Livin is involved in TGF-β1-induced renal tubular epithelial-mesenchymal transition through lncRNA-ATB

Effect of Porphyromonas gingivalis outer membrane vesicles on renal tubule epithelial-mesenchymal transition

BACKGROUND

Studies have shown that Porphyromonas gingivalis (P. gingivalis) can promote the development of chronic kidney disease (CKD). In this study, we explored the epithelial-mesenchymal transition (EMT) process promoted by P. gingivalis outer membrane vesicles (OMVs) in renal interstitial fibrosis (RIF), thereby providing new ideas for the study of the relationship between periodontitis and CKD.

METHODS

For in vivo experiments, RIF models induced by unilateral ureteral obstruction (UUO) were constructed in 6-week-old C57BL/6 mice, followed by administration of P. gingivalis OMVs (100 µg) through the tail vein once every other day for 2 weeks. For in vitro experiments, the RIF model was established by transforming growth factor-beta (TGF-β)1-induced mouse renal tubular epithelial cells (RTECs), followed by the administration of 100 µg P. gingivalis OMVs. In vivo imaging system (IVIS) imaging and immunofluorescence were used to detect whether peripheral injection of P. gingivalis OMVs through the tail vein could enter mouse kidney tissue. Serum biochemical assays were performed to detect the renal function of the injected mice. Hematoxylin-eosin (HE) staining and Masson's trichrome staining were used to assess tubulointerstitial lesions and fibrosis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect gene expression levels of cytokines related to renal inflammation and fibrosis. The expression levels of EMT-related proteins in kidney tissue and RTECs were evaluated by immunofluorescence and Western blotting. The expression levels of EMT-related regulatory factors Snail1 and β-catenin in the renal tissues of mice in each group were detected by qRT-PCR and Western blotting.

RESULTS

P. gingivalis OMVs successfully entered the kidney tissue of the mice via circulation. P. gingivalis OMVs aggravated renal dysfunction, renal tubulointerstitial lesions, and fibrosis in UUO mice. P. gingivalis OMVs upregulated the gene expression of inflammatory and fibrosis-related factors. P. gingivalis OMVs induced renal tubular EMT exacerbation both in vivo and in vitro. P. gingivalis OMVs upregulated gene and protein expression levels of EMT-related regulatory factors such as β-catenin and Snail1.

CONCLUSION

P. gingivalis OMVs can aggravate renal dysfunction, tubulointerstitial disease, and RIF and may further aggravate EMT by regulating the expression of β-catenin and Snail1.

PLAIN LANGUAGE SUMMARY

Porphyromonas gingivalis is the main pathogenic factor of periodontitis. Chronic kidney disease (CKD) is a global epidemic that affects about 10% of the world's population. Renal interstitial fibrosis (RIF) is the common pathway of progression from CKD to end-stage kidney disease (ESKD). During the development of RIF, renal tubular epithelial cells (RTECs), as the most vulnerable intrinsic cells of the kidney, can be transformed into myofibroblasts through epithelial-mesenchymal transition (EMT). P. gingivalis outer membrane vesicles (OMVs) can reach deep tissues and activate host inflammatory response. Several studies have shown that P. gingivalis can increase kidney inflammation and immunosuppression through complex mechanisms, induce renal insufficiency, and affect CKD development. However, there are few reports about P. gingivalis OMVs and EMT. Our study found that P. gingivalis OMVs can aggravate renal dysfunction, tubulointerstitial disease, and RIF and may further aggravate EMT by regulating the expression of β-catenin and Snail1. Therefore, this finding provides a new strategy for preventing CKD/EMT from the perspective of treating periodontitis.

Role of LncRNA in Pathogenesis, Diagnosis and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is a clinical syndrome of metabolic disorder caused by progressive kidney impairment for more than 3 months. CKD has become a global public health problem due to its high morbidity and mortality, which is difficult to be cured for most patients. The pathogenesis of CKD is still unclear, which is closely related to glomerulosclerosis, kidney tubular injury and kidney fibrosis. LncRNA is a non-coding RNA with a length of more than 200 nucleotides. It not only participates in intracellular transcriptional regulation, post-transcriptional regulation and epigenetic activities, but also forms a regulatory network together with miRNA and mRNA, to further conduct the reticular regulation in cells. Recently, it has been found that lncRNA participates in pathophysiological mechanism of CKD by regulating glomerulosclerosis, kidney tubular injury and kidney fibrosis. This has also become a new direction of lncRNA in early diagnosis and targeted therapy of CKD.

Astragalus mongholicus bunge and panax notoginseng formula (A&P) improves renal fibrosis in UUO mice via inhibiting the long non-coding RNA A330074K22Rik and downregulating ferroptosis signaling

BACKGROUND

Chronic kidney disease (CKD) and its associated end-stage renal disease (ESRD) are significant health problems that pose a threat to human well-being. Renal fibrosis is a common feature and ultimate pathological outcome of various CKD leading to ESRD. The Astragalus mongholicus Bunge and Panax notoginseng formula (A&P) is a refined compound formulated by our research group, which has been clinically administered for over a decade and has demonstrated the ability to improve the inflammatory state of various acute or chronic kidney diseases. However, the underlying mechanism by which A&P ameliorates renal fibrosis remains unclear.

METHODS

We established a mouse model by surgically ligating the unilateral ureter to induce renal injury in vivo. And we utilized renal in situ electroporation of a plasmid with low LncRNA A33 expression to establish the unilateral ureteral obstruction(UUO)mouse model. In vitro, we stimulated primary tubular epithelial cells(pTEC) injury using TGF-β1, siRNA-A33, and pcDNA3.1-A33 plasmids were transfected into pTECs to respectively knockdown and overexpress LncRNA A33, and both in vitro and in vivo models were intervened with A&P.

RESULTS

The results demonstrated that A&P effectively alleviated renal fibrosis in mice. Subsequent findings indicated high expression of LncRNA A33 in the kidneys of UUO mice and TGF-β1-induced renal tubular cells. In situ, renal electroporation of a plasmid with reduced LncRNA A33 expression revealed that inhibiting LncRNA A33 significantly improved renal fibrosis in UUO mice. Moreover, A&P effectively suppressed LncRNA A33 expression both in vitro and in vivo. Subsequent downregulation of LncRNA A33 in renal tubular epithelial cells resulted in the downregulation of numerous fibrotic markers, a significant inhibition of LncRNA A33, and a notable reduction in downstream ferroptosis signaling. Cell experiments demonstrated that A&P improved renal fibrosis in UUO mice by inhibiting LncRNA A33 and downregulating ferroptosis signaling.

CONCLUSION

Through the inhibition of LncRNA A33 and subsequent downregulation of ferroptosis signaling, A&P showed potential as a therapeutic approach for improving renal fibrosis in UUO mice, providing a potential treatment avenue for CKD.

The long noncoding RNA Meg3 mediates TLR4-induced inflammation in experimental obstructive nephropathy

Kidney inflammation contributes to the progression of chronic kidney disease (CKD). Modulation of Toll-like receptor 4 (TLR4) signaling is a potential therapeutic strategy for this pathology, but the regulatory mechanisms of TLR4 signaling in kidney tubular inflammation remains unclear. Here, we demonstrated that tubule-specific deletion of TLR4 in mice conferred protection against obstruction-induced kidney injury, with reduction in inflammatory cytokine production, macrophage infiltration and kidney fibrosis. Transcriptome analysis revealed a marked down-regulation of long noncoding RNA (lncRNA) Meg3 in the obstructed kidney from tubule-specific TLR4 knockout mice compared with wild-type control. Meg3 was also induced by lipopolysaccharide in tubular epithelial cells via a p53-dependent signaling pathway. Silencing of Meg3 suppressed LPS-induced cytokine production of CCL-2 and CXCL-2 and the activation of p38 MAPK pathway in vitro and ameliorated kidney fibrosis in mice with obstructive nephropathy. Together, these findings identify a proinflammatory role of lncRNA Meg3 in CKD and suggest a novel regulatory pathway in TLR4-driven inflammatory responses in tubular epithelial cells.

Long non-coding RNA lnc-CHAF1B-3 promotes renal interstitial fibrosis by regulating EMT-related genes in renal proximal tubular cells

Renal interstitial fibrosis (RIF) is a common pathological manifestation of chronic kidney diseases. Epithelial-mesenchymal transition (EMT) of tubular epithelial cells is considered a major cause of RIF. Although long non-coding RNAs (lncRNAs) are reportedly involved in various pathophysiological processes, the roles and underlying molecular mechanisms of lncRNAs in the progression of RIF are poorly understood. In this study, we investigated the function of lncRNAs in RIF. Microarray assays showed that expression of the lncRNA lnc-CHAF1B-3 (also called claudin 14 antisense RNA 1) was significantly upregulated in human renal proximal tubular cells by both transforming growth factor-β1 (TGF-β1) and hypoxic stimulation, accompanied with increased expression of EMT-related genes. Knockdown of lnc-CHAF1B-3 significantly suppressed TGF-β1-induced upregulated expression of collagen type I alpha 1, cadherin-2, plasminogen activator inhibitor-1, snail family transcriptional repressor I (SNAI1) and SNAI2. Quantitative reverse transcriptase PCR analyses of paraffin-embedded kidney biopsy samples from IgA nephropathy patients revealed lnc-CHAF1B-3 expression was correlated positively with urinary protein levels and correlated negatively with estimated glomerular filtration rate. In situ hybridization demonstrated that lnc-CHAF1B-3 is expressed only in proximal tubules. These findings suggest lnc-CHAF1B-3 affects the progression of RIF by regulating EMT-related signaling. Thus, lnc-CHAF1B-3 is a potential target in the treatment of RIF.

RNA-binding proteins and their role in kidney disease

RNA-binding proteins (RBPs) are of fundamental importance for post-transcriptional gene regulation and protein synthesis. They are required for pre-mRNA processing and for RNA transport, degradation and translation into protein, and can regulate every step in the life cycle of their RNA targets. In addition, RBP function can be modulated by RNA binding. RBPs also participate in the formation of ribonucleoprotein complexes that build up macromolecular machineries such as the ribosome and spliceosome. Although most research has focused on mRNA-binding proteins, non-coding RNAs are also regulated and sequestered by RBPs. Functional defects and changes in the expression levels of RBPs have been implicated in numerous diseases, including neurological disorders, muscular atrophy and cancers. RBPs also contribute to a wide spectrum of kidney disorders. For example, human antigen R has been reported to have a renoprotective function in acute kidney injury (AKI) but might also contribute to the development of glomerulosclerosis, tubulointerstitial fibrosis and diabetic kidney disease (DKD), loss of bicaudal C is associated with cystic kidney diseases and Y-box binding protein 1 has been implicated in the pathogenesis of AKI, DKD and glomerular disorders. Increasing data suggest that the modulation of RBPs and their interactions with RNA targets could be promising therapeutic strategies for kidney diseases.

The ILEI/LIFR complex induces EMT via the Akt and ERK pathways in renal interstitial fibrosis

BACKGROUND

Chronic kidney disease (CKD) is characterized by high morbidity and mortality and is difficult to cure. Renal interstitial fibrosis (RIF) is a major determinant of, and commonly occurs within, CKD progression. Epithelial mesenchymal transition (EMT) has been identified as a crucial process in triggering renal interstitial fibrosis (RIF). Interleukin-like EMT inducer (ILEI) is an important promotor of EMT; this study aims to elucidate the mechanisms involved.

METHODS

Male C57BL6/J mouse were randomly divided into 6 groups: sham (n = 10), sham with negative control (NC) shRNA (sham + NC, n = 10), sham with ILEI shRNA (sham + shILEI, n = 10), unilateral ureteral obstruction (UUO, n = 10), UUO with NC (UUO + NC, n = 10) and UUO with ILEI shRNA (UUO + shILEI, n = 10). Hematoxylin and eosin (H&E), Masson, and immunohistochemical (IHC) staining and western blotting (WB) were performed on murine kidney tissue to identify the function and mechanism of ILEI in RIF. In vitro, ILEI was overexpressed to induce EMT in HK2 cells and analyzed via transwell, WB, real-time PCR, and co-immunoprecipitation. Finally, tissue from 12 pediatric CKD patients (seven with RIF and five without RIF) were studied with H&E, Masson, and IHC staining.

RESULTS

Our in vitro model revealed that ILEI facilitates RIF in the UUO model via the Akt and ERK pathways. Further experiments in vivo and in vitro revealed that ILEI promotes renal tubular EMT by binding and activating leukemia inhibitory factor receptor (LIFR), in which phosphorylation of Akt and ERK is involved. We further find markedly increased expression levels of ILEI and LIFR in kidneys from pediatric CKD patients with RIF.

CONCLUSION

Our results indicate that ILEI may be a useful biomarker for renal fibrosis and a potential therapeutic target for modulating RIF.

Detection and analysis of long noncoding RNA expression profiles related to epithelial-mesenchymal transition in keloids

BACKGROUND

The role of epithelial-mesenchymal transition (EMT) in the pathogenesis of keloids is currently raising increasing attention. Long noncoding RNAs (lncRNAs) govern a variety of biological processes, such as EMT, and their dysregulation is involved in many diseases including keloid disease. The aim of this study was to identify differentially expressed EMT-related lncRNAs in keloid tissues versus normal tissues and to interpret their functions.

RESULTS

Eleven lncRNAs and 16 mRNAs associated with EMT were identified to have differential expression between keloid and normal skin tissues (fold change > 1.5, P < 0.05). Gene Ontology (GO) analysis showed that these differentially expressed mRNAs functioned in the extracellular matrix, protein binding, the positive regulation of cellular processes, the Set1C/COMPASS complex and histone acetyltransferase activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that these mRNAs are involved in pathways in cancer. The lncRNA, XLOC_000587 may promote cell proliferation and migration by enhancing the expression of ENAH, while AF268386 may facilitate the invasive growth of keloids by upregulating DDR2.

CONCLUSIONS

We characterized the differential expression profiles of EMT-related lncRNAs and mRNAs in keloids, which may contribute to preventing the occurrence and development of keloids by targeting the corresponding signaling pathways. These lncRNAs and mRNAs may provide biomarkers for keloid diagnosis and serve as potential targets for the treatment of this disease.

Long Non-coding RNA: An Emerging Contributor and Potential Therapeutic Target in Renal Fibrosis

Renal fibrosis (RF) is a pathological process that culminates in terminal renal failure in chronic kidney disease (CKD). Fibrosis contributes to progressive and irreversible decline in renal function. However, the molecular mechanisms involved in RF are complex and remain poorly understood. Long non-coding RNAs (lncRNAs) are a major type of non-coding RNAs, which significantly affect various disease processes, cellular homeostasis, and development through multiple mechanisms. Recent investigations have implicated aberrantly expressed lncRNA in RF development and progression, suggesting that lncRNAs play a crucial role in determining the clinical manifestation of RF. In this review, we comprehensively evaluated the recently published articles on lncRNAs in RF, discussed the potential application of lncRNAs as diagnostic and/or prognostic biomarkers, proposed therapeutic targets for treating RF-associated diseases and subsequent CKD transition, and highlight future research directions in the context of the role of lncRNAs in the development and treatment of RF.

LncRNA-ATB regulates epithelial-mesenchymal transition progression in pulmonary fibrosis via sponging miR-29b-2-5p and miR-34c-3p

Dysregulation of non‐coding RNAs (ncRNAs) has been proved to play pivotal roles in epithelial‐mesenchymal transition (EMT) and fibrosis. We have previously demonstrated the crucial function of long non‐coding RNA (lncRNA) ATB in silica‐induced pulmonary fibrosis‐related EMT progression. However, the underlying molecular mechanism has not been fully elucidated. Here, we verified miR‐29b‐2‐5p and miR‐34c‐3p as two vital downstream targets of lncRNA‐ATB. As opposed to lncRNA‐ATB, a significant reduction of both miR‐29b‐2‐5p and miR‐34c‐3p was observed in lung epithelial cells treated with TGF‐β1 and a murine silicosis model. Overexpression miR‐29b‐2‐5p or miR‐34c‐3p inhibited EMT process and abrogated the pro‐fibrotic effects of lncRNA‐ATB in vitro. Further, the ectopic expression of miR‐29b‐2‐5p and miR‐34c‐3p with chemotherapy attenuated silica‐induced pulmonary fibrosis in vivo. Mechanistically, TGF‐β1‐induced lncRNA‐ATB accelerated EMT as a sponge of miR‐29b‐2‐5p and miR‐34c‐3p and shared miRNA response elements with MEKK2 and NOTCH2, thus relieving these two molecules from miRNA‐mediated translational repression. Interestingly, the co‐transfection of miR‐29b‐2‐5p and miR‐34c‐3p showed a synergistic suppression effect on EMT in vitro. Furthermore, the co‐expression of these two miRNAs by using adeno‐associated virus (AAV) better alleviated silica‐induced fibrogenesis than single miRNA. Approaches aiming at lncRNA‐ATB and its downstream effectors may represent new effective therapeutic strategies in pulmonary fibrosis.

Transforming Growth Factor-β and Long Non-coding RNA in Renal Inflammation and Fibrosis

Renal fibrosis is one of the most characterized pathological features in chronic kidney disease (CKD). Progressive fibrosis eventually leads to renal failure, leaving dialysis or allograft transplantation the only clinical option for CKD patients. Transforming growth factor-β (TGF-β) is the key mediator in renal fibrosis and is an essential regulator for renal inflammation. Therefore, the general blockade of the pro-fibrotic TGF-β may reduce fibrosis but may risk promoting renal inflammation and other side effects due to the diverse role of TGF-β in kidney diseases. Long non-coding RNAs (lncRNAs) are RNA transcripts with more than 200 nucleotides and have been regarded as promising therapeutic targets for many diseases. This review focuses on the importance of TGF-β and lncRNAs in renal inflammation, fibrogenesis, and the potential applications of TGF-β and lncRNAs as the therapeutic targets and biomarkers in renal fibrosis and CKD are highlighted.

LncRNA Gas5 regulates Fn1 deposition via Creb5 in renal fibrosis

Aim: Although studies on lncRNAs in renal fibrosis have focused on target genes and functions of lncRNAs, a comprehensive interaction analysis of lncRNAs is lacking. Materials & methods: Differentially expressed genes in renal fibrosis were screened, and the interaction between lncRNAs and miRNAs was searched. Results: We constructed a ceRNA network associated with renal fibrosis, by which we found the transcription factor Creb5, a target gene of lncRNA Gas5 that might regulate extracellular Fn1 deposition. Conclusion: Our study not only provides a theoretical basis for the ceRNA regulation mechanism of Gas5 but also provides experimental evidence supporting the use of Gas5 targeting in the treatment of renal fibrosis.

MiR-27b-3p inhibits the progression of renal fibrosis via suppressing STAT1

Renal fibrosis is a pathologic change in chronic kidney disease (CKD). MicroRNAs (miRNAs) have been shown to play an important role in the development of renal fibrosis. However, the biological role of miR-27b-3p in renal fibrosis remains unclear. Thus, this study aimed to investigate the role of miR-27b-3p in the progression of renal fibrosis. In this study, HK-2 cells were stimulated with transforming growth factor (TGF)-β1 for mimicking fibrosis progression in vitro. The unilateral ureteric obstruction (UUO)-induced mice renal fibrosis in vivo was established as well. The results indicated that the overexpression of miR-27b-3p significantly inhibited epithelial-to-mesenchymal transition (EMT) in TGF-β1-stimulated HK-2 cells, as shown by the decreased expressions of α-SMA, collagen III, Fibronectin and Vimentin. In addition, overexpression of miR-27b-3p markedly decreased TGF-β1-induced apoptosis in HK-2 cells, as evidenced by the decreased levels of Fas, active caspase 8 and active caspase 3. Meanwhile, dual-luciferase assay showed that miR-27b-3p downregulated signal transducers and activators of transcription 1 (STAT1) expression through direct binding with the 3′-UTR of STAT1. Furthermore, overexpression of miR-27b-3p attenuated UUO-induced renal fibrosis via downregulation of STAT1, α-SMA and collagen III. In conclusion, miR-27b-3p overexpression could alleviate renal fibrosis via suppressing STAT1 in vivo and in vitro. Therefore, miR-27b-3p might be a promising therapeutic target for the treatment of renal fibrosis.

Identification of candidate lncRNA biomarkers for renal fibrosis: A systematic review

AIMS

To combine the results of dysregulated lncRNAs in individual renal fibrosis lncRNA expression profiling studies and to identify potential lncRNA biomarkers.

MATERIALS AND METHODS

We systematically searched three databases to identify lncRNA expression studies of renal fibrosis in animal models and humans. The lncRNA expression data were extracted from 24 included studies, and a lncRNA vote-counting strategy was applied to identify significant lncRNA biomarkers. The lncLocator algorithm was utilized to predict the potential subcellular localization of these lncRNAs. The predicted targets of the identified lncRNA biomarkers were obtained by searching LncBase v.2 and catRAPID. Finally, GO enrichment and KEGG pathway analyses were performed.

KEY FINDINGS

We recognized a significant lncRNA signature of 95 differentially expressed lncRNAs in 731 samples from rodent models of renal fibrosis and CKD patients, among which TCONS_01181049 and TCONS_01496394 were commonly upregulated in both urine and renal tissues, while lncRNA-Cancer Susceptibility Candidate 2 was downregulated in both blood and renal tissues. About 73.33% dysregulated lncRNAs in renal fibrosis animal models and 81.82% dysregulated lncRNAs in CKD patients were predicted to be localized to the cytoplasm. The most relevant biological processes and molecular functions associated with these lncRNAs were mRNA processing and RNA binding.

SIGNIFICANCE

The present systematic review identified 95 significantly dysregulated lncRNAs from 24 studies and future investigations should focus on exploring their potential effects on renal fibrosis and their clinical utility as biomarkers or therapeutic targets.

LncRNA PVT1 Suppresses the Progression of Renal Fibrosis via Inactivation of TGF-β Signaling Pathway

BACKGROUND

Renal fibrosis is a frequent pathway leading to end-stage kidney dysfunction. In addition, renal fibrosis is the ultimate manifestation of chronic kidney diseases (CKD). Long noncoding RNAs (lncRNAs) are known to be involved in occurrence of renal fibrosis, and lncRNA plasmacytoma variant translocation 1 (PVT1) has been reported to act as a key biomarker in renal diseases. However, the role of PVT1 in renal fibrosis remains unclear.

MATERIALS AND METHODS

HK-2 cells were treated with TGF-β1 to mimic renal fibrosis in vitro. Gene and protein expressions in HK-2 cells were measured by qRT-PCR and Western-blot, respectively. ELISA was used to test the level of creatinine (CR) and blood urea nitrogen (BUN) in serum of mice. Additionally, unilateral ureteral obstruction (UUO)-induced renal fibrosis mice model was established to investigate the effect of PVT1 on renal fibrosis in vivo.

RESULTS

PVT1 was upregulated in TGF-β1-treated HK-2 cells. In addition, TGF-β1-induced upregulation of α-SMA and fibronectin in HK-2 cells was significantly reversed by PVT1 knockdown. Meanwhile, PVT1 bound to miR-181a-5p in HK-2 cells. Moreover, miR-181a-5p directly targeted TGF-βR1. Furthermore, miR-181a-5p antagonist could significantly reverse the anti-fibrotic effect of PVT1 knockdown. Besides, knockdown of PVT1 notably attenuated the symptom of renal fibrosis in vivo.

CONCLUSION

Knockdown of PVT1 significantly inhibited the progression of renal fibrosis in vitro and in vivo. Thus, PVT1 may serve as a potential target for the treatment of renal fibrosis.

Long Non-Coding RNA (LncRNA)-ATB Promotes Inflammation, Cell Apoptosis and Senescence in Transforming Growth Factor-β1 (TGF-β1) Induced Human Kidney 2 (HK-2) Cells via TGFβ/SMAD2/3 Signaling Pathway

Background

Renal fibrosis occurs in the end-stage of all chronic kidney disease. Transforming growth factor-β1 (TGF-β1) is a central contributor in fibrosis. Identifying effective biomarkers that targets TGF-β1 is necessary for the development of therapeutic agents for kidney disease. In this study, we investigated the effects and mechanism of long non-coding RNA (LncRNA)-ATB in TGF-β1 induced human kidney 2 (HK-2) cells.

Material/Methods

We investigated the effects of either overexpression or knockdown of LncRNA-ATB on inflammation, cell apoptosis, and senescence in TGF-β1 induced HK-2 cells. TGF-β1 induced HK-2 cells served as the cell model. The gene level was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and protein expressions by western blot. Cell Counting Kit-8 (CCK-8) assay was performed for assessment of cell viability. Flow cytometry was applied for detection of cell apoptosis. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were measured by corresponding kits.

Results

LncRNA-ATB was highly expressed in TGF-β1 induced HK-2 cells. Inflammation, cell apoptosis, and senescence were enhanced by TGF-β1 and these effects were all reduced by knockdown of LncRNA-ATB. Whereas overexpression of LncRNA-ATB had the opposite effects with knockdown of LncRNA-ATB. The TGFβ/SMAD2/3 signaling pathway was activated by TGF-β1 and this effect was further enhanced by LncRNA-ATB overexpression. Silencing LncRNA-ATB inhibited the TGFβ/SMAD2/3 signaling pathway in TGF-β1 induced cells. The effects of LncRNA-ATB overexpression aforementioned in TGF-β1 induced cells were abolished by blockage of the TGFβ/S0MAD2/3 signaling pathway.

Conclusions

LncRNA-ATB overexpression have promoting effects on inflammation, cell apoptosis and senescence in TGF-β1 induced HK-2 cells via activating the TGFβ/SMAD2/3 signaling pathway. LncRNA-ATB act as a key downstream mediator via activating the TGFβ/SMAD2/3 signaling pathway and silencing LncRNA-ATB might be a new strategy for chronic kidney disease treatment.

Diverse Role of TGF-β in Kidney Disease

Inflammation and fibrosis are two pathological features of chronic kidney disease (CKD). Transforming growth factor-β (TGF-β) has been long considered as a key mediator of renal fibrosis. In addition, TGF-β also acts as a potent anti-inflammatory cytokine that negatively regulates renal inflammation. Thus, blockade of TGF-β inhibits renal fibrosis while promoting inflammation, revealing a diverse role for TGF-β in CKD. It is now well documented that TGF-β1 activates its downstream signaling molecules such as Smad3 and Smad3-dependent non-coding RNAs to transcriptionally and differentially regulate renal inflammation and fibrosis, which is negatively regulated by Smad7. Therefore, treatments by rebalancing Smad3/Smad7 signaling or by specifically targeting Smad3-dependent non-coding RNAs that regulate renal fibrosis or inflammation could be a better therapeutic approach. In this review, the paradoxical functions and underlying mechanisms by which TGF-β1 regulates in renal inflammation and fibrosis are discussed and novel therapeutic strategies for kidney disease by targeting downstream TGF-β/Smad signaling and transcriptomes are highlighted.