MicroRNA-144 regulates hepatic ATP binding cassette transporter A1 and plasma high-density lipoprotein after activation of the nuclear receptor farnesoid X receptor

Rethinking Bile Acid Metabolism and Signaling for Type 2 Diabetes Treatment

PURPOSE OF REVIEW

Herein, we review the role of FXR and TGR5 in the regulation of hepatic bile acid metabolism, with a focus on how our understanding of bile acid metabolic regulation by these receptors has evolved in recent years and how this improved understanding may facilitate targeting bile acids for type 2 diabetes treatment.

RECENT FINDINGS

Bile acid profile is a key regulator of metabolic homeostasis. Inhibition of expression of the enzyme that is required for cholic acid synthesis and thus determines bile acid profile, Cyp8b1, may be an effective target for type 2 diabetes treatment. FXR and, more recently, TGR5 have been shown to regulate bile acid metabolism and Cyp8b1 expression and, therefore, may provide a mechanism with which to target bile acid profile for type 2 diabetes treatment. Inhibition of Cyp8b1 expression is a promising therapeutic modality for type 2 diabetes; however, further work is needed to fully understand the pathways regulating Cyp8b1 expression.

Dietary compounds have potential in controlling atherosclerosis by modulating macrophage cholesterol metabolism and inflammation via miRNA

Atherosclerosis (AS) is a typical example of a widespread fatal cardiovascular disease. Accumulation of cholesterol-laden macrophages in the artery wall forms the starting point of AS. Increased influx of oxidized low-density lipoprotein to macrophages and decreased efflux of free cholesterol out of macrophages constitute major factors promoting the development of AS. Inflammation further aggravates the development of AS along or via interaction with the cholesterol metabolism. Many microRNAs (miRNAs) are related to the regulation of macrophage in AS in aspects of cholesterol metabolism and inflammation signaling. Dietary compounds perform AS inhibitory effects via miRNAs in the cholesterol metabolism (miR-19b, miR-378, miR-10b, miR-33a, and miR-33b) and two miRNAs in the inflammation signaling (miR-155 and miR-146a). The targeted miRNAs in the cholesterol metabolism vary greatly among different food compounds; however, in inflammation signaling, most food compounds target miR-155. Many receptors are involved in macrophages via miRNAs, including ABCA1 and ABCG1 as major receptors in the cholesterol metabolism, while nuclear factor-κB (NF-κB) and Nrf2 signaling and PI3K/AKT signaling pathways are targeted during inflammation. This article reviews current literature to investigate possible AS therapy with dietary compounds via targeting miRNAs. Currently existing problems were also discussed to guide further studies.

Deciphering Non-coding RNAs in Cardiovascular Health and Disease

After being long considered as “junk” in the human genome, non-coding RNAs (ncRNAs) currently represent one of the newest frontiers in cardiovascular disease (CVD) since they have emerged in recent years as potential therapeutic targets. Different types of ncRNAs exist, including small ncRNAs that have fewer than 200 nucleotides, which are mostly known as microRNAs (miRNAs), and long ncRNAs that have more than 200 nucleotides. Recent discoveries on the role of ncRNAs in epigenetic and transcriptional regulation, atherosclerosis, myocardial ischemia/reperfusion (I/R) injury and infarction (MI), adverse cardiac remodeling and hypertrophy, insulin resistance, and diabetic cardiomyopathy prompted vast interest in exploring candidate ncRNAs for utilization as potential therapeutic targets and/or diagnostic/prognostic biomarkers in CVDs. This review will discuss our current knowledge concerning the roles of different types of ncRNAs in cardiovascular health and disease and provide some insight on the cardioprotective signaling pathways elicited by the non-coding genome. We will highlight important basic and clinical breakthroughs that support employing ncRNAs for treatment or early diagnosis of a variety of CVDs, and also depict the most relevant limitations that challenge this novel therapeutic approach.

Non-coding RNAs in lipid metabolism

Cardiovascular disease (CVD), the leading cause of death and morbidity in the Western world, begins with lipid accumulation in the arterial wall, which is the initial step in atherogenesis. Alterations in lipid metabolism result in increased risk of cardiometabolic disorders, and treatment of lipid disorders remains the most common strategy aimed at reducing the incidence of CVD. Work done over the past decade has identified numerous classes of non-coding RNA molecules including microRNAs (miRNAs) and long-non-coding RNAs (lncRNAs) as critical regulators of gene expression involved in lipid metabolism and CVD, mostly acting at post-transcriptional level. A number of miRNAs, including miR-33, miR-122 and miR-148a, have been demonstrated to play important role in controlling the risk of CVD through regulation of cholesterol homeostasis and lipoprotein metabolism. lncRNAs are recently emerging as important regulators of lipid and lipoprotein metabolism. However, much additional work will be required to fully understand the impact of lncRNAs on CVD and lipid metabolism, due to the high abundance of lncRNAs and the poor-genetic conservation between species. This article reviews the role of miRNAs and lncRNAs in lipid and lipoprotein metabolism and their potential implications for the treatment of CVD.

Pathobiology of biliary epithelia

Cholangiocytes are epithelial cells that line the intra- and extrahepatic biliary tree. They serve predominantly to mediate the content of luminal biliary fluid, which is controlled via numerous signaling pathways influenced by endogenous (e.g., bile acids, nucleotides, hormones, neurotransmitters) and exogenous (e.g., microbes/microbial products, drugs etc.) molecules. When injured, cholangiocytes undergo apoptosis/lysis, repair and proliferation. They also become senescent, a form of cell cycle arrest, which may prevent propagation of injury and/or malignant transformation. Senescent cholangiocytes can undergo further transformation to a senescence-associated secretory phenotype (SASP), where they begin secreting pro-inflammatory and pro-fibrotic signals that may contribute to disease initiation and progression. These and other concepts related to cholangiocyte pathobiology will be reviewed herein. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

miR144-3p inhibits PMVECs excessive proliferation in angiogenesis of hepatopulmonary syndrome via Tie2

BACKGROUND/AIM

Increasing evidence show microRNAs (miRNAs) are associated with hepatopulmonary syndrome (HPS). The aim of this study was to investigate the role of miR-144 in the angiogenesis of HPS, as well as to identify its underlying mechanism.

METHODS

The expression levels of miR-144-3p were assessed in pulmonary micro-vascular endothelial cells (PMVECs), as well as in lung tissues from rats with HPS. We predicted the potential target of miR-144-3p. Tyrosine kinase 2(Tie2) was identified as a target gene of miR144-3p, which has an essential role in the angiogenesis of lung vessel. In addition, the effects of miR-144-3p regulated on Tie2 was examined. The upregulation and down-regulation of miR-144-3p can affect the proliferation of PMVECs.

RESULTS

We found that the levels of miR-144-3p were frequently downregulated in HPS tissues and cell lines, and overexpression of miR-144-3p dramatically inhibited PMVECs proliferation and cell cycle. We further verified the Tie2 as a novel and direct target of miR-144-3p in HPS.

CONCLUSION

miR-144-3p can negatively regulate PMVECs proliferation by Tie2 expression. In addition, overexpression of miR-144-3p may prove beneficial as a therapeutic strategy for HPS treatment.

Study of formation of green eggshell color in ducks through global gene expression

The green eggshell color produced by ducks is a threshold trait that can be influenced by various factors, such as hereditary, environment and nutrition. The aim of this study was to investigate the genetic regulation of the formation of eggs with green shells in Youxian ducks. We performed integrative analysis of mRNAs and miRNAs expression profiling in the shell gland samples from ducks by RNA-Seq. We found 124 differentially expressed genes that were associated with various pathways, such as the ATP-binding cassette (ABC) transporter and solute carrier supper family pathways. A total of 31 differentially expressed miRNAs were found between ducks laying green eggs and white eggs. KEGG pathway analysis of the predicted miRNA target genes also indicated the functional characteristics of these miRNAs; they were involved in the ABC transporter pathway and the solute carrier (SLC) supper family. Analysis with qRT-PCR was applied to validate the results of global gene expression, which showed a correlation between results obtained by RNA-seq and RT-qPCR. Moreover, a miRNA-mRNA interaction network was established using correlation analysis of differentially expressed mRNA and miRNA. Compared to ducks that lay white eggs, ducks that lay green eggs include six up-regulated miRNAs that had regulatory effects on 35 down-regulated genes, and seven down-regulated miRNAs which influenced 46 up-regulated genes. For example, the ABC transporter pathway could be regulated by expressing gga-miR-144-3p (up-regulated) with ABCG2 (up-regulated) and other miRNAs and genes. This study provides valuable information about mRNA and miRNA regulation in duck shell gland tissues, and provides foundational information for further study on the eggshell color formation and marker-assisted selection for Youxian duck breeding.

NGS Reveals Molecular Pathways Affected by Obesity and Weight Loss-Related Changes in miRNA Levels in Adipose Tissue

Both obesity and weight loss may cause molecular changes in adipose tissue. This study aimed to characterize changes in adipose tissue miRNome in order to identify molecular pathways affected by obesity and weight changes. Next generation sequencing (NGS) was applied to identify microRNAs (miRNAs) differentially expressed in 47 samples of visceral (VAT) and subcutaneous (SAT) adipose tissues from normal-weight (N), obese (O) and obese after surgery-induced weight loss (PO) individuals. Subsequently miRNA expression was validated by real-time PCR in 197 adipose tissues and bioinformatics analysis performed to identify molecular pathways affected by obesity-related changes in miRNA expression. NGS identified 344 miRNAs expressed in adipose tissues with ≥5 reads per million. Using >2 and <−2 fold change as cut-offs we showed that the expression of 54 miRNAs differed significantly between VAT-O and SAT-O. Equally, between SAT-O and SAT-N, the expression of 20 miRNAs differed significantly, between SAT-PO and SAT-N the expression of 79 miRNAs differed significantly, and between SAT-PO and SAT-O, the expression of 61 miRNAs differed significantly. Ontological analyses disclosed several molecular pathways regulated by these miRNAs in adipose tissue. NGS-based miRNome analysis characterized changes of the miRNA profile of adipose tissue, which are associated with changes of weight possibly responsible for a differential regulation of molecular pathways in adipose tissue when the individual is obese and after the individual has lost weight.

Posttranscriptional regulation of lipid metabolism by non-coding RNAs and RNA binding proteins

Alterations in lipoprotein metabolism enhance the risk of cardiometabolic disorders including type-2 diabetes and atherosclerosis, the leading cause of death in Western societies. While the transcriptional regulation of lipid metabolism has been well characterized, recent studies have uncovered the importance of microRNAs (miRNAs), long-non-coding RNAs (lncRNAs) and RNA binding proteins (RBP) in regulating the expression of lipid-related genes at the posttranscriptional level. Work from several groups has identified a number of miRNAs, including miR-33, miR-122 and miR-148a, that play a prominent role in controlling cholesterol homeostasis and lipoprotein metabolism. Importantly, dysregulation of miRNA expression has been associated with dyslipidemia, suggesting that manipulating the expression of these miRNAs could be a useful therapeutic approach to ameliorate cardiovascular disease (CVD). The role of lncRNAs in regulating lipid metabolism has recently emerged and several groups have demonstrated their regulation of lipoprotein metabolism. However, given the high abundance of lncRNAs and the poor-genetic conservation between species, much work will be needed to elucidate the specific role of lncRNAs in controlling lipoprotein metabolism. In this review article, we summarize recent findings in the field and highlight the specific contribution of lncRNAs and RBPs in regulating lipid metabolism.

RNA-binding protein ZFP36L1 maintains posttranscriptional regulation of bile acid metabolism

Bile acids function not only as detergents that facilitate lipid absorption but also as signaling molecules that activate the nuclear receptor farnesoid X receptor (FXR). FXR agonists are currently being evaluated as therapeutic agents for a number of hepatic diseases due to their lipid-lowering and antiinflammatory properties. FXR is also essential for maintaining bile acid homeostasis and prevents the accumulation of bile acids. Elevated bile acids activate FXR, which in turn switches off bile acid synthesis by reducing the mRNA levels of bile acid synthesis genes, including cholesterol 7α-hydroxylase (Cyp7a1). Here, we show that FXR activation triggers a rapid posttranscriptional mechanism to degrade Cyp7a1 mRNA. We identified the RNA-binding protein Zfp36l1 as an FXR target gene and determined that gain and loss of function of ZFP36L1 reciprocally regulate Cyp7a1 mRNA and bile acid levels in vivo. Moreover, we found that mice lacking hepatic ZFP36L1 were protected from diet-induced obesity and steatosis. The reduced adiposity and antisteatotic effects observed in ZFP36L1-deficient mice were accompanied by impaired lipid absorption that was consistent with altered bile acid metabolism. Thus, the ZFP36L1-dependent regulation of bile acid metabolism is an important metabolic contributor to obesity and hepatosteatosis.

MicroRNAs in dysfunctional adipose tissue: cardiovascular implications

In this review, we focus on the emerging role of microRNAs, non-coding RNAs that regulate gene expression and signaling pathways, in dysfunctional adipose tissue. We highlight current paradigms of microRNAs involved in adipose differentiation and function in depots such as white, brown, and beige adipose tissues and potential implications of microRNA dysregulation in human disease such as obesity, inflammation, microvasculature dysfunction, and related cardiovascular diseases. We highlight accumulating studies indicating that adipocyte-derived microRNAs may not only serve as biomarkers of cardiometabolic disease, but also may directly regulate gene expression of other tissues. Finally, we discuss the future prospects, challenges, and emerging strategies for microRNA delivery and targeting for therapeutic applications in cardiovascular disease states associated with adipocyte dysfunction.

MicroRNAs in Ischemic Heart Disease: From Pathophysiology to Potential Clinical Applications

Despite rapid advances in cardiovascular research and therapeutic strategies, ischemic heart disease (IHD) remains the leading cause of mortality worldwide. MicroRNAs (miRNAs) are small, noncoding RNAs which post transcriptionally regulate gene expression. In the past few years, miRNAs have emerged as key tools for the understanding of the pathophysiology of IHD, with potential uses as new biomarkers and therapeutic targets. Several studies report a regulatory role of miRNAs, with regard to fundamental components of IHD pathogenesis and progression, such as lipoprotein metabolism, atherogenesis, vascular calcification, platelet function, and angiogenesis. Due to their high stability in biofluids, circulating miRNAs have attracted attention as promising biomarkers of IHD, especially in cardiovascular risk prediction and the diagnosis of myocardial infarction. Furthermore, experimental studies have demonstrated the potential of miRNA-targeted therapy in improving hyperlipidemia, atherosclerosis, and angiogenesis. In this review, the current knowledge on the role of miRNAs in IHD and translational perspectives of their use is discussed.

microRNAs in lipoprotein and lipid metabolism: from biological function to clinical application

microRNAs (miRNAs) are short (~22 nucleotides), non-coding, single-stranded RNA molecules that regulate the expression of target genes by partial sequence-specific base-pairing to the targeted mRNA 3'UTR, blocking its translation, and promoting its degradation or its sequestration into processing bodies. miRNAs are important regulators of several physiological processes including developmental and metabolic functions, but their concentration in circulation has also been reported to be altered in many pathological conditions such as familial hypercholesterolemia, cardiovascular diseases, obesity, type 2 diabetes, and cancers. In this review, we focus on the role of miRNAs in lipoprotein and lipid metabolism, with special attention to the well-characterized miR-33a/b, and on the huge potential of miRNAs for clinical application as biomarkers and therapeutics in the context of cardiometabolic diseases.

Induction of MiR133a expression by IL-19 targets LDLRAP1 and reduces oxLDL uptake in VSMC

The transformation of vascular smooth muscle cells [VSMC] into foam cells leading to increased plaque size and decreased stability is a key, yet understudied step in atherogenesis. We reported that Interleukin-19 (IL-19), a novel, anti-inflammatory cytokine, attenuates atherosclerosis by anti-inflammatory effects on VSMC. In this work we report that IL-19 induces expression of miR133a, a muscle-specific miRNA, in VSMC. Although previously unreported, we report that miR133a can target and reduce mRNA abundance, mRNA stability, and protein expression of Low Density Lipoprotein Receptor Adaptor Protein 1, (LDLRAP1), an adaptor protein which functions to internalize the LDL receptor. Mutations in this gene lead to LDL receptor malfunction and cause the Autosomal Recessive Hypercholesterolemia (ARH) disorder in humans. Herein we show that IL-19 reduces lipid accumulation in VSMC, and LDLRAP1 expression and oxLDL uptake in a miR133a-dependent mechanism. We show that LDLRAP1 is expressed in plaque and neointimal VSMC of mouse and human injured arteries. Transfection of miR133a and LDLRAP1 siRNA into VSMC reduces their proliferation and uptake of oxLDL. miR133a is significantly increased in plasma from hyperlipidemic compared with normolipidemic patients. Expression of miR133a in IL-19 stimulated VSMC represents a previously unrecognized link between vascular lipid metabolism and inflammation, and may represent a therapeutic opportunity to combat vascular inflammatory diseases.

MicroRNAs in the Pathobiology and Therapy of Atherosclerosis

MicroRNAs are short noncoding RNAs, expressed in humans and involved in sequence-specific post-transcriptional regulation of gene expression. They have emerged as key players in a wide array of biological processes, and changes in their expression and/or function have been associated with plethora of human diseases. Atherosclerosis and its related clinical complications, such as myocardial infarction or stroke, represent the leading cause of death in the Western world. Accumulating experimental evidence has revealed a key role for microRNAs in regulating cellular and molecular processes related to atherosclerosis development, ranging from risk factors, to plaque initiation and progression, up to atherosclerotic plaque rupture. In this review, we focus on how microRNAs can influence atherosclerosis biology, as well as the potential clinical applications of microRNAs, which are being developed as targets as well as therapeutic agents for a growing industry hoping to harness the power of RNA-guided gene regulation to fight disease and infection.

MitomiRs Keep the Heart Beating

In this chapter, we focus on the microRNAs (miRNAs or miRs) that have been found in the mitochondrial compartment, and target either mitochondrial or nuclear encoded genes present in mitochondria, leading to an alteration of mitochondrial function. We term this subset of miRNAs as "MitomiRs".

Bile acids at the cross-roads of gut microbiome-host cardiometabolic interactions

While basic and clinical research over the last several decades has recognized a number of modifiable risk factors associated with cardiometabolic disease progression, additional and alternative biological perspectives may offer novel targets for prevention and treatment of this disease set. There is mounting preclinical and emerging clinical evidence indicating that the mass of metabolically diverse microorganisms which inhabit the human gastrointestinal tract may be implicated in initiation and modulation of cardiovascular and metabolic disease outcomes. The following review will discuss this gut microbiome-host metabolism axis and address newly proposed bile-mediated signaling pathways through which dysregulation of this homeostatic axis may influence host cardiovascular risk. With a central focus on the major nuclear and membrane-bound bile acid receptor ligands, we aim to review the putative impact of microbial bile acid modification on several major phenotypes of metabolic syndrome, from obesity to heart failure. Finally, attempting to synthesize several separate but complementary hypotheses, we will review current directions in preclinical and clinical investigation in this evolving field.

Truths and controversies concerning the role of miRNAs in atherosclerosis and lipid metabolism

PURPOSE OF REVIEW

Better tools are sorely needed for both the prevention and treatment of cardiovascular diseases, which account for more than one-third of the deaths in Western countries. MicroRNAs typically regulate the expression of several mRNAs involved in the same biological process. Therapeutic manipulation of miRNAs could restore the expression of multiple players within the same physiologic pathway, and ideally offer better curative outcomes than conventional approaches that target only one single player within the pathway. This review summarizes available studies on the prospective value of targeting miRNAs to prevent dyslipidemia and atherogenesis.

RECENT FINDINGS

Silencing the expression of miRNAs that target key genes involved in lipoprotein metabolism in vivo with antisense oligonucleotides results in the expected de-repression of target mRNAs in liver and atherosclerotic plaques. However, the consequences of long-term antimiRNA treatment on both circulating lipoproteins and athero-protection are yet to be established.

SUMMARY

A number of studies have demonstrated the efficacy of miRNA mimics and inhibitors as novel therapeutic tools for treating dyslipidemia and cardiovascular diseases. Nevertheless, concerns over unanticipated side-effects related to de-repression of additional targets should not be overlooked for miRNA-based therapies.

Liver microRNAs: potential mediators and biomarkers for metabolic and cardiovascular disease?

Recent discoveries have revealed that microRNAs (miRNAs) play a key role in the regulation of gene expression. In this review, we summarize the rapidly evolving knowledge about liver miRNAs (including miR-33, -33*, miR-223, -30c, -144, -148a, -24, -29, and -122) and their link to hepatic lipid metabolism, atherosclerosis and cardiovascular disease, non-alcoholic fatty liver disease, metabolic syndrome, and type-2 diabetes. With regards to its biomarker potential, the main focus is on miR-122 as the most abundant liver miRNA with exquisite tissue specificity. MiR-122 has been proposed to play a central role in the maintenance of lipid and glucose homeostasis and is consistently detectable in serum and plasma. This miRNA may therefore constitute a novel biomarker for cardiovascular and metabolic diseases.

Biological roles of microRNAs in the control of insulin secretion and action

microRNAs (miRNAs) are intracellular and circulating molecular components contributing to genome expression control through binding mRNA targets, which generally results in downregulated mRNA expression. One miRNA can target several mRNAs, and one transcript can be targeted by several miRNAs, resulting in complex fine-tuning of regulation of gene networks and signaling pathways. miRNAs regulate metabolism, adipocyte differentiation, pancreatic development, β-cell mass, insulin biosynthesis, secretion, and signaling, and their role in diabetes and obesity is emerging. Their pathophysiological effects are essentially dependent on cellular coexpression with their mRNA targets, which can show tissue-specific transcriptional responses to disease conditions and environmental challenges. Current knowledge of miRNA biology and their impact on the pathogenesis of diabetes and obesity is based on experimental data documenting miRNA expression generally in single tissue types that can be correlated with expression of target mRNAs to integrate miRNA in functional pathways and gene networks. Here we present results from the most significant studies dealing with miRNA function in liver, fat, skeletal muscle, and endocrine pancreas and their implication in diabetes and obesity.

The effect of maternal undernutrition on the rat placental transcriptome: protein restriction up-regulates cholesterol transport

Background

Fetal exposure to a maternal low protein diet during rat pregnancy is associated with hypertension, renal dysfunction and metabolic disturbance in adult life. These effects are present when dietary manipulations target only the first half of pregnancy. It was hypothesised that early gestation protein restriction would impact upon placental gene expression and that this may give clues to the mechanism which links maternal diet to later consequences.

Methods

Pregnant rats were fed control or a low protein diet from conception to day 13 gestation. Placentas were collected and RNA sequencing performed using the Illumina platform.

Results

Protein restriction down-regulated 67 genes and up-regulated 24 genes in the placenta. Ingenuity pathway analysis showed significant enrichment in pathways related to cholesterol and lipoprotein transport and metabolism, including atherosclerosis signalling, clathrin-mediated endocytosis, LXR/RXR and FXR/RXR activation. Genes at the centre of these processes included the apolipoproteins ApoB, ApoA2 and ApoC2, microsomal triglyceride transfer protein (Mttp), the clathrin-endocytosis receptor cubilin, the transcription factor retinol binding protein 4 (Rbp4) and transerythrin (Ttr; a retinol and thyroid hormone transporter). Real-time PCR measurements largely confirmed the findings of RNASeq and indicated that the impact of protein restriction was often striking (cubilin up-regulated 32-fold, apoC2 up-regulated 17.6-fold). The findings show that gene expression in specific pathways is modulated by maternal protein restriction in the day-13 rat placenta.

Conclusions

Changes in cholesterol transport may contribute to altered tissue development in the fetus and hence programme risk of disease in later life.

Electronic supplementary material

The online version of this article (doi:10.1186/s12263-016-0541-3) contains supplementary material, which is available to authorized users.

MicroRNAs in lipid metabolism and atherosclerosis

Numerous studies have examined the role of microRNAs (miRNAs) in cell homeostasis and cardiovascular disease and have markedly improved our understanding of RNA biology in general and the potential role of miRNAs in atherosclerosis. In atherosclerosis, several miRNAs, such as miR-33a,b, miR-92a, miR-126 and others, have been identified that are relevant mediators of pathological processes, including regulation of cholesterol and lipid biosynthesis, lipoprotein metabolism and cholesterol efflux, but also immune responses, endothelial cell biology and vascular function. Further understanding of the specific roles of miRNAs in the distinct cell types involved in atherosclerosis initiation, progression and resolution may reveal new intervention strategies for the prevention and treatment of atherosclerotic cardiovascular disease.

MicroRNA-33 Regulates the Innate Immune Response via ATP Binding Cassette Transporter-mediated Remodeling of Membrane Microdomains

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression by promoting degradation and/or repressing translation of specific target mRNAs. Several miRNAs have been identified that regulate the amplitude of the innate immune response by directly targeting Toll-like receptor (TLR) pathway members and/or cytokines. miR-33a and miR-33b (the latter present in primates but absent in rodents and lower species) are located in introns of the sterol regulatory element-binding protein (SREBP)-encoding genes and control cholesterol/lipid homeostasis in concert with their host gene products. These miRNAs regulate macrophage cholesterol by targeting the lipid efflux transporters ATP binding cassette (ABC)A1 and ABCG1. We and others have previously reported that Abca1(-/-) and Abcg1(-/-) macrophages have increased TLR proinflammatory responses due to augmented lipid raft cholesterol. Given this, we hypothesized that miR-33 would augment TLR signaling in macrophages via a raft cholesterol-dependent mechanism. Herein, we report that multiple TLR ligands down-regulate miR-33 in murine macrophages. In the case of lipopolysaccharide, this is a delayed, Toll/interleukin-1 receptor (TIR) domain-containing adapter-inducing interferon-β-dependent response that also down-regulates Srebf-2, the host gene for miR-33. miR-33 augments macrophage lipid rafts and enhances proinflammatory cytokine induction and NF-κB activation by LPS. This occurs through an ABCA1- and ABCG1-dependent mechanism and is reversible by interventions upon raft cholesterol and by ABC transporter-inducing liver X receptor agonists. Taken together, these findings extend the purview of miR-33, identifying it as an indirect regulator of innate immunity that mediates bidirectional cross-talk between lipid homeostasis and inflammation.

Circulating MicroRNAs as Biomarkers in Biliary Tract Cancers

Biliary tract cancers (BTCs) are a group of highly aggressive malignant tumors with a poor prognosis. The current diagnosis is based mainly on imaging and intraoperative exploration due to brush cytology havinga low sensitivity and the standard markers, such as carcinoembryonic antigen (CEA) and carbohydrate 19-9 (CA19-9), not having enough sensitivity nor specificity to be used in a differential diagnosis and early stage detection. Thus, better non-invasive methods that can distinguish between normal and pathological tissue are needed. MicroRNAs (miRNAs) are small, single-stranded non-coding RNA molecules of ~20–22 nucleotides that regulate relevant physiological mechanisms and can also be involved in carcinogenesis. Recent studies have demonstrated that miRNAs are detectable in multiple body fluids, showing great stability, either free or trapped in circulating microvesicles, such as exosomes. miRNAs are ideal biomarkers that may be used in screening and prognosis in biliary tract cancers, aiding also in the clinical decisions at different stages of cancer treatment. This review highlights the progress in the analysis of circulating miRNAs in serum, plasma and bile as potential diagnostic and prognostic markers of BTCs.

MicroRNAs in brain cholesterol metabolism and their implications for Alzheimer's disease

Cholesterol is important for various neuronal functions in the brain. Brain has elaborate regulatory mechanisms to control cholesterol metabolism that are distinct from the mechanisms in periphery. Interestingly, dysregulation of the cholesterol metabolism is strongly associated with a number of neurodegenerative diseases. MicroRNAs are short non-coding RNAs acting as post-transcriptional gene regulators. Recently, several microRNAs are demonstrated to be involved in regulating cholesterol metabolism in the brain. This article reviews the regulatory mechanisms of cellular cholesterol homeostasis in the brain. In addition, we discuss the role of microRNAs in brain cholesterol metabolism and their potential implications for the treatment of Alzheimer's disease. This article is part of a special issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

MicroRNA: a connecting road between apoptosis and cholesterol metabolism

Resistance to apoptosis leads to tumorigenesis and failure of anti-cancer therapy. Recent studies also highlight abrogated lipid/cholesterol metabolism as one of the root causes of cancer that can lead to metastatic transformations. Cancer cells are dependent on tremendous supply of cellular cholesterol for the formation of new membranes and continuation of cell signaling. Cholesterol homeostasis network tightly regulates this metabolic need of cancer cells on cholesterol and other lipids. Genetic landscape is also shared between apoptosis and cholesterol metabolism. MicroRNAs (miRNAs) are the new fine tuners of signaling pathways and cellular processes and are known for their ability to post-transcriptionally repress gene expression in a targeted manner. This review summarizes the current knowledge about the cross talk between apoptosis and cholesterol metabolism via miRNAs. In addition, we also emphasize herein recent therapeutic modulations of specific miRNAs and their promising potential for the treatment of deadly diseases including cancer and cholesterol related pathologies. Understanding of the impact of miRNA-based regulation of apoptosis and metabolic processes is still at its dawn and needs further research for the development of future miRNA-based therapies. As both these physiological processes affect cellular homeostasis, we believe that this comprehensive summary of miRNAs modulating both apoptosis and cholesterol metabolism will open uncharted territory for scientific exploration and will provide the foundation for discovering novel drug targets for cancer and metabolic diseases.

Micro-RNAs and High-Density Lipoprotein Metabolism

Improved prevention and treatment of cardiovascular diseases is one of the challenges in Western societies, where ischemic heart disease and stroke are the leading cause of death. Early epidemiological studies have shown an inverse correlation between circulating high-density lipoprotein-cholesterol (HDL-C) and cardiovascular diseases. The cardioprotective effect of HDL is because of its ability to remove cholesterol from plaques in the artery wall to the liver for excretion by a process known as reverse cholesterol transport. Numerous studies have reported the role that micro-RNAs (miRNA) play in the regulation of the different steps in reverse cholesterol transport, including HDL biogenesis, cholesterol efflux, and cholesterol uptake in the liver and bile acid synthesis and secretion. Because of their ability to control different aspects of HDL metabolism and function, miRNAs have emerged as potential therapeutic targets to combat cardiovascular diseases. In this review, we summarize the recent advances in the miRNA-mediated control of HDL metabolism. We also discuss how HDL particles serve as carriers of miRNAs and the potential use of HDL-containing miRNAs as cardiovascular diseases biomarkers.

MicroRNA-144 suppresses osteosarcoma growth and metastasis by targeting ROCK1 and ROCK2

Osteosarcoma (OS) is the most common primary tumor of bone. MicroRNAs (miRNAs) are a class of endogenously expressed small non-coding RNAs that are strongly implicated in cancerous processes. However, our current understanding of the biological role of miRNAs in OS remains incomplete. In the present study, miR-144 was markedly downregulated in OS cell lines and clinical specimens. Low-level expression of miR-144 was significantly associated with distant metastasis and poor prognosis. Functional studies demonstrated that ectopic expression of miR-144 suppresses tumor cell proliferation and metastasis in vitro as well as in vivo. Furthermore, we identified Rho-associated kinases 1 and 2 (ROCK1 and ROCK2) as direct targets for miR-144 binding, resulting in suppression of their expression. Exogenous expression of ROCK1 or ROCK2 in 143B-miR-144 cells partially restored miR-144-inhibited cell proliferation and invasion. In clinical OS specimens, ROCK1 and ROCK2 levels were elevated, relative to that in paired normal bone tissues, and inversely correlated with miR-144 expression. Taken together, miR-144 suppresses OS progression by directly downregulating ROCK1 and ROCK2 expression, and may be a promising therapeutic target for OS.

MicroRNA Regulation of Atherosclerosis

Atherosclerosis and its attendant clinical complications, such as myocardial infarction, stroke, and peripheral artery disease, are the leading cause of morbidity and mortality in Western societies. In response to biochemical and biomechanical stimuli, atherosclerotic lesion formation occurs from the participation of a range of cell types, inflammatory mediators, and shear stress. Over the past decade, microRNAs (miRNAs) have emerged as evolutionarily conserved, noncoding small RNAs that serve as important regulators and fine-tuners of a range of pathophysiological cellular effects and molecular signaling pathways involved in atherosclerosis. Accumulating studies reveal the importance of miRNAs in regulating key signaling and lipid homeostasis pathways that alter the balance of atherosclerotic plaque progression and regression. In this review, we highlight current paradigms of miRNA-mediated effects in atherosclerosis progression and regression. We provide an update on the potential use of miRNAs diagnostically for detecting increasing severity of coronary disease and clinical events. Finally, we provide a perspective on therapeutic opportunities and challenges for miRNA delivery in the field.

Macrophage miRNAs in atherosclerosis

The discovery of endogenous microRNAs (miRNAs) in the early 1990s has been followed by the identification of hundreds of miRNAs and their roles in regulating various biological processes, including proliferation, apoptosis, lipid metabolism, glucose homeostasis and viral infection Esteller (2011), Ameres and Zamore (2013) [1,2]. miRNAs are small (~22 nucleotides) non-coding RNAs that function as "rheostats" to simultaneously tweak the expression of multiple genes within a genetic network, resulting in dramatic functional modulation of biological processes. Although the last decade has brought the identification of miRNAs, their targets and function(s) in health and disease, there remains much to be deciphered from the human genome and its complexities in mechanistic regulation of entire genetic networks. These discoveries have opened the door to new and exciting avenues for therapeutic interventions to treat various pathological diseases, including cardiometabolic diseases such as atherosclerosis, diabetes and obesity. In a complex multi-factorial disease like atherosclerosis, many miRNAs have been shown to contribute to disease progression and may offer novel targets for future therapy. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

miRNAs and High-Density Lipoprotein metabolism

Altered lipoprotein metabolism plays a key role during atherogenesis. For over 50years, epidemiological data have fueled the proposal that HDL-cholesterol (HDL-c) in circulation is inversely correlated to cardiovascular risk. However, the atheroprotective role of HDL is currently the focus of much debate and remains an active field of research. The emerging picture from research in the past decade suggests that HDL function, rather than HDL-c content, is important in disease. Recent developments demonstrate that miRNAs play an important role in fine-tuning the expression of key genes involved in HDL biogenesis, lipidation, and clearance, as well as in determining the amounts of HDL-c in circulation. Thus, it has been proposed that miRNAs that affect HDL metabolism might be exploited therapeutically in patients. Whether HDL-based therapies, alone or in combination with LDL-based treatments (e.g. statins), provide superior outcomes in patients has been recently questioned by human genetics studies and clinical trials. The switch in focus from "HDL-cholesterol" to "HDL function" opens a new paradigm to understand the physiology and therapeutic potential of HDL, and to find novel modulators of cardiovascular risk. In this review we summarize the current knowledge on the regulation of HDL metabolism and function by miRNAs. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

microRNAs in lipoprotein metabolism and cardiometabolic disorders

Circulating levels of low-density lipoprotein cholesterol (LDL), and high-density lipoprotein cholesterol (HDL) are two of the most important risk factors for the development of cardiovascular disease (CVD), the leading cause of death worldwide. Recently, miRNAs have emerged as critical regulators of cholesterol metabolism and promising therapeutic targets for the treatment of CVD. A great deal of work has established numerous miRNAs as important regulators of HDL metabolism. This includes miRNAs that target ABCA1, a critical factor for HDL biogenesis and reverse cholesterol transport (RCT), the process through which cells, including arterial macrophages, efflux cellular cholesterol for transport to and removal by the liver. The most well studied of these miRNAs, miR-33, has been demonstrated to target ABCA1, as well as numerous other genes involved in metabolic function and RCT, and therapeutic inhibition of miR-33 was found to increase HDL levels in mice and non-human primates. Moreover, numerous studies have demonstrated the beneficial effects of miR-33 inhibition or knockout on reducing atherosclerotic plaque burden. Even more recent work has identified miRNAs that regulate LDL cholesterol levels, including direct modulation of LDL uptake in the liver through targeting of the LDL receptor. Among these, inhibition of miR-128-1, miR-148a, or miR-185 was found to reduce plasma LDL levels, and inhibition of miR-185 was further demonstrated to reduce atherosclerotic plaque size in ApoE(-/-) mice. Due to their ability to target many different genes, miRNAs have the ability to mediate complex physiologic changes through simultaneous regulation of multiple interrelated pathways. Of particular importance for CVD, inhibition of miR-148a may prove an important therapeutic approach for combating dyslipidemia, as this has been demonstrated to both raise plasma HDL levels and lower LDL levels in mice by targeting both ABCA1 and LDLR, respectively. In this review we highlight recent advances in our understanding of how miRNAs regulate cholesterol metabolism and the development of atherosclerotic plaques and discuss the potential of anti-miRNA therapies for the treatment and prevention of CVD.

miRNA and cholesterol homeostasis

MicroRNAs (miRNAs) have recently emerged as a novel class of epigenetic regulators of gene expression. They are systemically involved in the control of lipid metabolism through a complex interactive mechanism that involves gene regulatory networks. Hence, they can contribute to defective lipid metabolism and metabolic diseases. Here, we review recent advances in the roles of lipid-sensing transcription factors in regulating miRNA gene networks, as well as miRNA expression and function in the regulation of cholesterol metabolism. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

An integrated analysis of differential miRNA and mRNA expressions in human gallstones

Gallstone disease, including cholesterol precipitation in bile, increased bile salt hydrophobicity and gallbladder inflammation. Here, we investigated miRNA and mRNA involved in the formation of gallstones, and explored the molecular mechanisms in the development of gallstones. Differentially expressed 17 miRNAs and 525 mRNA were identified based on Illumina sequencing from gallbladder mucosa of patients with or without gallstones, and were validated by randomly selected 6 miRNAs and 8 genes using quantitative RT-PCR. 114 miRNA target genes were identified, whose functions and regulating pathways were related to gallstones. The differentially expressed genes were enriched upon lipoprotein binding and some metabolic pathways, and differentially expressed miRNAs enriched upon ABC transportation and cancer related pathways. A molecular regulatory network consisting of 17 differentially expressed miRNAs, inclusive of their target genes, was constructed. miR-210 and its potential target gene ATP11A were found to be differentially expressed in both miRNA and mRNA profiles. ATP11A was a direct target of miR-210, which was predicted to regulate the ABC-transporters pathway. The expression levels of ATP11A in the gallstone showed inverse correlation with miR-210 expression, and up-regulation of miR-210 could reduce ATP11A expression in HGBEC. This is the first report that indicates the existence of differences in miRNA and mRNA expression in patients with or without gallstones. Our data shed light on further investigating the mechanisms of gallstone formation.

Macrophage-mediated cholesterol handling in atherosclerosis

Formation of foam cells is a hallmark at the initial stages of atherosclerosis. Monocytes attracted by pro-inflammatory stimuli attach to the inflamed vascular endothelium and penetrate to the arterial intima where they differentiate to macrophages. Intimal macrophages phagocytize oxidized low-density lipoproteins (oxLDL). Several scavenger receptors (SR), including CD36, SR-A1 and lectin-like oxLDL receptor-1 (LOX-1), mediate oxLDL uptake. In late endosomes/lysosomes of macrophages, oxLDL are catabolysed. Lysosomal acid lipase (LAL) hydrolyses cholesterol esters that are enriched in LDL to free cholesterol and free fatty acids. In the endoplasmic reticulum (ER), acyl coenzyme A: cholesterol acyltransferase-1 (ACAT1) in turn catalyses esterification of cholesterol to store cholesterol esters as lipid droplets in the ER of macrophages. Neutral cholesteryl ester hydrolases nCEH and NCEH1 are involved in a secondary hydrolysis of cholesterol esters to liberate free cholesterol that could be then out-flowed from macrophages by cholesterol ATP-binding cassette (ABC) transporters ABCA1 and ABCG1 and SR-BI. In atherosclerosis, disruption of lipid homoeostasis in macrophages leads to cholesterol accumulation and formation of foam cells.

MicroRNA-148a regulates LDL receptor and ABCA1 expression to control circulating lipoprotein levels

The hepatic low-density lipoprotein receptor (LDLR) pathway is essential for clearing circulating LDL-cholesterol (LDL-C). While the transcriptional regulation of LDLR is well-characterized, the post-transcriptional mechanisms which govern LDLR expression are just beginning to emerge. Here, we developed a high-throughput genome-wide screening assay to systematically identify microRNAs (miRNAs) that regulate LDLR activity in human hepatic cells. From this screen, we characterize miR-148a as a negative regulator of LDLR expression and activity, and define a novel SREBP1-mediated pathway by which miR-148a regulates LDL-C uptake. Importantly, inhibition of miR-148a increases hepatic LDLR expression and decreases plasma LDL-C in vivo. We also provide evidence that miR-148a regulates hepatic ABCA1 expression and circulating HDL-C levels. Collectively, these studies uncover miR-148a as an important regulator of hepatic LDL-C clearance through direct regulation of LDLR expression, and demonstrate the therapeutic potential of inhibiting miR-148a to ameliorate the elevated LDL-C/HDL-C ratio, a prominent risk factor for cardiovascular disease.

MicroRNAs in obesity-associated disorders

The emergence of a worldwide obesity epidemic has dramatically increased the prevalence of insulin resistance and metabolic syndrome, predisposing individuals to a greater risk for the development of non-alcoholic fatty liver disease, type II diabetes and atherosclerotic cardiovascular diseases. Current available pharmacological interventions combined with diet and exercise-based managements are still poorly effective for weight management, likely in part due to an incomplete understanding of regulatory mechanisms and pathways contributing to the systemic metabolic abnormalities under disturbed energy homeostasis. MicroRNAs, small non-coding RNAs that regulate posttranscriptional gene expression, have been increasingly described to influence shifts in metabolic pathways under various obesity-related disease settings. Here we review recent discoveries of the mechanistic role that microRNAs play in regulating metabolic functions in liver and adipose tissues involved in obesity associated disorders, and briefly discusses the potential candidates that are being pursued as viable therapeutic targets.

Role of miR-511 in the Regulation of OATP1B1 Expression by Free Fatty Acid

MicroRNAs (miRNAs) are a family of non-coding RNA that are able to adjust the expression of many proteins, including ATP-binding cassette transporter and organic cation transporter. We sought to evaluate the effect of miR-511 on the regulation of OATP1B1 expression by free fatty acids. When using free fatty acids to stimulate Chang liver cells, we found that the expression of miR-511 increased significantly while the expression of OATP1B1 decreased. We also proved that SLCO1B1 is the target gene of miR-511 with a bioinformatics analysis and using the dual luciferase reporter assay. Furthermore, the expressions of SLCO1B1 and OATP1B1 decreased if transfecting Chang liver cells with miR-511, but did not increase when transfecting the inhibitors of miR-511 into steatosis cells. Our study indicates that miR-511 may play an important role in the regulation of OATP1B1 expression by free fatty acids.

Mammalian hibernation and regulation of lipid metabolism: a focus on non-coding RNAs

Numerous species will confront severe environmental conditions by undergoing significant metabolic rate reduction. Mammalian hibernation is one such natural model of hypometabolism. Hibernators experience considerable physiological, metabolic, and molecular changes to survive the harsh challenges associated with winter. Whether as fuel source or as key signaling molecules, lipids are of primary importance for a successful bout of hibernation and their careful regulation throughout this process is essential. In recent years, a plethora of non-coding RNAs has emerged as potential regulators of targets implicated in lipid metabolism in diverse models. In this review, we introduce the general characteristics associated with mammalian hibernation, present the importance of lipid metabolism prior to and during hibernation, as well as discuss the potential relevance of non-coding RNAs such as miRNAs and lncRNAs during this process.

miRNA-144 suppresses proliferation and migration of colorectal cancer cells through GSPT1

MicroRNAs play a key role in carcinogenesis or tumor progression, which negatively and posttranscriptionally regulate gene expression and function as oncogenes or tumor suppressors, as well as regulators of cell cycle, proliferation, apoptosis, migration and other processes. A number of miRNAs are reported be related to the occurrence and development of colorectal cancer (CRC). However, these studies were not involved in the effect of miRNA 144 of CRC, whose function remains unclear. In this study, we demonstrated that the expression level of miRNA 144 was markedly down-regulated in colorectal cancer HCT116 cells compared with normal control FHC cells. Meanwhile, we found that GSPT1 was over-expressed in human colorectal cancer HCT116 cells. Subsequently, GSPT1 was identified as a target of miRNA 144 through bioinformatics and luciferase reporter assays. Besides, we also confirmed that miRNA 144 can inhibit the proliferation and migration of colorectal cancer HCT116 cells . Next, we observed RNA-mediated knockdown of GSPT1 can also inhibit the proliferation and migration of colorectal cancer cells. Thus, we concluded that miRNA 144 inhibits cell proliferation and migration through GSPT1 in CRC. In addition, further mechanic investigations revealed that miRNA-144 suppressed the expression of GSPT1 to regulate the expression of c-myc, survivin and Bcl2L15 which are involved in cell proliferation, and that metastasis related factor MMP28 was also down-regulated by miRNA144. Our findings suggested that microRNA 144 might be an important element to control the status of colorectal cancer, which has provided a new insight into the mechanism of proliferation and migration and a new target in therapy against colorectal cancer.

Noncoding RNAs and the control of signalling via nuclear receptor regulation in health and disease

Nuclear receptors belong to a superfamily of proteins that play central roles in human biology, orchestrating a large variety of biological functions in both health and disease. Understanding the interactions and regulatory pathways of NRs will allow development of potential therapeutic interventions for a multitude of disease processes. Non-coding RNAs have recently been discovered to have significant interactions with NR signalling pathways via a variety of biological connections. This review summarises the known interactions between ncRNAs and the NR superfamily in health, embryogenesis and a plethora of human diseases.

The Regulation of Reverse Cholesterol Transport and Cellular Cholesterol Homeostasis by MicroRNAs

MicroRNAs (miRNAs) are small, non-coding RNAs that have the ability to post-transcriptionally regulate gene expression. Hundreds of miRNAs have been identified in humans and they are involved in the regulation of almost every process, including cholesterol transport, metabolism, and maintenance of cholesterol homeostasis. Because of their small size and their ability to very specifically regulate gene expression, miRNAs are attractive targets for the regulation of dyslipidemias and other lipid-related disorders. However, the complex interactions between miRNAs, transcription factors, and gene expression raise great potential for side effects as a result of miRNA overexpression or inhibition. Many dietary components can also target specific miRNAs, altering the expression of downstream genes. Therefore, much more research is necessary to fully understand the role(s) of each miRNA in the body and how they may be impacted by diet and health. The present review aims to summarize the known roles of miRNAs in the regulation of reverse cholesterol transport and the maintenance of cholesterol homeostasis, as well as the potential clinical consequences of their manipulation.

Unlocking the door to new therapies in cardiovascular disease: microRNAs hold the key

MicroRNAs are the most abundant class of regulatory noncoding RNA and are estimated to regulate over half of all human protein-coding genes. The heart is comprised of some of the most complex and highly conserved genetic networks and is thus under tight regulation by post-transcriptional mechanisms. MicroRNAs (miRNAs) have been found to regulate virtually all aspects of cardiac physiology and pathophysiology, from the development of inflammatory atherosclerosis to hypertrophic remodeling in heart failure. Owing to the wide-spread involvement of miRNAs in the development of and protection from many diseases, there has been increasing excitement surrounding their potential as novel therapeutic targets to treat and prevent the worldwide epidemic of cardiovascular disease.

Inhibiting microRNA-144 abates oxidative stress and reduces apoptosis in hearts of streptozotocin-induced diabetic mice

INTRODUCTION

Hyperglycemia-induced reactive oxygen species (ROS) generation contributes to the development of diabetic cardiomyopathy. However, little is known about the role of microRNAs in the regulation of ROS formation and myocardial apoptosis in streptozotocin (STZ)-induced diabetic mice.

METHODS AND RESULTS

It was observed that microRNA-144 (miR-144) level was lower in heart tissues of STZ-induced diabetic mice. High glucose exposure also reduced miR-144 levels in cultured cardiomyocytes. Moreover, miR-144 modulated high glucose-induced oxidative stress in cultured cardiomyocytes by directly targeting nuclear factor-erythroid 2-related factor 2 (Nrf2), which was a central regulator of cellular response to oxidative stress. The miR-144 mimics aggravated high glucose-induced ROS formation and apoptosis in cardiomyocytes, which could be attenuated by treatment with Dh404, an activator of Nrf2. Meanwhile, inhibition of miR-144 suppressed ROS formation and apoptosis induced by high glucose in cultured cardiomyocytes. What was more important is that reduced myocardial oxidative stress and apoptosis and improved cardiac function were identified in STZ-induced diabetic mice when treated with miR-144 antagomir.

CONCLUSION

Although miR-144 cannot explain the increased oxidative stress in STZ, therapeutic interventions directed at decreasing miR-144 may help to decrease oxidative stress in these hearts. Inhibition of miR-144 might have clinical potential to abate oxidative stress as well as to reduce cardiomyocyte apoptosis and improve cardiac function in diabetic cardiomyopathy.