Characterization of microRNA expression profiles in Leishmania-infected human phagocytes

Leishmania are intracellular protozoa that influence host immune responses eliciting parasite species-specific pathologies. MicroRNAs (miRNAs) are short single-stranded ribonucleic acids that complement gene transcripts to block protein translation and have been shown to regulate immune system molecular mechanisms. Human monocyte-derived dendritic cells (DC) and macrophages (MP) were infected in vitro with Leishmania major or Leishmania donovani parasites. Small RNAs were isolated from total RNA and sequenced to identify mature miRNAs associated with leishmanial infections. Normalized sequence read count profiles revealed a global downregulation in miRNA expression among host cells following infection. Most identified miRNAs were expressed at higher levels in L. donovani-infected cells relative to L. major-infected cells. Pathway enrichments using in silico-predicted gene targets of differentially expressed miRNAs showed evidence of potentially universal MAP kinase signalling pathway effects. Whereas JAK-STAT and TGF-β signalling pathways were more highly enriched using targets of miRNAs upregulated in L. donovani-infected cells, these data provide evidence in support of a selective influence on host cell miRNA expression and regulation in response to differential Leishmania infections.

Research progress in signalling pathway in diabetic nephropathy

Diabetic nephropathy, a lethal diabetic complication, is a leading cause of end-stage renal disease, which is pathologically characterized by thickened tubular basal and glomerular membranes, accumulated extracellular matrix, and progressive mesangial hypertrophy. Growing evidence indicates that diabetic nephropathy is induced by multiple conditions, such as glucose metabolism disorder, oxidative stress, numerous inflammatory factors and cytokines, and haemodynamic changes that lead to the occurrence and development of diabetic nephropathy based on genetic susceptibility. A variety of abnormalities in the signalling pathway may interact to produce these pathologic processes. Research has aimed to highlight the signalling pathway mechanisms that lead to diabetic nephropathy so that preventative strategies and effective therapies might be developed. In this review, important pathways that appear to be involved in driving these processes are discussed.

miRNAs in urine: a mirror image of kidney disease?

miRNAs are short non-coding RNAs that control post-transcriptional regulation of gene expression. They are found ubiquitously in tissue and body fluids and participate in the pathogenesis of many diseases. Due to these characteristics and their stability, miRNAs could serve as biomarkers of different pathologies of the kidney. Urine is a non-invasive reservoir of molecules, especially indicative of the urinary system. In this review, we focus on urinary miRNAs and their potential to serve as biomarkers in kidney disease. Past studies show that urinary miRNAs correlate with renal dysfunctions and with processes involved in the pathophysiology. However, these studies also stress the need for future research focusing on large-scale studies to confirm the usability of urinary miRNAs as diagnostic and/or prognostic markers of different kidney diseases in clinical practice.

Partial loss of Smad7 function impairs bone remodeling, osteogenesis and enhances osteoclastogenesis in mice

Smad7 is well demonstrated as a negative regulator of TGF-β signaling. Its alteration in expression often results in diseases such as cancer and fibrosis. However, the exact role of Smad7 in regulating bone remodeling during mammalian development has not been properly delineated. In this study we performed experiments to clarify the involvement of Smad7 in regulating osteogenesis and osteoclastogenesis both invivo and invitro. Genetically engineered Smad7(ΔE1) (KO) mice were used, whereby partial functional of Smad7 is lost by deleting exon I of the Smad7 gene and the truncated proteins cause a hypomorphic allele. Analysis with μCT imagery and bone histomorphometry showed that the KO mice had lower TbN, TbTh, higher TbSp in the metaphysic region of the femurs at 6, 12, 24weeks from birth, as well as decreased MAR and increased osteoclast surface compared with the WT mice. In vitro BM-MSC multi-lineage differentiation evaluation showed that the KO group had reduced osteogenic potential, fewer mineralized nodules, lower ALP activity, and reduced gene expression of Col1A1, Runx2 and OCN. The adipogenic potential was elevated in the KO group with more formation of lipid droplets, and increased gene expression of Adipsin and C/EBPα. The osteoclastogenic potential of KO mice BMMs was elevate, with emergence of more osteoclasts, larger resorptive areas, and increased gene expression of TRAP and CTR. Our results indicate that partial loss of Smad7 function in mice leads to compromised bone formation and enhanced bone resorption. Thus, Smad7 is acknowledged as a novel key regulator between osteogenesis and osteoclastogenesis.

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.

Transforming growth factor β1 (TGF-β1) enhances expression of profibrotic genes through a novel signaling cascade and microRNAs in renal mesangial cells

Increased expression of transforming growth factor-β1 (TGF-β1) in glomerular mesangial cells (MC) augments extracellular matrix accumulation and hypertrophy during the progression of diabetic nephropathy (DN), a debilitating renal complication of diabetes. MicroRNAs (miRNAs) play key roles in the pathogenesis of DN by modulating the actions of TGF-β1 to enhance the expression of profibrotic genes like collagen. In this study, we found a significant decrease in the expression of miR-130b in mouse MC treated with TGF-β1. In parallel, there was a down-regulation in miR-130b host gene 2610318N02RIK (RIK), suggesting host gene-dependent expression of this miRNA. TGF-β receptor 1 (TGF-βR1) was identified as a target of miR-130b. Interestingly, the RIK promoter contains three NF-Y binding sites and was regulated by NF-YC. Furthermore, NF-YC expression was inhibited by TGF-β1, suggesting that a signaling cascade, involving TGF-β1-induced decreases in NF-YC, RIK, and miR-130b, may up-regulate TGF-βR1 to augment expression of TGF-β1 target fibrotic genes. miR-130b was down-regulated, whereas TGF-βR1, as well as the profibrotic genes collagen type IV α 1 (Col4a1), Col12a1, CTGF, and PAI-1 were up-regulated not only in mouse MC treated with TGF-β1 but also in the glomeruli of streptozotocin-injected diabetic mice, supporting in vivo relevance. Together, these results demonstrate a novel miRNA- and host gene-mediated amplifying cascade initiated by TGF-β1 that results in the up-regulation of profibrotic factors, such as TGF-βR1 and collagens associated with the progression of DN.

Role of MAPK signal pathways in differentiation process of M2 macrophages induced by high-ambient glucose and TGF-β1

Macrophage can be alternatively activated by TGF-β1, whether high-ambient glucose can enhance the sensitivity of TGF-β1 and the intracellular mechanisms involved in this process are not fully understood. We examined whether the mitogen-activated protein kinase is involved in the activation of macrophage induced by TGF-β1 and high-ambient glucose. The expression of arginase-1, CD206 and TGF-β1 was accessed by Western blot and immunofluorescence in RAW 264.7 cells stimulated with TGF-β1 and high-ambient glucose. The activation of MAPK pathways in the process was investigated by Western blot. The role of MAPK was assessed using biochemical inhibitors. The protein of arginase-1, CD206 and TGF-β1 was significantly overexpressed in RAW264.7 cells stimulated by TGF-β1 and high-ambient glucose. ERK and JNK phosphorylation occurred in 30 min and p38MAPK phosphorylation occurred in 30 min and 24 h after the stimulation. And the expression of arginase-1 and TGF-β1 was partially blocked by the pretreated ERK biochemical inhibitor (U0126) instead of the JNK inhibitor (SP600125) and p38MAPK inhibitor (SB203580). In conclusion, high-ambient glucose can enhance the sensitivity of TGF-β1 in RAW264.7 cells, which resulted in overexpression of TGF-β1 and arginase-1 in macrophages. ERK plays a role in this process.

Role of transcription factor acetylation in diabetic kidney disease

Nuclear factor (NF)-κB and signal transducer and activator of transcription 3 (STAT3) play a critical role in diabetic nephropathy (DN). Sirtuin-1 (SIRT1) regulates transcriptional activation of target genes through protein deacetylation. Here, we determined the roles of Sirt1 and the effect of NF-κB (p65) and STAT3 acetylation in DN. We found that acetylation of p65 and STAT3 was increased in both mouse and human diabetic kidneys. In human podocytes, advanced glycation end products (AGEs) induced p65 and STAT3 acetylation and overexpression of acetylation-incompetent mutants of p65 and STAT3 abrogated AGE-induced expression of NF-κB and STAT3 target genes. Inhibition of AGE formation in db/db mice by pyridoxamine treatment attenuated proteinuria and podocyte injury, restored SIRT1 expression, and reduced p65 and STAT3 acetylation. Diabetic db/db mice with conditional deletion of SIRT1 in podocytes developed more proteinuria, kidney injury, and acetylation of p65 and STAT3 compared with db/db mice without SIRT1 deletion. Treatment of db/db mice with a bromodomain and extraterminal (BET)-specific bromodomain inhibitor (MS417) which blocks acetylation-mediated association of p65 and STAT3 with BET proteins, attenuated proteinuria, and kidney injury. Our findings strongly support a critical role for p65 and STAT3 acetylation in DN. Targeting protein acetylation could be a potential new therapy for DN.

Klotho attenuates high glucose-induced fibronectin and cell hypertrophy via the ERK1/2-p38 kinase signaling pathway in renal interstitial fibroblasts

Although exogenous klotho attenuates renal fibrosis, it is not known if exogenous klotho attenuates diabetic nephropathy (DN). Thus, we studied the anti-fibrotic mechanisms of klotho in terms of transforming growth factor-β (TGF-β) and signaling pathways in high glucose (HG, 30 mM)-cultured renal interstitial fibroblast (NRK-49F) cells. We found that HG increased klotho mRNA and protein expression. HG also activated TGF-β Smad2/3 signaling and activated extracellular signal-regulated kinase (ERK1/2) and p38 kinase signaling. Exogenous klotho (400 pM) attenuated HG-induced TGF-β bioactivity, type II TGF-β receptor (TGF-βRII) protein expression and TGF-β Smad2/3 signaling. Klotho also attenuated HG-activated ERK1/2 and p38 kinase. Additionally, klotho and inhibitors of ERK1/2 or p38 kinase attenuated HG-induced fibronectin and cell hypertrophy. Finally, renal tubular expression of klotho decreased in the streptozotin-diabetic rats at 8 weeks. Thus, exogenous klotho attenuates HG-induced profibrotic genes, TGF-β signaling and cell hypertrophy in NRK-49F cells. Moreover, klotho attenuates HG-induced fibronectin expression and cell hypertrophy via the ERK1/2 and p38 kinase-dependent pathways.

High glucose induces sumoylation of Smad4 via SUMO2/3 in mesangial cells

Recent studies have shown that sumoylation is a posttranslational modification involved in regulation of the transforming growth factor-β (TGF-β) signaling pathway, which plays a critical role in renal fibrosis in diabetic nephropathy (DN). However, the role of sumoylation in the regulation of TGF-β signaling in DN is still unclear. In the present study, we investigated the expression of SUMO (SUMO1 and SUMO2/3) and Smad4 and the interaction between SUMO and Smad4 in cultured rat mesangial cells induced by high glucose. We found that SUMO1 and SUMO2/3 expression was significantly increased in the high glucose groups compared to the normal group (P < 0.05). Smad4 and fibronectin (FN) levels were also increased in the high glucose groups in a dose-dependent manner. Coimmunoprecipitation and confocal laser scanning revealed that Smad4 interacted and colocalized with SUMO2/3, but not with SUMO1 in mesangial cells. Sumoylation (SUMO2/3) of Smad4 under high glucose condition was strongly enhanced compared to normal control (P < 0.05). These results suggest that high glucose may activate TGF-β/Smad signaling through sumoylation of Samd4 by SUMO2/3 in mesangial cells.

New insights into molecular mechanisms of diabetic kidney disease

Diabetic kidney disease remains a major microvascular complication of diabetes and the most common cause of chronic kidney failure requiring dialysis in the United States. Medical advances over the past century have substantially improved the management of diabetes mellitus and thereby have increased patient survival. However, current standards of care reduce but do not eliminate the risk of diabetic kidney disease, and further studies are warranted to define new strategies for reducing the risk of diabetic kidney disease. In this review, we highlight some of the novel and established molecular mechanisms that contribute to the development of the disease and its outcomes. In particular, we discuss recent advances in our understanding of the molecular mechanisms implicated in the pathogenesis and progression of diabetic kidney disease, with special emphasis on the mitochondrial oxidative stress and microRNA targets. Additionally, candidate genes associated with susceptibility to diabetic kidney disease and alterations in various cytokines, chemokines, and growth factors are addressed briefly.

Diabetes-related heart failure

As the link between heart failure (HF) and diabetes mellitus (DM) becomes unignorable, so the need is further increasing for pathological comprehension: What is "diabetic cardiomyopathy (DMC)?" In response to current concern, the most updated guidelines stated by the ACCF/AHA and by the ESC/EASD take one step further, including the definition of DMC, although it is a matter yet to be completed. For more than 40 years, coronary artery disease and hypertension have been considered as the main causes of diabetes-related cardiac dysfunction. HF was originally considered as a result of reduced left ventricular ejection fraction (HF-REF); however, it has been recognized that HF symptoms are often observed in patients with preserved EF (HF-PEF). DMC includes HF with both reduced and preserved entities independent of coronary stenosis and hypertension. Cardiologists are thus facing a sort of chaos without clear guidelines for the "deadly intersection" of DM and HF. Today, the increasing interest and concern have caused DMC to be revisited and the first step in controlling the chaos around DMC is to organize and analyze all of the available evidence from preclinical and clinical studies. This review aims to illustrate the current concepts of DMC by shedding light on the new molecular mechanisms.  (Circ J 2014; 78: 576-583).

Aldose reductase regulates miR-200a-3p/141-3p to coordinate Keap1-Nrf2, Tgfβ1/2, and Zeb1/2 signaling in renal mesangial cells and the renal cortex of diabetic mice

Aberrant regulation in oxidative stress, fibrogenesis, and the epithelial-mesenchymal transition (EMT) in renal cells under hyperglycemic conditions contributes significantly to the onset and progression of diabetic nephropathy. The mechanisms underlying these hyperglycemia-induced dysregulations, however, have not been clearly elucidated. Herein, we report that aldose reductase is capable of regulating the expression of miR-200a-3p/141-3p negatively in renal mesangial cells. MiR-200a-3p/141-3p, in turn, act to target Keap1, Tgfβ2, fibronectin, and Zeb2 directly and regulate Tgfβ1 and Nrf2 indirectly under high-glucose conditions, resulting in profound dysregulations in Keap1-Nrf2, Tgfβ1/2, and Zeb1/2 signaling. In vivo in streptozotocin-induced diabetic mice, we found that aldose reductase deficiency caused significant elevations in miR-200a-3p/141-3p in the renal cortex, which were accompanied by a significant downregulation of Keap1, Tgfβ1/2, and fibronectin but significant upregulation of Nrf2. Moreover, in vivo administration of inhibitors of miR-200a-3p in diabetic animals significantly exacerbated cortical and glomerular fibrogenesis and increased urinary albumin excretion, tightly linking dysregulated miR-200a-3p with the development of diabetic nephropathy. Collectively, our results reveal a novel mechanism whereby hyperglycemia induces aldose reductase to regulate renal expression of miR-200a-3p/141-3p to coordinately control hyperglycemia-induced renal oxidative stress, fibrogenesis, and the EMT. Our novel findings also suggest that inhibition of aldose reductase and in vivo renal cortical restoration of miR-200a-3p/141-3p or their combination are very promising avenues for the development of therapeutic strategies or drugs against diabetic nephropathy.

Receptor for Advanced Glycation Endproducts (RAGE), Its Ligands, and Soluble RAGE: Potential Biomarkers for Diagnosis and Therapeutic Targets for Human Renal Diseases

Receptor for advanced glycation endproducts (RAGE) is a multi-ligand receptor that is able to bind several different ligands, including advanced glycation endproducts, high-mobility group protein (B)1 (HMGB1), S-100 calcium-binding protein, amyloid-β-protein, Mac-1, and phosphatidylserine. Its interaction is engaged in critical cellular processes, such as inflammation, proliferation, apoptosis, autophagy, and migration, and dysregulation of RAGE and its ligands leads to the development of numerous human diseases. In this review, we summarize the signaling pathways regulated by RAGE and its ligands identified up to date and demonstrate the effects of hyper-activation of RAGE signals on human diseases, focused mainly on renal disorders. Finally, we propose that RAGE and its ligands are the potential targets for the diagnosis, monitoring, and treatment of numerous renal diseases.

Inhibition of KCa3.1 suppresses TGF-β1 induced MCP-1 expression in human proximal tubular cells through Smad3, p38 and ERK1/2 signaling pathways

It is well known that TGF-β1 plays a central role in renal fibrosis due in large part to stimulation of inflammatory responses. KCa3.1, a potassium channel protein, has been suggested as a potential therapeutic target for diseases such as sickle cell anemia, autoimmunity, atherosclerosis and more recently, kidney fibrosis. Blockade of KCa3.1 has been shown to ameliorate renal fibrosis in diabetic mice in association with reduced TGF-β1 signaling. However, the centrality of KCa3.1 activation to TGF-β1 induced inflammation remains unknown. In this study, human proximal tubular cells (HK2 cells) were incubated with TGF-β1 (2 ng/ml) for 48 h in the presence or absence of KCa3.1 siRNA or the KCa3.1 inhibitor TRAM34. HK2 cells overexpressing KCa3.1 were studied in parallel. The mRNA and protein expression of monocyte chemoattractant protein-1 (MCP-1) were measured by qRT-PCR and ELISA. Downstream TGF-β1 signaling molecules Smad3, p38 and ERK1/2 were measured by Western blot analysis. Using whole-cell patch clamp techniques we found that TGFβ-1 induced a large KCa3.1 K-current that was inhibited by TRAM34. TGF-β1 also increased MCP-1 mRNA and protein expression in HK2 cells compared to control, an effect that was reversed by in the presence of KCa3.1 siRNA. Similarly, TRAM34 significantly reduced the TGF-β1-mediated increase in MCP-1 at both the mRNA and protein levels. Inhibition of KCa3.1 with KCa3.1 siRNA or TRAM34 also reduced TGF-β1-induced phosphorylation of Smad3, p38 and ERK1/2 MAPK pathways. Conversely overexpression of KCa3.1 induced TGF-β1 signaling cascades and expression of MCP-1. The present study is consistent with a key role for KCa3.1 renal proximal tubular cells in mediating the TGF-β1 induction of MCP-1 expression in HK2 cells via Smad3, p38 and ERK1/2 MAPK signaling pathways.

Attenuation of diabetic nephropathy by Chaihuang-Yishen granule through anti-inflammatory mechanism in streptozotocin-induced rat model of diabetics

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medical herbs have been used in China for a long time to treat different diseases. Based on traditional Chinese medicine (TCM) principle, Chaihuang-Yishen granule (CHYS) was developed and has been employed clinically to treat chronic kidney disease including diabetic nephropathy (DN). The present study was designed to investigate its mechanism of action in treatment of DN.

MATERIALS AND METHODS

Diabetic rats were established by having a right uninephrectomy plus a single intraperitoneal injection of STZ. Rats were divided into four groups of sham, diabetes, diabetes with CHYS and diabetes with fosinopril. CHYS and fosinopril were given to rats by gavage for 20 weeks. Samples from blood, urine and kidney were collected for biochemical, histological, immunohistochemical and molecular analyses.

RESULTS

Rats treated with CHYS showed reduced 24h urinary protein excretion, decreased serum TC and TG levels, but CHYS treatment did not affect blood glucose level. Glomerular mesangial expansion and tubulointerstitial fibrosis in diabetic rats were significantly alleviated by CHYS treatment. Moreover, CHYS administration markedly reduced mRNA levels of NF-κB p65 and TGF-β1, as well as decreased protein levels of NF-κB p65, MCP-1, TNF-α and TGF-β1 in the kidney of diabetic rats.

CONCLUSIONS

CHYS ameliorates renal injury in diabetic rats through reduction of inflammatory cytokines and their intracellular signaling.

Knockdown of thioredoxin-interacting protein ameliorates high glucose-induced epithelial to mesenchymal transition in renal tubular epithelial cells

Epithelial to mesenchymal transition (EMT) of tubular cells contributes to the renal accumulation of matrix protein that is associated with diabetic nephropathy. Both high glucose and transforming growth factor-β (TGF-β) are able to induce EMT in cell culture. In this study, we examined the role of the thioredoxin-interacting protein (TXNIP) on EMT induced by high glucose or TGF-β1 in HK-2 cells. EMT was assessed by the expression of α-smooth muscle actin (α-SMA) and E-cadherin and the induction of a myofibroblastic phenotype. High glucose (30mM) was shown to induce EMT at 72h. This was blocked by knockdown of TXNIP or antioxidant NAC. Meanwhile, we also found that knockdown of TXNIP or antioxidant NAC inhibited high glucose-induced generation of reactive oxygen species (ROS), phosphorylation of p38 MAPK and ERK1/2 and expression of TGF-β1. HK-2 cells that were exposed to TGF-β1 (4ng/ml) also underwent EMT. The expression of TXNIP gene and protein was increased in HK-2 cells treated with TGF-β1. Transfection with TXNIP shRNA was able to attenuate TGF-β1 induced-EMT. These results suggested that knockdown of TXNIP antagonized high glucose-induced EMT by inhibiting ROS production, activation of p38 MAPK and ERK1/2, and expression of TGF-β1, highlighting TXNIP as a potential therapy target for diabetic nephropathy.

Effect of catalpol on diabetic nephropathy in rats

PURPOSE

To investigate the effect of catalpol on diabetic nephropathy in rats.

METHODS

Male Sprague-Dawley rats were randomly divided into two groups and fed with normal pallet diet (NPD) or high-fat diet (HFD) for 4 weeks respectively. Then the HFD-fed rats were injected with 35 mg/kg streptozotocin (STZ) for establishing diabetic model. The diabetic rats were randomly divided into five groups: model group, model plus catalpol 30, 60, 120 mg/kg groups and model plus metformin 200 mg/kg group. The NPD-fed rats were randomly divided into two groups: normal control group and normal plus catalpol 60 mg/kg control group. After administration for 10 weeks, random blood glucose (RBG), glycated serum protein (GSP), 24h urinary protein excretion (UPE), serum creatinine (Scr), blood urea nitrogen (BUN), and kidney weight index (KWI) were determined. The kidney pathological changes were evaluated by periodic acid-Schiff (PAS) staining. The concentrations of angiotensin II (Ang II), transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), fibronectin (FN), collagen type IV (Col IV) in renal cortex were determined. Real time RT-PCR was used to detect the mRNA expressions of TGF-β1 and CTGF.

RESULTS

Catalpol could significantly reduce the KWI, improve the kidney function and pathological change, decrease the tissue level of Ang II, TGF-β1, CTGF, FN, Col IV. Catalpol could also down regulate the mRNA expressions of TGF-β1 and CTGF in renal cortex.

CONCLUSION

Catalpol may have beneficial effects against diabetic nephropathy. The mechanisms may be related to reducing the extracellular matrix accumulation by restraining the expression of TGF-β1, CTGF and Ang II.

Glycemic memories and the epigenetic component of diabetic nephropathy

A strong case for the deregulation of epigenetic chromatin modifications in the development and progression of various chronic complications of diabetes has emerged from recent experimental observations. Clinical trials of type 1 and type 2 diabetes patients highlight the importance of early and intensive treatment and the prolonged damage of hyperglycemia on organs such as the kidney. The functional relationship between the regulation of chromatin architecture and persistent gene expression changes conferred by prior hyperglycemia represents an important avenue of investigation for explaining diabetic nephropathy. While several studies implicate epigenetic changes at the chromatin template in the deregulated gene expression associated with diabetic nephropathy, the molecular determinants of metabolic memory in renal cells remain poorly understood. There is now strong evidence from experimental animals and cell culture of persistent glucose-driven changes in vascular endothelial gene expression that may also have relevance for the microvasculature of the kidney. Exploration of epigenetic mechanisms underlying the hyperglycemic cue mediating persistent transcriptional changes in renal cells holds novel therapeutic potential for diabetic nephropathy.

MiRNA-200b represses transforming growth factor-β1-induced EMT and fibronectin expression in kidney proximal tubular cells

MicroRNAs (miRNAs) comprise of a novel class of endogenous small noncoding RNAs that frequently downregulate the expression of target genes. Recent reports suggest that miRNA-200b prevents epithelial-to-mesenchymal transition (EMT) in cancer cells by targeting the E-box binding transcription factors Zinc finger E-box-binding homeobox 1 (ZEB1) and Zinc finger E-box-binding homeobox 2 (ZEB2). About 35% of active fibroblasts are derived from EMT which is central to the development of progressive renal fibrosis. Hence, this study was designed to assess the effect of miRNA-200b on transforming growth factor-β (TGF-β1)-induced fibrotic responses in renal tubular cells. Morphologically, human kidney-2 cells transfected with miRNA-200b retained their epithelial cell characteristics when exposed to TGF-β1. miRNA-200b significantly increased E-cadherin (P < 0.001) and reduced fibronectin mRNA and protein expression (both P < 0.01) independent of phospho-Smad2/3 and phospho-p38 and p42/44 signaling. Increased E-cadherin expression was associated with decreased expression of ZEB1 and ZEB2 and repression of fibronectin was mediated through direct targeting of the fibronectin mRNA, demonstrated using pMIR luciferase reporter assay and site-directed mutagenesis. These results suggest that miRNA-200b suppresses TGF-β1-induced EMT via inhibition of ZEB1 and ZEB2 and the extracellular matrix protein fibronectin by directing targeting of its 3'UTR mRNA, independent of pathways directly involved in TGF-β1 signaling.

Urinary sediment miRNA levels in adult nephrotic syndrome

BACKGROUND

MicroRNAs are a group of non-coding RNA molecules that play important roles in the pathogenesis of various kidney diseases. We investigate the urinary sediment miRNA levels of adult patients with nephrotic syndrome.

METHODS

We study 20 patients with diabetic glomerulosclerosis (DGS), 21 with minimal change nephropathy (MCN) or focal glomerulosclerosis (FGS), 23 with membranous nephropathy (MGN), and 10 healthy controls. Urinary sediment miRNA levels are quantified.

RESULTS

Urinary sediment miR-29a, miR-192, and miR-200c levels were significantly different between diagnosis groups. Post hoc analysis showed that urinary miR-638 level was significantly lower in all causes of nephrotic syndrome than healthy controls, while the DGS group had lower urinary miR-192 level than other diagnosis groups. In contrast, the MCN/FGS group had higher urinary miR-200c level than other diagnosis groups. For each specific pathology group, urinary level of several miRNA targets significantly correlated with kidney function and histological scarring.

CONCLUSIONS

Urinary miR-29a, miR-192 and miR-200c levels have characteristic alterations among patients with different causes of nephrotic syndrome. Our results suggest that urinary miRNA levels have the potential of being developed as the diagnosis tool and marker of disease severity in adult nephrotic syndrome.

Myofibroblast-mediated mechanisms of pathological remodelling of the heart

The syncytium of cardiomyocytes in the heart is tethered within a matrix composed principally of type I fibrillar collagen. The matrix has diverse mechanical functions that ensure the optimal contractile efficiency of this muscular pump. In the diseased heart, cardiomyocytes are lost to necrotic cell death, and phenotypically transformed fibroblast-like cells-termed 'myofibroblasts'-are activated to initiate a 'reparative' fibrosis. The structural integrity of the myocardium is preserved by this scar tissue, although at the expense of its remodelled architecture, which has increased tissue stiffness and propensity to arrhythmias. A persisting population of activated myofibroblasts turns this fibrous tissue into a living 'secretome' that generates angiotensin II and its type 1 receptor, and fibrogenic growth factors (such as transforming growth factor-β), all of which collectively act as a signal-transducer-effector signalling pathway to type I collagen synthesis and, therefore, fibrosis. Persistent myofibroblasts, and the resultant fibrous tissue they produce, cause progressive adverse myocardial remodelling, a pathological hallmark of the failing heart irrespective of its etiologic origin. Herein, we review relevant cellular, subcellular, and molecular mechanisms integral to cardiac fibrosis and consequent remodelling of atria and ventricles with a heterogeneity in cardiomyocyte size. Signalling pathways that antagonize collagen fibrillogenesis provide novel strategies for cardioprotection.

Anti-fibrosis therapy and diabetic nephropathy

Diabetes mellitus is rapidly becoming a global health issue that may overtake cancer during the next two decades as it covertly affects multiple organ systems that goes undiagnosed long after the onset. A number of complications are associated with poorly controlled hyperglycemia. Diabetic nephropathy is one of the most common complications of diabetes mellitus. Other than angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blocker (ARB) there is not much in the armamentarium with which to treat patients with overt diabetic nephropathy. Research points towards a multifactorial etiology and complex interplay of several pathogenic pathways that can contribute to the declining kidney function in diabetes. Patients with diabetic nephropathy (and with any chronic kidney disease) eventually develop kidney fibrosis. Despite the financial and labor investment spent on determining the basic mechanism of fibrosis, not much progress has been made in terms of therapeutic targets available to us today. This may be in part due to paucity in the experimental animal models available. However, there now seems to be a concerted effort from several pharmaceutical companies to develop a drug that would halt/delay the process of fibrosis, if not reverse it. This review discusses the current state of research in the field while staying within the context of diabetic nephropathy.