Association of Vascular Calcification with Serum lncRNA H19 and Runx2 mRNA Expression in Patients with Uremia.

Background: The objective of this study was to investigate the relationship between vascular calcification, serum lncRNA H19, and Runt-Related Transcription Factor 2 mRNA expression in patients with uremia. Methods: This study is a retrospective study which recruited 146 patients with uremia on dialysis from December 2021 to November 2022. Participants were divided into the VC and non-VC groups based on their chest X-ray calcification ratings. General and clinical data were collected from all patients. Serum H19, Runx2 mRNA, mineral bone disease effectors, and other blood markers were tested. Univariate analysis was performed to compare the changes in each clinical index between these two groups of patients. A multi-factor logistic regression analysis of risk factors for VC was performed. Receiver operating characteristics analyzed the H19 and Runx2 for their diagnostic values for VC. Pearson's test was used to analyze the correlation between the H19 and Runx2 expression and the factors influencing VC. Results: Patients in the VC group had significantly higher creatinine, serum phosphorus, calcium, BMP-2, FGF-23, OPG, and iPTH levels than those in the non-VC group (P < .05), while their albumin levels were significantly lower than those in the non-VC group (P < .05). The expression of H19 and Runx2 mRNA was significantly upregulated in the serum of VC patients (P < .05). H19 was significantly positively correlated with creatinine, serum phosphorus, calcium, BMP-2, OPG, and iPTH (P < .05). Runx2 mRNA was significantly positively correlated with creatinine, FGF-23, and iPTH (P < .05 ), while there was no significant correlation with other factors(P > .05). Albumin, BMP-2, iPTH, H19, and Runx2 were independent correlative-factors of uremic VC. In addition, the combined H19 and Runx2 test (AUC=0.850; 95% CI: 0.781-0.903) had good diagnostic values for the development of VC. Conclusion: Serum H19 and Runx2 levels are significantly associated with VC-related factors and are independent risk factors for uremic VC, and their levels contribute to the diagnosis of uremic VC.

Hypomethylation of the LncRNA H19 promoter accelerates osteogenic differentiation of vascular smooth muscle cells by activating the Erk1/2 pathways.

OBJECTIVE: Vascular calcification is a common chronic kidney disease complication. This study aimed to investigate the function of long non-coding RNA (LncRNA) H19 in vascular calcification to explore new therapeutic strategies. METHODS: We induced osteogenic differentiation and calcification of vascular smooth muscle cells (VSMCs) using ß-glycerophosphate. Then, we detected the LncRNA H19 promoter methylation status and Erk1/2 pathways using methylation-specific polymerase chain reaction and western blotting, respectively. RESULTS: Compared with the control group, high phosphorus levels induced VSMC calcification, accompanied by increases in LncRNA H19 and the osteogenic marker Runx2 and reduction of the contractile phenotype marker SM22a. LncRNA H19 knockdown inhibited osteogenic differentiation and calcification of VSMCs. However, the suppressed role of VSMC calcification caused by shRNA H19 was partially reversed by simultaneous activation of the Erk1/2 pathways. Mechanically, we found that the methylation rate of CpG islands in the LncRNA H19 promoter region was significantly lower in the high-phosphorus group, and the hypomethylation state elevated LncRNA H19 levels, which in turn regulated phosphorylated Erk1/2 expression. CONCLUSIONS: LncRNA H19 promoted osteogenic differentiation and calcification of VSMCs by regulating the Erk1/2 pathways. Additionally, hypomethylation of LncRNA H19 promoter CpG islands upregulated LncRNA H19 levels and subsequently activated Erk1/2 phosphorylation.

Transgelin-2 as an Early Detection for Diabetic Nephropathy Through Inflammation, Periostin and E-cadherin by STAT3 Signaling Through ANXA2.

BACKGROUND: Diabetic nephropathy (hereinafter referred to as DN) is one of the important causes of chronic renal failure, with great harm. We aimed to elucidate the role of transgelin-2, a key early detection for diabetic ne-phropathy. METHOD: The serum samples of 12 DN patients and 12 normal volunteers were collected for this experiment. Mice of the model group were injected intraperitoneally with streptozotocin following a high fat diet. Mouse podocyte (MPC5) cells were induced with 20 mmol/L d-glucose. RESULT: Transgelin-2 was highly expressed in DN patients with diabetic nephropathy both at the expression levels of mRNA and protein. Transgelin-2 expression was correlated with blood sugar in patients with DN. Transgelin-2 gene up-regulation enhanced inflammation and periostin levels, and reduced E-cadherin activity level in mice with DN. Over-expression of transgelin-2 increased inflammation and periostin levels, and reduced E-cadherin activity level in the in vitro model. Down-regulation of Transgelin-2 reduced inflammation and periostin levels and induced E-cadherin activity level in the in vitro model. Transgelin-2 induced ANXA2/ STAT3 signaling in a mouse model or an in vitro model. ANXA2 was one of the regulatory factors for the effects of transgelin-2 with inflammation, periostin, and E-cadherin in a model of DN. CONCLUSIONS: Taken together, these findings demonstrated that transgelin-2 promoted inflammation and periostin levels, and suppressed E-cadherin levels in DN by STAT3 signaling through ANXA2.

Interference of periostin attenuates pathological changes, proinflammatory markers and renal fibrosis in diabetic kidney injury.

BACKGROUND: Diabetic nephropathy (DN) is a prevalent complication of diabetes, in which inflammation and fibrosis are the significant pathogenesis. Periostin is a matricellular protein that functions on stabilizing the extracellular matrix by binding to integrins during development. This study aimed to explored the role of periostin in DN. METHODS: The animal and cell models of DN were constructed in streptozocin (STZ)-induced mice and high glucose-challenged human mesangial cells (HMCs). The role of periostin in pathological changes, inflammation and fibrosis in DN was investigated through biochemical detection, HE and Masson staining and scores, western blot, enzyme­linked immunosorbent assay (ELISA) and real-time quantitative PCR (RT-qPCR) assays. RESULTS: Knockdown of periostin counteracted the STZ-induced the ratio of kidney weight and body weight, and the concentrations of urine albumin excretion (UAE), serum creatinine (Scr), urine albumin/creatinine ratio (UACR) and blood urea nitrogen (BUN) in mice. Moreover, silencing of periostin alleviated the pathological manifestations and reduced the concentrations of IL-6, TNF-α and IL-1ß in mice kidney tissues and sera. Also, downregulation of periostin decreased the relative protein expression of fibronectin, collagen IV and α-SMA in kidney tissues. Meanwhile, interference of periostin attenuated the levels of pro-inflammation factors and the expressions of fibrosis markers in HG-induced HMCs. CONCLUSION: Interference of periostin resisted DN via attenuating the pro-inflammatory cytokines release and renal fibrosis in diabetic kidney injury. Our study establishes a basis for its further study and underlying application in clinical practice in diagnosing and treating diabetic kidney injury or other relevant diseases.

LncTUG1 ameliorates renal tubular fibrosis in experimental diabetic nephropathy through the miR-145-5p/dual-specificity phosphatase 6 axis.

The renal interstitial fibrosis contributes to the progression and deterioration of diabetic nephropathy (DN). Long noncoding RNA taurine-up-regulated gene 1 (TUG1) in kidneys may be down-regulated by hyperglycemia. We aim to explore its role in tubular fibrosis caused by high glucose and the possible target genes of TUG1. In this study, a streptozocin-induced accelerated DN mouse model and a high glucose-stimulated HK-2 cells model was established to evaluate TUG1 expression. Potential targets of TUG1 were analyzed by online tools and confirmed by luciferase assay. A rescue experiment and gene silencing assay were used to investigate whether TUG1 plays its regulation role via miR-145-5p/dual-specificity phosphatase 6 (DUSP6) in HK2 cells. The effects of TUG1 on inflammation and fibrosis in high glucose treated tubular cells were evaluated by in vitro study, as well as in vivo DN mice model through AAV-TUG1 delivery. Results showed TUG1was downregulated in HK2 cells incubated with high glucose while miR-145-5p was upregulated. Overexpression of TUG1 alleviated renal injury by suppressing inflammation and fibrosis in vivo. Overexpression of TUG1 inhibited HK-2 cell fibrosis and relieved the inflammation. A mechanism study demonstrated that TUG1 directly sponged to miR-145-5p, and DUSP6 was identified as a target downstream of miR-145-5p. In addition, miR-145-5 overexpression and DUSP6 inhibition countervailed the impacts of TUG1. Our findings revealed that TUG1 overexpression alleviates kidney injury in DN mice and decreases the inflammatory response and fibrosis of high glucose-stimulated HK-2 cells via miR-145-5p/DUSP6 axis.

Zinc finger protein A20 regulates the development and progression of osteoarthritis by affecting the activity of NF-κB p65.

OBJECTIVE: To investigate the role of Zinc finger protein A20 in osteoarthritis (OA) by regulating NF-κB p65. METHODS: A20, MMP1, MMP13 and IL-1ß expressions in human OA cartilage samples were detected by qRT-PCR. IL-1ß-induced chondrocyte was treated with A20 lentivirus activation particle, pyrrolidine dithiocarbamate (PDTC, a NF-κB inhibitor) with/without A20 siRNA. IL-6, TNF-α, and PGE2 levels were measured by ELISA, and NO production by Greiss reaction. Destabilization of the medial meniscus (DMM) surgery was used to construct the OA models, followed by injection of A20 adenovirus. MMP1 and MMP13 expression was measured by immunohistochemistry. The mRNA and protein expression were performed by qRT-PCR and western blotting, respectively. RESULTS: A20 was down-regulated in human OA cartilage samples, and negatively correlated with the expressions of MMP1, MMP13 and IL-1ß. The IL-1ß-induced chondrocyte manifested decreased A20 with increased NF-κB p65 activity. A20 overexpression suppressed the NF-κB p65 activity in IL-1ß-induced chondrocyte. Furthermore, PDTC decreased IL-1ß-induced chondrocyte apoptosis with the upregulated COL1A1, COL2A1, COL10A1 and ACAN, as well as the down-regulated MMP1, MMP13, COX2, iNOS, IL-6, TNF-α, NO and PGE2, which was reversed by A20 siRNA. In vivo, OA mice gained higher OARSI score and Mankin's score, exhibited up-regulations of MMP1 and MMP13, and decreased NF-κB p65 activity, which was improved after injection of A20 adenovirus. CONCLUSION: A20 was reduced in OA cartilage samples, and its overexpression, by suppressing the activity of NF-κB p65, could improve IL-1ß-induced chondrocyte degradation and apoptosis in vitro, as well as mitigate the inflammation in OA mice.

Knockout of NGAL aggravates tubulointerstitial injury in a mouse model of diabetic nephropathy by enhancing oxidative stress and fibrosis.

Neutrophil gelatinase-associated lipocalin (NGAL), also called lipocalin 2, is considered a promising biomarker for acute and chronic kidney injuries. Several studies have demonstrated that its levels increase in plasma and urine in diabetic nephropathy (DN), and its urine concentration increases upon kidney function deterioration. However, its role in DN progression remains unclear. The current study used in vitro gene expression knockdown in human proximal tubular cell line human kidney (HK)2 to investigate the role of NGAL in oxidation and extracellular matrix secretion under high-glucose (HG) incubation. In addition, type 1 diabetes was induced in vivo in knockout NGAL-/- and wild-type mice in order to investigate role of NGAL in the progression of DN. The results demonstrated that NGAL knockdown in HK2 cells significantly increased oxidative stress under HG stimulation tested by flow cytometry, and increased the secretion of interleukin-6, fibronectin (FN) and collagen IV examined by ELISA. Western blotting demonstrated that the phosphorylation of Smad2/3 also increased in HK2 cells under transforming growth factor-ß1 stimulation. In vivo experiments demonstrated that diabetic NGAL-/- mice showed deteriorated renal function compared with that of diabetic wild-type mice. Histopathological analysis suggests that diabetic NGAL-/- mice had more serious glomerulosclerosis and tubular vascular degeneration than wild-type mice. Immunohistochemistry suggested that the absence of NGAL lead to increased FN deposition in glomeruli in a mouse model of DN. In conclusion, NGAL appears to have renal protective effects by slowing down the progression of DN, and its effect may be associated with a reduction in oxidation, fibrosis and inflammation.

PKCα regulates vasopressin-induced aquaporin-2 trafficking in mouse kidney collecting duct cells in vitro via altering microtubule assembly.

AIM: Aquaporin-2 (AQP2) is a vasopressin-regulated water channel located in the collecting tubule and collecting duct cells of mammalian kidney. The aim of this study is to investigate whether PKCα plays a role in vasopressin-induced AQP2 trafficking in mouse inner medullary collecting duct 3 (mIMCD3) cells. METHODS: AQP2-mIMCD3 stable cell line was constructed by transfection of mouse inner medullary collecting duct 3 (mIMCD3) cells with AQP2-GFP construct. Then the cells were transfected with PKCα shRNA, PKCα A/25E, or PKCα scrambled shRNA. The expression levels of PKCα, AQP2, and phospho-S256-AQP2 were analyzed using Western blot. The interaction between AQP2 and PKCα was examined using immunoprecipitation. The distribution of AQP2 and microtubules was studied using immunocytochemistry. The AQP2 trafficking was examined using the biotinylation of surface membranes. RESULTS: Treatment of AQP2-mIMCD3 cells with 100 µmol/L of 1-desamino-8-D-arginine vasopressin (DdAVP) for 30 min stimulated the translocation of AQP2 from the cytoplasm to plasma membrane through influencing the microtubule assembly. Upregulation of active PKCα by transfection with PKCα A/25E plasmids resulted in de-polymerization of α-tubulin and redistributed AQP2 in the cytoplasm. Down-regulation of PKCα by PKCα shRNA partially inhibited DdAVP-stimulated AQP2 trafficking without altering α-tubulin distribution. Although 100 µmol/L of DdAVP increased AQP2 phosphorylation at serine 256, down-regulation of PKCα by PKCα shRNA did not influence DdAVP-induced AQP2 phosphorylation, suggesting that AQP2 phosphorylation at serine 256 was independent of PKCα. Moreover, PKCα did not physically interact with AQP2 in the presence or absence of DdAVP. CONCLUSION: Our results suggested that PKCα regulates AQP2 trafficking induced by DdAVP via microtubule assembly.

Effects of hyperosmolality on expression of urea transporter A2 and aquaporin 2 in mouse medullary collecting duct cells.

In this study, the effects of hyperosmolality on the expression of urea transporter A2 (UTA2) and aquaporin 2 (AQP2) were investigated in transfected immortalized mouse medullary collecting duct (mIMCD3) cell line. AQP2-GFP-pCMV6 and UTA2-GFP-pCMV6 plasmids were stably transfected into mIMCD3 cells respectively. Transfected mIMCD3 and control cells were cultured in different hypertonic media, which were made by NaCl alone, urea alone, or an equiosmolar mixture of NaCl and urea. The mRNA and protein expression of AQP2 was elevated by the stimulation of NaCl alone, urea alone and NaCl plus urea in AQP2-mIMCD3 cells; whereas NaCl alone and NaCl plus urea rather than urea alone increased the mRNA and protein expression of UTA2 in UTA2-mIMCD3 cells, and all the expression presented an osmolality-dependent manner. Moreover, the mRNA and protein expression of UTA2 rather than AQP2 was found to be synergistically up-regulated by a combination of NaCl and urea in mIMCD3 cells. It is concluded that NaCl and urea synergistically induce the expression of UTA2 rather than AQP2 in mIMCD3 cells, and hyperosmolality probably mediates the expression of AQP2 and UTA2 through different mechanisms.

Effects of Hyperosmolality on Expression of Urea Transporter A2 and Aquaporin 2 in Mouse Medullary Collecting Duct Cells / 华中科技大学学报（医学）（英德文版）

In this study,the effects of hyperosmolality on the expression of urea transporter A2 (UTA2) and aquaporin 2 (AQP2) were investigated in transfected immortalized mouse medullary collecting duct (mIMCD3) cell line.AQP2-GFP-pCMV6 and UTA2-GFP-pCMV6 plasmids were stably transfected into mIMCD3 cells respectively.Transfected mIMCD3 and control cells were cultured in different hypertonic media,which were made by NaCl alone,urea alone,or an equiosmolar mixture of NaCl and urea.The mRNA and protein expression of AQP2 was elevated by the stimulation of NaCl alone,urea alone and NaCl plus urea in AQP2-mIMCD3 cells; whereas NaCl alone and NaCl plus urea rather than urea alone increased the mRNA and protein expression of UTA2 in UTA2-mIMCD3 cells,and all the expression presented an osmolality-dependent manner.Moreover,the mRNA and protein expression of UTA2 rather than AQP2 was found to be synergistically up-regulated by a combination of NaC1 and urea in mIMCD3 cells.It is concluded that NaC1 and urea synergistically induce the expression of UTA2 rather than AQP2 in mIMCD3 cells,and hyperosmolality probably mediates the expression of AQP2 and UTA2 through different mechanisms.