Impact of L-Arginine on diabetes-induced neuropathy and myopathy: Roles of PAI-1, Irisin, oxidative stress, NF-κβ, autophagy and microRNA-29a

BACKGROUND

T2DM is a chronic disorder with progressive neuromuscular alterations. L-arginine (ARG) is the most common semi-essential amino acid having several metabolic functions.

AIM

to investigate the impact of L-arginine in combating diabetic-induced neuromyopathy and its possible mechanisms.

MATERIALS & METHODS

24 rats were divided into CON, CON+ARG, DC, DC+ARG. Behavioral tests, Body weight (BW), fasting blood glucose (FBG), insulin, total antioxidant capacity (TAC), malondialdehyde (MDA), plasminogen activator inhibitor-1 (PAI-1), and irisin were done. Creatine kinase-MM (CK-MM), interleukin 4 (IL-4), interleukin 6 (IL-6), TAC, MDA, expression of microRNA-29a mRNA & light chain 3 protein were determined in muscle. Histological and NF-κβ immunohistochemical expression in muscle and nerve were assessed.

RESULTS

ARG supplementation to diabetic rats improved altered behavior, significantly increased BW, insulin, TAC, irisin and Il-4, decreased levels of glucose, microRNA-29a, NF-κβ and LC3 expression, PAI-1, CK-MM and restored the normal histological appearance.

CONCLUSIONS

ARG supplementation potently alleviated diabetic-induced neuromuscular alterations.

Extracellular vesicles derived from mesenchymal stem cells mediate extracellular matrix remodeling in osteoarthritis through the transport of microRNA-29a

BACKGROUND

Knee osteoarthritis (KOA) is a common orthopedic condition with an uncertain etiology, possibly involving genetics and biomechanics. Factors like changes in chondrocyte microenvironment, oxidative stress, inflammation, and immune responses affect KOA development. Early-stage treatment options primarily target symptom relief. Mesenchymal stem cells (MSCs) show promise for treatment, despite challenges. Recent research highlights microRNAs (miRNAs) within MSC-released extracellular vesicles that can potentially promote cartilage regeneration and hinder KOA progression. This suggests exosomes (Exos) as a promising avenue for future treatment. While these findings emphasize the need for effective KOA progression management, further safety and efficacy validation for Exos is essential.

AIM

To explore miR-29a's role in KOA, we'll create miR-29a-loaded vesicles, testing for early treatment in rat models.

METHODS

Extraction of bone marrow MSC-derived extracellular vesicles, preparation of engineered vesicles loaded with miR-29a using ultrasonication, and identification using quantitative reverse transcription polymerase chain reaction; after establishing a rat model of KOA, rats were randomly divided into three groups: Blank control group injected with saline, normal extracellular vesicle group injected with normal extracellular vesicle suspension, and engineered extracellular vesicle group injected with engineered extracellular vesicle suspension. The three groups were subjected to general behavioral observation analysis, imaging evaluation, gross histological observation evaluation, histological detection, and immunohistochemical detection to compare and evaluate the progress of various forms of arthritis.

RESULTS

General behavioral observation results showed that the extracellular vesicle group and engineered extracellular vesicle group had better performance in all four indicators of pain, gait, joint mobility, and swelling compared to the blank control group. Additionally, the engineered extracellular vesicle group had better pain relief at 4 wk and better knee joint mobility at 8 wk compared to the normal extracellular vesicle group. Imaging examination results showed that the blank control group had the fastest progression of arthritis, the normal extracellular vesicle group had a relatively slower progression, and the engineered extracellular vesicle group had the slowest progression. Gross histological observation results showed that the blank control group had the most obvious signs of arthritis, the normal extracellular vesicle group showed signs of arthritis, and the engineered extracellular vesicle group showed no significant signs of arthritis. Using the Pelletier gross score evaluation, the engineered extracellular vesicle group had the slowest progression of arthritis. Results from two types of staining showed that the articular cartilage of rats in the normal extracellular vesicle and engineered extracellular vesicle groups was significantly better than that of the blank control group, and the engineered extracellular vesicle group had the best cartilage cell and joint surface condition. Immunohistochemical detection of type II collagen and proteoglycan showed that the extracellular matrix of cartilage cells in the normal extracellular vesicle and engineered extracellular vesicle groups was better than that of the blank control group. Compared to the normal extracellular vesicle group, the engineered extracellular vesicle group had a better regulatory effect on the extracellular matrix of cartilage cells.

CONCLUSION

Engineered Exos loaded with miR-29a can exert anti-inflammatory effects and maintain extracellular matrix stability, thereby protecting articular cartilage, and slowing the progression of KOA.

MiR-29a inhibits MPP + - Induced cell death and inflammation in Parkinson's disease model in vitro by potential targeting of MAVS

Parkinson's disease (PD) primarily affects the motor system and is the second most common age-related neurodegenerative disorder after Alzheimer's disease. Mitochondrial complex I deficiency and functional abnormalities are implicated in the development of PD. MicroRNA-29a (miR-29a) has emerged as a critical miRNA in PD. This study aims to investigate the protective role of miR-29a in MPP+ in SH-SY5Y cell lines in vitro PD model by targeting mitochondrial antiviral signaling protein (MAVS). Administration of MPP + inhibited miR-29a expression in SH-SY5Y cell lines. Our findings prove that miR-29a mimic treatment decreased cell death, ROS production, MAVS, p-IRF3, p-NFκBp65, IL-6, cleaved caspase-3, cleaved-PARP, LC3BII, and death while increasing glutathione peroxidase 1 and manganese superoxide dismutase after MPP + treatment in SH-SY5Y cells. Furthermore, MAVS expression was significantly corrected with the above genes in our in vitro model of PD. Luciferase activity analysis also confirmed that miR-29a specific binding 3'UTR of MAVS repressed expression. In conclusion, this research provides novel insight into a neuroprotective pathway of miR-29a and could thus serve as a possible therapeutic target for improving the treatment of PD.

The Protective Effect of Notoginsenoside R1 on Isoflurane-Induced Neurological Impairment in the Rats via Regulating miR-29a Expression and Neuroinflammation

INTRODUCTION

Isoflurane inhalation leads to apoptotic neurodegeneration and further results in learning and cognitive dysfunction. Notoginsenoside R1 (NGR1), a major ingredient from Radix notoginseng, has been reported to exert neuroprotective effect during brain or neuron injury. This study aimed to investigate the effect of NGR1 on neurological impairment.

METHODS

Sixty-four male Sprague Dawley rat pups (15-20 g) of postnatal day 7 were recruited. Spatial learning and memory were assessed by the Morris water maze test, and the neurological severity score was determined. Real-time quantitative PCR was used to detect the expression levels of microRNA (miR)-29a. Enzyme-linked immunosorbent assay was applied to estimate the levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the hippocampal tissues.

RESULTS

NGR1 attenuated neurological impairment induced by isoflurane, shown by the decrease in neurological function score and escape latency and the increase in staying time in the original quadrant in rats. NGR1 reversed the downregulation of miR-29a expression induced by isoflurane treatment. After the treatment of NGR1, the elevated levels of IL-6, TNF-α, and IL-1β induced by isoflurane were all decreased significantly in the hippocampal tissues of rats. Additionally, the repressive action of NGR1 in neurological impairment and neuroinflammation was eliminated by downregulating miR-29a in rats.

CONCLUSION

NGR1 protects against isoflurane-induced neurological impairment. The protective effect of NGR1 might be achieved by promoting the expression of miR-29a and preventing inflammatory response.

MicroRNA-29a functions as a tumor suppressor through targeting STAT3 in laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is a common head and neck cancer with high mortality in developing countries. A comprehensive understanding of the molecular mechanisms of tumor progression in laryngeal cancer is needed for new treatment strategies. MicroRNA-29a has been emerged as a critical miRNA in various cancers, and shown to regulate multiple oncogenic processes. In this study, we investigated the tumor suppressive role of miRNA-29a in laryngeal squamous cell carcinoma. We performed cell-based functional analysis after overexpression of miR-29a in AMC-HN-8 and HEP2 cells in vitro. It turned out that ectopic expression of miR-29a significantly inhibited cell proliferation, invasion, and migration in two LSCC cell lines (AMC-HN-8 and Hep2) in vitro. Further downstream target analysis by western blotting and luciferease reporter assay showed that overexpression of miR-29a significantly downregulated expression of STAT3, and STAT3 is a putative direct target of miR-29a in LSCC. In addition, the tumor suppressive function of miR-29a can be abrogated by forced expression of STAT3. Taken together, our data suggest that miR-29a functions as a tumor suppressor through targeting STAT3 in laryngeal squamous cell carcinoma.

[Significance of microRNA 216a, 324-5p and 29a expression in peripheral blood in patients with acute pancreatitis and their correlation with liver injury]

Objective: To investigate the significance of microRNA (miR)-216a, miR-324-5p, miR-29a expression in peripheral blood in patients with acute pancreatitis (AP) and their correlation with liver injury. Methods: It was a case-control study design. To select 130 AP patients admitted from June 2017 to May 2019 in the First People's Hospital of Shangqiu, and the patients were divided into mild AP group (MAP group) and moderately severe AP group (SAP group) according to the disease severity, or 54 patients in the liver injury group (20 were MAP and 34 were SAP) and 76 in the non-liver injury group(all were MAP) according to liver injury. And another 40 healthy volunteers were selected as the healthy group. The expressions of miR-216a, miR-324-5p and miR-29a in peripheral blood of MAP group, SAP group, healthy group and liver injury group, non-liver injury group were compared, and the correlation between the miRNA levels and clinical indexes was analyzed. The predictive value of miRNA levels in peripheral blood for AP complicated with liver injury was analyzed by receiver operating characteristic (ROC) curve. Results: The levels of miR-216a and miR-29a in MAP group and SAP group were higher than those in healthy group, and the level of miR-324-5p was lower than that in healthy group (all P<0.01). The levels of miR-216a and miR-29a in SAP group were higher than those in MAP group, and the level of miR-324-5p was lower than that in healthy group (all P<0.01). Balthazar CT Score, acute physiology and chronic health evaluations (APACHE Ⅱ) score, C-reactive protein level, length of hospital stay were positively correlated with the levels of miR-216a and miR-29a in peripheral blood (all P<0.05), and negatively correlated with the levels of miR-324-5p (P<0.05). The levels of miR-216a and miR-29a in the peripheral blood in the liver injury group were higher than those in the non-liver injury group, and they were higher inSAP patients than those in MAP patients in the liver injury group (all P<0.05). The level of miR-324-5p in the peripheral blood in the liver injury group was lower than that in the non-liver injury group, and it was lower in SAP patients than that in MAP patientsin the liver injury group (all P<0.05). The area under ROC curve of miR-216a, miR-324-5p, and miR-29a in peripheral blood to predicate the AP complicated with liver damage was 0.694, 0.750 and 0.814, respectively. Conclusions: The levels of miR-216a and miR-29a increase in peripheral blood and the level of miR-324-5p decreases in patients with AP, and they are closely related to Balthazar CT score, APACHEⅡ score, C-reactive protein and length of hospital stay. The levels of miR-216a, miR-324-5p, miR-29a has certain predictive value for AP with liver injury, of which miR-29a has the highest predictive value.

MicroRNA-29a attenuates angiotensin-II induced-left ventricular remodeling by inhibiting collagen, TGF-β and SMAD2/3 expression

Background

Left ventricular (LV) remodeling is the most common target organ damage in hypertension. Previously, our study found that plasma microRNA-29a (miR-29a) level was associated with the LV remodeling in hypertensive patients. However, the causal relationship between miR-29a and LV remodeling remains unknown. Thus, the aim of this study was to investigate the regulation mechanism of miR-29a in LV remodeling.

Methods & Results

Overexpression and knockdown miR-29a mice were generated by tail-intravenous injection of miR-29a-mimic and inhibitor lentivirus for one week respectively. Then the mice were subjected to angiotensin-II (AngII) induced LV remodeling by subcutaneous AngII capsule osmotic pumping into AngII for four weeks. AngII-induced LV remodeling mice as the model group (n = 9). Age-matched male SPF C57/BL6J mice (6-8 weeks old) were treated with the pumping of saline as a vehicle (n = 6). In vivo, overexpression miR-29a ameliorated AngII-induced LV remodeling, while knockdown miR-29a deteriorated LV remodeling. Simultaneously, we observed that overexpression miR-29a mice inhibited but knockdown miR-29a mice increased cardiac cross-sectional area, indicating that miR-29a has an antagonistic effect on cardiac hypertrophy. Further studies found that overexpression miR-29a inhibited the content of the LV collagen including collagen I and III. Moreover, the expression of transforming growth factor-β (TGF-β) and phosphorylated SMAD2/3 decreased with the down-regulation of collagen I and III in overexpression miR-29a mice.

Conclusions

Our finding indicates that overexpression miR-29a attenuates LV remodeling by inhibiting collagen deposition, TGF-β, and phosphorylated SMAD2/3 expression. Thus, intervention miR-29a may be a therapeutic target for attenuating LV remodeling.

Secondary toxic effect of graphene oxide and graphene quantum dots alters the expression of miR-21 and miR-29a in human cell lines

For in vitro studies, non-toxic doses of nanomaterials are routinely selected by quantification of live cells after exposing to different concentrations of nanoparticles but considering only morphological changes or viability of cells is not sufficient to conclude that these nanomaterials are non-cytotoxic. Here we investigated if secondary toxicity is active in the cells exposed to non-toxic doses of graphene oxide (GO) and graphene quantum dots (GQDs). Non-cytotoxic dose of 15 μg mL^-1 of GO (100 nm) and GQDs (50 nm) was selected according to MTT and Hoechst 33342/PI double staining assays. In order to investigate the secondary toxicity, the expression of miR-21, miR-29a and three genes at both mRNA and protein level were evaluated in MCF-7, HUVEC, KMBC/71 cells 4 and 24 h post exposure. Mitochondrial membrane potential (MMP) was assessed by Rhodamine 123 staining. According to our results, there was no significant decrease in viability of cells after exposure to the non-cytotoxic dose of GO and GQDs, but we observed significant alterations in the expression level of miR-21, miR-29a, Bax, Bcl2 and PTEN genes after treatment in all three cells. In addition to molecular changes, we observed alteration in mitochondrial activity at cellular level. However, we also observed that GO influenced the basal level of genes and MMP more compare to GQDs. Considering that all these genes are involved in breast tumor development and metastasis, the observed changes in miRNA expression and protein synthesis may alter cell fate and susceptibility and cause deviation in the desired outcome of GO and GQDs application in medical research.

Inhibition of microRNA-29a alleviates hyperoxia-induced bronchopulmonary dysplasia in neonatal mice via upregulation of GAB1

Background

The main features of bronchopulmonary dysplasia (BPD) are alveolar simplification, pulmonary growth arrest, and abnormal lung function. Multiple studies have highlighted microRNA-29 (miR-29) as a potential biomarker for lung diseases and cancers. Upregulation of miR-29a has been known to downregulate GRB2-associated-binding protein 1 (GAB1), which is often highly expressed in the lung. The current study was designed to investigate the potential role of miR-29a in hyperoxia-induced BPD by targeting GAB1 in a neonatal mouse model.

Methods

The expression of miR-29a and GAB1 in lung tissues of neonatal mice with hyperoxia-induced BPD and mouse alveolar epithelial cells (MLE-12) was determined using RT-qPCR and western blot analysis. Subsequently, the relationship between miR-29a and GAB1 was verified using in silico analysis. In order to assess the effects of miR-29a or GAB1 on BPD, the pathological characteristics of alveoli, as well as proliferation and apoptosis of cells were measured through gain- and loss-of-function studies.

Results

Upregulation of miR-29a and downregulation of GAB1 were evident in both lung tissues and MLE-12 cells following BPD modeling. GAB1 was a direct target gene of miR-29a. Inhibition of miR-29a and overexpression of GAB1 were shown to alleviate lung injury, promote cell proliferation and inhibit apoptosis but reduce chord length in lung tissues of neonatal mice following hyperoxia-induced BPD modeling.

Conclusion

Altogether, down-regulation of miR-29a can potentially elevate GAB1 expression, reducing cell apoptosis and stimulating proliferation, ultimately retarding the development of BPD in mice. This study highlights the potential of a promising new target for preventing BPD.

Exosomal microRNA-29a mediates cardiac dysfunction and mitochondrial inactivity in obesity-related cardiomyopathy

PURPOSE

Present study aims to explore the pathophysiological role of microRNA (miR)-29a in the process of obesity-related cardiomyopathy in human subjects and mice.

METHODS

The expression level of circulating exosomal miR-29a was measured in 37 lean and 30 obese human subjects, and correlated with cardiac parameters. The effects of miR-29a on mitochondrial activity and cardiac function were investigated by treatment of miR-29a sponge in primary mouse cardiomyocytes and diet-induced obesity-related cardiomyopathy in mice.

RESULTS

The increased circulating miR-29a level was closely associated with impaired human cardiac function, including ejection fraction (r = -0.2663, p < 0.05) and NT-proBNP levels (r = 0.4270, p < 0.001). Exosomes from obese human plasma mediated cardiomyocyte mitochondrial inactivity, but pre-treatment with miR-29a sponge attenuated the exosomal miR-29a-induced reduction of ATP production (p < 0.001), basal oxygen consumption (p < 0.01) and mitochondrial complex I activity (p < 0.01). In vivo mouse study, high fat diet damaged cardiac function, normal structure, and mitochondrial activity, whereas miR-29a sponge improved the cardiac status.

CONCLUSIONS

Present study uncovered the correlation between circulating miR-29a and cardiac parameters in human subjects, and provided solid evidence of the therapeutic application of miR-29a sponge in combating obesity-mediated cardiac dysfunction.

MicroRNA-29a mitigation of endoplasmic reticulum and autophagy aberrance counteracts in obstructive jaundice-induced fibrosis in mice

Hepatic fibrosis was caused by a number of signaling pathways that damage liver integrity. We have previously shown that microRNA-29a (miR-29a) protects against liver fibrosis. Aberrant endoplasmic reticulum (ER) and autophagy function reportedly exaggerate hepatic disorders. The aim of this study was to characterize the biological influence of miR-29a on ER function in injured livers with bile duct ligation (BDL). We performed BDL on miR-29a transgenic mice (miR-29aTg) and wild-type mice to induce cholestatic liver injury. Rat T6 cells were transfected with miR-29a mimic and tunicamycin. Compared to the wild-type mice, the BDL deterioration of liver function in terms of total bilirubin, alanine transaminase, and aspartate transaminase activity in the miR-29aTg mice was significantly reduced. Affected livers in the miR-29aTg mice demonstrated a slight fibrotic matrix formation. miR-29a over-expression reduced the BDL disturbance of the expressions of inositol-requiring kinase 1alpha, double-stranded RNA-activated protein kinase-like endoplasmic reticulum kinase, spliced-X-box binding protein 1 (sXBP1), CCAAT/enhancer-binding protein homologous protein (CHOP), ULK, LC3BII, p62, and cleaved caspase-8, 9 and 3. In vitro, T6 cells exposed to tunicamycin by increasing abundances of CHOP, sXBP1, cleaved caspase-3, and LC3BII were diminished in the cell cultures transfected with the miR-29a mimic. On the other hand, we observed that miR-29a signaling protected liver tissues from BDL-mediated metabolic dysfunction and excessive fibrosis histopathology. This study provides new molecular insight into the miR-29a stabilization of ER integrity that slows the progression of cholestatic liver deterioration. Impact statement Long-term hepatic damage caused by hepatitis and cholestasis can accelerate fibrosis matrix over-production, which is a harmful process attributed to the dysregulation of a number of cellular and molecular events. The purpose of this study is to characterize the biological influence of miR-29a on endoplasmic reticulum (ER) function in bile duct ligation (BDL)-injured livers. To the best of our knowledge, this report is the first demonstration that miR-29a over-expression diminishes BDL provocation of ER stress (unfolded protein response, UPR) effector protein expression. This work also demonstrates that miR-29a decreased caspases protein expression in cholestatic livers, while an increase in miR-29a function reduced sXBP1 and CHOP expressions in T6 cells in mice. Analyses of this study highlight that controlling miR-29a signaling can serve as an innovative strategy in the future for microRNA regulation of ER homeostasis to combat cholestasis induction hepatic disorders.

Role of microRNA-29a in the development of diabetic retinopathy by targeting AGT gene in a rat model

OBJECTIVES

This study intends to explore the role of microRNA-29a (miRNA-29a) in the development of diabetic retinopathy by targeting AGT gene in a rat model.

METHODS

Fifty-six DR rat models were established and divided into 7 groups (with 8 rats in each group): the model group, the miRNA-29a group, the miRNA-29a knockdown group, the negative control (NC) group, the AGT group, the miRNA-29a+AGT group, and the miRNA-29a knockdown+AGT group respectively, while 8 normal rats were selected as the normal group. The qRT-PCR was used to detect the expression of miRNA-29a and AGT mRNA. The AGT protein expression was measured using Western blotting. The ADPase histochemical staining was applied to detect retinal neo-vascular morphology. The number of retinal vascular endothelial cells was counted by H&E staining.

RESULTS

MiRNA-29a and AGT mRNA expressions were negatively correlated. Compared with rats in the normal group, the miRNA-29a expression in DR rats of each group decreased, but the AGT mRNA and protein expression increased; the vascular distribution was in disorder, and the new retinal vessels, vascular density, and endothelial nuclei all increased. Compared with the model group, miRNA-29a increased, and the AGT mRNA and protein expression decreased in the miRNA-29a group; additionally, the vascular density, tortuosity, and endothelial cell nuclei significantly decreased. The opposite trend was found in the miRNA-29a knockdown group, the miRNA-29a knockdown+AGT group, and the AGT group, particularly in the miRNA-29a knockdown+AGT group.

CONCLUSION

Overexpression of miRNA-29a could down-regulate AGT expression, thereby preventing the development of DR in a rat model.

miR-29a Promotes Lipid Droplet and Triglyceride Formation in HCV Infection by Inducing Expression of SREBP-1c and CAV1

Aims: To examine the regulation of SREBP-1c and CAV1 by microRNA-29a (miR-29a) in cells infected with hepatitis C virus (HCV) in an attempt to control HCV-induced non-alcoholic fatty liver disease. Methods: In order to examine the manipulation of SREBP-1c and CAV1 by miR-29a, oleic acid (OA)-treated JFH-I-infected Huh-7 cells were used. OA was added 24 h post-transfection and gene expression was investigated by qRT-PCR at 48 h post treatment. The functional impact of the observed alteration in SREBP-1c and CAV1 expression was analyzed by examining lipid droplet (LD) and triglyceride (TG) content at 72 h post-OA treatment using light microscopy and spectrophotometry, respectively. Viral load was quantified by qRT-PCR at 72 h post-transfection. Results: OA treatment induced the expression of miR-29a and SREBP-1c, as compared to untreated cells. Forced miR-29a expression led to a significant up-regulation of SREBP-1c as well as CAV1 compared to mock untransfected cells. Ectopic expression of miR-29a resulted in a marked increase in LDs and their respective TGs, while miR-29a antagomirs decreased both the LD and TG content compared to mock untransfected cells. Moreover, forcing the expression of miR-29a in JFH-1 HCV-infected Huh-7 cells resulted in 53% reduction in viral titers compared to mock untransfected Huh-7 cells. Conclusion: Inducing miR-29a expression significantly induces SREBP-1c and CAV1 expression, thereby increasing LDs as well as their respective TGs. Nonetheless, forcing the expression of miR-29a resulted in reduction of HCV RNA levels in Huh-7 cells.

Long non-coding RNA H19 regulates glioma angiogenesis and the biological behavior of glioma-associated endothelial cells by inhibiting microRNA-29a

Long non-coding RNAs (lncRNAs) play crucial roles in the development and progression of glioma. Previous studies indicated that lncRNA H19 regulated tumor carcinogenesis, angiogenesis and metastasis. This study aimed to investigate its functional role in glioma-induced endothelial cell proliferation, migration and tube formation as well as its possible molecular mechanisms. H19 was up-regulated in microvessels from glioma tissues and glioma-associated endothelial cells (GEC) cultured in glioma conditioned medium. Knockdown of H19 suppressed glioma-induced endothelial cell proliferation, migration and tube formation in vitro and meanwhile up-regulated the expression of miR-29a. Bioinformatics analysis and luciferase reporter assay defined that H19 mediated the above effects via directly binding to miR-29a. In addition, miR-29a targeted 3'-UTR region of vasohibin 2 (VASH2) and decreased its expression. VASH2 has been identified as an angiogenic factor. Knockdown of H19 also decreased the VASH2 expression by up-regulating miR-29a. In conclusion, the results indicated that knockdown of H19 suppressed glioma induced angiogenesis by inhibiting microRNA-29a, which may modulate the onset of glioma by regulating biological behaviors of glioma vascular endothelial cells.

MicroRNA-29a suppresses cardiac fibroblasts proliferation via targeting VEGF-A/MAPK signal pathway

Cardiac fibroblasts proliferation is the most important pathophysiological character of cardiac fibrosis while the underlying mechanisms are still incompletely known. MicroRNAs (miRNAs) regulate gene expression by binding to specific sites. Studies have been indicated that miRNA-29a play a key role in cardiac fibrosis. VEGF-A carries out its functions through MAPK signaling pathway in cardiac fibrosis. Existing proofs predict that the VEGF-A is one of the potential targets of miRNA-29a. We therefore probe the role of miRNA-29a and its latent target VEGF-A during cardiac fibrosis. In our study, miRNA-29a was down-regulated while VEGF-A was up-regulated in cardiac fibrosis tissues. The rat cardiac fibroblasts that were transfected with miRNA-29a inhibitor exhibited low-expression of miRNA-29a, enhanced VEGF-A protein and mRNA expression. Nevertheless, the cardiac fibroblasts transfected with miRNA-29a mimics obtained the opposite expression result. Furthermore, over-expression of miRNA-29a suppresses cardiac fibroblasts proliferation. In conclusion, these results suggested that miRNA-29a suppresses cardiac fibrosis and fibroblasts proliferation via targeting VEGF-A/MAPK signal pathway implicating that miRNA-29a might play a role in the treatment of cardiac fibrosis.

Protective role of microRNA-29a in denatured dermis and skin fibroblast cells after thermal injury

Our previous study has suggested that downregulated microRNA (miR)-29a in denatured dermis might be involved in burn wound healing. However, the exact role of miR-29a in healing of burn injury still remains unclear. Here, we found that expression of miR-29a was notably upregulated in denatured dermis tissues and skin fibroblast cells after thermal injury, and thereafter gradually downregulated compared with control group. By contrast, the expression of collagen, type I, alpha 2 (COL1A2) and vascular endothelial growth factor (VEGF-A) were first reduced and subsequently upregulated in denatured dermis tissues and skin fibroblast cells after thermal injury. We further identified COL1A2 as a novel target of miR-29a, which is involved in type I collagen synthesis, and showed that miR-29a negatively regulated the expression level of COL1A2 in skin fibroblast cells. In addition, VEGF-A, another target gene of miR-29a, was also negatively mediated by miR-29a in skin fibroblast cells. Inhibition of miR-29a expression significantly promoted the proliferation and migration of skin fibroblast cells after thermal injury, and knockdown of COL1A2 and VEGF-A reversed the effects of miR-29a on the proliferation and migration of skin fibroblast cells. Furthermore, we found that Notch2/Jagged2 signaling was involved in miR-29a response to burn wound healing. Our findings suggest that downregulated miR-29a in denatured dermis may help burn wound healing in the later phase, probably via upregulation of COL1A2 and VEGF-A expression, which can further enhance type I collagen synthesis and angiogenesis.

Summary: Inhibition of miR-29a can promote the proliferation and migration of skin fibroblast cells after thermal injury, and upregulate the production of COL1A2 and VEGF-A to further enhance the collagen synthesis and angiogenesis in skin and help burn wound healing in the later phase.