The Role of Non-Coding RNAs in Kidney Diseases.

Renal diseases include different pathologies, such as acute kidney injury (AKI), chronic kidney disease (CKD), end-stage renal disease (ESRD), diabetic nephropathy (DN), kidney cancer, polycystic kidney disease, etc [...].

miR-126-3p is essential for CXCL12-induced angiogenesis.

Atherosclerosis, in the ultimate stage of cardiovascular diseases, causes an obstruction of vessels leading to ischemia and finally to necrosis. To restore vascularization and tissue regeneration, stimulation of angiogenesis is necessary. Chemokines and microRNAs (miR) were studied as pro-angiogenic agents. We analysed the miR-126/CXCL12 axis and compared impacts of both miR-126-3p and miR-126-5p strands effects in CXCL12-induced angiogenesis. Indeed, the two strands of miR-126 were previously shown to be active but were never compared together in the same experimental conditions regarding their differential functions in angiogenesis. In this study, we analysed the 2D-angiogenesis and the migration assays in HUVEC in vitro and in rat's aortic rings ex vivo, both transfected with premiR-126-3p/-5p or antimiR-126-3p/-5p strands and stimulated with CXCL12. First, we showed that CXCL12 had pro-angiogenic effects in vitro and ex vivo associated with overexpression of miR-126-3p in HUVEC and rat's aortas. Second, we showed that 2D-angiogenesis and migration induced by CXCL12 was abolished in vitro and ex vivo after miR-126-3p inhibition. Finally, we observed that SPRED-1 (one of miR-126-3p targets) was inhibited after CXCL12 treatment in HUVEC leading to improvement of CXCL12 pro-angiogenic potential in vitro. Our results proved for the first time: 1-the role of CXCL12 in modulation of miR-126 expression; 2-the involvement of miR-126 in CXCL12 pro-angiogenic effects; 3-the involvement of SPRED-1 in angiogenesis induced by miR-126/CXCL12 axis.

Non-Coding RNAs in Kidney Diseases: The Long and Short of Them.

Recent progress in genomic research has highlighted the genome to be much more transcribed than expected. The formerly so-called junk DNA encodes a miscellaneous group of largely unknown RNA transcripts, which contain the long non-coding RNAs (lncRNAs) family. lncRNAs are instrumental in gene regulation. Moreover, understanding their biological roles in the physiopathology of many diseases, including renal, is a new challenge. lncRNAs regulate the effects of microRNAs (miRNA) on mRNA expression. Understanding the complex crosstalk between lncRNA-miRNA-mRNA is one of the main challenges of modern molecular biology. This review aims to summarize the role of lncRNA on kidney diseases, the molecular mechanisms involved, and their function as emerging prognostic biomarkers for both acute and chronic kidney diseases. Finally, we will also outline new therapeutic opportunities to diminish renal injury by targeting lncRNA with antisense oligonucleotides.

Syndecan-1 and Free Indoxyl Sulfate Levels Are Associated with miR-126 in Chronic Kidney Disease.

Chronic kidney disease (CKD) is a major cause of death worldwide and is associated with a high risk for cardiovascular and all-cause mortality. In CKD, endothelial dysfunction occurs and uremic toxins accumulate in the blood. miR-126 is a regulator of endothelial dysfunction and its blood level is decreased in CKD patients. In order to obtain a better understanding of the physiopathology of the disease, we correlated the levels of miR-126 with several markers of endothelial dysfunction, as well as the representative uremic toxins, in a large cohort of CKD patients at all stages of the disease. Using a univariate analysis, we found a correlation between eGFR and most markers of endothelial dysfunction markers evaluated in this study. An association of miR-126 with all the evaluated uremic toxins was also found, while uremic toxins were not associated with the internal control, specifically cel-miR-39. The correlation between the expression of endothelial dysfunction biomarker Syndecan-1, free indoxyl sulfate, and total p-cresyl glucuronide on one side, and miR-126 on the other side was confirmed using multivariate analysis. As CKD is associated with reduced endothelial glycocalyx (eGC), our results justify further evaluation of the role of correlated parameters in the pathophysiology of CKD.

The expanding roles of microRNAs in kidney pathophysiology.

MicroRNAs (miRNAs) are short single-stranded RNAs that control gene expression through base pairing with regions within the 3'-untranslated region of target mRNAs. These small non-coding RNAs are now increasingly known to be involved in kidney physiopathology. In this review we will describe how miRNAs were in recent years implicated in cellular and animal models of kidney disease but also in chronic kidney disease, haemodialysed and grafted patients, acute kidney injury patients and so on. At the moment miRNAs are considered as potential biomarkers in nephrology, but larger cohorts as well as the standardization of methods of measurement will be needed to confirm their usefulness. It will further be of the utmost importance to select specific tissues and biofluids to make miRNAs appropriate in day-to-day clinical practice. In addition, up- or down-regulating miRNAs that were described as deregulated in kidney diseases may represent innovative therapeutic methods to cure these disorders. We will enumerate in this review the most recent methods that can be used to deliver miRNAs in a specific and suitable way in kidney and other organs damaged by kidney failure, such as the cardiovascular system.

The Involvement of miRNA in Carotid-Related Stroke.

Cardiovascular disease is the leading cause of morbidity and mortality in developed countries. Stroke is associated with a marked disability burden and has a major economic impact; this is especially true for carotid artery stroke. Major advances in primary and secondary prevention during the last few decades have helped to tackle this public health problem. However, better knowledge of the physiopathology of stroke and its underlying genetic mechanisms is needed to improve diagnosis and therapy. miRNAs are an important, recently identified class of post-transcriptional regulators of gene expression and are known to be involved in cerebrovascular disease. These endogenous, small, noncoding RNAs may have applications as noninvasive biomarkers and therapeutic tools in practice. Here, we review the involvement of several miRNAs in cell-based and whole-animal models of stroke, with a focus on human miRNA profiling studies of carotid artery stroke. Lastly, we describe the miRNAs' potential role as a biomarker of stroke.

TRIMming down to TRIM37: Relevance to Inflammation, Cardiovascular Disorders, and Cancer in MULIBREY Nanism.

TRIpartite motif (TRIM) proteins are part of the largest subfamilies of E3 ligases that mediate the transfer of ubiquitin to substrate target proteins. In this review, we focus on TRIM37 in the normal cell and in pathological conditions, with an emphasis on the MULIBREY (MUscle-LIver-BRain-EYe) genetic disorder caused by TRIM37 mutations. TRIM37 is characterized by the presence of a RING domain, B-box motifs, and a coiled-coil region, and its C-terminal part includes the MATH domain specific to TRIM37. MULIBREY nanism is a rare autosomal recessive caused by TRIM37 mutations and characterized by severe pre- and postnatal growth failure. Constrictive pericarditis is the most serious anomaly of the disease and is present in about 20% of patients. The patients have a deregulation of glucose and lipid metabolism, including type 2 diabetes, fatty liver, and hypertension. Puzzlingly, MULIBREY patients, deficient for TRIM37, are plagued with numerous tumors. Among non-MULIBREY patients affected by cancer, a wide variety of cancers are associated with an overexpression of TRIM37. This suggests that normal cells need an optimal equilibrium in TRIM37 expression. Finding a way to keep that balance could lead to potential innovative drugs for MULIBREY nanism, including heart condition and carcinogenesis treatment.

microRNAs in the pathophysiology of CKD-MBD: Biomarkers and innovative drugs.

microRNAs comprise a novel class of endogenous small non-coding RNAs that have been shown to be implicated in both vascular damage and bone pathophysiology. Chronic kidney disease-mineral bone disorder (CKD-MBD) is characterized by vessel and bone damage secondary to progressive loss of kidney function. In this review, we will describe how several microRNAs have been implicated, in recent years, in cellular and animal models of CKD-MBD, and have been very recently shown to be deregulated in patients with CKD. Particular emphasis has been placed on the endothelial-specific miR-126, a potential biomarker of endothelial dysfunction, and miR-155 and miR-223, which play a role in both vascular smooth muscle cells and osteoclasts, with an impact on the vascular calcification and osteoporosis process. Finally, as these microRNAs may constitute useful targets to prevent or treat complications of CKD-MBD, we will discuss their potential as innovative drugs, describe how they could be delivered in a timely and specific way to vessels and bone by using the most recent techniques such as nanotechnology, viral vectors or CRISPR gene targeting.

miR-92a: A Novel Potential Biomarker of Rapid Aortic Valve Calcification.

BACKGROUND AND AIM OF THE STUDY: The study aim was to compare the tissular expression of microRNAs (miRs) in bicuspid and tricuspid valves, and to evaluate their use as potential novel biomarkers of aortic valve calcification in bicuspid valves. METHODS: A prospective single-center observational study was conducted on stenotic bicuspid and tricuspid human aortic valves. According to their potential role in valve vascular and valvular calcification, a decision was taken to include miR- 92a, miR-141, and miR-223 in this analysis. A real-time quantitative polymerase chain reaction was used to measure the expression of each miR, using U6 and Cel-miR-39 as endogenous and exogenous gene controls, respectively. RESULTS: Among a total of 47 human calcified aortic valves collected, 30 (63.8%) were tricuspid valves. The mean preoperative transvalvular gradient was 50.8 mmHg (range: 37-89 mmHg), with no significant difference between bicuspid and tricuspid valves (50 mmHg versus 51.2 mmHg; p = 0.729). The mean aortic valve area was 0.79 cm2 (range: 0.33-1.3 cm2), again with no significant difference between the two groups (p = 0.34). The level of miR-92a expression was twofold higher in bicuspid valves compared to tricuspid valves (0.38 versus 0.17; p = 0.016), but no significant difference in miR-141 and miR-223 expression was observed between the two groups (p = 0.68 and p = 0.35, respectively). A positive correlation was observed between miR-92a expression and mean preoperative transvalvular gradient (r = 0.3257, p = 0.04). CONCLUSIONS: miR-92a is overexpressed in calcified bicuspid aortic valves, and may serve as a potential biomarker of rapid aortic valve calcification. Further studies based on these results may be designed to correlate the relative expression of miR-92a in the serum with its tissular expression in AS.

High inorganic phosphate concentration inhibits osteoclastogenesis by modulating miR-223.

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication of CKD, and uremic toxins have been shown to be instrumental in this process. We have previously shown that miR-223 is increased in smooth muscle cells subjected to the uremic toxin inorganic phosphate (Pi). In the present study we investigated the influence of this miRNA in osteoclastogenesis in order to elucidate its role in the course of CKD-MBD. RT-qPCR demonstrated that high Pi concentration decreased miR-223 expression in differentiated RAW 264.7 cells. Up- and down-regulation of miR-223 was performed using specific pre-miR and anti-miR-223. Differentiation of monocyte/macrophage precursors was assessed by using RAW 264.7 cells and peripheral blood mononuclear cells (PBMC). TRAP activity and bone resorption were used to measure osteoclast activity. Pi induced a marked decrease in osteoclastogenesis in RAW cells and miR-223 levels were concomitantly decreased. Anti-miR-223 treatment inhibited osteoclastogenesis in the same way as Pi. In contrast, overexpression of miR-223 triggered differentiation, as reflected by TRAP activity. We showed that miR-223 affected the expression of its target genes NFIA and RhoB, but also osteoclast marker genes and the Akt signalling pathway, which induces osteoclastogenesis. These results were confirmed by measuring bone resorption activity of human PBMC differentiated into osteoclasts. We thus demonstrate a role of miR-223 in osteoclast differentiation, with rational grounds to use deregulation of this miRNA to selectively increase osteoclast-like activity in calcified vessels of CKD-MBD. This approach could alleviate vascular calcification without altering bone structure.

miR-223: An inflammatory oncomiR enters the cardiovascular field.

MicroRNAs (miRNAs) are small, noncoding RNAs of 18-22 nucleotides in length that regulate post-transcriptional expression by base-pairing with target mRNAs. It is now clearly established that miRNAs are involved in most of the cell's physiopathological processes (including carcinogenesis and metabolic disorders). This review focuses on miR-223, which was first described as a modulator of hematopoietic lineage differentiation. We outline the role of miR-223 deregulation in several types of cancers and highlight its inclusion in a newly identified and fast-growing family of miRNAs called oncomiRs. We then look at miR-223's emerging role in inflammatory and metabolic disorders, with a particular focus on muscle diseases, type II diabetes, atherosclerosis and vascular calcification. miR-223 is one of the growing number of RNA biomarkers of various human metabolic diseases and is thus of special interest to both researchers and clinicians in the cardiovascular field.

Possible involvement of microRNAs in vascular damage in experimental chronic kidney disease.

Chronic kidney disease (CKD) is associated with vascular calcifications and atherosclerosis. There is a need for novel predictors to allow earlier diagnosis of these disorders, predict disease progression, and improve assessment of treatment response. We focused on microRNAs since they are implicated in a variety of cellular functions in cardiovascular pathology. We examined changes of microRNA expression in aortas of CKD and non-CKD wild type mice and apolipoprotein E knock-out mice, respectively. Both vascular smooth muscle-specific miR-143 and miR-145 expressions were decreased in states of atherosclerosis and/or CKD or both, and the expression level of protein target Myocardin was increased. The inflammatory miR-223 was increased in more advanced stages of CKD, and specific protein targets NFI-A and GLUT-4 were dramatically decreased. Expression of miR-126 was markedly increased and expression of protein targets VCAM-1 and SDF-1 was altered during the course of CKD. The drug sevelamer, commonly used in CKD, corrected partially these changes in microRNA expression, suggesting a direct link between the observed microRNA alterations and uremic vascular toxicity. Finally, miR-126, -143 and -223 expression levels were deregulated in murine serum during the course of experimental CKD. In conclusion, these miRNAs could have role(s) in CKD vascular remodeling and may therefore represent useful targets to prevent or treat complications of CKD.

MicroRNA deregulation in symptomatic carotid plaque.

OBJECTIVE: Embolization of carotid stenotic plaques is the direct cause of stroke in nearly 20% of cases. Genetic mechanisms and especially the roles played by microRNAs in the regulation of plaque destabilization and rupture are mostly unknown. The aim of this pilot study was to compare the expression of seven microRNAs allegedly involved in plaque growth and instability (miR-100, 125a, 127, 133a, 145, 155, and 221), between symptomatic and asymptomatic human carotid plaques. METHODS: Thirty patients undergoing carotid endarterectomy in our department were prospectively included. Carotid plaques were subdivided into symptomatic (n = 15) and asymptomatic (n = 15) according to the presence or absence of stroke. After isolation of total RNA from atherosclerotic plaques, microRNAs were quantified by real-time polymerase chain reaction. RESULTS: The two groups of patients were comparable in terms of age, gender, risk factors for cerebral ischemia, medication, and stenosis severity. All seven microRNAs were quantified in extracted carotid plaques. miR-100, miR-125a, miR-127, miR-133a, miR-145, and miR-221 were significantly overexpressed in symptomatic vs asymptomatic plaques. miR-125a expression was significantly inversely correlated with the circulating level of low-density lipoprotein cholesterol in the symptomatic group. CONCLUSIONS: This pilot study evaluated the expression of seven selected miRNAs in human carotid plaques from a small group of patients and suggested a potential regulatory role for these miRNAs in evolution of the plaque towards growth, instability and rupture. Studies based on larger sample sizes are required to determine the potential use of miR-100, miR-125a, miR-127, miR-133a, miR-145, and miR-221 as biomarkers or therapeutic targets for stroke.

Versatility of non-native forms of human cytochrome c: pH and micellar concentration dependence.

In addition to its electron transfer activity, cytochrome c is now known to trigger apoptosis via peroxidase activity. This new function is related to a structural modification of the cytochrome upon association with anionic lipids, particularly cardiolipin present in the mitochondrial membrane. However, the exact nature of the non-native state induced by this interaction remains an active subject of debate. In this work, using human cytochromes c (native and two single-histidine mutants and the corresponding double mutant) and micelles as a hydrophobic medium, we succeeded, through UV-visible spectroscopy, circular dichroism spectroscopy and NMR spectroscopy, in fully characterizing the nature of the sixth ligand replacing the native methionine. Furthermore, careful pH titrations permitted the identification of the amino acids involved in the iron binding over a range of pH values. Replacement of the methionine by lysine was only observed at pH above 8.5, whereas histidine binding is dependent on both pH and micelle concentration. The pH variation range for histidine protonation is relatively narrow and is consistent with the mitochondrial intermembrane pH changes occurring during apoptosis. These results allow us to rule out lysine as the sixth ligand at pH values close to neutrality and reinforce the role of histidines (preferentially His33 vs. His26) as the main candidate to replace methionine in the non-native cytochrome c. Finally, on the basis of these results and molecular dynamics simulations, we propose a 3D model for non-native cytochrome c in a micellar environment.

Is there adaptation of the exocrine pancreas in wild animal? The case of the Roe deer.

BACKGROUND: Physiology of the exocrine pancreas has been well studied in domestic and in laboratory animals as well as in humans. However, it remains quite unknown in wildlife mammals. Roe deer and cattle (including calf) belong to different families but have a common ancestor. This work aimed to evaluate in the Roe deer, the adaptation to diet of the exocrine pancreatic functions and regulations related to animal evolution and domestication. RESULTS: Forty bovine were distributed into 2 groups of animals either fed exclusively with a milk formula (monogastric) or fed a dry feed which allowed for rumen function to develop, they were slaughtered at 150 days of age. The 35 Roe deer were wild animals living in the temperate broadleaf and mixed forests, shot during the hunting season and classified in two groups adult and young. Immediately after death, the pancreas was removed for tissue sample collection and then analyzed. When expressed in relation to body weight, pancreas, pancreatic protein weights and enzyme activities measured were higher in Roe deer than in calf. The 1st original feature is that in Roe deer, the very high content in pancreatic enzymes seems to be related to specific digestive products observed (proline-rich proteins largely secreted in saliva) which bind tannins, reducing their deleterious effects on protein digestion. The high chymotrypsin and elastase II quantities could allow recycling of proline-rich proteins. In contrast, domestication and rearing cattle resulted in simplified diet with well digestible components. The 2nd feature is that in wild animal, both receptor subtypes of the CCK/gastrin family peptides were present in the pancreas as in calf, although CCK-2 receptor subtype was previously identified in higher mammals. CONCLUSIONS: Bovine species could have lost some digestive capabilities (no ingestion of great amounts of tannin-rich plants, capabilities to secrete high amounts of proline-rich proteins) compared with Roe deer species. CCK and gastrin could play an important role in the regulation of pancreatic secretion in Roe deer as in calf. This work, to the best of our knowledge is the first study which compared the Roe deer adaptation to diet with a domesticated animal largely studied.

Uremic Toxins Affect Erythropoiesis during the Course of Chronic Kidney Disease: A Review.

Chronic kidney disease (CKD) is a global health problem characterized by progressive kidney failure due to uremic toxicity and the complications that arise from it. Anemia consecutive to CKD is one of its most common complications affecting nearly all patients with end-stage renal disease. Anemia is a potential cause of cardiovascular disease, faster deterioration of renal failure and mortality. Erythropoietin (produced by the kidney) and iron (provided from recycled senescent red cells) deficiencies are the main reasons that contribute to CKD-associated anemia. Indeed, accumulation of uremic toxins in blood impairs erythropoietin synthesis, compromising the growth and differentiation of red blood cells in the bone marrow, leading to a subsequent impairment of erythropoiesis. In this review, we mainly focus on the most representative uremic toxins and their effects on the molecular mechanisms underlying anemia of CKD that have been studied so far. Understanding molecular mechanisms leading to anemia due to uremic toxins could lead to the development of new treatments that will specifically target the pathophysiologic processes of anemia consecutive to CKD, such as the newly marketed erythropoiesis-stimulating agents.

Aortic valve calcification in the era of non-coding RNAs: The revolution to come in aortic stenosis management?

Aortic valve stenosis remains the most frequent structural heart disease, especially in the elderly. During the last decade, we noticed an important consideration and a huge number of publications related to the medical and surgical treatment of this disease. However, the molecular aspect of this degenerative issue has also been more widely studied recently. As evidenced in oncologic but also cardiac research fields, the emergence of microRNAs in the molecular screening and follow-up makes them potential biomarkers in the future, for the diagnosis, follow-up and treatment of aortic stenosis. Herein, we present a review on the implication of microRNAs in the aortic valve disease management. After listing and describing the main miRNAs of interest in the field, we provide an outline to develop miRNAs as innovative biomarkers and innovative therapeutic strategies, and describe a groundbreaking pre-clinical study using inhibitors of miR-34a in a pre-clinical model of aortic valve stenosis.

TRIM37 is highly expressed during mitosis in CHON-002 chondrocytes cell line and is regulated by miR-223.

Multiple molecular disorders can affect mechanisms regulating proliferation and differentiation of growth plate chondrocytes. Mutations in the TRIM37 gene cause the Mulibrey nanism, a heritable growth disorder. Since chondrocytes are instrumental in long bone growth that is deficient in nanism, we hypothesized that TRIM37 defect could contribute to dysregulation of the chondrocyte cell cycle. Western blotting, confocal microscopy and imaging flow cytometry determined TRIM37 expression in CHON-002 cell lineage. We showed that TRIM37 is expressed during mitosis of chondrocytes and directly impacted their proliferation. During the chondrocyte cell cycle, TRIM37 was present in both nucleus and cytoplasm. During M phase we observed an increase of the TRIM37-Tubulin co-localization in comparison with G1, S and G2 phases. TRIM37 knock down inhibited proliferation, together with cell cycle anomalies and increased autophagy, while overexpression accordingly enhanced cell proliferation. We demonstrated that microRNA-223 directly targets TRIM37, and suggest that miR-223 regulates TRIM37 gene expression during the cell cycle. In summary, our results give clues to explain why TRIM37 deficiency in chondrocytes impacts bone growth. Modulating TRIM37 using miR-223 could be an approach to increase chondrogenesis.

Inhibition of miR-223 Expression Using a Sponge Strategy Decreases Restenosis in Rat Injured Carotids.

OBJECTIVE: Restenosis is a frequent complication of angioplasty. It consists of a neointimal hyperplasia resulting from progression and migration of vascular smooth muscle cells (VSMC) into the vessel lumen. microRNA miR-223 has recently been shown to be involved in cardiovascular diseases including atherosclerosis, vascular calcification and arterial thrombosis. In this study, our aim was to assess the impact of miR-223 modulation on restenosis in a rat model of carotid artery after balloon injury. METHODS: The over and down-expression of miR-223 was induced by adenoviral vectors, containing either a pre-miR-223 sequence allowing artificial miR-223 expression or a sponge sequence, trapping the native microRNA, respectively. Restenosis was quantified on stained rat carotid sections. RESULTS: In vitro, three mRNA (Myocyte Enhancer Factor 2C (MEF2C), Ras homolog gene family, member B (RhoB) and Nuclear factor 1 A-type (NFIA)) reported as miR-223 direct targets and known to be implicated in VSMC differentiation and contractility were studied by RT-qPCR. Our findings showed that down-expression of miR-223 significantly reduced neointimal hyperplasia by 44% in carotids, and was associated with a 2-3-fold overexpression of MEF2C, RhoB and NFIA in a murine monocyte macrophage cell line, RAW 264.7 cells. CONCLUSION: Down-regulating miR-223 could be a potential therapeutic approach to prevent restenosis after angioplasty.