Circ-Luc7l Absence Attenuates Diabetic Nephropathy Progression by Reducing Mesangial Cell Excessive Proliferation, Inflammation, and Extracellular Matrix Accumulation via Mediating the miR-205-5p/Tgfbr1 Pathway

Diabetic nephropathy (DN) threatens the survival quality of patients, with complex pathogenesis. Circular RNA (circRNA) dysregulation occurs in DN development. This work aimed to investigate the role of circ-Luc7l in DN cell models and related molecular mechanisms. The expression of circ-Luc7l, microRNA (miR)-205-5p, and transforming growth factor-beta receptor 1 (Tgfbr1) was examined by real-time quantitative PCR (RT-qPCR). Cell viability and proliferation were detected by Cell Counting Kit-8 (CCK-8) assay and EdU assay. The expression of extracellular matrix (ECM)-related markers and Tgrbr1 protein was measured by Western blot. The binding between miR-205-5p and circ-Luc7l or Tgfbr1 was validated by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay, or RNA pull-down assay. Experimental animal models were established to elucidate the function of circ-Luc7l in vivo. Circ-Luc7l expression was notably enhanced in high glucose (HG)-treated mesangial cells. Knockdown of circ-Luc7l attenuated HG-induced cell proliferation, inflammation, and ECM accumulation in vitro and relieved inflammation and ECM accumulation of kidneys of diabetic mice in vivo. Circ-Luc7l targeted miR-205-5p, and miR-205-5p inhibition rescued the depletion effects of circ-Luc7l knockdown on cell proliferation, inflammation, and ECM accumulation. MiR-205-5p bound to Tgfbr1 whose expression was negatively regulated by circ-Luc7l. Tgfbr1 overexpression also rescued the depletion effects of circ-Luc7l knockdown on cell proliferation, inflammation, and ECM accumulation. In HG conditions, increased circ-Luc7l upregulated Tgfbr1 expression via targeting miR-205-5p to induce DN progression.

tRNA-derived small RNA, 5'tiRNA-Gly-CCC, promotes skeletal muscle regeneration through the inflammatory response

BACKGROUND

Increasing evidence shows that tRNA-derived small RNAs (tsRNAs) are not only by-products of transfer RNAs, but they participate in numerous cellular metabolic processes. However, the role of tsRNAs in skeletal muscle regeneration remains unknown.

METHODS

Small RNA sequencing revealed the relationship between tsRNAs and skeletal muscle injury. The dynamic expression level of 5'tiRNA-Gly after muscle injury was confirmed by real-time quantitative PCR (q-PCR). In addition, q-PCR, flow cytometry, the 5-ethynyl-2'-deoxyuridine (Edu), cell counting kit-8, western blotting and immunofluorescence were used to explore the biological function of 5'tiRNA-Gly. Bioinformatics analysis and dual-luciferase reporter assay were used to further explore the mechanism of action under the biological function of 5'tiRNA-Gly.

RESULTS

Transcriptome analysis revealed that tsRNAs were significantly enriched during inflammatory response immediately after muscle injury. Interestingly, we found that 5'tiRNA-Gly was significantly up-regulated after muscle injury (P < 0.0001) and had a strong positive correlation with inflammation in vivo. In vitro experiments showed that 5'tiRNA-Gly promoted the mRNA expression of proinflammatory cytokines (IL-1β, P = 0.0468; IL-6, P = 0.0369) and the macrophages of M1 markers (TNF-α, P = 0.0102; CD80, P = 0.0056; MCP-1, P = 0.0002). On the contrary, 5'tiRNA-Gly inhibited the mRNA expression of anti-inflammatory cytokines (IL-4, P = 0.0009; IL-10, P = 0.0007; IL-13, P = 0.0008) and the mRNA expression of M2 markers (TGF-β1, P = 0.0016; ARG1, P = 0.0083). Flow cytometry showed that 5'tiRNA-Gly promoted the percentage of CD86⁺ macrophages (16%, P = 0.011) but inhibited that of CD206⁺ macrophages (10.5%, P = 0.012). Immunofluorescence showed that knockdown of 5'tiRNA-Gly increased the infiltration of M2 macrophages to the skeletal muscles (13.9%, P = 0.0023) and inhibited the expression of Pax7 (P = 0.0089) in vivo. 5'tiRNA-Gly promoted myoblast the expression of myogenic differentiation marker genes (MyoD, P = 0.0002; MyoG, P = 0.0037) and myotube formation (21.3%, P = 0.0016) but inhibited the positive rate of Edu (27.7%, P = 0.0001), cell viability (22.6%, P = 0.003) and the number of myoblasts in the G2 phase (26.3%, P = 0.0016) in vitro. Mechanistically, we found that the Tgfbr1 gene is a direct target of 5'tiRNA-Gly mediated by AGO1 and AGO3. 5'tiRNA-Gly dysregulated the expression of downstream genes related to inflammatory response, activation of satellite cells and differentiation of myoblasts through the TGF-β signalling pathway by targeting Tgfbr1.

CONCLUSIONS

These results reveal that 5'tiRNA-Gly potentially regulated skeletal muscle regeneration by inducing inflammation via the TGF-β signalling pathway. The findings of this study uncover a new potential target for skeletal muscle regeneration treatment.

Igf2bp2 knockdown improves CCl4-induced liver fibrosis and TGF-β-activated mouse hepatic stellate cells by regulating Tgfbr1

Progressive liver fibrosis is a dynamic process characterized by the net accumulation of extracellular matrix (ECM), which could eventually develop into cirrhosis, leading to malignant transformation. In this study, insulin-like growth factor 2 mRNA binding protein 2 (Igf2bp2) was found to be up-regulated in carbon tetrachloride (CCl₄)-induced liver fibrosis and transforming growth factor-beta 1 (TGF-β)-activated hepatic stellate cells (HSCs). Igf2bp2 knockdown in the CCl₄-induced hepatic fibrosis mice model significantly improved CCl₄-induced liver damage by decreasing necrosis and fibrotic septa, reducing hydroxyproline levels, and down-regulating fibrotic markers levels. In TGF-β-activated HSCs, Igf2bp2 knockdown partially attenuated TGF-β-induced cellular effects by suppressing HSCs viability and DNA synthesis and reducing the ECM-associated factors such as α-SMA, COLLAGEN I, and COLLAGEN III. Integrative network and signaling analysis revealed that the Igf2bp2 could bind to Tgfbr1. Transforming growth factor-beta receptor 1 (Tgfbr1) was found to be significantly up-regulated in the fibrotic liver and activated HSCs, and positively correlated with Igf2bp2. Tgfbr1 knockdown partially eliminated TGF-β-induced fibrotic changes and Igf2bp2 overexpression effects on TGF-β-activated HSCs in vitro. Moreover, Igf2bp2 overexpression promoted the phosphorylation of SMAD2/SMAD3, AKT, and PI3K, whereas Tgfbr1 knockdown exhibited the opposite effect; Tgfbr1 knockdown also partially attenuated the effects of Igf2bp2 overexpression on the phosphorylation of SMAD2/SMAD3, AKT, and PI3K. In closing, Igf2bp2 and Tgfbr1 are up-regulated in CCl₄-induced liver fibrosis and TGF-β-activated mHSCs. Igf2bp2 knockdown improved CCl₄-induced liver fibrosis and TGF-β-activated HSCs by targeting Tgfbr1, possibly through the PI3K/Akt pathway.

Myricetin suppresses the proliferation and migration of vascular smooth muscle cells and inhibits neointimal hyperplasia via suppressing TGFBR1 signaling pathways

BACKGROUND

Neointimal formation, mediated by the proliferation and migration of vascular smooth muscle cells (VSMCs), is a common pathological basis for atherosclerosis and restenosis. Myricetin, a natural flavonoid, reportedly exerts anti-atherosclerotic effects. However, the effect and mechanism of myricetin on VSMCs proliferation and migration and neointimal hyperplasia (NIH) remain unknown.

PURPOSE

We investigated myricetin's effect on NIH, as well as the potential involvement of transforming growth factor-beta receptor 1 (TGFBR1) signaling in mediating myricetin's anti-atherosclerotic and anti-restenotic actions.

METHODS

Myricetin's effects on the proliferation and migration of HASMCs and A7R5 cells were determined by CCK-8, EdU assays, wound healing, Transwell assays, and western blotting (WB).Molecular docking, molecular dynamics (MD) simulation, surface plasmon resonance (SPR) and TGFBR1 kinase activity assays were employed to investigate the interaction between myricetin and TGFBR1. An adenovirus vector encoding TGFBR1 was used to verify the effects of myricetin. In vivo, the left common carotid artery (LCCA) ligation mouse model was adopted to determine the impacts of myricetin on neointimal formation and TGFBR1 activation.

RESULTS

Myricetin dose-dependently inhibited the migration and proliferation in VSMCs, suppressed the expression of CDK4, cyclin D3, MMP2, and MMP9. Molecular docking revealed that myricetin binds to key regions for TGFBR1 antagonist binding, and the binding energy was -9.61 kcal/mol. MD simulation indicated stable binding between TGFBR1 and myricetin. Additionally, SPR revealed an equilibrium dissociation constant of 4.35 × 10^-5 M between myricetin and TGFBR1. According to the TGFBR1 kinase activity assay, myricetin directly inhibited TGFBR1 kinase activity (IC₅₀ = 8.551 μM). Furthermore, myricetin suppressed the phosphorylation level of TGFBR1, Smad2, and Smad3 in a dose-dependent pattern, which was partially inhibited by TGFBR1 overexpression. Consistently, TGFBR1 overexpression partially rescued the suppressive roles of myricetin on VSMCs migration and proliferation. Moreover, myricetin dramatically inhibited NIH and reduced TGFBR1, Smad2, and Smad3 phosphorylation in the LCCA.

CONCLUSION

This is the first study to demonstrate that myricetin suppresses NIH and VSMC proliferation and migration via inhibiting TGFBR1 signaling. Myricetin can be developed as a potential therapeutic candidate for treating atherosclerosis and vascular restenosis.

MicroRNA-183 exerts a protective role in lupus nephritis through blunting the activation of TGF-β/Smad/TLR3 pathway via reducing Tgfbr1

PURPOSE

The role of microRNA (miR)-183 has been elucidated in systemic lupus erythematosus, while whether it is also engaged in the lupus nephritis (LN) development remains opaque. The intention of this study is to examine the relevance of miR-183 downregulation in the pathogenesis of LN.

METHODS

The expression of miR-183 was first detected in MRL/lpr mice at weeks 8 and 12, followed by the assessment the effects of miR-183 on renal fibrosis and inflammatory response after overexpression or silencing of miR-183 in mice with LN. We further overexpressed or knocked-down miR-183 in human renal glomerular endothelial cells (HRGECs), and detected the expression patterns of inflammatory factors and Vimentin and α-SMA in the cells. Differentially expressed genes in HRGECs overexpressing miR-183 by microarrays were intersected with targeting mRNAs of miR-183 predicted by bioinformatics websites. The effects of transforming growth factor beta receptor 1 (Tgfbr1) and TGF-β/Smad/TLR3 pathway on renal damage in mice were verified by rescue experiments.

RESULTS

miR-183 expression was notably lower in MRL/lpr mice, and increased miR-183 expression inhibited renal fibrosis and inflammatory response in mice with LN. Moreover, miR-183 inhibitor in HRGECs remarkably promoted the expression of Vimentin and α-SMA and the secretion of inflammatory factors. miR-183 protected the mouse kidney from pathological damages by targeting and inhibiting Tgfbr1 expression.

CONCLUSION

miR-183 inhibited the expression of Tgfbr1 by direct targeting to disrupt the TGF-β/Smad/TLR3 pathway, thus repressing renal fibrosis and the secretion of inflammatory factors in LN.

TGF-β Regulates Collagen Type I Expression in Myoblasts and Myotubes via Transient Ctgf and Fgf-2 Expression

Transforming Growth Factor β (TGF-β) is involved in fibrosis as well as the regulation of muscle mass, and contributes to the progressive pathology of muscle wasting disorders. However, little is known regarding the time-dependent signalling of TGF-β in myoblasts and myotubes, as well as how TGF-β affects collagen type I expression and the phenotypes of these cells. Here, we assessed effects of TGF-β on gene expression in C2C12 myoblasts and myotubes after 1, 3, 9, 24 and 48 h treatment. In myoblasts, various myogenic genes were repressed after 9, 24 and 48 h, while in myotubes only a reduction in Myh3 expression was observed. In both myoblasts and myotubes, TGF-β acutely induced the expression of a subset of genes involved in fibrosis, such as Ctgf and Fgf-2, which was subsequently followed by increased expression of Col1a1. Knockdown of Ctgf and Fgf-2 resulted in a lower Col1a1 expression level. Furthermore, the effects of TGF-β on myogenic and fibrotic gene expression were more pronounced than those of myostatin, and knockdown of TGF-β type I receptor Tgfbr1, but not receptor Acvr1b, resulted in a reduction in Ctgf and Col1a1 expression. These results indicate that, during muscle regeneration, TGF-β induces fibrosis via Tgfbr1 by stimulating the autocrine signalling of Ctgf and Fgf-2.

Estrogen-induced Tgfbr1 and Bmpr1a Expression Repressed via Estrogen Receptor Beta in MC3T3-E1 Cells

Background

Estrogen, as an important hormone in human physiological process, is closely related to bone metabolism. The aim of this study was to investigate the mechanism of estrogen on osteoblasts metabolism in MC3T3-E1 cells.

Methods

We treated the MC3T3-E1 cells with different concentrations of β-estradiol (0.01, 0.1, 1, and 10 nmol/L), observed the morphological changes of the cells, and detected the cell's proliferation and apoptosis of MC3T3-E1 cells. Two transcriptome libraries were constructed and sequenced. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to confirm the differentially expressed genes (DEGs), and then treated the MC3T3-E1 cells with estrogen receptor (ER) inhibitors α and β, respectively, and then examined the expression of Tgfbr1 and Bmpr1a genes. The promoter of Tgfbr1 and Bmpr1a gene was analyzed, and the ER response elements were identified. Finally, ChIP was used to verify the binding of ER to Tgfbr1 and Bmpr1a promoter.

Results

In the high-concentration β-estradiol treatment group (1 nmol/L and 10 nmol/L), there was no significant difference in the morphology of the cells under the microscope, 1 nmol/L and 10 nmol/L treated group appeared statistically significant difference in cell apoptosis and proliferation (P < 0.05 and P < 0.01, respectively). We found 460 DEGs compared with the control group. Among the DEGs, there were 66 upregulated genes and 394 downregulated genes. Gene ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that many bone metabolism-related biological processes and cell signaling pathways were disordered. The qRT-PCR verification showed that the expressions of Tgfbr1- and Bmpr1a-related genes in bone metabolism pathway in the 10 nmol/L treatment group were significantly decreased (P < 0.05). ER β was involved in the inhibitory effect of Tgfbr1 and Bmpr1a genes. The bioinformatics of the promoter found that there were three ER response elements in the promoter of Tgfbr1, and there were two ER response elements in Bmpr1a promoter regions. ChIP experiments showed that estrogen could enhance the binding of ERs to Tgfbr1 and Bmpr1a genes.

Conclusions

Estrogen can promote the apoptosis and proliferation of osteoblasts simultaneously, and the mechanism may be the joint action of transforming growth factor-beta, Wnt, mitogen-activated protein kinase, and nuclear factor-kappaB bone metabolism-related signaling pathway. Estrogen inhibits the expression of Tgfbr1 and Bmpr1a genes through ER β and affects the metabolism of MC3T3-E1 osteoblasts.

MicroRNA-181a-5p enhances cell proliferation in medullary thymic epithelial cells via regulating TGF-β signaling

The expression profiles of miRNAs in thymus tissues from mice of different age have been demonstrated in our previous study. After an integrated analysis of the miRNA expression profiles, we demonstrated that the expression of miR-181a-5p was significantly decreased in thymic epithelial cells (TECs) from 10- to 19-month-old mice when compared with that in TECs from 1-month-old mice by quantitative reverse transcriptase polymerase chain reaction. We hypothesized that miR-181a-5p in TECs might be associated with the age-related thymus involution through regulating some genes or signaling pathway. To test this hypothesis, the mouse medullary thymic epithelial cells (MTEC1) were used. Transfection with miR-181a-5p mimic promoted the proliferation of MTEC1 cells, but did not affect apoptosis. The effect was reversed when the expression of miR-181a-5p was suppressed in MTEC1 cells. Furthermore, the transforming growth factor beta receptor I (Tgfbr1) was confirmed as a direct target of miR-181a-5p by luciferase assay. Moreover, it was found that overexpression of miR-181a-5p down-regulated the phosphorylation of Smad3 and blocked the activation of the transforming growth factor beta signaling. Nevertheless, an inversely correlation was observed between the expression of Tgfbr1 and miR-181a-5p in TECs derived from mice of different age. Collectively, we provide evidence that miR-181a-5p may be an important endogenous regulator in the proliferation of TECs, and the expression levels of miR-181a-5p in TECs may be associated with the age-related thymus involution.