly downregulated in patients with IS compared with that in healthy controls. On the 14th day in the hospital, the SERPINB9P1 level in patients with moderate and severe stroke was significantly downregulated compared with the normal group. After stratification by gender, the rs375556 polymorphism was significantly associated with susceptibility to female IS in the recessive model, and the significant association remained after adjusting for age. After adjusting for gender and age, rs318429 was significantly associated with FPG and D-D levels, and rs375556 was significantly associated with INR and PTA levels in IS cases. Besides, the lncRNA SERPINB9P1 expressed downregulated in OGD/reoxygenation-treated human A172 cells. In conclusion, the lncRNA SERPINB9P1 may protect against cerebral ischemia-reperfusion injury and neurological impairment after IS. The SERPINB9P1 rs375556 polymorphism was associated with susceptibility to female IS, and SERPINB9P1 polymorphisms may influence the metabolism of blood glucose and regulation of coagulation function in patients with IS.

The Association of MEG3 Gene rs7158663 Polymorphism With Cancer Susceptibility

Although the association of MEG3 gene rs7158663 polymorphism with cancer susceptibility has been investigated, the findings are inconsistent. The aim of this study was to analyze the association between the rs7158663 polymorphism and cancer susceptibility through a case-control study and meta-analysis. In a case-control study with 430 colorectal cancer (CRC) cases and 445 healthy controls, the rs7158663 polymorphism was genotyped by direct sequencing. STATA software was used to calculate the pooled odds ratio and 95% confidence interval in a meta-analysis including 4,649 cancer cases and 5,590 controls. Both the case-control study and meta-analysis showed that the rs7158663 polymorphism was associated with increased susceptibility to CRC. Individuals carrying the AA or GA genotype were more likely to develop CRC than those carrying the rs7158663 GG genotype. Interestingly, MEG3 expression was significantly lower in colorectal tissues of the AA or GA genotype compared to those of the rs7158663 GG genotype. In addition, the meta-analysis suggested that the rs7158663 polymorphism was also associated with increased susceptibility to breast cancer and gastric cancer. Bioinformatics analysis showed that the rs7158663 A allele contributed to the binding of hsa-miR-4307 and hsa-miR-1265 to MEG3. In conclusion, the current findings suggest that the MEG3 gene rs7158663 polymorphism may serve as a genetic marker for predicting the risk of cancers, such as breast cancer, gastric cancer and CRC. However, the sample size of the current study is still insufficient, especially in the subgroup analysis. Therefore large and well-designed studies are needed to validate our findings.

The role of long non-coding RNAs in the regulation of pancreatic beta cell identity

Type 2 diabetes (T2D) is a widespread disease affecting millions in every continental population. Pancreatic β-cells are central to the regulation of circulating glucose, but failure in the maintenance of their mass and/or functional identity leads to T2D. Long non-coding RNAs (lncRNAs) represent a relatively understudied class of transcripts which growing evidence implicates in diabetes pathogenesis. T2D-associated single nucleotide polymorphisms (SNPs) have been identified in lncRNA loci, although these appear to function primarily through regulating β-cell proliferation. In the last decade, over 1100 lncRNAs have been catalogued in islets and the roles of a few have been further investigated, definitively linking them to β-cell function. These studies show that lncRNAs can be developmentally regulated and show highly tissue-specific expression. lncRNAs regulate neighbouring β-cell-specific transcription factor expression, with knockdown or overexpression of lncRNAs impacting a network of other key genes and pathways. Finally, gene expression analysis in studies of diabetic models have uncovered a number of lncRNAs with roles in β-cell function. A deeper understanding of these lncRNA roles in maintaining β-cell identity, and its deterioration, is required to fully appreciate the β-cell molecular network and to advance novel diabetes treatments.

Genetic polymorphisms in lncRNAs predict recurrence of ischemic stroke

Genetic polymorphisms in long non-coding RNAs (lncRNAs) are considered as potential genetic biomarkers for the prediction of human complex diseases such as ischemic stroke (IS). However, so far, no reports have focused on the relationship of lncRNA polymorphisms with IS onset and prognosis. In our study, eight potential functional polymorphisms of four well-known lncRNAs (H19 rs2107425 and rs2251375, MALAT1 rs4102217 and rs3200401, MEG3 rs11160608 and rs4081134, SENCR rs4526784 and rs555172) were genotyped in 657 ischemic stroke patients. Then, the association between lncRNA polymorphisms and IS onset and recurrence were investigated. These lncRNA variants were not associated with age onset of IS. However, we observed that MEG3 rs4081134 AA genotype was statistically related with a reduced risk of stroke recurrence, particularly for patients with large-artery atherosclerotic stroke. Also, the decreased risk was more prominent in elders, non-smokers, non-drinkers and hypertensive patients. Furthermore, the variant genotype AA of rs4081134 was an independent predictor for IS recurrence using the multivariate Cox regression model. Our findings indicated that MEG3 rs4081134 can serve as a useful biomarker and potential therapeutic target in IS recurrence. More researches are needed to verify our results and explore the underlying molecular mechanisms.

Dysregulation of lncRNA-H19 in cardiometabolic diseases and the molecular mechanism involved : a systematic review

Introduction: Cardiometabolic diseases are a global public health problem, with significant increases in their prevalence. Different epigenetic factors involved in the progression of metabolic alterations have been described, such as long non-coding RNAs (lncRNAs). H19 is a multifunctional lncRNA expressed from the maternal allele, with low expression after birth, except in the skeletal muscle and heart. Recent studies have linked its dysregulation to alterations in cell metabolism.Areas covered: H19 plays a role in the pathogenesis of coronary artery disease, nonalcoholic fatty liver disease, hepatic and renal fibrosis, insulin resistance, type 2 diabetes, and inflammation. H19 acts mainly as a competitive endogenous RNA of molecules involved in pathways that regulate cell metabolism. In this review, we analyzed the dysregulation of H19 in cardiometabolic diseases and its relationship with molecular alterations in different signaling pathways.Expert opinion: The association of H19 with the development of cardiometabolic diseases, indicates that H19 could be a therapeutic target and prognostic biomarker for these diseases. Controversies have been reported regarding the expression of H19 in some metabolic diseases, therefore, it is necessary to continue research to clarify its pathogenic effect in different organs.

Insights into how H19 works in glioma cells. A review article

Glioblastoma is a highly aggressive brain tumor and considered to be the most common primary one. Recurrence after treatment is a significant problem, with a survival rate after one year of about 39.7%. The recurrence of GBM is linked to different cellular pathways and molecular signaling. Long non-coding RNA (LncRNA) comprises more than 200 nucleotides and is suggested to play a role in controlling genes that regulate the cell cycle, apoptosis and cellular growth in various tissues. Little is known about LncRNA compared to microRNAs, which are extensively studied in the literature. H19 is one of the most plentiful and conserved transcripts suggested to be involved in mammalian development and tumorigenesis. H19 is one of the LncRNA members transcribed by RNA polymerase II, spliced and polyadenylated, and the product is transferred to the cytoplasm without translation. HI9 maps to 1lp15, a region thought to be relevant to some childhood tumors as embryonal rhabdomyosarcoma and Wilm's Tumor. In these tumors, the analysis of the 11p15 locus showed loss of heterozygosity which is a feature associated with the tumor-suppressing activity. However, the role played by H19 in GBM is still enigmatic and needs further extensive evaluation. Uncovering the hidden role of such molecules in the pathogenesis in glioma will help tailor new targeted therapies that may affect the prognosis and survival of GBM.

Non-Coding RNAs Based Molecular Links in Type 2 Diabetes, Ischemic Stroke, and Vascular Dementia

This article reviews recent advances in the study of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and their functions in type 2 diabetes mellitus (T2DM), ischemic stroke (IS), and vascular dementia (VaD). miRNAs and lncRNAs are gene regulation markers that both regulate translational aspects of a wide range of proteins and biological processes in healthy and disease states. Recent studies from our laboratory and others have revealed that miRNAs and lncRNAs expressed differently are potential therapeutic targets for neurological diseases, especially T2DM, IS, VaD, and Alzheimer's disease (AD). Currently, the effect of aging in T2DM, IS, and VaD and the cellular and molecular pathways are largely unknown. In this article, we highlight results from the works on the molecular connections between T2DM and IS, and IS and VaD. In each disease, we also summarize the pathophysiology and the differential expressions of miRNAs and lncRNAs. Based on current research findings, we hypothesize that 1) T2DM bi-directionally and age-dependently induces IS and VaD, and 2) these changes are precursors to the onset of dementia in elderly people. Research into these hypotheses is required to examine further whether research efforts on reducing T2DM, IS, and VaD may affect dementia and/or delay the AD disease process in the aged population.

Long non-coding RNA H19 expression and functional polymorphism rs217727 are linked to increased ischemic stroke risk

Background

Efforts to identify potential biomarkers for the diagnosis of ischemic stroke (IS) are valuable. The H19 gene plays a functional role in increasing the prevalence of IS risk factors. We evaluated the correlation between H19 rs217727 polymorphism and the expression level of H19 lncRNA with susceptibility to IS among the Iranian population.

Methods

Blood samples were collected from IS patients (n = 114) and controls (n = 114). We concentrated on the expression pattern of H19 at different time points (i.e., 0–24, 24–48, and 48–72 h after stroke). The tetra-amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) method was applied for DNA genotyping. We used the quantitative real-time PCR to evaluate H19 expression levels. We used the receiver operating characteristic (ROC) curve to evaluate the diagnosis and prognosis of IS.

Results

The rs217727polymorphism of H19 was related with IS susceptibility in the co-dominant (OR = 2.92, 95% CI = 0.91–10.92, P = 0.04) and recessive models (OR = 2.80, 95% CI = 0.96–8.15, P = 0.04). H19 expression was significantly upregulated in IS and remained high for 72 h after stroke. ROC curves showed that H19 expression within the first 24 h from stroke onset might serve as a biomarker for the early diagnosis of IS with 79.49% sensitivity and 80.00% specificity. H19 expression in small vessel occlusion (SVO) and large-artery atherosclerosis (LAA) patients were 3.74 and 3.34 times higher than the undetermined (UD) subtype, respectively [OR = 3.74 95% CL (1.14–12.27) P = 0.030 and OR = 3.34 95% CL (1.13–9.85) P = 0.029].

Conclusion

The rs217727 polymorphism of the H19 is correlated with IS susceptibility, and H19 expression levels were higher in SVO and LAA patients. The upregulation of H19 may be considered as a diagnostic biomarker in IS among the Iranian population, but it cannot serve as a useful prognostic marker.

Association of Genetic Variants in IGF2-Related Genes With Risk of Metabolic Syndrome in the Chinese Han Population

AIMS

To explore associations between polymorphisms of IGF2-related genes including H19, IGF2, IGF2BP2 and IGF2R and Metabolic syndrome (MetS) susceptibility in the Chinese Han population.

METHODS

66 subjects with MetS and 257 control subjects were collected for inclusion in a case-control study. PCR-RFLP was used to investigate polymorphisms in the H19, IGF2, IGF2BP2 and IGF2R genes. Elisa was used to detect the serum IGF2 concentrations.

RESULTS

Females carrying the GG and AG genotypes of rs680 (IGF2) exhibited a lower risk of MetS, compared with those harboring AA (adjusted OR = 0.388, p = 0.027), while GG and AG genotypes were associated with lower fasting glucose and HbA1c. In males, the Waist-to-Hip Ratio (WHR) and the level of TG were significantly higher in GG and AG genotypes than in the AA genotype of rs680 in IGF2. Levels of HDL-c were lower in men with GG and AG genotypes compared with those carrying the AA genotype. Serum IGF2 concentrations did not change among different genotypes. Finally, multifactor dimensionality reduction (MDR) analysis identified interactions between four polymorphisms: rs3741279 (H19), rs680 (IGF2), rs1470579 (IGF2BP2) and rs629849 (IGF2R).

CONCLUSIONS

Our study suggests that IGF2-related genes including H19, IGF2, IGF2BP2 and IGF2R genes may play pivotal roles in the development of MetS.

Long noncoding RNAs as novel biomarkers for Type 2 diabetes

Type 2 diabetes (T2D) is a metabolic disease characterized by disordered glucagon secretion, insulin resistance in target tissues, and decreased islet β-cell mass and function. The routine diagnosis was based on measurements of metabolic markers, while genetic risk factors have been considered to increase the probability of predicting the development of the disease. Recent evidence suggests that long noncoding RNAs (lncRNAs) regulate gene expression in various physiological and pathological processes. As increasing lncRNAs are identified in β cells, understanding the regulatory roles of lncRNAs in T2D becomes indispensable. In this review, we discuss the potential role of lncRNAs contributing to β-cell identity and T2D susceptibility, which provide a perspective insight into the development of novel diagnosis biomarkers for T2D.

LncRNA MEG3 Participates in Caerulein-Induced Inflammatory Injury in Human Pancreatic Cells via Regulating miR-195-5p/FGFR2 Axis and Inactivating NF-κB Pathway

Acute pancreatitis (AP) is a dysfunctional pancreas disease marked by severe inflammation. Long non-coding RNAs (lncRNAs) involving in the regulation of inflammatory responses have been frequently mentioned. The purpose of this study was to ensure the function and action mode of lncRNA maternally expressed gene 3 (MEG3) in caerulein-induced AP cell model. HPDE cells were treated with caerulein to establish an AP model in vitro. The expression of MEG3, miR-195-5p, and fibroblast growth factor receptor 2 (FGFR2) was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation and apoptosis were detected by 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry assay, respectively. The expression of CyclinD1, B cell lymphoma/leukemia-2 (Bcl-2), Bcl-2-associated X protein (Bax), FGFR2, P65, phosphorylated P65 (p-P65), alpha inhibitor of nuclear factor kappa beta (NF-κB) (IκB-α), and phosphorylated IκB-α (p-IκB-α) at the protein level was quantified by western blot. The concentrations of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) were monitored by enzyme-linked immunosorbent assay (ELISA). The targeted relationship between miR-195-5p and MEG3 or FGFR2 was forecasted by the online software starBase v2.0 and verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. As a result, the expression of MEG3 and FGFR2 was decreased in caerulein-induced HPDE cells, while the expression of miR-195-5p was increased. MEG3 overexpression inhibited cell apoptosis and inflammatory responses that were induced by caerulein. Mechanically, miR-195-5p was targeted by MEG3 and abolished the effects of MEG3 overexpression. FGFR2 was a target of miR-195-5p, and MEG3 regulated the expression of FGFR2 by sponging miR-195-5p. FGFR2 overexpression abolished miR-195-5p enrichment-aggravated inflammatory injuries. Moreover, the NF-κB signaling pathway was involved in the MEG3/miR-195-5p/FGFR2 axis. Collectively, MEG3 participates in caerulein-induced inflammatory injuries by targeting the miR-195-5p/FGFR2 regulatory axis via mediating the NF-κB pathway in HPDE cells.

Long non-coding RNA MEG3 promotes fibrosis and inflammatory response in diabetic nephropathy via miR-181a/Egr-1/TLR4 axis

Long non-coding RNAs (lncRNAs) play vital roles in diabetic nephropathy (DN). This research aimed to study the potential role and underlying molecular mechanisms of long non-coding RNA MEG3 in DN. We found that MEG3 was upregulated in DN in vivo and in vitro and could enhance cell fibrosis and inflammatory response in DN. MEG3 functioned as an endogenous sponge for miR-181a in mesangial cells (MCs) via direct targeting and in an Ago2-dependent manner. MiR-181a inhibition promoted MC fibrosis and inflammatory response. In addition, Egr-1 was confirmed as a target gene of miR-181a. Further investigations verified that MEG3 promotes fibrosis and inflammatory response via the miR-181a/Egr-1/TLR4 axis in vitro and in vivo. These results provide new insights into the regulation between MEG3 and the miR-181a/Egr-1/TLR4 signaling pathway during DN progression.

Upregulation of long non-coding RNA MEG3 in type 2 diabetes mellitus complicated with vascular disease: a case-control study

Previous studies have indicated that long non-coding RNAs (lncRNAs) were closely related to diabetes. In this study, we aimed to explore the possible role and mechanism of lncRNA MEG3 in the occurrence and development of type 2 diabetes mellitus (T2DM) and its vascular complications. A case-control study involving 115 subjects was conducted, including 53 T2DM patients (37 patients with vascular complication and 16 patients without vascular complications) and 62 healthy subjects. We performed real-time polymerase chain reaction (RT-PCR) analysis of the lncRNA MEG3 and miR-146a levels in peripheral blood mononuclear cells (PBMCs) in the 115 samples. We found that the expression of lncRNA MEG3 was upregulated in the T2DM patients with vascular complication (DC group) compared with T2DM patients without vascular complication (D group) (P < 0.05) and the control group (P < 0.01). miR-146a levels in DC group were significantly lower compared with control group. There was a significant positive correlation between the expression of lncRNA MEG3 and glucose (GLU) (r = 0.301, P = 0.0011) and hemoglobin A1C (HbA1c) (r = 0.477, P = 0.0006). Our study suggests MEG3 may play as an important role in progression of diabetes-related vascular complications, contributing to a novel understanding of pathogenesis and prognosis for diabetes and its complications.

Non-Coding RNAs as Potential Novel Biomarkers for Early Diagnosis of Hepatic Insulin Resistance

In the recent years, the prevalence of metabolic conditions such as type 2 Diabetes (T2D) and metabolic syndrome (MetS) raises. The impairment of liver metabolism resulting in hepatic insulin resistance is a common symptom and a critical step in the development of T2D and MetS. The liver plays a crucial role in maintaining glucose homeostasis. Hepatic insulin resistance can often be identified before other symptoms arrive; therefore, establishing methods for its early diagnosis would allow for the implementation of proper treatment in patients before the disease develops. Non-coding RNAs such as miRNAs (micro-RNA) and lncRNAs (long-non-coding RNA) are being recognized as promising novel biomarkers and therapeutic targets—especially due to their regulatory function. The dysregulation of miRNA and lncRNA activity has been reported in the livers of insulin-resistant patients. Many of those transcripts are involved in the regulation of the hepatic insulin signaling cascade. Furthermore, for several miRNAs (miR-802, miR-499-5p, and miR-122) and lncRNAs (H19 imprinted maternally expressed transcript (H19), maternally expressed gene 3 (MEG3), and metastasis associated lung adenocarcinoma transcript 1 (MALAT1)), circulating levels were altered in patients with prediabetes, T2D, and MetS. In the course of this review, the role of the aforementioned ncRNAs in hepatic insulin signaling cascade, as well as their potential application in diagnostics, is discussed. Overall, circulating ncRNAs are precise indicators of hepatic insulin resistance in the development of metabolic diseases and could be applied as early diagnostic and/or therapeutic tools in conditions associated with insulin resistance.

Melatonin inhibits Müller cell activation and pro-inflammatory cytokine production via upregulating the MEG3/miR-204/Sirt1 axis in experimental diabetic retinopathy

Diabetic retinopathy (DR) is the most common ocular complication caused by diabetes mellitus and is the main cause of visual impairment in working-age people. Reactive gliosis and pro-inflammatory cytokine production by Müller cells contribute to the progression of DR. Melatonin is a strong anti-inflammatory hormone, mediating the cytoprotective effect of a variety of retinal cells against hyperglycemia. In this study, melatonin inhibited the gliosis activation and inflammatory cytokine production of Müller cells in both in vitro and in vivo models of DR. The melatonin membrane blocker, Luzindole, invalidated the melatonin-mediated protective effect on Müller cells. Furthermore, melatonin inhibited Müller cell activation and pro-inflammatory cytokine production by upregulating the long noncoding RNA maternally expressed gene 3/miR-204/sirtuin 1 axis. In conclusion, our study suggested that melatonin treatment could be a novel therapeutic strategy for DR.

Correlation between polymorphisms in IGF2/H19 gene locus and epithelial ovarian cancer risk in Chinese population

To investigate the association between SNPs in human IGF2/H19 gene locus and epithelial ovarian cancer (EOC) risk, we performed a case-control study in 422 individuals (219 EOC patients and 203 cancer-free controls). Four SNPs (rs2525885, rs2839698, rs3741206, rs3741219) were found to be related with EOC risk. Specifically, the minor allele C of rs2525885 and allele A of rs2839698 was associated with elevated EOC genetic susceptibility under both dominant and recessive models (TC + CC vs TT: adjusted OR: 1.61, P = .031; CC vs TT + TC: adjusted OR: 4.87, P = .014; GA + AA vs GG: adjusted OR: 1.63, P = .023; AA vs GG + GA: adjusted OR: 2.43, P = .007). For rs3741206, the genotype TC + CC was associated with a significant decrease in EOC risk with the TT genotype as reference in a dominant genetic model (adjusted OR: 0.44, P = .003), while for rs3741219, genotype AA was associated with a 59% decrease in EOC risk only in the recessive model (adjusted OR: 0.41, P = .038). In the stratified analysis, an increased risk associated with the variant genotypes was observed in only subjects aged >47 years for rs2525885 (adjusted OR = 2.04, P = .024), rs2839698 (adjusted OR = 2.50, P = .047) and rs3741206 (adjusted OR = 0.37, P = .009), respectively. What's more, the TC + CC genotype of rs2525885 was significantly associated with advanced FIGO stage (III vs II, adjusted OR = 2.73, P = .040).

Association analyses of a genetic variant in long non-coding RNA MEG3 with breast cancer susceptibility and serum MEG3 expression level in the Egyptian population

BACKGROUND

LncRNA MEG3 rs7158663 has been shown to confer cancer susceptibility, maybe through altering its gene expression level.

OBJECTIVE

We aimed to weigh the effect of rs7158663 on MEG3 serum level and breast cancer susceptibility.

METHODS

We genotyped rs7158663 G > A and measured serum MEG3 in 150 breast cancer, 95 fibroadenoma , and 154 controls by the TaqMan method.

RESULTS

The presence of rs7158663 G > A is a risk factor for breast cancer among fibroadenoma patients and controls, AA vs. GG genotypes (OR = 6.320, 95% CI = 2.587-15.439, P< 0.0001 when compared to controls and OR = 10.825, 95% CI = 1.929-60.742, P= 0.007 when compared to fibroadenoma). Decreased serum MEG3 was observed in breast cancer group when compared with fibroadenoma and/or controls [median (IQR) = 0.43 (0.27-0.55)] (P< 0.0001). However, increased serum MEG3 was noted in fibroadenoma group when compared with controls (P< 0.0001). A significance decreased serum MEG3 was found to be associated with mutant A allele than with wild G allele (P< 0.0001). The results showed that rs7158663 and lower MEG3 were significantly associated with patients with higher TNM staging and larger tumor size > 5 cm.

CONCLUSION

The presence of both rs7158663 and low MEG3 are diagnostic and unfavorable prognostic factors for BC patients.

The effects of placental long noncoding RNA H19 polymorphisms and promoter methylation on H19 expression in association with preeclampsia susceptibility

The effect of DNA methylation on gene expression triggered it as a susceptibility factor in various diseases including preeclampsia (PE). The pathogenesis of PE is closely associated with the methylation status and genetic variants of relevant genes. Therefore, the aim of the study was to investigate the possible impacts of the placental DNA methylation and rs3741219, rs217727, and rs2107425 polymorphisms of the H19 gene on the PE susceptibility as well as the its mRNA expression. Moreover, eight haplotypes of three loci in the H19 gene were analyzed. In this case-control study, the placentas of 107 preeclamptic and 113 non-preeclamptic women were collected after delivery. The methylation status was assessed by methylation-specific polymerase chain reaction (PCR). The H19 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism or amplification refractory mutation system-polymerase chain reaction methods. The quantitative real time PCR was used for mRNA expression assay. The placental H19 rs3741219 and rs2107425 polymorphisms were not associated with PE. However, H19 rs217727CT and TT genotypes might be associated with a 9.2- and 17.7-fold increased risk of PE, respectively. The T_rs3741219 C_rs217727 C_rs2107425 and T_rs3741219 C_rs217727 T_rs2107425 haplotypes were significantly lower, whereas the T_rs3741219 T_rs217727 C_rs2107425 and C_rs3741219 T_rs217727 C_rs2107425 haplotypes were significantly higher in PE women. Promoter but not upstream region hypermethylation of H19 gene could be led to decreased risk of PE (MM vs. UM + UU). No significant difference was observed in the placental mRNA expression between two groups. The H19 expression was significantly higher in women with unmethylated (UU), compared to methylated promoter (MM). The H19 expression was 17- and 15-fold higher in H19-rs2107425 CC and CT genotypes in PE women. In conclusion, the H19 rs2107425 polymorphism was associated with a higher risk of PE and increased H19 mRNA expression. The promoter hypermethylation of H19 gene was associated with a lower risk of PE and decreased H19 mRNA expression.

The role of long non-coding RNA H19 in breast cancer

Breast cancer is the most common malignant tumor in women in the majority of countries, such as China, Britain and Australia, and its morbidity and mortality rates remain very high. Long non-coding RNAs (lncRNAs) are non-coding RNAs (ncRNAs) >200 nucleotides in length that lack open reading frames. LncRNA H19 is a transcription product of the H19 gene, and the aberrant expression of H19 can be demonstrated in various types of tumor cell. The purpose of the present review was to elaborate the role of H19 in breast cancer. H19 can regulate gene expression in breast cancer at multiple levels, including epigenetic, transcriptional and posttranscriptional. The abnormal expression of H19 is closely associated with the tumorigenesis and progression of breast cancer via different underlying molecular mechanisms, such as encoding microRNA-675, competing endogenous RNA regulation and interacting with MYC. A large number of clinical studies have suggested that H19 can serve as a potential biomarker for the diagnosis of breast cancer. High expression levels of H19 increases the drug resistance of breast cancer cells and is associated with poor prognosis within patients with breast cancer. Therefore, serum H19 levels may have momentous significance in the clinical setting.

The Neglected Insulin: IGF-II, a Metabolic Regulator with Implications for Diabetes, Obesity, and Cancer

When originally discovered, one of the initial observations was that, when all of the insulin peptide was depleted from serum, the vast majority of the insulin activity remained and this was due to a single additional peptide, IGF-II. The IGF-II gene is adjacent to the insulin gene, which is a result of gene duplication, but has evolved to be considerably more complicated. It was one of the first genes recognised to be imprinted and expressed in a parent-of-origin specific manner. The gene codes for IGF-II mRNA, but, in addition, also codes for antisense RNA, long non-coding RNA, and several micro RNA. Recent evidence suggests that each of these have important independent roles in metabolic regulation. It has also become clear that an alternatively spliced form of the insulin receptor may be the principle IGF-II receptor. These recent discoveries have important implications for metabolic disorders and also for cancer, for which there is renewed acknowledgement of the importance of metabolic reprogramming.

Maternally expressed gene 3 in metabolic programming

Maternally Expressed Gene 3 (MEG3) is a long noncoding RNA (lncRNA) that coordinates a diverse array of cellular processes requiring epigenetic regulation of genes and interactions with key signaling proteins and by acting as a competitive endogenous (ce)RNA. Epigenetic modifications driven by in utero nutrition affect MEG3 expression and its role in the development of multiple metabolic disorders. This review examines how epigenetic modification of MEG3 expression can confer adaptedness to different metabolic environments. To this end, we discuss how nutritional status that leads to an increase of MEG3 expression can protect against cancer and metabolic dysfunctions, while interventions that promote MEG3 downregulation minimize the pleiotropic costs associated with its expression. Lastly, we identify research directions that would further shed light on the role of MEG3 in metabolic regulation and in functional imprinted gene networks. This article is part of a Special Issue entitled: ncRNA in control of gene expression edited by Kotb Abdelmohsen.