The expression of LEP, LEPR, IGF1 and IL10 in obesity and the relationship with microRNAs

miRNA and leptin signaling in metabolic diseases and at extreme environments

The burden of growing concern about the dysregulation of metabolic processes arises due to complex interplay between environment and nutrition that has great impact on genetics and epigenetics of an individual. Thereby, any abnormality at the level of food intake regulating hormones may contribute to the development of metabolic diseases in any age group due to malnutrition, overweight, changing lifestyle, and exposure to extreme environments such as heat stress (HS), cold stress, or high altitude (HA). Hormones such as leptin, adiponectin, ghrelin, and cholecystokinin regulate appetite and satiety to maintain energy homeostasis. Leptin, an adipokine and a pleiotropic hormone, play major role in regulating the food intake, energy gain and energy expenditure. Using in silico approach, we have identified the major genes (LEP, LEPR, JAK2, STAT3, NPY, POMC, IRS1, SOCS3) that play crucial role in leptin signaling pathway. Further, eight miRNAs (hsa-miR-204-5p, hsa-miR-211-5p, hsa-miR-30, hsa-miR-3163, hsa-miR-33a-3p, hsa-miR-548, hsa-miR-561-3p, hsa-miR-7856-5p) from TargetScan 8.0 database were screened out that commonly target these genes. The role of these miRNAs should be explored as they might play vital role in regulating the appetite, energy metabolism, metabolic diseases (obesity, type 2 diabetes, cardiovascular diseases, inflammation), and to combat extreme environments. The miRNAs regulating leptin signaling and appetite may be useful for developing novel therapeutics for metabolic diseases.

Associations of leptin receptors and miRNA polymorphisms with susceptibility to hypertension

Leptin receptors (LEPR) are located in the central nervous system and other tissues including adipocytes and endothelial cells, where they play a key role in mediating the effects of leptin. MicroRNA (miR/miRNA)-27a and miR-155 have been shown to play an important role in the regulation of LEPR expression and are differentially expressed in various diseases. Therefore, the present study analyzed potential associations of LEPR deletion/insertion (Del/Ins), miR-27aA>G (rs895819) and miR-155T>A (rs767649) polymorphisms with a predisposition to hypertension (HTN). Genotyping was performed by a PCR-restriction fragment length polymorphism assay. Frequencies of LEPR Del/Ins and miRNA gene polymorphisms in patients diagnosed with HTN (n=232) and randomly selected healthy controls (n=247) were assessed. The present study found that Del/Ins and Ins/Ins genotypes and the Ins allele of the LEPR Del/Ins polymorphism were associated with a decreased risk of HTN compared with controls, whereas the miR-27aA>G rs895819 polymorphism was associated with an increased risk of HTN. Combined genotype and allele analyses for LEPR Del/Ins and two miRNA polymorphisms revealed an association with an increased risk or a decreased risk of HTN. Furthermore, stratification analysis revealed that HTN risk factors were associated with waist circumference (WC) and high-density lipoprotein cholesterol (HDL-C) values in LEPR Del/Ins polymorphism. They were also associated with body mass index, WC, triglyceride and HDL-C values in miR-27aA>G polymorphism. The present study revealed a combined effect of LEPR Del/Ins and miR-27aA>G polymorphisms on the risk of HTN in Koreans, suggesting that these gene polymorphisms could be potential markers for predicting HTN risk.

Altered expression levels of TAS1R2 and TAS1R3 genes among SARS-CoV-2 variants of concerns

BACKGROUND

The most common symptoms of coronavirus infections are fever, cough, shortness of breath, headache, ache of joints, a loss of smell and loss of taste, and etc. Early studies suggested that smell and taste receptors were associated with pathogenic detection and immunity. Thus, we aimed to evaluate the expression profile of gene receptors that are related to taste, smell, and appetite control in COVID-19 patients and their putative correlation with SARS-CoV-19 variants.

METHOD

Gene expression levels of TAS1R2, TAS1R3, TAS2R38, OR51E1, LEPR, GHRL were analyzed in 100 COVID-19 patients and 100 SARS-CoV-2 RT-qPCR negative group.

RESULTS

The expression levels of TAS1R2 and TAS1R3 genes were significantly decreased in COVID-19 patients who were infected with Delta variant. However, the TAS2R38 gene expression level was significantly lower when compared to the control group. The TAS1R2 gene expression was positively correlated with TAS1R3, and TAS2R38 genes (p = 0.001, p = 0.025, respectively).

CONCLUSION

TAS1R2, TAS1R3, and TAS2R38 gene expression levels were decreased in the Delta variant compared to the Omicron BA.1 variant in the studied groups. These results provided a significant clue for the temporary taste loss, especially in patients infected with the Delta variant, which is the most disruptive and symptomatic variant causing hospitalizations, and deaths compared to other variants may be because ACE2 is expressed in the taste buds and high replication of SARS-CoV-2 in the infected gustatory cells in the taste bud generates inflammation and then could eventually destroy the cells. This gustatory cell damage may cause malfunction of the gustatory system.

Genetics, genomics, and diet interactions in obesity in the Latin American environment

Obesity is a chronic disease characterized by abnormal or excessive fat accumulation that could impact an individual's health; moreover, the World Health Organization (WHO) has declared obesity a global epidemic since 1997. In Latin America, in 2016, reports indicated that 24.2% of the adult population was obese. The environmental factor or specific behaviors like dietary intake or physical activity have a vital role in the development of a condition like obesity, but the interaction of genes could contribute to that predisposition. Hence, it is vital to understand the relationship between genes and disease. Indeed, genetics in nutrition studies the genetic variations and their effect on dietary response; while genomics in nutrition studies the role of nutrients in gene expression. The present review represents a compendium of the dietary behaviors in the Latin American environment and the interactions of genes with their single nucleotide polymorphisms (SNPs) associated with obesity, including the risk allele frequencies in the Latin American population. Additionally, a bibliographical selection of several studies has been included; these studies examined the impact that dietary patterns in Latin American environments have on the expression of numerous genes involved in obesity-associated metabolic pathways.

MicroRNAs as Mediators of Adipose Thermogenesis and Potential Therapeutic Targets for Obesity

Obesity is a growing health problem worldwide, associated with an increased risk of multiple chronic diseases. The thermogenic activity of brown adipose tissue (BAT) correlates with leanness in adults. Understanding the mechanisms behind BAT activation and the process of white fat "browning" has important implications for developing new treatments to combat obesity. MicroRNAs (miRNAs) are small transcriptional regulators that control gene expression in various tissues, including adipose tissue. Recent studies show that miRNAs are involved in adipogenesis and adipose tissue thermogenesis. In this review, we discuss recent advances in the role of miRNAs in adipocyte thermogenesis and obesity. The potential for miRNA-based therapies for obesity and recommendations for future research are highlighted, which may help provide new targets for treating obesity and obesity-related diseases.

Epiregulin as an Alternative Ligand for Leptin Receptor Alleviates Glucose Intolerance without Change in Obesity

The leptin receptor (LepR) acts as a signaling nexus for the regulation of glucose uptake and obesity, among other metabolic responses. The functional role of LepR under leptin-deficient conditions remains unclear. This study reports that epiregulin (EREG) governed glucose uptake in vitro and in vivo in Lep^ob mice by activating LepR under leptin-deficient conditions. Single and long-term treatment with EREG effectively rescued glucose intolerance in comparative insulin and EREG tolerance tests in Lep^ob mice. The immunoprecipitation study revealed binding between EREG and LepR in adipose tissue of Lep^ob mice. EREG/LepR regulated glucose uptake without changes in obesity in Lep^ob mice via mechanisms, including ERK activation and translocation of GLUT4 to the cell surface. EREG-dependent glucose uptake was abolished in Lepr^db mice which supports a key role of LepR in this process. In contrast, inhibition of the canonical epidermal growth factor receptor (EGFR) pathway implicated in other EREG responses, increased glucose uptake. Our data provide a basis for understanding glycemic responses of EREG that are dependent on LepR unlike functions mediated by EGFR, including leptin secretion, thermogenesis, pain, growth, and other responses. The computational analysis identified a conserved amino acid sequence, supporting an evolutionary role of EREG as an alternative LepR ligand.

MiRNA-27a mediates insulin resistance in 3T3-L1 cells through the PPARγ

The biological actions of insulin have been originated by activation of membrane receptors, which trigger a diversity of signaling pathways in facilitating their biological activities. Insulin homeostasis functions in promoting metabolism balance and promotes cell growth and proliferation. If these mechanisms are reformed, this could lead to insulin resistance as a result of defective insulin signaling triggered by mutations in receptors or effector molecules located downstream or by abnormal posttranslational modifications. The purpose of this is to preliminarily investigate the mechanism of miRNA-27a-mediating insulin resistance in 3T3-L1 cells. Insulin resistance in 3T3-L1 adipocytes as a cell model was induced by tumor necrosis factor-alpha (TNF-α) and the miRNA-27a expression in 3T3-L1 adipocytes had been experiential. The regulation of peroxisome proliferator-activated receptor-gamma (PPARγ) mRNA by miRNA-27a had been studied by reverse transcription receptor polymerase chain reaction (RT-PCR). MiRNA-27a was up-regulated in 3T3-L1 cells, miRNA-27a mimics reserved expression of PPARγ mRNA, and miRNA-27a inhibitors up-regulated the expression of PPARγ mRNA. The insulin resistance in 3T3-L1 cells mediated by miRNA-27a may be achieved by targeting PPARγ.

PPAR-γ Gene Expression in Human Adipose Tissue Is Associated with Weight Loss After Sleeve Gastrectomy

BACKGROUND

The peroxisome proliferator-activated receptor (PPAR)-γ plays a key role in adipose tissue differentiation and fat metabolism. However, it is unclear which factors may regulate its expression and whether obese patients have changes in adipose tissue expression of PPAR-γor potential regulators such as miR-27. Thus, our aims were to analyze PPAR-γ and miR-27 expression in adipose tissue of obese patients, and to correlate their levels with clinical variables.

SUBJECTS AND METHODS

We included 43 morbidly obese subjects who underwent sleeve gastrectomy (31 of them completed 1-year follow-up) and 19 non-obese subjects. mRNA expression of PPAR-γ1 and PPAR-γ2, miR-27a, and miR-27b was measured by qPCR in visceral and subcutaneous adipose tissue. Clinical variables and serum adipokine and hormone levels were correlated with PPAR-γ and miR-27 expression. In addition, a systematic review of the literature regarding PPAR-γ expression in adipose tissue of obese patients was performed.

RESULTS

We found no differences in the expression of PPAR-γ and miR-27 in adipose tissue of obese patients vs. controls. The literature review revealed discrepant results regarding PPAR-γ expression in adipose tissue of obese patients. Of note, we described a significant negative correlation between pre-operative PPAR-γ1 expression in adipose tissue of obese patients and post-operative weight loss, potentially linked with insulin resistance markers.

CONCLUSION

PPAR-γ1 expression in adipose tissue is associated with weight loss after sleeve gastrectomy and may be used as a biomarker for response to surgery.

MicroRNAs: The Link between the Metabolic Syndrome and Oncogenesis

Metabolic syndrome (MetS) represents a cluster of disorders that increase the risk of a plethora of conditions, in particular type two diabetes, cardiovascular diseases, and certain types of cancers. MetS is a complex entity characterized by a chronic inflammatory state that implies dysregulations of adipokins and proinflammatory cytokins together with hormonal and growth factors imbalances. Of great interest is the implication of microRNA (miRNA, miR), non-coding RNA, in cancer genesis, progression, and metastasis. The adipose tissue serves as an important source of miRs, which represent a novel class of adipokines, that play a crucial role in carcinogenesis. Altered miRs secretion in the adipose tissue, in the context of MetS, might explain their implication in the oncogenesis. The interplay between miRs expressed in adipose tissue, their dysregulation and cancer pathogenesis are still intriguing, taking into consideration the fact that miRNAs show both carcinogenic and tumor suppressor effects. The aim of our review was to discuss the latest publications concerning the implication of miRs dysregulation in MetS and their significance in tumoral signaling pathways. Furthermore, we emphasized the role of miRNAs as potential target therapies and their implication in cancer progression and metastasis.

Adipocyte, Immune Cells, and miRNA Crosstalk: A Novel Regulator of Metabolic Dysfunction and Obesity

Obesity is characterized as a complex and multifactorial excess accretion of adipose tissue (AT) accompanied with alterations in the immune response that affects virtually all age and socioeconomic groups around the globe. The abnormal accumulation of AT leads to several metabolic diseases, including nonalcoholic fatty liver disorder (NAFLD), low-grade inflammation, type 2 diabetes mellitus (T2DM), cardiovascular disorders (CVDs), and cancer. AT is an endocrine organ composed of adipocytes and immune cells, including B-Cells, T-cells and macrophages. These immune cells secrete various cytokines and chemokines and crosstalk with adipokines to maintain metabolic homeostasis and low-grade chronic inflammation. A novel form of adipokines, microRNA (miRs), is expressed in many developing peripheral tissues, including ATs, T-cells, and macrophages, and modulates the immune response. miRs are essential for insulin resistance, maintaining the tumor microenvironment, and obesity-associated inflammation (OAI). The abnormal regulation of AT, T-cells, and macrophage miRs may change the function of different organs including the pancreas, heart, liver, and skeletal muscle. Since obesity and inflammation are closely associated, the dysregulated expression of miRs in inflammatory adipocytes, T-cells, and macrophages suggest the importance of miRs in OAI. Therefore, in this review article, we have elaborated the role of miRs as epigenetic regulators affecting adipocyte differentiation, immune response, AT browning, adipogenesis, lipid metabolism, insulin resistance (IR), glucose homeostasis, obesity, and metabolic disorders. Further, we will discuss a set of altered miRs as novel biomarkers for metabolic disease progression and therapeutic targets for obesity.

A functional variant in the promoter region of IGF1 gene is associated with chicken abdominal fat deposition

Insulin-like growth factor 1 (IGF1) plays an important role in the regulation of cell growth, proliferation, differentiation, and apoptosis. Previously several studies revealed that genotypes of chicken IGF1 c.-366A > C were significantly associated with abdominal fat weight and body weight in chickens. But the underlying mechanism is still unknown. To investigate the mechanism underlying the association, herein, we performed IGF1 gene mRNA expression profiling, a dual-luciferase reporter assay and electrophoretic mobility shift assay (EMSA). Quantitative real-time PCR results showed that IGF1 gene was widely expressed in 14 tissues. The mRNA expression levels of IGF1 gene in both abdominal fat and jejunum were significantly higher in fat broilers than in lean broilers. However, the opposite results were observed in the pancreas. The reporter gene assay showed that the promoter luciferase activity of allele A was significantly higher than that of allele C (P < 0.05). In addition, the luciferase activity of allele A promoted by the transcription factor AP1 and OCT1 was higher than that of allele C (P < 0.05). Electrophoretic mobility shift assay result showed that allele A binding to the transcription factor AP1 and OCT1 was stronger than that of allele C. All in all, our data indicated that the IGF1 gene c.-366A > C is a functional SNP responsible for chicken adipose deposition.

MicroRNA Expression Profiles in the Subcutaneous Adipose Tissues of Morbidly Obese Chinese Women

INTRODUCTION

Obesity is a main global health issue and an outstanding cause of morbidity and mortality. Exploring miRNA profiling may help further studies on obesity.

METHODS

Three morbidly obese and 5 normal-weight Chinese women were enrolled in the microarray testing group. Abdominal subcutaneous adipose tissue (SAT) samples were excised. Total RNAs including miRNAs were extracted. Affymetrix GeneChip miRNA 4.0 Array was used to compare the expression profiles of miRNAs between the 2 groups. Two algorithms, miRanda and TargetScan, were used to predict target messenger RNAs (mRNAs). Bioinformatics analysis was then done based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The sample sizes were further expanded to 8 morbidly obese and 9 normal-weight subjects, and quantitative real-time PCR (qRT-PCR) was utilized to verify the expression of differential miRNAs and target genes.

RESULTS

As per the microarray assay, 58 miRNAs were differentially expressed in the SAT from the morbidly obese and normal-weight groups (Fold >4, p < 0.01, FDR <0.05); 54 of these were downregulated and 4 were upregulated in morbidly obese subjects. A total of 1,333 target genes were jointly predicted by miRanda and TargetScan. Further bioinformatics analysis showed that the differential miRNAs were involved in 269 significant biological functions and 89 significant signaling pathways. The validation experiment by qRT-PCR showed that the expression levels of miRNA-143-5p, miRNA-143-3p, miRNA-145-5p, and let-7a-5p were downregulated in morbidly obese subjects, consistent with the microarray detection. High-mobility group A2 (HMGA2), a target gene of the downregulated miRNA let-7a-5p, was first found to be upregulated 3.19-fold in the SAT of morbidly obese Chinese women when compared to normal-weight controls.

CONCLUSIONS

MiRNA downregulation is a hallmark of intact SAT in a morbidly obese state. Transcription (DNA-dependent), small-molecule metabolic processes, the MAPK signaling pathway, and cancer-related pathways may play important roles in the occurrence and development of obesity. For the first time, we proved that HMGA2, a target gene of let-7a-5p, is upregulated in the SAT of morbidly obese Chinese women.

The role of miR-320 in glucose and lipid metabolism disorder-associated diseases

Glucose and lipids are important nutrients that provide the majority of energy for each organ to maintain homeostasis of the body. With the continuous improvement in living standards, the incidence of metabolic disorder-associated diseases, such as diabetes, hyperlipidemia, and atherosclerosis, is increasing worldwide. Among them, diabetes, which could be induced by both glucose and lipid metabolic disorders, is one of the five diseases with the highest incidence and mortality worldwide. However, the detailed molecular mechanisms underlying glucose and lipid metabolism disorders and target-organ damage are still not fully defined. MicroRNAs (miRNAs) are small, non-coding, single-stranded RNAs, which usually affect their target mRNAs in the cytoplasm by post-transcriptional regulation. Previously, we have found that miR-320 contributed to glucose and lipid metabolism via different signaling pathways. Most importantly, we identified that nuclear miR-320 mediated diabetes-induced cardiac dysfunction by activating the transcription of fatty acid metabolic genes to cause lipotoxicity in the heart. Here, we reviewed the roles of miR-320 in glucose and lipid metabolism and target-organ damage.

Leptin System in Obese Dog Skin: A Pilot Study

Simple Summary

Obesity is a widespread phenomenon in pets and its growing trend is similar to the human one. It can be associated with skin pathologies but there is little information on this field in domestic animals. Since in obesity adipokine plasmatic levels changes, in this study leptin (LEP) system was evaluated in the skin of obese dogs to observe changes in peripheral tissue. LEP is a hormone produced mainly by the adipose tissue and its serum level may reflect body mass index and BCS. LEP is also expressed in the skin and it has a prominent role in the biology of this tissue promoting cell proliferation and regulating the wound healing process. Investigation performed in obese and normal-weight dogs evidenced LEP and leptin receptor (LEPR) immunostaining in several skin structures. As LEP expression regards, differences were non-significant, while the LEPR transcripts appeared 10 fold higher in obesedogs. No differences were observed in the composition of skin associated immune system. The obese group-increased LEPR expression suggests that the receptor modulates the system control. The LEP system changes in the skin under obesity conditions however, the exact role of LEP in obese dog skin needs further insights.

Abstract

Obesity predisposes to several health problems including skin diseases. However, information on the relationship between obesity and skin disorders in pets is very scarce. Leptin (LEP) is mainly produced by adipose tissue and has a prominent role in skin biology. This study evaluated the LEP system in the skin of obese dogs compared to normal-weight animals. The investigation was carried out on 10 obese (Obese group) and 10 normal-weight (Normal-weight group) dogs through Real-time PCR and immunohistochemistry. Cells of skin associated immune system were also evaluated. No differences were evidenced between the two groups as well as skin inflammation. LEP differences were no significant, while LEPR transcript appeared 10-fold higher in obesedogs than in normal-weight ones. Immunostaining for both molecules was observed in several skin structures such as the epidermis, hair follicles, and glands. No differences appeared in the skin associated immune system composition. This study is a preliminary report showing that LEP system changes in obese dog skin. The increased LEPR expression observed in the obese group suggests that the receptor plays a modulating role in the system control. However, the exact role of LEPin the skin under obesity conditions needs further elucidation.

Potential use of serum insulin-like growth factor 1 and E-cadherin as biomarkers of colorectal cancer

AIM

Despite many efforts, reliable biomarkers for the prediction and diagnosis of colorectal cancer (CRC) are still missing. Insulin-like growth factor 1 (IGF-1) and E-cadherin are recognized as potential biomarkers, but their diagnostic capacity is largely unexplored in CRC. The aim of this work is to investigate IGF-1 and E-cadherin levels with respect to various characteristics of CRC and to estimate their diagnostic potential.

METHOD

Seventy CRC patients and 75 healthy individuals were enrolled. IGF-1 and E-cadherin were determined using enzyme-linked immunosorbent assay. The predictive and diagnostic capacities of IGF-1 and E-cadherin were estimated by logistic regression analysis and by determination of the area under the receiver operating characteristic (ROC) curve (AUC).

RESULTS

Concentrations of IGF-1 were lower (P = 0.019) while levels of E-cadherin were higher (P < 0.001) in CRC patients than in controls. IGF-1 concentration decreased in parallel with age and progression of CRC (P = 0.023). Also, IGF-1 was higher in men with CRC than in women (P = 0.003). E-cadherin levels were unaffected by variations in either anthropometric characteristics of CRC patients, or localization, grade and stage of the tumour. Both IGF-1 and E-cadherin were independently associated with CRC (P = 0.040; P < 0.001, respectively). The diagnostic accuracy of IGF-1 was estimated as acceptable (AUC = 0.757; P < 0.001), while the diagnostic accuracy of E-cadherin was outstanding (AUC = 0.954; P < 0.001).

CONCLUSIONS

Decreased IGF-1 and increased E-cadherin levels were found in CRC patients. IGF-1, but not E-cadherin, concentrations differed according to age, gender and stage of CRC. Both markers were independently associated with the presence of the disease, while E-cadherin demonstrated high diagnostic accuracy.

miR-27b Modulates Insulin Signaling in Hepatocytes by Regulating Insulin Receptor Expression

Insulin resistance (IR) is one of the key contributing factors in the development of type 2 diabetes mellitus (T2DM). However, the molecular mechanisms leading to IR are still unclear. The implication of microRNAs (miRNAs) in the pathophysiology of multiple cardiometabolic pathologies, including obesity, atherosclerotic heart failure and IR, has emerged as a major focus of interest in recent years. Indeed, upregulation of several miRNAs has been associated with obesity and IR. Among them, miR-27b is overexpressed in the liver in patients with obesity, but its role in IR has not yet been thoroughly explored. In this study, we investigated the role of miR-27b in regulating insulin signaling in hepatocytes, both in vitro and in vivo. Therefore, assessment of the impact of miR-27b on insulin resistance through the hepatic tissue is of special importance due to the high expression of miR-27b in the liver together with its known role in regulating lipid metabolism. Notably, we found that miR-27b controls post-transcriptional expression of numerous components of the insulin signaling pathway including the insulin receptor (INSR) and insulin receptor substrate 1 (IRS1) in human hepatoma cells. These results were further confirmed in vivo showing that overexpression and inhibition of hepatic miR-27 enhances and suppresses hepatic INSR expression and insulin sensitivity, respectively. This study identified a novel role for miR-27 in regulating insulin signaling, and this finding suggests that elevated miR-27 levels may contribute to early development of hepatic insulin resistance.

Investigation of Leptin and its receptor (LEPR) for single nucleotide polymorphisms in colorectal cancer: a case-control study involving 2,306 subjects

Single nucleotide polymorphisms (SNPs) in the genes coding for leptin (LEP) and its receptor (LEPR) might regulate energy balance and be implicated in the development of colorectal cancer (CRC). In the present investigation, 1,003 CRC cases and 1,303 matched controls was compared. Five functional SNPs in LEP and LEPR genes were chosen to evaluate the correlation of these chosen SNPs with CRC susceptibility. We used the SNPscan^TM genotyping assay to genotype LEP and LEPR SNPs. A significantly decreased risk of CRC was found to be associated with the LEPR rs6588147 polymorphism (GA vs. GG: crude P=0.007 and GA/AA vs. GG: crude P=0.018). With adjustments for risk factors (e.g. age, gender, drinking, BMI and smoking), these associations were not changed. In subgroup analyses, the association of LEP rs2167270 with a decreased risk of CRC was found in the ≥61 years old subgroup. For LEPR rs1137100, the association of this SNP with an increased susceptibility of CRC was found in the BMI <24 kg/m² subgroup. In subgroup analyses for LEPR rs6588147, we identified that this locus also decreased the susceptibility of CRC in the male subgroup, <61 years old subgroup, never smoking subgroup and never drinking subgroup. For LEPR rs1137101, the relationship of this polymorphism with a decreased susceptibility to CRC was found in the never drinking subgroup. In summary, the present study highlights that LEPR rs6588147, rs1137101 and LEP rs2167270 may decrease the risk of CRC. However, LEPR rs1137100 is associated with susceptibility to CRC. Further case-control studies with larger sample sizes should be conducted to validate our findings.

MicroRNA Profiling in Adipose Before and After Weight Loss Highlights the Role of miR-223-3p and the NLRP3 Inflammasome

OBJECTIVE

Adipose tissue plays a key role in obesity-related metabolic dysfunction. MicroRNA (miRNA) are gene regulatory molecules involved in intercellular and inter-organ communication. It was hypothesized that miRNA levels in adipose tissue would change after gastric bypass surgery and that this would provide insights into their role in obesity-induced metabolic dysregulation.

METHODS

miRNA profiling (Affymetrix GeneChip miRNA 2.0 Array) of omental and subcutaneous adipose (n = 15 females) before and after gastric bypass surgery was performed.

RESULTS

One omental and thirteen subcutaneous adipose miRNAs were significantly differentially expressed after gastric bypass, including downregulation of miR-223-3p and its antisense relative miR-223-5p in both adipose tissues. mRNA levels of miR-223-3p targets NLRP3 and GLUT4 were decreased and increased, respectively, following gastric bypass in both adipose tissues. Significantly more NLRP3 protein was observed in omental adipose after gastric bypass (P = 0.02). Significant hypomethlyation of NLRP3 and hypermethylation of miR-223 were observed in both adipose tissues after gastric bypass. In subcutaneous adipose, significant correlations were observed between both miR-223-3p and miR-223-5p and glucose and between NLRP3 mRNA and protein levels and blood lipids.

CONCLUSIONS

This is the first report detailing genome-wide miRNA profiling of omental adipose before and after gastric bypass, and it further highlights the association of miR-223-3p and the NLRP3 inflammasome with obesity.

Obesity impacts the regulation of miR-10b and its targets in primary breast tumors

BACKGROUND

Obesity increases breast cancer (BC) risk in post-menopausal women by mostly unknown molecular mechanisms which may partly be regulated by microRNAs (miRNAs).

METHODS

We isolated RNA from paired benign and malignant biopsies from 83 BC patients and determined miRNA profiles in samples from 12 women at the extremes of the BMI distribution by RNA-seq. Candidates were validated in all samples. Associations between miR-10b expression and validated target transcript levels, and effects of targeted manipulation of miR-10b levels in a primary BC cell line on proliferation and invasion potential, were explored.

RESULTS

Of the 148 miRNAs robustly expressed in breast tissues, the levels of miR-21, miR-10b, miR-451a, miR-30c, and miR-378d were significantly associated with presence of cancer. Of these, miR-10b showed a stronger down-regulation in the tumors of the obese subjects, as opposed to the lean. In ductal but not lobular tumors, significant inverse correlations were observed between the tumor levels of miR-10b and miR-30c and the mRNA levels of cancer-relevant target genes SRSF1, PIEZO1, MAPRE1, CDKN2A, TP-53 and TRA2B, as well as tumor grade. Suppression of miR-10b levels in BT-549 primary BC-derived cells increased cell proliferation and invasive capacity, while exogenous miR-10b mimic decreased invasion. Manipulation of miR-10b levels also inversely affected the mRNA levels of miR-10b targets BCL2L11, PIEZO1 and NCOR2.

CONCLUSIONS

Our findings suggest that miR-10b may be a mediator between obesity and cancer in post-menopausal women, regulating several known cancer-relevant genes. MiR-10b expression may have diagnostic and therapeutic implications for the incidence and prognosis of BC in obese women.

MiR27a Promotes the Development of Macrophage-like Characteristics in 3T3-L1 Preadipocytes

Recruitment and polarization of classically activated (M1) macrophages within adipose tissue contribute to chronic low-grade inflammation in obesity. Adipose tissue precursor cells exhibit the capacity to develop macrophage-like characteristics and adipocyte-derived miR27a is known to promote reprogramming of somatic cells. It was unknown whether exogenous addition of miR27a promote the development of macrophage-like characteristics of adipose precursor cells. We examined macrophage surface antigen, phagocytosis and migration ability in 3T3-L1 preadipocytes transfected with miR27a mimics. Transfection of 3T3-L1 preadipocytes with miR27a mimics increased phagocytosis and migration and increased the number of cells expressing the macrophage makers F4/80 and MHC compared to controls. M2 and CD206 macrophage markers were unaltered. In addition, transfection of 3T3-L1 preadipocytes with miR27a mimics reduced PPARγ expression, activated NF-κB and promoted secretion of the inflammatory cytokines MCP-1, TNF-α and IL-1β compared to controls. The level of anti-inflammatory factors Arg-1, IL-10, Ym1 and Fizz1 were unaltered. Secretion of miR27a was increased in conditioned medium prepared from palmitic acid-treated differentiated 3T3-L1 adipocytes compared to controls. Incubation of 3T3-L1 preadipocytes with this conditioned medium increased phagocytosis and migration compared to controls. Finally, conditioned medium prepared from differentiated 3T3-L1 adipocytes transfection with miR27a inhibitors reduced phagocytosis and migration in 3T3-L1 preadipocytes compared to controls. The data indicate that PPARγ agonists may reverse the activation of NF-κB pathway mediated by miR27a overexpression and reduce phagocytosis and migration of adipose precursor cells. In addition, miR27a may promote the development of macrophage-like characteristics in 3T3-L1 preadipocytes.

The Destiny of Glucose from a MicroRNA Perspective

Glucose serves as a primary, and for some tissues the unique, fuel source in order to generate and maintain the biological functions. Hyperglycemia is a hallmark of type 2 diabetes and is the direct consequence of perturbations in the glucose homeostasis. Insulin resistance, referred to as a reduced response of target tissues to the hormone, contributes to the development of hyperglycemia. The molecular mechanisms responsible for the altered glucose homeostasis are numerous and not completely understood. MicroRNAs (miRNAs) are now recognized as regulators of the lipid and glucose metabolism and are involved in the onset of metabolic diseases. Indeed, these small non-coding RNA molecules operate in the RNA silencing and posttranscriptional regulation of gene expression and may modulate the levels of kinases and enzymes in the glucose metabolism. Therefore, a better characterization of the function of miRNAs and a deeper understanding of their role in disease may represent a fundamental step toward innovative treatments addressing the causes, not only the symptoms, of hyperglycemia, using approaches aimed at restoring either miRNAs or their specific targets. In this review, we outline the current understanding regarding the impact of miRNAs in the glucose metabolism and highlight the need for further research focused on altered key kinases and enzymes in metabolic diseases.

Tumor-linked HER2 expression: association with obesity and lipid-related microenvironment

Obesity is associated with the risk of several health disorders including certain cancers. Among obesity-related cancers, postmenopausal breast carcinoma is a well-studied one. Apart from an increase in certain types of lipids in obesity, excess adipose tissue releases many hormone-like cytokines/adipokines, which are usually pro-inflammatory in nature. Leptin is one of such adipokines and significantly linked with the intracellular signaling pathways of other growth factors such as insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER2). In general, HER2 is overexpressed in roughly 30% of breast carcinomas; its presence indicates aggressive tumor behavior. Conversely, HER2 has certain effects in normal conditions such as differentiation of preadipocytes, cardiovascular health and vitamin D metabolism. HER2 has no known endogenous ligand, but it may form dimers with other three members of the epidermal growth factor receptor (EGFR) family and can activate downstream signaling pathways. Furthermore, HER2 is intimately connected with several enzymes, e.g. fatty acid synthase (FASN), phosphatidylinositol 3-kinase (PI3K), AKT and mechanistic target of rapamycin (mTOR), all of which play significant regulatory roles in lipogenic pathways or lipid metabolism. In obesity-related carcinogenesis, characteristics like insulin resistance and elevated IGF-1 are commonly observed. Both IGF-1 and leptin can modulate EGFR and HER2 signaling pathways. Although clinical studies have shown mixed results, the behavior of HER2+ tumor cells including HER2 levels can be altered by several factors such as obesity, leptin and fatty acids. A precise knowledge is useful in new therapeutic approaches against HER+ tumors.

Adipogenic miR-27a in adipose tissue upregulates macrophage activation via inhibiting PPARγ of insulin resistance induced by high-fat diet-associated obesity

Chronic low degree inflammation caused by macrophage activation is a crucial factor underlying insulin resistance induced by obesity. To illustrate the mechanism of regulating of macrophage activation in adipose tissue, the role of adipogenic miR-27a activating M1 macrophage polarization via blocking PPARγ was evaluated. Obese mice model and miR-27a overexpression or knockdown mice model were established and related biochemical index were examined. Raw264.7 and 3T3-L1 were cultured and co-cultured for mimicking the microenvironment of local inflammation. Macrophage infiltration was observed. MiR-27a and cytokines levels in serum and adipose tissue were measured. Macrophage polarization markers and protein expression in insulin or inflammatory signaling pathways were observed. Impaired glucose tolerance and insulin tolerance was observed in 4w, 8w and 12w of high fat diet and miR-27a overexpression mice. Concurrently, miR-27a was increased in serum in a time-dependent manner, along with M1 cytokines and M1 macrophages increasing in adipose tissue clearly. Insulin signaling pathway was blocked, and PPARγ was suppressed. However, NF-κB was activated. On the other hand, activated macrophages and hypertrophic adipocytes induced by miR-27a could increase the ratio of Raw264.7 migration, including improving cytokines generation, and blocking PPARγ expression markedly. The present studies are conducted to clarify that miR-27a has increased along with up-regulation in the process of proinflammatory cytokines generation, macrophage influx and M1 macrophage polarization in obesity. These indicate that miR-27a gives the novel target of intervention for inflammation and insulin resistance in obesity.

Leptin and insulin up-regulate miR-4443 to suppress NCOA1 and TRAF4, and decrease the invasiveness of human colon cancer cells

Background

Obesity is a risk factor for colorectal cancer (CRC). Normal and tumor cells respond to metabolic hormones, such as leptin and insulin. Thus, obesity-associated resistance to these hormones likely leads to changes in gene expression and behavior of tumor cells. However, the mechanisms affected by leptin and insulin signaling in CRC cells remain mostly unknown.

Methods

We hypothesized that microRNAs (miRNAs) are involved in the regulation of tumorigenesis-related gene expression in CRC cells by leptin and insulin. To test this hypothesis, miRNA levels in the CRC-derived cell lines HCT-116, HT-29 and DLD-1 were profiled, following leptin and insulin treatment. Candidate miRNAs were validated by RT-qPCR. Predicted miRNA targets with known roles in cancer, were validated by immunoblots and reporter assays in HCT-116 cells. Transfection of HCT-116 cells with candidate miRNA mimic was used to test in vitro effects on proliferation and invasion.

Results

Of ~800 miRNAs profiled, miR-4443 was consistently up-regulated by leptin and insulin in HCT-116 and HT-29, but not in DLD-1, which lacked normal leptin receptor expression. Dose response experiments showed that leptin at 100 ng/ml consistently up-regulated miR-4443 in HCT-116 cells, concomitantly with a significant decrease in cell invasion ability. Transfection with miR-4443 mimic decreased invasion and proliferation of HCT-116 cells. Moreover, leptin and miR-4443 transfection significantly down-regulated endogenous NCOA1 and TRAF4, both predicted targets of miR-4443 with known roles in cancer metastasis. miR-4443 was found to directly regulate TRAF4 and NCOA1, as validated by a reporter assay. The up-regulation of miR-4443 by leptin or insulin was attenuated by the inhibition of MEK1/2.

Conclusions

Our findings suggest that miR-4443 acts in a tumor-suppressive manner by down-regulating TRAF4 and NCOA1 downstream of MEK-C/EBP-mediated leptin and insulin signaling, and that insulin and/or leptin resistance (e.g. in obesity) may suppress this pathway and increase the risk of metastatic CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2938-1) contains supplementary material, which is available to authorized users.

The investigation of circulating microRNAs associated with lipid metabolism in childhood obesity

BACKGROUND

Childhood obesity is an increasing health challenge related to increased risk of chronic diseases. microRNAs (miRNAs) are noncoding short RNA molecules regulating multiple biological processes linked to obesity.

OBJECTIVES

We aimed at evaluating the association between circulating miRNA levels and lipid metabolism in obese and non-obese children and adolescents.

METHODS

By constituting study group, 45 obese children and adolescents were recruited. To perform comparisons with study group, 41 lean controls were matched for age and sex. Using real-time quantitative PCR analysis, circulating miRNAs were evaluated in both groups.

RESULTS

Circulating miR-335 (P < 0.001), miR-143 (P = 0.001) and miR-758 (P = 0.006) in obese children were significantly lower than those of controls. However, circulating miR-27 (P = 0.032), miR-378 (P < 0.001) and miR-370 (P = 0.045) in obese children were significantly higher, compared with those of controls. In addition, circulating miR-33 in obese children was higher than those of controls, but no significant difference was present (P = 0.687).

CONCLUSION

Our findings showed that a significant association is present between circulating miR-370, miR-33, miR-378, miR-27, miR-335, miR-143 and miR-758 values, and childhood obesity. Low levels of miR-335, miR-143 and miR-758, and high levels of miR-27, miR-378, miR-33 and miR-370 may have been responsible for elevated triglycerides and low-density lipoprotein (LDL-C) levels, and low level of high-density lipoprotein (HDL-C) in obese subjects. Therefore, miRNAs may be a good novel biomarker for childhood obesity.

An assessment of molecular pathways of obesity susceptible to nutrient, toxicant and genetically induced epigenetic perturbation

In recent years, the etiology of human disease has greatly improved with the inclusion of epigenetic mechanisms, in particular as a common link between environment and disease. However, for most diseases we lack a detailed interpretation of the epigenetic regulatory pathways perturbed by environment and causal mechanisms. Here, we focus on recent findings elucidating nutrient-related epigenetic changes linked to obesity. We highlight studies demonstrating that obesity is a complex disease linked to disruption of epigenetically regulated metabolic pathways in the brain, adipose tissue and liver. These pathways regulate (1) homeostatic and hedonic eating behaviors, (2) adipocyte differentiation and fat accumulation, and (3) energy expenditure. By compiling these data, we illustrate that obesity-related phenotypes are repeatedly linked to disruption of critical epigenetic mechanisms that regulate key metabolic genes. These data are supported by genetic mutation of key epigenetic regulators, and many of the diet-induced epigenetic mechanisms of obesity are also perturbed by exposure to environmental toxicants. Identifying similarly perturbed epigenetic mechanisms in multiple experimental models of obesity strengthens the translational applications of these findings. We also discuss many of the ongoing challenges to understanding the role of environmentally induced epigenetic pathways in obesity and suggest future studies to elucidate these roles. This assessment illustrates our current understanding of molecular pathways of obesity that are susceptible to environmental perturbation via epigenetic mechanisms. Thus, it lays the groundwork for dissecting the complex interactions between diet, genes and toxicants that contribute to obesity and obesity-related phenotypes.

The association between circulating IGF1, IGFBP3, and calcium: results from NHANES III

BACKGROUND

Despite mounting evidence linking both calcium and IGF1, there is a lack of studies investigating any association between circulating levels of IGF1 and serum calcium.

METHODS

Serum calcium, IGF1, and IGF-binding protein 3 (IGFBP3) were measured for 5368 participants in NHANES III. We calculated multivariable-adjusted geometric means of serum concentrations of IGF1, IGFBP3, and IGF1/IGFBP3 by categories of calcium (lowest 5% (<1.16 mmol/l), mid 90%, and top 5% (≥1.31 mmol/l)). We also performed stratified analyses by sex, age, ethnicity, BMI, serum levels of vitamin D, and bone mineral density (BMD).

RESULTS

Overall, we found that circulating calcium was positively associated with circulating levels of IGF1 and IGFBP3, but not their molar ratio (i.e., geometric mean of IGF1 by increasing calcium categories: 237.63, 246.51, and 264.22 ng/nl; Ptrend: 0.43; Pfirst vs third category: 0.01). In particular, these associations were observed in women, people aged <60, non-Hispanic whites, those with vitamin D levels above the mean, and those with low BMD. In contrast, there was an inverse association with the molar ratio for those with BMI ≥30 kg/m(2).

CONCLUSION

We found an overall positive association between circulating levels of IGF1 and IGFBP3 and serum calcium. However, stratification by potential effect-modifiers did not support all suggested hypotheses. Our findings provide more insight into the interplay between calcium and IGF1, which in the future can be investigated in larger observational studies allowing for additional stratifications based on a combination of the different effect-modifiers investigated here.

MicroRNAs as regulators of metabolic disease: pathophysiologic significance and emerging role as biomarkers and therapeutics

The prevalence of overweight and obesity in developed and developing countries has greatly increased the risk of insulin resistance and type 2 diabetes mellitus. It is evident from human and animal studies that obesity alters microRNA (miRNA) expression in metabolically important organs, and that miRNAs are involved in changes to normal physiology, acting as mediators of disease. miRNAs regulate multiple pathways including insulin signaling, immune-mediated inflammation, adipokine expression, adipogenesis, lipid metabolism, and food intake regulation. Thus, miRNA-based therapeutics represent an innovative and attractive treatment modality, with non-human primate studies showing great promise. In addition, miRNA measures in plasma or bodily fluids may be used as disease biomarkers and predictors of metabolic disease in humans. This review analyzes the role of miRNAs in obesity and insulin resistance, focusing on the miR-17/92, miR-143-145, miR-130, let-7, miR-221/222, miR-200, miR-223, miR-29 and miR-375 families, as well as miRNA changes by relevant tissue (adipose, liver and skeletal muscle). Further, the current and future applications of miRNA-based therapeutics and diagnostics in metabolic disease are discussed.

Anti-inflammatory effects of gastric bypass surgery and their association with improvement in metabolic profile

Obesity is associated with chronic inflammation and metabolic disease. Bariatric surgery offers a treatment that can effectively reduce weight and improve the metabolic function. However, the effect of bariatric surgery on chronic inflammation in obesity is under-investigated. In this expert review, the authors outline the effect of Roux-en-Y gastric bypass, the most commonly performed bariatric surgery in current practice, on the markers of inflammation. They include a discussion of the relationship between inflammation and weight loss after surgery, the interaction between these markers and metabolic disease, and the effect on adipose tissue inflammation. They also briefly explore the role of glucagon-like-peptide 1 in remediating inflammation and the changes in gut microbiota after Roux-en-Y gastric bypass, and how they may be important in inflammation.