MicroRNA: a new frontier in kidney and blood pressure research

Computational Analysis Reveals Distinctive Interaction of miRNAs with Target Genes in the Pathogenesis of Chronic Kidney Disease

The regulation of genes is crucial for maintaining a healthy intracellular environment, and any dysregulation of gene expression leads to several pathological complications. It is known that many diseases, including kidney diseases, are regulated by miRNAs. However, the data on the use of miRNAs as biomarkers for the diagnosis and treatment of chronic kidney disease (CKD) are not conclusive. The purpose of this study was to elucidate the potential of miRNAs as an efficient biomarker for the detection and treatment of CKD at its early stages. Gene expression profiling data were acquired from the Gene Expression Omnibus (GEO) and differentially expressed genes (DEGs) were identified. miRNAs directly associated with CKD were obtained from an extensive literature search. Network illustration of miRNAs and their projected target differentially expressed genes (tDEGs) was accomplished, followed by functional enrichment analysis. hsa-miR-1-3p, hsa-miR-206, hsa-miR-494 and hsa-miR-577 exhibited a strong association with CKD through the regulation of genes involved in signal transduction, cell proliferation, the regulation of transcription and apoptotic process. All these miRNAs have shown significant contributions to the inflammatory response and the processes which eventually lead to the pathogenesis of CKD. The in silico approach used in this research represents a comprehensive analysis of identified miRNAs and their target genes for the identification of molecular markers of disease processes. The outcomes of the study recommend further efforts for developing miRNA biomarkers set for the early diagnosis of CKD.

Effects of hypoxia and reoxygenation on mitochondrial functions and transcriptional profiles of isolated brain and muscle porcine cells

Oxygen fluctuations might occur in mammalian tissues under physiological (e.g. at high altitudes) or pathological (e.g. ischemia-reperfusion) conditions. Mitochondria are the key target and potential amplifiers of hypoxia-reoxygenation (H-R) stress. Understanding the mitochondrial responses to H-R stress is important for identifying adaptive mechanisms and potential therapeutic solutions for pathologies associated with oxygen fluctuations. We explored metabolic response to H-R stress in two tissue types (muscle and brain) with different degrees of hypoxia tolerance in a domestic pig Sus scrofa focusing on the cellular responses independent of the systemic regulatory mechanisms. Isolated cells from the skeletal muscle (masseter) and brain (thalamus) were exposed to acute short-term (15 min) hypoxia followed by reoxygenation. The mitochondrial oxygen consumption, reactive oxygen species (ROS) production rates and transcriptional profiles of hypoxia-responsive mRNA and miRNA were determined. Mitochondria of the porcine brain cells showed a decrease in the resting respiration and ATP synthesis capacity whereas the mitochondria from the muscle cells showed robust respiration and less susceptibility to H-R stress. ROS production was not affected by the short-term H-R stress in the brain or muscle cells. Transcriptionally, prolyl hydroxylase domain protein EGLN3 was upregulated during hypoxia and suppressed during reoxygenation in porcine muscle cells. The decline in EGLN3 mRNA during reoxygenation was accompanied by an upregulation of hypoxia-inducible factor subunit α (HIF1A) transcripts in the muscle cells. However, in the brain cells, HIF1A mRNA levels were suppressed during reoxygenation. Other functionally important transcripts and miRNAs involved in antioxidant response, apoptosis, inflammation, and substrate oxidation were also differentially expressed between the muscle and brain cells. Suppression of miRNA levels during acute intermittent hypoxia was stronger in the brain cells affecting ~ 55% of all studied miRNA transcripts than in the muscle cells (~ 25% of miRNA) signifying transcriptional derepression of the respective mRNA targets. Our study provides insights into the potential molecular and physiological mechanisms contributing to different hypoxia sensitivity of the studied tissues and can serve as a starting point to better understand the biological processes associated with hypoxia stress, e.g. during ischemia and reperfusion.

Histologically resolved small RNA maps in primary focal segmental glomerulosclerosis indicate progressive changes within glomerular and tubulointerstitial regions

Pathological heterogeneity is common in clinical tissue specimens and complicates the interpretation of molecular data obtained from the specimen. As a typical example, a kidney biopsy specimen often contains glomeruli and tubulointerstitial regions with different levels of histological injury, including some that are histologically normal. We reasoned that the molecular profiles of kidney tissue regions with specific histological injury scores could provide new insights into kidney injury progression. Therefore, we developed a strategy to perform small RNA deep sequencing analysis for individually scored glomerular and tubulointerstitial regions in formalin-fixed, paraffin-embedded kidney needle biopsies. This approach was applied to study focal segmental glomerulosclerosis (FSGS), the leading cause of nephrotic syndrome in adults. Large numbers of small RNAs, including microRNAs, 3'-tRFs, 5'-tRFs, and mitochondrial tRFs, were differentially expressed between histologically indistinguishable tissue regions from patients with FSGS and matched healthy controls. A majority of tRFs were upregulated in FSGS. Several small RNAs were differentially expressed between tissue regions with different histological scores in FSGS. Notably, with increasing levels of histological damage, miR-21-5p was upregulated progressively and miR-192-5p was downregulated progressively in glomerular and tubulointerstitial regions, respectively. This study marks the first genome scale molecular profiling conducted in histologically characterized glomerular and tubulointerstitial regions. Thus, substantial molecular changes in histologically normal kidney regions in FSGS might contribute to initiating tissue injury or represent compensatory mechanisms. In addition, several small RNAs might contribute to subsequent progression of glomerular and tubulointerstitial injury, and histologically mapping small RNA profiles may be applied to analyze tissue specimens in any disease.

Role of MicroRNAs and their corresponding ACE2/Apelin signaling pathways in hypertension

Hypertension is controlled via the alteration of microRNAs (miRNAs), their therapeutic targets angiotensin II type I receptor (AT1R) and cross talk of signaling pathways. The stimulation of the Ang II/AT1R pathway by deregulation of miRNAs, has also been linked to cardiac remodeling as well as the pathophysiology of high blood pressure. As miRNAs have been associated to ACE2/Apelin and Mitogen-activated protein kinases (MAPK) signaling, it has revealed an utmost protective impact over hypertension and cardiovascular system. The ACE2-coupled intermodulation between RAAS, Apelin system, MAPK signaling pathways, and miRNAs reveal the practicalities of high blood pressure. The research of miRNAs may ultimately lead to the expansion of an innovative treatment strategy for hypertension, which indicates the need to explore them further at the molecular level. Therefore, here we have focused on the mechanistic importance of miRNAs in hypertension, ACE2/Apelin signaling as well as their biological functions, with a focus on interplay and crosstalk between ACE2/Apelin signaling, miRNAs, and hypertension, and the progress in miRNA-based diagnostic techniques with the goal of facilitating the development of new hypertension-controlling therapeutics.

Overexpression of MicroRNA-429 Transgene Into the Renal Medulla Attenuated Salt-Sensitive Hypertension in Dahl S Rats

BACKGROUND

We have previously shown that high salt stimulates the expression of miR-429 in the renal medulla, which induces mRNA decay of HIF prolyl-hydroxylase 2 (PHD2), an enzyme to promote the degradation of hypoxia-inducible factor (HIF)-1α, and increases the HIF-1α-mediated activation of antihypertensive genes in the renal medulla, consequently promoting extra sodium excretion. Our preliminary results showed that high salt-induced increase of miR-429 was not observed in Dahl S rats. This present study determined whether correction of this impairment in miR-429 would reduce PHD2 levels, increase antihypertensive gene expression in the renal medulla and attenuate salt-sensitive hypertension in Dahl S rats.

METHODS

Lentiviruses encoding rat miR-429 were transfected into the renal medulla in uninephrectomized Dahl S rats. Sodium excretion and blood pressure were then measured.

RESULTS

Transduction of lentiviruses expressing miR-429 into the renal medulla increased miR-429 levels, decreased PHD2 levels, and upregulated HIF-1α target gene NOS-2, which restored the adaptive mechanism to increase the antihypertensive gene after high-salt intake in Dahl S rats. Functionally, overexpression of miR-429 transgene in the renal medulla significantly improved pressure natriuretic response, enhanced urinary sodium excretion, and reduced sodium retention upon extra sodium loading, and consequently, attenuated the salt-sensitive hypertension in Dahl S rats.

CONCLUSIONS

Our results suggest that the impaired miR-429-mediated PHD2 inhibition in response to high salt in the renal medulla may represent a novel mechanism for salt-sensitive hypertension in Dahl S rats and that correction of this impairment in miR-429 pathway could be a therapeutic approach for salt-sensitive hypertension.

miR-204: Molecular Regulation and Role in Cardiovascular and Renal Diseases

The field of microRNA research has evolved from studies aiming to gauge the importance of microRNAs to those focusing on understanding a subset of specific microRNAs that have emerged as potent regulators of molecular systems and pathophysiological conditions. In this article, we review the molecular features and regulation of miR-204 and the growing body of evidence for an important role of miR-204 in the regulation of cardiovascular and renal physiology and pathophysiological processes. miR-204 exhibits a highly tissue-specific expression pattern, and miR-204 abundance is regulated by several transcriptional and posttranscriptional mechanisms. Strong evidence supports a role for miR-204 in attenuating pulmonary arterial hypertension and hypertensive and diabetic renal injury while promoting hypertension and endothelial dysfunction in a wide range of model systems. miR-204 may influence these disease processes by targeting several biological pathways in a tissue-specific manner. miR-204 is dysregulated in patients with cardiovascular and renal diseases. The unequivocal functional roles and clear clinical relevance indicate that miR-204 is a high-value microRNA in cardiovascular and renal diseases.

MicroRNA-133a-Dependent Inhibition of Proximal Tubule Angiotensinogen by Renal TNF (Tumor Necrosis Factor)

We showed that intrarenal suppression of TNF (tumor necrosis factor) production under low salt (LS) conditions increases renal cortical AGT (angiotensinogen) mRNA and protein expression. Intrarenal injection of murine recombinant TNF attenuated increases of AGT in mice ingesting LS. Moreover, AGT mRNA and protein expression increased ≈6-fold and 2-fold, respectively, in mice ingesting LS that also received an intrarenal injection of a lentivirus construct that specifically silenced TNF in the kidney (U6-TNF-ex4). Silencing of TNF under normal salt and high salt (HS) conditions also resulted in increased AGT expression. Since renal TNF production decreases in response to LS and increases in response to HS, the data suggest that alterations in TNF production under these conditions modulate the degree of AGT expression. We also tested the hypothesis that TNF inhibits intrarenal AGT expression by a mechanism involving miR-133a. Expression of miR-133a decreased in mice given LS and increased in response to HS for 7 days. Intrarenal silencing of TNF reversed the effects of HS on miR-133a-dependent AGT expression. In contrast, intrarenal TNF administration increased miR-133a expression in the kidney. Collectively, the data suggest that miR-133a is a salt-sensitive microRNA that inhibits AGT in the kidney and is increased by TNF. The HS-induced increase in blood pressure observed following silencing of TNF was markedly reduced upon intrarenal administration of miR-133a suggesting that intrinsic effects of TNF in the kidney to limit the blood pressure response to HS include an increase in miR-133a, which suppresses AGT expression.

MicroRNAs (−146a, −21 and −34a) are diagnostic and prognostic biomarkers for diabetic retinopathy

Background

Diabetic retinopathy (DR) is implicated in blindness of diabetic patients. Early diagnosis of DR is very essential to ensure good prognosis. The role of microRNAs (miRs) as biomarker diagnostic tools in DR is not fully investigated. The present study aimed to find the relation between serum relative expression of microRNAs (miR-146a, miR-21 and miR-34a) and severity of DR and to what extent their expression pattern can be used as either diagnostic or prognostic.

Methods

Eighty type 2 diabetic patients were classified according to severity of DR into normal, mild, moderate, severe non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). Serum relative expressions of miRNAs were evaluated by qPCR and statistically analysed in each stage using Analysis of Variance (ANOVA) followed by Tuckey-Kramer post-test.

Results

Serum relative expressions of miR-146a and miR-21 were increased with increased severity of DR. miR-34a decreased with the severity of DR. The expression pattern in each group in relation to normal fundus group could be diagnostic and prognostic where miR-146a was only increased in mild group and continued with the severity. In moderate group miR-21 start to increase along with slight decrease in miR-34a. In severe NPDR group along with highly increased levels of both miR-146a and miR-21, a marked decrease in miR-34a. In PDR group miR-34a was almost diminished along with very high levels of both miR-146a and miR-21.

Conclusions

miRs (−146a,-21 and-34a) are promising biomarkers in DR and can help to avoid disease progression.

Endogenous miR-204 Protects the Kidney against Chronic Injury in Hypertension and Diabetes

BACKGROUND

Aberrant microRNA (miRNA) expression affects biologic processes and downstream genes that are crucial to CKD initiation or progression. The miRNA miR-204-5p is highly expressed in the kidney but whether miR-204-5p plays any role in the development of chronic renal injury is unknown.

METHODS

We used real-time PCR to determine levels of miR-204 in human kidney biopsies and animal models. We generated Mir204 knockout mice and used locked nucleic acid-modified anti-miR to knock down miR-204-5p in mice and rats. We used a number of physiologic, histologic, and molecular techniques to analyze the potential role of miR-204-5p in three models of renal injury.

RESULTS

Kidneys of patients with hypertension, hypertensive nephrosclerosis, or diabetic nephropathy exhibited a significant decrease in miR-204-5p compared with controls. Dahl salt-sensitive rats displayed lower levels of renal miR-204-5p compared with partially protected congenic SS.13^BN26 rats. Administering anti-miR-204-5p to SS.13^BN26 rats exacerbated interlobular artery thickening and renal interstitial fibrosis. In a mouse model of hypertensive renal injury induced by uninephrectomy, angiotensin II, and a high-salt diet, Mir204 gene knockout significantly exacerbated albuminuria, renal interstitial fibrosis, and interlobular artery thickening, despite attenuation of hypertension. In diabetic db/db mice, administering anti-miR-204-5p exacerbated albuminuria and cortical fibrosis without influencing blood glucose levels. In all three models, inhibiting miR-204-5p or deleting Mir204 led to upregulation of protein tyrosine phosphatase SHP2, a target gene of miR-204-5p, and increased phosphorylation of signal transducer and activator of transcription 3, or STAT3, which is an injury-promoting effector of SHP2.

CONCLUSIONS

These findings indicate that the highly expressed miR-204-5p plays a prominent role in safeguarding the kidneys against common causes of chronic renal injury.

Classic and Nonclassic Apparent Mineralocorticoid Excess Syndrome

CONTEXT

Arterial hypertension (AHT) is one of the most frequent pathologies in the general population. Subtypes of essential hypertension characterized by low renin levels allowed the identification of 2 different clinical entities: aldosterone-mediated mineralocorticoid receptor (MR) activation and cortisol-mediated MR activation.

EVIDENCE ACQUISITION

This review is based upon a search of Pubmed and Google Scholar databases, up to August 2019, for all publications relating to endocrine hypertension, apparent mineralocorticoid excess (AME) and cortisol (F) to cortisone (E) metabolism.

EVIDENCE SYNTHESIS

The spectrum of cortisol-mediated MR activation includes the classic AME syndrome to milder (nonclassic) forms of AME, the latter with a much higher prevalence (7.1%) than classic AME but different phenotype and genotype. Nonclassic AME (NC-AME) is mainly related to partial 11βHSD2 deficiency associated with genetic variations and epigenetic modifications (first hit) and potential additive actions of endogenous or exogenous inhibitors (ie, glycyrrhetinic acid-like factors [GALFS]) and other factors (ie, age, high sodium intake) (second hit). Subjects with NC-AME are characterized by a high F/E ratio, low E levels, normal to elevated blood pressure, low plasma renin and increased urinary potassium excretion. NC-AME condition should benefit from low-sodium and potassium diet recommendations and monotherapy with MR antagonists.

CONCLUSION

NC-AME has a higher prevalence and a milder phenotypical spectrum than AME. NC-AME etiology is associated to a first hit (gene and epigene level) and an additive second hit. NC-AME subjects are candidates to be treated with MR antagonists aimed to improve blood pressure, end-organ damage, and modulate the renin levels.

MiR-192-5p in the Kidney Protects Against the Development of Hypertension

MicroRNA miR-192-5p is one of the most abundant microRNAs in the kidney and targets the mRNA for ATP1B1 (β1 subunit of Na⁺/K⁺-ATPase). Na⁺/K⁺-ATPase drives renal tubular reabsorption. We hypothesized that miR-192-5p in the kidney would protect against the development of hypertension. We found miR-192-5p levels were significantly lower in kidney biopsy specimens from patients with hypertension (n=8) or hypertensive nephrosclerosis (n=32) compared with levels in controls (n=10). Similarly, Dahl salt-sensitive (SS) rats showed a reduced abundance of miR-192-5p in the renal cortex compared with congenic SS.13^BN26 rats that had reduced salt sensitivity (n=9; P<0.05). Treatment with anti-miR-192-5p delivered through renal artery injection in uninephrectomized SS.13^BN26 rats exacerbated hypertension significantly. Mean arterial pressure on a 4% NaCl high-salt diet at day 14 post anti-miR-192-5p treatment was 16 mm Hg higher than in rats treated with scrambled anti-miR (n=8 and 6; P<0.05). Similarly, Mir192 knockout mice on the high-salt diet treated with Ang II (angiotensin II) for 14 days exhibited a mean arterial pressure 22 mm Hg higher than wild-type mice (n=9 and 5; P<0.05). Furthermore, protein levels of ATP1B1 were higher in Dahl SS rats than in SS.13^BN26 rats. Na⁺/K⁺-ATPase activity increased in the renal cortex of SS.13^BN26 rats 9 days posttreatment with anti-miR-192-5p compared with that of control anti-miR treated rats. Intrarenal knockdown of ATP1B1 attenuated hypertension in SS.13^BN26 rats with intrarenal knockdown of miR-192-5p. In conclusion, miR-192-5p in the kidney protects against the development of hypertension, which is mediated, at least in part, by targeting Atp1b1.

A therapeutic approach towards microRNA29 family in vascular diabetic complications: A boon or curse?

Diabetes Mellitus (DM) is one of the major metabolic disorders and its severity leads to death. Enhancement in hyperglycaemic conditions of DM gives rise to endothelial impairment in small and large blood vessels contributing towards microvascular and macrovascular complications respectively. The pathogenesis of diabetic complications is associated with interruption of various signal transduction pathways due to epigenetic modifications such as aberrant histone modifications, DNA methylation and expression of miRNAs along with the long non-coding RNAs (lncRNAs). Amongst these epigenetic alterations, modulated expressions of miRNAs confer to apoptosis and endothelial dysfunction of organs that gives rise to vascular complications. In this review, we principally focussed on physiological role of miR29 family in DM and have discussed crosstalk between miR29 family and numerous genes involved in signal transduction pathways of Diabetic vascular complications. Incidences of diabetic retinopathy exploiting the role of miR29 in regulation of EMT process, differential expression patterns of miR29 and promising therapeutic role of miR29 have been discussed. We have summarised the therapeutic role of miR29 in podocyte impairment and how miR29 regulates the expressions of profibrotic, inflammatory and ECM encoding genes in renal fibrosis under diabetic conditions. We have also highlighted impact of miR29 expression patterns in cardiac angiopathy, cardiomyocyte's apoptosis and cardiac fibrosis. Additionally, we have also presented the contradictory actions of miR29 family in amelioration as well as in enhancement of diabetic complications.

Unique interstitial miRNA signature drives fibrosis in a murine model of autosomal dominant polycystic kidney disease

AIM

To delineate changes in miRNA expression localized to the peri-cystic local microenvironment (PLM) in an orthologous mouse model of autosomal dominant polycystic kidney disease (ADPKD) (mcwPkd1^(nl/nl)).

METHODS

We profiled miRNA expression in the whole kidney and laser captured microdissection (LCM) samples from PLM in mcwPkd1^(nl/nl) kidneys with Qiagen miScript 384 HC miRNA PCR arrays. The three times points used are: (1) post-natal (PN) day 21, before the development of trichrome-positive areas; (2) PN28, the earliest sign of trichrome staining; and (3) PN42 following the development of progressive fibrosis. PN21 served as appropriate controls and as the reference time point for comparison of miRNA expression profiles.

RESULTS

LCM samples revealed three temporally upregulated miRNAs [2 to 2.75-fold at PN28 and 2.5 to 4-fold (P ≤ 0.05) at PN42] and four temporally downregulated miRNAs [2 to 2.75 fold at PN28 and 2.75 to 5-fold (P ≤ 0.05) at PN42]. Expression of twenty-six miRNAs showed no change until PN42 [six decreased (2.25 to 3.5-fold) (P ≤ 0.05) and 20 increased (2 to 4-fold) (P ≤ 0.05)]. Many critical miRNA changes seen in the LCM samples from PLM were not seen in the contralateral whole kidney.

CONCLUSION

Precise sampling with LCM identifies miRNA changes that occur with the initiation and progression of renal interstitial fibrosis (RIF). Identification of the target proteins regulated by these miRNAs will provide new insight into the process of fibrosis and identify unique therapeutic targets to prevent or slow the development and progression of RIF in ADPKD.

Reduced Autophagy by a microRNA-mediated Signaling Cascade in Diabetes-induced Renal Glomerular Hypertrophy

Autophagy plays a key role in the pathogenesis of kidney diseases, however its role in diabetic nephropathy (DN), and particularly in kidney glomerular mesangial cells (MCs) is not very clear. Transforming Growth Factor- β1 (TGF-β), a key player in the pathogenesis of DN, regulates expression of various microRNAs (miRNAs), some of which are known to regulate the expression of autophagy genes. Here we demonstrate that miR-192, induced by TGF-β signaling, plays an important role in regulating autophagy in DN. The expression of key autophagy genes was decreased in kidneys of streptozotocin-injected type-1 and type-2 (db/db) diabetic mice and this was reversed by treatment with Locked Nucleic Acid (LNA) modified miR-192 inhibitors. Changes in autophagy gene expression were also attenuated in kidneys of diabetic miR-192-KO mice. In vitro studies using mouse glomerular mesangial cells (MMCs) also showed a decrease in autophagy gene expression with TGF-β treatment. miR-192 mimic oligonucleotides also decreased the expression of certain autophagy genes. These results demonstrate that TGF-β and miR-192 decrease autophagy in MMCs under diabetic conditions and this can be reversed by inhibition or deletion of miR-192, further supporting miR-192 as a useful therapeutic target for DN.

Renal Delivery of Anti-microRNA Oligonucleotides in Rats

MicroRNAs are endogenous small, non-protein-coding RNA molecules that play an important role in the regulation of a wide variety of cellular functions and disease processes. A novel role for microRNAs in the development of hypertension and hypertensive tissue injury is emerging in recent studies. Development of hypertension involves multiple organ systems and cannot be modeled in vitro. Therefore, the ability to experimentally alter genes, gene products, or biological pathways, including microRNAs, in an organ-specific manner in intact animal models is particularly valuable to hypertension research. The kidney plays a central role in the long-term regulation of arterial blood pressure. In this chapter, we describe a detailed protocol for using a renal interstitial injection method to deliver anti-miR oligonucleotides to knock down microRNA specifically in the kidney in conscious rats.

Tissue-Specific MicroRNA Expression Patterns in Four Types of Kidney Disease

MicroRNAs contribute to the development of kidney disease. Previous analyses of microRNA expression in human kidneys, however, were limited by tissue heterogeneity or the inclusion of only one pathologic type. In this study, we used laser-capture microdissection to obtain glomeruli and proximal tubules from 98 human needle kidney biopsy specimens for microRNA expression analysis using deep sequencing. We analyzed specimens from patients with diabetic nephropathy (DN), FSGS, IgA nephropathy (IgAN), membranoproliferative GN (MPGN) (n=19-23 for each disease), and a control group (n=14). Compared with control glomeruli, DN, FSGS, IgAN, and MPGN glomeruli exhibited differential expression of 18, 12, two, and 17 known microRNAs, respectively. The expression of several microRNAs also differed between disease conditions. Specifically, compared with control or FSGS glomeruli, IgAN glomeruli exhibited downregulated expression of hsa-miR-3182. Furthermore, in combination, the expression levels of hsa-miR-146a-5p and hsa-miR-30a-5p distinguished DN from all other conditions except IgAN. Compared with control proximal tubules, DN, FSGS, IgAN, and MPGN proximal tubules had differential expression of 13, 14, eight, and eight microRNAs, respectively, but expression of microRNAs did not differ significantly between the disease conditions. The abundance of several microRNAs correlated with indexes of renal function. Finally, we validated the differential glomerular expression of select microRNAs in a second cohort of patients with DN (n=19) and FSGS (n=21). In conclusion, we identified tissue-specific microRNA expression patterns associated with several kidney pathologies. The identified microRNAs could be developed as biomarkers of kidney diseases and might be involved in disease mechanisms.

miR-382 Contributes to Renal Tubulointerstitial Fibrosis by Downregulating HSPD1

Redox imbalance plays an important role in the pathogenesis of CKD progression. Previously, we demonstrated that microRNA-382 (miR-382) contributed to TGF-β1-induced loss of epithelial polarity in human kidney epithelial cells, but its role in the development of renal tubulointerstitial fibrosis remains unknown. In this study, we found that with 7 days of unilateral ureteral obstruction (UUO) in mice, the abundance of miR-382 in the obstructed kidney was significantly increased. Meanwhile, the protein expression of heat shock protein 60 (HSPD1), a predicted target of miR-382, was reduced after 7 days of UUO. Expression of 3-nitrotyrosine (3-NT) was upregulated, but expression of thioredoxin (Trx) was downregulated. Anti-miR-382 treatment suppressed the upregulation of miR-382, attenuated renal interstitial fibrosis in the obstructed kidney, and reversed the downregulation of HSPD1/Trx and upregulation of 3-NT after UUO. Furthermore, in vitro study revealed that overexpression of HSPD1 significantly restored Trx expression and reversed TGF-β1-induced loss of E-cadherin, while in vivo study found that direct siRNA-mediated suppression of HSPD1 in the UUO kidney promoted oxidative stress despite miR-382 blockade. Our clinical data showed that upregulation of miR-382/3-NT and downregulation of HSPD1/Trx were also observed in IgA nephropathy patients with renal interstitial fibrosis. These data supported a novel mechanism in which miR-382 targets HSPD1 and contributes to the redox imbalance in the development of renal fibrosis.

MiR-146a/b: a family with shared seeds and different roots

MicroRNAs are small, noncoding, RNAs known for their powerful modulation of molecular processes, making them a major focus for studying pathological mechanisms. The human miR-146 family of microRNAs consists of two member genes, MIR146A and MIR146B These two microRNAs are located on different chromosomes and exhibit differential regulation in many cases. However, they are nearly identical in sequence, sharing a seed region, and are thus predicted to target the same set of genes. A large proportion of the microRNA (miR)-146 literature focuses on its role in regulating the innate immune response in the context of various pathologies by modulating two widely studied target genes in the toll-like receptor signaling cascade. A growing subset of the literature reports a role of miR-146 in cardiovascular and renal disease, and data suggest there is exciting potential for miR-146 as a diagnostic and therapeutic target. Nevertheless, the published literature is confounded by unclear and imprecise language concerning the specific effects of the two miR-146 family members. The present review will compare the genomic origin and regulation of miR-146a and miR-146b, discuss some approaches to overcome analytical and experimental challenges, and summarize findings in major areas of miR-146 research. Moving forward, careful evaluation of miR-146a/b specificity in analytical and experimental approaches will aid researchers in elucidating the functional relevance of differential regulation of the miR-146 family members in health and disease.

Urinary Exosomes and Their Cargo: Potential Biomarkers for Mineralocorticoid Arterial Hypertension?

Arterial hypertension (AHT) currently affects approximately 40% of adults worldwide, and its pathological mechanisms are mainly related to renal, vascular, and endocrine systems. Steroid hormones as aldosterone and cortisol are highly relevant to human endocrine physiology, and also to endocrine hypertension. Pathophysiological conditions, such as primary aldosteronism, affect approximately 10% of patients diagnosed with AHT and are secondary to a high production of aldosterone, increasing the risk also for cardiovascular damage and heart diseases. Excess of aldosterone or cortisol increases the activity of the mineralocorticoid receptor (MR) in epithelial and non-epithelial cells. Current research in this field highlights the potential regulatory mechanisms of the MR pathway, including pre-receptor regulation of the MR (action of 11BHSD2), MR activating proteins, and the downstream genes/proteins sensitive to MR (e.g., epithelial sodium channel, NCC, NKCC2). Mineralocorticoid AHT is present in 15-20% of hypertensive subjects, but the mechanisms associated to this condition have been poorly described, due mainly to the absence of reliable biomarkers. In this way, steroids, peptides, and lately urinary exosomes are thought to be potential reporters of biological processes. This review highlight exosomes and their cargo as potential biomarkers of metabolic changes associated to mineralocorticoid AHT. Recent reports have shown the presence of RNA, microRNAs, and proteins in urinary exosomes, which could be used as biomarkers in physiological and pathophysiological conditions. However, more studies are needed in order to benefit from exosomes and the exosomal cargo as a diagnostic tool in mineralocorticoid AHT.

Inhibition of the processing of miR-25 by HIPK2-Phosphorylated-MeCP2 induces NOX4 in early diabetic nephropathy

Phosphorylated methyl-CpG binding protein2 (p-MeCP2) suppresses the processing of several microRNAs (miRNAs). Homeo-domain interacting protein kinase2 (HIPK2) phosphorylates MeCP2, a known transcriptional repressor. However, it is not known if MeCP2 and HIPK2 are involved in processing of miRNAs implicated in diabetic nephropathy. p-MeCP2 and HIPK2 levels were significantly increased, but Seven in Absentia Homolog1 (SIAH1), which mediates proteasomal degradation of HIPK2, was decreased in the glomeruli of streptozotocin injected diabetic mice. Among several miRNAs, miR-25 and its precursor were significantly decreased in diabetic mice, whereas primary miR-25 levels were significantly increased. NADPH oxidase4 (NOX4), a target of miR-25, was significantly increased in diabetic mice. Protein levels of p-MeCP2, HIPK2, and NOX4 were increased in high glucose (HG)- or TGF-β-treated mouse glomerular mesangial cells (MMCs). miR-25 (primary, precursor, and mature) and mRNA levels of genes indicated in the in vivo study showed similar trends of regulation in MMCs treated with HG or TGF-β. The HG- or TGF-β-induced upregulation of p-MeCP2, NOX4 and primary miR-25, but downregulation of precursor and mature miR-25, were attenuated by Hipk2 siRNA. These results demonstrate a novel role for the SIAH1/HIPK2/MeCP2 axis in suppressing miR-25 processing and thereby upregulating NOX4 in early diabetic nephropathy.

Circulating Organ-Specific MicroRNAs Serve as Biomarkers in Organ-Specific Diseases: Implications for Organ Allo- and Xeno-Transplantation

Different cell types possess different miRNA expression profiles, and cell/tissue/organ-specific miRNAs (or profiles) indicate different diseases. Circulating miRNA is either actively secreted by living cells or passively released during cell death. Circulating cell/tissue/organ-specific miRNA may serve as a non-invasive biomarker for allo- or xeno-transplantation to monitor organ survival and immune rejection. In this review, we summarize the proof of concept that circulating organ-specific miRNAs serve as non-invasive biomarkers for a wide spectrum of clinical organ-specific manifestations such as liver-related disease, heart-related disease, kidney-related disease, and lung-related disease. Furthermore, we summarize how circulating organ-specific miRNAs may have advantages over conventional methods for monitoring immune rejection in organ transplantation. Finally, we discuss the implications and challenges of applying miRNA to monitor organ survival and immune rejection in allo- or xeno-transplantation.

Role of miR-21 in alkalinity stress tolerance in tilapia

MicroRNAs (miRNAs) are a class of short, evolutionary conserved non-coding RNA molecules, which are shown as the key regulators of many biological functions. External stress can alter miRNA expression levels, thereby changing the expression of mRNA target genes. Here, we show that miR-21 is involved in the regulation of alkalinity tolerance in Nile tilapia. Alkalinity stress results in a marked reduction in miR-21 levels. miR-21 loss of function could affect ion balance regulation, ROS production, and antioxidant enzyme activity in vivo. Moreover, miR-21 knockdown protects cell against alkalinity stress-induced injury in vitro. miR-21 directly regulates VEGFB and VEGFC expression by targeting the 3'-untranslated regions (UTRs) of their mRNAs, and inhibition of miR-21 significantly increases the levels of VEGFB and VEGFC expression in vivo. Taken together, our study reveals that miR-21 knockdown plays a protective role in alkalinity tolerance in tilapia.

Relationship of cell-free urine MicroRNA with lupus nephritis in children

BACKGROUND

MicroRNAs (miRNAs) are involved in the post-transcriptional regulation of genes. The objective of this study was to investigate whether select urinary cell-free microRNA's may serve as biomarkers in children with active lupus nephritis (LN) and to assess their relationship to the recently identified combinatorial urine biomarkers, a.k.a. the LN-Panel (neutrophil gelatinase associated lipocalin, monocyte chemotactic protein 1, transferrin, and beta-trace protein).

METHODS

miRNAs (125a, 127, 146a, 150 and 155) were measured using real-time polymerase chain reaction in the urine pellet (PEL) and supernatant (SUP) in 14 patients with active LN, 10 patients with active extra-renal lupus, and 10 controls. The concentrations of the LN-Panel biomarkers (neutrophil gelatinase associated lipocalin, monocyte chemotactic protein-1, transferrin, beta-trace protein) was assayed. Traditional laboratory and clinical measures of LN and lupus (complements, protein to creatinine ratio; Systemic Lupus Erythematosus Disease Activity Index) were also measured.

RESULTS

All tested miRNAs in the SUP, but not the PEL, were associated with the LN-Panel biomarkers (0.3 < |r Pearson| < 0.73; p < 0.05), miRNA125a, miRNA127,miRNA146a also with C3 and dsDNA antibody levels (|r Pearson| > 0.24; p < 0.05), and miRNA146a with the renal domain of the SLEDAI (|r Pearson| = 0.32; p < 0.05). Mean miRNA levels of patients with active LN did not statistically (P > 0.05) differ from those of SLE patients without LN or controls.

CONCLUSION

Levels of cell-free miR-125a, miR-150, and miR-155 in the urine supernatant are associated with the expression of LN-Panel biomarkers and some LN measures. These miRNA's may complement, but are unlikely superior to the LN-Panel for estimating concurrent LN activity.

Xenon Protects Against Septic Acute Kidney Injury via miR-21 Target Signaling Pathway

Objectives:

Septic acute kidney injury is one of the most common and life-threatening complications in critically ill patients, and there is no approved effective treatment. We have shown xenon provides renoprotection against ischemia-reperfusion injury and nephrotoxicity in rodents via inhibiting apoptosis. Here, we studied the effects of xenon preconditioning on septic acute kidney injury and its mechanism.

Design:

Experimental animal investigation.

Setting:

University research laboratory.

Subjects:

Experiments were performed with male C57BL/6 mice, 10 weeks of age, weighing 20–25 g.

Interventions:

We induced septic acute kidney injury by a single intraperitoneal injection of Escherichia coli lipopolysaccharide at a dose of 20 mg/kg. Mice were exposed for 2 hours to either 70% xenon or 70% nitrogen, 24 hours before the onset of septic acute kidney injury. In vivo knockdown of miR-21 was performed using locked nucleic acid-modified anti-miR, the role of miR-21 in renal protection conferred by the xenon preconditioning was examined, and miR-21 signaling pathways were analyzed.

Measurements and Main Results:

Xenon preconditioning provided morphologic and functional renoprotection, characterized by attenuation of renal tubular damage, apoptosis, and a reduction in inflammation. Furthermore, xenon treatment significantly upregulated the expression of miR-21 in kidney, suppressed proinflammatory factor programmed cell death protein 4 expression and nuclear factor-κB activity, and increased interleukin-10 production. Meanwhile, xenon preconditioning also suppressed the expression of proapoptotic protein phosphatase and tensin homolog deleted on chromosome 10, activating protein kinase B signaling pathway, subsequently increasing the expression of antiapoptotic B-cell lymphoma-2, and inhibiting caspase-3 activity. Knockdown of miR-21 upregulated its target effectors programmed cell death protein 4 and phosphatase and tensin homolog deleted on chromosome 10 expression, resulted in an increase in apoptosis, and exacerbated lipopolysaccharide-induced acute kidney injury.

Conclusion:

Our findings demonstrated that xenon preconditioning protected against lipopolysaccharide-induced acute kidney injury via activation of miR-21 target signaling pathways.

Novel role of microRNAs in renal ischemia reperfusion injury

Renal ischemia reperfusion injury (IRI) contributes to the development of acute kidney injury (AKI). Several processes are involved in the development of renal IRI with the generation of reactive oxygen species, inflammation and apoptosis. MicroRNAs (miRNAs) are endogenous, small and noncoding RNAs that repress gene expression of target mRNA in animals post-transcriptionally. miRNA-mediated gene repression is a major modulatory mechanism to regulate fundamental cellular processes such as the cell cycle, proliferation, growth, and apoptosis, which in turn have pivotal influences on pathophysiological outcomes. Recent studies have revealed the pathogenic roles played by miRNAs in many renal diseases, such as IRI, AKI and renal carcinoma. In addition, the majority of miRNAs identified appear to be differentially expressed, probably to quell the injury response by modulating inflammation, apoptosis and proliferation and may point us toward new pathways that can be targeted to regulate or prevent renal IRI. They may represent novel diagnostic biomarkers of renal IR injury.

Vasopressin-regulated miRNAs and AQP2-targeting miRNAs in kidney collecting duct cells

Mature microRNA (miRNA) acts as an important posttranscriptional regulator. We aimed to profile vasopressin-responsive miRNAs in kidney inner medullary collecting duct cells and to identify aquaporin-2 (AQP2)-targeting miRNAs. Microarray chip assay was carried out in inner medullary collecting duct tubule suspensions from rat kidneys in the absence or presence of desmopressin (dDAVP) stimulation (10−9 M, 2 h). The results demonstrated 19 miRNAs, including both precursor and mature miRNAs, as potential candidates that showed significant changes in expression after dDAVP stimulation ( P < 0.05). Nine mature miRNAs exhibiting >1.3-fold changes in expression on the microarray (miR-127, miR-1, miR-873, miR-16, miR-206, miR-678, miR-496, miR-298, and miR-463) were further examined by quantitative real-time PCR, and target genes of the selected miRNAs were predicted. Next, to identify AQP2-targeting miRNAs, in silico analysis was performed. Four miRNAs (miR-32, miR-137, miR-216a, and miR-216b) target the 3′-untranslated region of rat AQP2 mRNA. Target seed regions of miR-32 and miR-137 were also conserved in the 3′-untranslated region of mouse AQP2 mRNA. Quantitative real-time PCR and immunoblot analysis demonstrated that dDAVP-induced AQP2 expression was significantly attenuated in mpkCCDc14 cells when cells were transfected with miRNA mimics of miR-32 or miR-137. Moreover, luciferase reporter assay demonstrated a significant decrease of AQP2 translation in mpkCCDc14 cells transfected with miRNA mimics of miR-32 or miR-137. The present study provides novel insights into the regulation of AQP2 by RNA interference; however, vasopressin-regulated miRNAs did not include miR-32 or miR-137, indicating that the interaction of miRNAs with the AQP2 regulatory pathway requires further analysis.

Notoginsenoside R1 reduces blood pressure in spontaneously hypertensive rats through a long non-coding RNA AK094457

Notoginsenoside R1 (NR1) is the main bioactive component in panaxnotoginseng, an old herb medicine widely used in Asian countries in the treatment of microcirculatory diseases. However, little is known about the effect of NR1 on antihypertension and the underlying mechanisms are still not clear. This study is aim to investigate the effect and elicit the mechanism of NR1 in antihypertension. Firstly, to assess the ability of NR1 in antihypertension, NR1 was injected in spontaneously hypertensive rats (SHR) via the vena caudalis. Then we examined the rats systolic blood pressure and inducible nitric oxide synthase (iNOS) activation in rats thoracoabdominal aortic. To further investigate the molecular mechanism of NR1 reduce blood pressure, primary SHR and WYK rat vascular endothelial cells (RVECs) were used for next study. LncRNAs related to hypertension were gained from bioinformatics analysis. The role of LncRNAs was finally characterized in RVECs by siRNA. Our results showed that NR1 significantly reduce blood pressure in SHR and induce nitric oxide (NO) generation through increasing the phosphorylation of iNOS. Through bioinformatics analysis and knockdown LncRNA AK094457 in RVECs, we also found LncRNA AK094457 promoted iNOS expression and NO concentration. Thus, we conclude that NR1 reduces the caudal blood pressure of SHR through induction of iNOS regulated by long non-coding RNA AK094457. These findings may have important implications for understanding the mechanisms of NR1 regulation blood pressure.

MicroRNA-10b downregulation mediates acute rejection of renal allografts by derepressing BCL2L11

Kidney transplantation is the major therapeutic option for end-stage kidney diseases. However, acute rejection could cause allograft loss in some of these patients. Emerging evidence supports that microRNA (miRNA) dysregulation is implicated in acute allograft rejection. In this study, we used next-generation sequencing to profile miRNA expression in normal and acutely rejected kidney allografts. Among 75 identified dysregulated miRNAs, miR-10b was the most significantly downregulated miRNAs in rejected allografts. Transfecting miR-10b inhibitor into human renal glomerular endothelial cells recapitulated key features of acute allograft rejection, including endothelial cell apoptosis, release of pro-inflammatory cytokines (interleukin-6, tumor necrosis factor α, interferon-γ, and chemokine (C-C motif) ligand 2) and chemotaxis of macrophages whereas transfection of miR-10b mimics had opposite effects. Downregulation of miR-10b directly derepressed the expression of BCL2L11 (an apoptosis inducer) as revealed by luciferase reporter assay. Taken together, miR-10b downregulation mediates many aspects of disease pathogenicity of acute kidney allograft rejection. Restoring miR-10b expression in glomerular endothelial cells could be a novel therapeutic approach to reduce acute renal allograft loss.

Hypertensive epigenetics: from DNA methylation to microRNAs

The major epigenetic features of mammalian cells include DNA methylation, posttranslational histone modifications and RNA-based mechanisms including those controlled by small non-coding RNAs (microRNAs (miRNAs)). An important aspect of epigenetic mechanisms is that they are potentially reversible and may be influenced by nutritional-environmental factors and through gene-environment interactions. Studies on epigenetic modulations could help us understand the mechanisms involved in essential hypertension and further prevent it's progress. This review is focused on new knowledge on the role of epigenetics, from DNA methylation to miRNAs, in essential hypertension.

Urinary microRNAs as a new class of noninvasive biomarkers in oncology, nephrology, and cardiology

MicroRNAs (miRNAs) are small noncoding RNAs that posttranscriptionally regulate gene expression. In the last decade, number of evidences showing miRNAs contribution to the regulation of apoptosis, cellular proliferation, differentiation, and other important cellular processes is constantly growing. Specific miRNA expression signatures have been identified in variety of human cancers as well as pathologies of cardiovascular and urinary systems. Our chapter focuses on the potential of urinary miRNAs to serve as biomarkers in uro-oncology, nephrology, and cardiology. We discuss in detail recent knowledge about the origin of urinary miRNAs, their stability, quality control, and their utility as a potential new class of biomarkers in medicine. Finally, we summarize the studies focusing on detection and characterization of urinary miRNAs as potential biomarkers in urologic cancers, nephrology, and cardiology.

Non-coding RNAs and hypertension-unveiling unexpected mechanisms of hypertension by the dark matter of the genome

Hypertension is a major risk factor of cardiovascular diseases and a most important health problem in developed countries. Investigations on pathophysiology of hypertension have been based on gene products from coding region that occupies only about 1% of total genome region. On the other hand, non-coding region that occupies almost 99% of human genome has been regarded as "junk" for a long time and went unnoticed until these days. But recently, it turned out that noncoding region is extensively transcribed to non-coding RNAs and has various functions. This review highlights recent updates on the significance of non-coding RNAs such as micro RNAs and long non-coding RNAs (lncRNAs) on the pathogenesis of hypertension, also providing an introduction to basic biology of noncoding RNAs. For example, microRNAs are associated with hypertension via neuro-fumoral factor, sympathetic nerve activity, ion transporters in kidneys, endothelial function, vascular smooth muscle phenotype transformation, or communication between cells. Although reports of lncRNAs on pathogenesis of hypertension are scarce at the moment, new lncRNAs in relation to hypertension are being discovered at a rapid pace owing to novel techniques such as microarray or next-generation sequencing. In the clinical settings, clinical use of non-coding RNAs in identifying cardiovascular risks or developing novel tools for treating hypertension such as molecular decoy or mimicks is promising, although improvement in chemical modification or drug delivery system is necessary.

Involvement of microRNA-198 overexpression in the poor prognosis of esophageal cancer

OBJECTIVE

This study aimed to investigate whether the miR-198 expression level is related to clinicopathological factors and prognosis of esophageal cancer.

METHODS

MicroRNA was extracted from esophageal cancer patients who underwent surgery for assessment using the Taqman@ MicroRNA assay. The correlation between miR-198 expression and clinicopathological features was analyzed, and the significance of miR-198 as a prognostic factor and its relationship with survival was determined.

RESULTS

MicroRNA-198 (miR-198) expression was higher in patients with poor prognosis than those with good prognosis (P < 0.05). Kaplan-Meier analysis results showed that the miR-198 expression level had a significant correlation with survival time (P = 0.030) and that patients with a higher expression of miR-198 had a shorter survival time. Cox multi-factor model analysis showed that patient prognosis (P = 0.014), tumor length (P = 0.040) and expression (P = 0.012), and survival time had a significant correlation; the corresponding risks were 7.268, 1.246, and 3.524, respectively.

CONCLUSION

miR- 198 overexpression is involved in the poor prognosis of esophageal cancer and can be used as a biomarker for selection of cases requiring especial attention.

Characteristics of long non-coding RNAs in the Brown Norway rat and alterations in the Dahl salt-sensitive rat

Long non-coding RNAs (lncRNAs) are potentially important mediators of genomic regulation. lncRNAs, however, remain poorly characterized in the rat model organism widely used in biomedical research. Using poly(A)-independent and strand-specific RNA-seq, we identified 1,500 to 1,800 lncRNAs expressed in each of the following tissues of Brown Norway rats: the renal cortex, renal outer medulla, liver, cardiac left ventricle, adrenal gland, and hypothalamus. Expression and the binding of histone H3K4me3 to promoter regions were confirmed for several lncRNAs. Rat lncRNA expression appeared to be more tissue-specific than mRNA. Rat lncRNAs had 4.5 times fewer exons and 29% shorter transcripts than mRNA. The median cumulative abundance of rat lncRNAs was 53% of that of mRNA. Approximately 28% of the lncRNAs identified in the renal outer medulla appeared to lack a poly(A) tail. Differential expression of 74 lncRNAs was detected in the renal outer medulla between Dahl SS rats, a model of salt-sensitive hypertension, and salt-insensitive, congenic SS.13^BN26 rats fed a high-salt diet. Two of the differentially expressed lncRNAs, which were confirmed, were located within the congenic region and contained several sequence variants. The study identified genome-wide characteristics of lncRNAs in the rat model and suggested a role of lncRNAs in hypertension.

Circulating and renal vein levels of microRNAs in patients with renal artery stenosis

BACKGROUND

MicroRNAs (miRs) are small non-coding RNAs that are important regulators of gene expression and have been implicated in atherosclerosis. Kidney injury distal to atherosclerotic renal artery stenosis (ARAS) is aggravated by atherosclerosis. Therefore, this study tested the hypothesis that renal miR expression would be altered in patients with ARAS.

METHODS

Patients with essential hypertension (EH; n = 13) or ARAS (n = 13) underwent a 3-day protocol study under controlled conditions. For miR levels, blood samples were collected from EH and ARAS renal vein (RV) and inferior vena cava or peripheral vein of matched normotensive healthy volunteers (HV; n = 13) and patients with coronary atherosclerosis (CA; n = 11). Single-renal blood flow was measured in EH and ARAS using computer tomography to calculate renal gradients and release of miRs.

RESULTS

Glomerular filtration rate (GFR) was lower in ARAS compared with the other groups. Systemic levels of most miRs were elevated in CA. RV miR levels were lower than systemic levels in both ARAS and EH. GFR-adjusted RV levels of miR-21, 155 and 210 were reduced only in ARAS patients compared with systemic levels in HV, although cross-kidney gradients were not different from EH. RV levels of miR-21, 126, 155 and 210 correlated with GFR.

CONCLUSIONS

Levels of atherosclerosis-related miR-21, 126, 155 and 210 are decreased in the stenotic-kidney vein of ARAS compared with EH patients, likely due to decreased GFR. Yet, these miRs might be implicated in modulating renal injury in ARAS, and their RV level may be a marker reflecting their renal expression.

MICROFLUIDIC DEVICES FOR LABEL-FREE AND NON-INSTRUMENTED QUANTITATION OF UNAMPLIFIED NUCLEIC ACIDS BY FLOW DISTANCE MEASUREMENT

Timely biomarker quantitation has potential to improve human health but current methods have disadvantages either in terms of cost and complexity for benchtop instruments, or reduced performance in quantitation and/or multiplexing for point-of-care systems. We previously developed microfluidic devices wherein visually observed flow distances correlated with a model analyte's concentration.1 Here, we significantly expand over this prior result to demonstrate the measurement of unamplified DNA analogues of microRNAs (miRNAs), biomarkers whose levels can be altered in disease states. We have developed a method for covalently attaching nucleic acid receptors on poly(dimethylsiloxane) microchannel surfaces by silane and cross-linker treatments. We found a flow distance dependence on target concentrations from 10 μg/mL to 10 pg/mL for DNA in both buffer and synthetic urine. Moreover, flow time in addition to flow distance is correlated with target concentration. We also observed longer flow distances for single-base mismatches compared to the target sequence at the same concentration, indicating that our approach can be used to detect point mutations. Finally, experiments with DNA analogues of miRNA biomarkers for kidney disease (mir-200c-3p) and prostate cancer (mir-107) in synthetic urine showed the ability to detect these analytes near clinically relevant levels. Our results demonstrate that these novel microfluidic assays offer a simple route to sensitive, amplification-free nucleic acid quantitation, with strong potential for point-of-care application.

The Role of MicroRNAs in Diabetic Complications-Special Emphasis on Wound Healing

Overweight and obesity are major problems in today’s society, driving the prevalence of diabetes and its related complications. It is important to understand the molecular mechanisms underlying the chronic complications in diabetes in order to develop better therapeutic approaches for these conditions. Some of the most important complications include macrovascular abnormalities, e.g., heart disease and atherosclerosis, and microvascular abnormalities, e.g., retinopathy, nephropathy and neuropathy, in particular diabetic foot ulceration. The highly conserved endogenous small non-coding RNA molecules, the micro RNAs (miRNAs) have in recent years been found to be involved in a number of biological processes, including the pathogenesis of disease. Their main function is to regulate post-transcriptional gene expression by binding to their target messenger RNAs (mRNAs), leading to mRNA degradation, suppression of translation or even gene activation. These molecules are promising therapeutic targets and demonstrate great potential as diagnostic biomarkers for disease. This review aims to describe the most recent findings regarding the important roles of miRNAs in diabetes and its complications, with special attention given to the different phases of diabetic wound healing.

Association of angiotensin II type 1 receptor (A1166C) gene polymorphism and its increased expression in essential hypertension: a case-control study

OBJECTIVES

Hypertension is one of the major cardiovascular diseases. It affects nearly 1.56 billion people worldwide. The present study is about a particular genetic polymorphism (A1166C), gene expression and protein expression of the angiotensin II type I receptor (AT1R) (SNP ID: rs5186) and its association with essential hypertension in a Northern Indian population.

METHODS

We analyzed the A1166C polymorphism and expression of AT1R gene in 250 patients with essential hypertension and 250 normal healthy controls.

RESULTS

A significant association was found in the AT1R genotypes (AC+CC) with essential hypertension (χ2 = 22.48, p = 0.0001). Individuals with CC genotypes were at 2.4 times higher odds (p = 0.0001) to develop essential hypertension than individuals with AC and AA genotypes. The statistically significant intergenotypic variation in the systolic blood pressure was found higher in the patients with CC (169.4±36.3 mmHg) as compared to that of AA (143.5±28.1 mmHg) and AC (153.9±30.5 mmHg) genotypes (p = 0.0001). We found a significant difference in the average delta-CT value (p = 0.0001) wherein an upregulated gene expression (approximately 16 fold) was observed in case of patients as compared to controls. Furthermore, higher expression of AT1R gene was observed in patients with CC genotype than with AC and AA genotypes. A significant difference (p = 0.0001) in the protein expression of angiotensin II Type 1 receptor was also observed in the plasma of patients (1.49±0.27) as compared to controls (0.80±0.24).

CONCLUSION

Our findings suggest that C allele of A1166C polymorphism in the angiotensin II type 1 receptor gene is associated with essential hypertension and its upregulation could play an important role in essential hypertension.

Epigenomics of hypertension

Multiple genes and pathways are involved in the pathogenesis of hypertension. Epigenomic studies of hypertension are beginning to emerge and hold great promise of providing novel insights into the mechanisms underlying hypertension. Epigenetic marks or mediators including DNA methylation, histone modifications, and noncoding RNA can be studied at a genome or near-genome scale using epigenomic approaches. At the single gene level, several studies have identified changes in epigenetic modifications in genes expressed in the kidney that correlate with the development of hypertension. Systematic analysis and integration of epigenetic marks at the genome-wide scale, demonstration of cellular and physiological roles of specific epigenetic modifications, and investigation of inheritance are among the major challenges and opportunities for future epigenomic and epigenetic studies of hypertension.

MicroRNAs: role and therapeutic targets in viral hepatitis

MicroRNAs regulate gene expression by binding to the 3'-untranslated region (UTR) of target messenger RNAs (mRNAs). The importance of microRNAs has been shown for several liver diseases, for example, viral hepatitis. MicroRNA-122 is highly abundant in the liver and is involved in the regulation of lipid metabolism. MicroRNA-122 is also an important host factor for the HCV and promotes HCV replication. In contrast to HCV, microRNA-122 inhibits replication of the HBV. MicroRNA-122 acts as a tumour suppressor and reduced levels of microRNA-122 are associated with hepatocellular carcinoma. MicroRNAs other than microRNA-122 have been linked to viral hepatitis, fibrosis and inflammation. In this review, we discuss function and clinical implications of microRNA-122 and other microRNAs in liver diseases, especially viral hepatitis.

microRNA biomarkers in cystic diseases

microRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by targeting the 3’-untranslated region of multiple target genes. Pathogenesis results from defects in several gene sets; therefore, disease progression could be prevented using miRNAs targeting multiple genes. Moreover, recent studies suggest that miRNAs reflect the stage of the specific disease, such as carcinogenesis. Cystic diseases, including polycystic kidney disease, polycystic liver disease, pancreatic cystic disease, and ovarian cystic disease, have common processes of cyst formation in the specific organ. Specifically, epithelial cells initiate abnormal cell proliferation and apoptosis as a result of alterations to key genes. Cysts are caused by fluid accumulation in the lumen. However, the molecular mechanisms underlying cyst formation and progression remain unclear. This review aims to introduce the key miRNAs related to cyst formation, and we suggest that miRNAs could be useful biomarkers and potential therapeutic targets in several cystic diseases. [BMB Reports 2013; 46(7):338-345]

MicroRNAs in kidney diseases: new promising biomarkers for diagnosis and monitoring

A series of microRNAs (miRNAs) have a critical role in many cellular and physiological activities such as cell cycle, growth, proliferation, apoptosis and metabolism. miRNAs are also important in the maintenance of renal homeostasis and kidney diseases. In vitro and in vivo animal models have shown a critical role of miRNAs in the development of diabetic nephropathy (DN) and in the progression of renal fibrosis. Specific miRNAs in renal tissue and peripheral blood mononuclear cells (PBMCs) are up and downregulated in different kidney diseases. They represent new potential biomarkers for diagnosis and targeted therapy. In addition, urinary miRNAs may be considered non-invasive biomarkers for monitoring the progression of renal damage. The activity of miRNAs can be modified by different approaches such as the use of antisense oligonucleotide inhibitors (antagomirs), tandem miRNA-binding site repeats manufactured by Decoy or Sponge technologies and miRNA mimics. The use of miRNA blockers or antagonists as therapeutic agents is very attractive but new information will be necessary considering their role in other systems.

Connective tissue growth factor, matrix regulation, and diabetic kidney disease

PURPOSE OF REVIEW

Connective tissue growth factor, more recently officially known as CCN-2, is a member of the CCN family of secreted cysteine-rich modular matricellular proteins. Here, we review CCN-2 in diabetic nephropathy with focus on its regulation of extracellular matrix.

RECENT FINDINGS

CCN-2 is upregulated in the clinical and preclinical models of diabetic nephropathy by multiple stimuli, including elevated glucose, advanced glycation, some types of lipid, various hemodynamic factors, as well as hypoxia and oxidative stress. CCN-2 has bioactivities that suggest it may mediate diabetic nephropathy pathogenesis, especially in extracellular matrix accumulation, through both induction of new matrix and inhibition of matrix degradation. CCN-2 also has proinflammatory functions. Moreover, recent studies using antibodies or antisense technologies in animal and early phase clinical trial settings have shown that inhibition of renal CCN-2 expression or action may prevent diabetic nephropathy. Additionally, determination of renal and blood levels of CCN-2 as a marker of diabetic renal disease and its progression appears to have value.

SUMMARY

Recent publications implicate CCN-2 as both an evolving marker and mediator of diabetic nephropathy.

Intermittent exposure to xenon protects against gentamicin-induced nephrotoxicity

Aminoglycoside antibiotics, especially gentamicin, are widely used to treat Gram-negative infections due to their efficacy and low cost. Nevertheless the use of gentamicin is limited by its major side effect, nephrotoxicity. Xenon (Xe) provided substantial organoprotective effects in acute injury of the brain and the heart and protected against renal ischemic-reperfusion injury. In this study, we investigated whether xenon could protect against gentamicin-induced nephrotoxicity. Male Wistar rats were intermittently exposed to either 70% xenon or 70% nitrogen (N₂) balanced with 30% oxygen before and during gentamicin administration at a dose of 100 mg/kg for 7 days to model gentamicin-induced kidney injury. We observed that intermittent exposure to Xe provided morphological and functional renoprotection, which was characterized by attenuation of renal tubular damage, apoptosis, and oxidative stress, but not a reduction in inflammation. We also found that Xe pretreatment upregulated hypoxia-inducible factor 2α (HIF-2α) and its downstream effector vascular endothelial growth factor, but not HIF-1α. With regard to the three HIF prolyl hydroxylases, Xe pretreatment upregulated prolyl hydroxylase domain-containing protein-2 (PHD2), suppressed PHD1, and had no influence on PHD3 in the rat kidneys. Pretreatment with Xe also increased the expression of miR-21, a microRNA known to have anti-apoptotic effects. These results support Xe renoprotection against gentamicin-induced nephrotoxicity.