Recent advances in the involvement of epigenetics in the pathogenesis of systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a typical systemic autoimmune disease that manifests as skin rash, arthritis, lymphadenopathy, and multiple organ lesions. Epigenetics, including DNA methylation, histone modification, and non-coding RNA regulation, mainly affect the function and characteristics of cells through the regulation of gene transcription or translation. Increasing evidence indicates that there are a variety of complex epigenetic effects in patients with SLE, which interfere with the differentiation and function of T, and B lymphocytes, monocytes, and neutrophils, and enhance the expression of SLE-associated pathogenic genes. This paper summarizes our currently knowledge regarding pathogenesis of SLE, and introduces current advances in the epigenetic regulation of SLE from three aspects: immune function, inflammatory response, and lupus complications. We propose that epigenetic changes could be used as potential biomarkers and therapeutic targets of SLE.

Loss of FUT8 in renal tubules ameliorates ischemia-reperfusion injury-induced renal interstitial inflammation transition to fibrosis via the TLR3-NF-κB pathway.

Renal ischemia-reperfusion injury (IRI) is a common reason of acute kidney injury (AKI). AKI can progress to chronic kidney disease (CKD) in some survivors. Inflammation is considered the first-line response to early-stage IRI. We previously reported that core fucosylation (CF), specifically catalyzed by α-1,6 fucosyltransferase (FUT8), exacerbates renal fibrosis. However, the FUT8 characteristics, role, and mechanism in inflammation and fibrosis transition remain unclear. Considering renal tubular cells are the trigger cells that initiate the fibrosis in the AKI-to-CKD transition in IRI, we targeted CF by generating a renal tubular epithelial cell (TEC)-specific FUT8 knockout mouse and measured FUT8-driven and downstream signaling pathway expression and AKI-to-CKD transition. During the IRI extension phase, specific FUT8 deletion in the TECs ameliorated the IRI-induced renal interstitial inflammation and fibrosis mainly via the TLR3 CF-NF-κB signaling pathway. The results firstly indicated the role of FUT8 in the transition of inflammation and fibrosis. Therefore, the loss of FUT8 in TECs may be a novel potential strategy for treating AKI-CKD transition.

Bone marrow mesenchymal stem cell-derived exosomal miR-34c-5p ameliorates RIF by inhibiting the core fucosylation of multiple proteins.

Renal interstitial fibrosis (RIF) is an incurable pathological lesion in chronic kidney diseases. Pericyte activation is the major pathological characteristic of RIF. Fibroblast and macrophage activation are also involved in RIF. Studies have revealed that core fucosylation (CF), an important post-translational modification of proteins, plays a key role in pericyte activation and RIF by regulating multiple profibrotic signaling pathways as a hub-like target. Here, we reveal that mesenchymal stem cell (MSC)-derived exosomes reside specifically in the injured kidney and deliver microRNA (miR)-34c-5p to reduce cellular activation and RIF by inhibiting CF. Furthermore, we showed that the CD81-epidermal growth factor receptor (EGFR) ligand-receptor complex aids the entry of exosomal miR-34c-5p into pericytes, fibroblasts, and macrophages. Altogether, our findings reveal a novel role of MSC-derived exosomes in inhibiting multicellular activation via CF and provide a potential intervention strategy for renal fibrosis.

Durable Electrocatalytic Reduction of Nitrate to Ammonia over Defective Pseudobrookite Fe2 TiO5 Nanofibers with Abundant Oxygen Vacancies.

We propose the pseudobrookite Fe2 TiO5 nanofiber with abundant oxygen vacancies as a new electrocatalyst to ambiently reduce nitrate to ammonia. Such catalyst achieves a large NH3 yield of 0.73 mmol h-1 mg-1 cat. and a high Faradaic Efficiency (FE) of 87.6 % in phosphate buffer saline solution with 0.1 M NaNO3 , which is lifted to 1.36 mmol h-1 mg-1 cat. and 96.06 % at -0.9 V vs. RHE for nitrite conversion to ammonia in 0.1 M NaNO2 . It also shows excellent electrochemical durability and structural stability. Theoretical calculation reveals the enhanced conductivity of this catalyst and an extremely low free energy of -0.28 eV for nitrate adsorption at the presence of vacant oxygen.

Blocking core fucosylation of epidermal growth factor (EGF) receptor prevents peritoneal fibrosis progression.

OBJECTIVE: Peritoneal fibrosis (PF) ultimately causes ultrafiltration failure and peritoneal dialysis (PD) termination, but there are few effective therapies for it. Core fucosylation, which is catalyzed by α1,6-fucosyltransferase (Fut8) in mammals, may play a crucial role in PF development. This study aims to assess the effects of inhibiting core fucosylation of epidermal growth factor (EGF) receptor on PF rats. METHODS: PF rats (established by 4.25% glucose dialysate) were treated with either an adenovirus-Fut8 short hairpin RNA (Fut8shRNA) or adenovirus-control. Masson's staining and net ultrafiltration were performed at week six. Fut8 level and core fucosylation of EGF receptor and collagen I in the peritoneal membrane were assessed, and EGF signaling was detected, including signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa B (NF-κB) and their phosphorylation. Monocyte chemoattractant protein-1 (MCP-1) in peritoneal effluent was examined. RESULTS: Fut8 was upregulated in PF rats but decreased after Fut8shRNA treatment. EGF and EGF receptor expression was upregulated in PF rats, while core fucosylation of EGF receptor decreased after Fut8shRNA treatment. Masson's staining results showed an increase in peritoneal thickness in PF rats but a decrease after Fut8shRNA treatment. Fut8shRNA treatment increased net ultrafiltration, reduced the expression of collagen I and MCP-1 compared to PF rats. Fut8shRNA treatment suppressed phosphorylation of STAT3 and NF-κB in the peritoneal membrane of PF rats. CONCLUSIONS: Fut8shRNA treatment ameliorated the fibrotic changes in PF rats. A potential mechanism may be that Fut8shRNA treatment inactivated EGF signaling pathway by suppressing the phosphorylation of STAT3 and NF-κB.

Radial augmentation index may be an effective predictor of vascular calcification in patients on peritoneal dialysis.

Vascular calcification (VC) is an important promoter of cardiovascular disease (CVD) in patients undergoing peritoneal dialysis (PD). Several indices can be used to evaluate VC, including the abdominal aortic calcification index (AACI) and carotid artery intima-media thickness (IMT); however, simpler and lesser expensive predictors, such as the radial augmentation index (RAI), should be investigated. A total of 101 patients undergoing PD were recruited to measure RAI, AACI, and carotid artery IMT and perform echocardiography. Fifty healthy controls (HCs) were recruited to undergo RAI measurement. RAI in patients undergoing PD was significantly higher than the RAI in HCs (86.25%±8.39% vs. 76.05%±9.81%, p < 0.05). Patients undergoing PD and who suffer with diabetic mellitus, hypertension, and CVD had more severe VC than those without the abovementioned diseases. In patients with PD, RAI was positively correlated with AACI (r = 0.671, p < 0.05) and carotid artery IMT (r = 0.596, p < 0.05). RAI was positively correlated with left ventricular end-diastolic dimensions (LVDd; r = 0.678, p < 0.05), left ventricular mass index (r = 0.595, p < 0.05), and negatively correlated with early-diastolic mitral inflow velocity/late-diastolic mitral inflow velocity (r = -0.342, p < 0.05) and left ventricular ejection fraction (r= -0.497, p < 0.05). Multiple linear regression analysis showed that RAI was associated with AACI, LVDd, age, and serum phosphate (p < 0.05). RAI might be an effective predictor of VC and cardiac structural/functional abnormalities in patients undergoing PD.

Inhibition of core fucosylation limits progression of diabetic kidney disease.

BACKGROUND: FUT8-mediated core fucosylation, which transfers a fucose residue from GDP-fucose to core-GlcNAc of the N-linked type glycoproteins, is crucial for signaling receptors function. Core fucosylation is involved in various biological processes such as cell proliferation, apoptosis, differentiation and immune regulation. Our previous studies demonstrated that inhibiting core fucosylation prevented renal interstitial fibrosis of UUO murine models, but its role in the development of diabetic kidney disease (DKD) remains unclear. This study aimed to clarify the protective effects and molecular mechanisms during the progress of DKD by inhibiting core fucosylation in vivo. METHODS: Core fucosylation was examined in streptozotocin (STZ)-induced diabetic mouse model. Then a new Fut8 mutation mouse model in which exon 7 of Fut8 gene is deleted was constructed for diabetes induction. Metabolic and renal parameters were measured. Renal structure, fibrosis, and podocyte injury were assessed, and underlying mechanisms were investigated. RESULTS: The levels of fasting blood glucose, glycated hemoglobin, kidney-weight-to- body-weight (KW/BW) and urine albumin-to-creatinine (ACR) were increased at 16 weeks post injection. KW/BW and urine ACR were decreased significantly by inhibiting core fucosylation. The renal pathology, fibrosis, and podocyte injury were mitigated significantly by inhibiting core fucosylation. The protective effects of inhibiting core fucosylation were mediated by downregulated of the phosphorylation of Smad2/3 and extracellular signal-regulated kinase (ERK). CONCLUSIONS: Our results indicate that FUT8-based treatment might be a promising intervention strategy in therapeutic paradigm of DKD.

Inhibiting core fucosylation attenuates glucose-induced peritoneal fibrosis in rats.

Ultrafiltration failure is a major complication of long-term peritoneal dialysis, resulting in dialysis failure. Peritoneal fibrosis induced by continuous exposure to high glucose dialysate is the major contributor of ultrafiltration failure, for which there is no effective treatment. Overactivation of several signaling pathways, including transforming growth factor-ß1 (TGF-ß1) and platelet-derived growth factor (PDGF) pathways, contribute to the development of peritoneal fibrosis. Therefore, simultaneously blocking multiple signaling pathways might be a potential novel method of treating peritoneal fibrosis. Previously, we showed that core fucosylation, an important posttranslational modification of the TGF-ß1 receptors, can regulate the activation of TGF-ß1 signaling in renal interstitial fibrosis. However, it remains unclear whether core fucosylation affects the progression of peritoneal fibrosis. Herein, we show that core fucosylation was enriched in the peritoneal membrane of rats accompanied by peritoneal fibrosis induced by a high glucose dialysate. Blocking core fucosylation dramatically attenuated peritoneal fibrosis in the rat model achieved by simultaneously inactivating the TGF-ß1 and PDGF signaling pathways. Next the protective effects of blocking core fucosylation and imatinib (a selective PDGF receptor inhibitor) on peritoneal fibrosis were compared and found to exhibit a greater inhibitory effect over imatinib alone, suggesting that blocking activation of multiple signaling pathways may have superior inhibitory effects on the development of peritoneal fibrosis. Thus, core fucosylation is essential for the development of peritoneal fibrosis by regulating the activation of multiple signaling pathways. This may be a potential novel target for drug development to treat peritoneal fibrosis.

The interactions between mitochondria and sarcoplasmic reticulum and the proteome characterization of mitochondrion-associated membrane from rabbit skeletal muscle.

To obtain a comprehensive understanding of proteins involved in mitochondrion-sarcoplasmic reticulum (SR) linking, a catalog of proteins from mitochondrion-associated membrane (MAM) of New Zealand white rabbit skeletal muscle were analyzed by an optimized shotgun proteomic method. The membrane fractions were prepared by differential centrifugation and separated by 1D electrophoresis followed by a highly reproducible, automated LC-MS/MS on the hybrid linear ion trap (LTQ)-Orbitrap mass spectrometer. By integrating as low as 1% false discovery rate as one of the features for quality control method, 459 proteins were identified from both of the two independent MAM preparations. Protein pI value, molecular weight range, and transmembrane region were calculated using bioinformatics softwares. One hundred one proteins were recognized as membrane proteins. This protein database suggested that the MAM preparations composed of proteins from mitochondrion, SR, and transverse-tubule. This result indicated mitochondria physically linked with SR in rabbit skeletal muscle, voltage-dependent anion channel 1 (VDAC1), VDAC2, and VDAC3 might participate in formation of the tethers between SR and mitochondria.

Shotgun proteomic analysis of sarcoplasmic reticulum preparations from rabbit skeletal muscle.

To obtain a comprehensive understanding of proteins involved in excitation-contraction coupling, a catalog of proteins from sarcoplasmic reticulum (SR) membrane fractions of New Zealand white rabbit skeletal muscle was analyzed by an optimized shotgun proteomic method. Light and heavy SR membrane fractions were obtained by nonlinear sucrose gradient centrifugation and separated by 1DE followed by a highly reproducible, automated LC-MS/MS on the hybrid linear ion trap (LTQ) Orbitrap mass spectrometer. By integrating as low as 1% false discovery rate as one of the features for quality control method, 483 proteins were identified from both of the two independent SR preparations. Proteins involved in calcium release unit complex, including ryanodine receptor 1, dihydropyridine receptor, calmodulin, triadin, junctin, and calsequestrin, were all detected, which offered validation for this protein identification method. Rigorous bioinformatics analysis was performed. Protein pI value, molecular weight range, hydrophobicity index, and transmembrane region were calculated using bioinformatics softwares. Eighty-three proteins were classified as hydrophobic proteins and 175 proteins were recognized as membrane proteins. Based on the proteomic analysis results, we found as the first time that not only transverse tubule but also mitochondrion physically connected to SR. The complete mapping of these proteomes may help in the elucidation of the process of excitation-contraction coupling and excitation-metabolism coupling.

Core fucosylation involvement in the paracrine regulation of proteinuria-induced renal interstitial fibrosis evaluated with the use of a microfluidic chip.

Proteinuria is a clinical manifestation of chronic kidney disease that aggravates renal interstitial fibrosis (RIF), in which injury of peritubular microvessels is an important event. However, the changes in peritubular microvessels induced by proteinuria and their molecular mechanisms remain unclear. Thus, we aimed to develop a co-culture microfluidic device that contains renal tubules and peritubular microvessels to create a proteinuria model. We found that protein overload in the renal tubule induced trans-differentiation and apoptosis of endothelial cells (ECs) and pericytes. Moreover, profiling of secreted proteins in this model revealed that a paracrine network between tubules and microvessels was activated in proteinuria-induced microvascular injury. Multiple cytokine receptors in this paracrine network were core-fucosylated. Inhibition of core fucosylation significantly reduced ligand-receptor binding ability and blocked downstream pathways, alleviating trans-differentiation and apoptosis of ECs and pericytes. Furthermore, the protective effect of genetic FUT8 deficiency on proteinuria overload-induced RIF and pericyte-myofibroblast trans-differentiation was validated in FUT8 knockout heterozygous mice. In conclusion, we constructed and used a multiple-unit integrated microfluidic device to uncover the mechanism of proteinuria-induced RIF. Furthermore, FUT8 may serve as a hub-like therapeutic target to alleviate peritubular microvascular injury in RIF. STATEMENT OF SIGNIFICANCE: In this study, we constructed a multiple-unit integrated renal tubule-vascular chip. We reproduced human proteinuria on the chip and found that multiple receptors were modified by FUT8-catalyzed core fucosylation (CF) involved in the cross-talk between renal tubules and peritubular microvessels in proteinuria-induced RIF, and inhibiting the FUT8 of receptors could block the tubule-microvessel paracrine network and reverse the damage of peritubular microvessels and renal interstitial fibrosis. This tubule-vascular chip may provide a prospective platform to facilitate future investigations into the mechanisms of kidney diseases, and target-FUT8 inhibition may be an innovative and potential therapeutic strategy for RIF induced by proteinuria.

Positive association of serum FUT8 activity with renal tubulointerstitial injury in IgA nephropathy patients.

BACKGROUND: α-1,6 Fucosyltransferase (FUT8) appears to play an essential role in the pathogenesis of renal fibrosis. However, it remained unknown whether FUT8 also contributed to renal fibrosis in immunoglobulin A nephropathy (IgAN). In the present study, we explored the association of serum FUT8 activity with renal tubulointerstitial injury in IgAN patients. METHODS: Serum FUT8 activity was measured in 135 IgAN patients and 68 healthy controls from January 2016 to December 2018. The relationships of serum FUT8 activity with clinical and pathological features were analyzed. RESULTS: Relative to healthy controls, IgAN patients had significantly higher serum FUT8 activity and upregulation of renal FUT8 protein (p < .05). Among IgAN patients, there was a positive correlation of serum FUT8 activity with renal FUT8 protein expression (p < .05). Multivariable logistic regression analyses showed that serum FUT8 activity was significantly associated with serum creatinine and eGFR (p < .05). Based on a cut-off value determined from ROC curve analysis, we divided IgAN patients into a low serum FUT8 activity group (≤12.2 pmol/h/mL, n = 40) and a high serum FUT8 activity group (>12.2 pmol/h/ml, n = 95). The high serum FUT8 activity group had a higher Oxford T score, increased inflammatory cell infiltration, more severe fibrosis and poor renal function (p < .05). CONCLUSION: Serum FUT8 activity was positive association with renal tubulointerstitial injury in IgAN patients.

Blocking Posttranslational Core Fucosylation Ameliorates Rat Peritoneal Mesothelial Cell Epithelial-Mesenchymal Transition.

BACKGROUND:: Core fucosylation (CF), catalyzed by α-1,6 fucosyltransferase (Fut8) in mammals, plays an important role in pathological processes through posttranslational modification of key signaling receptor proteins, including transforming growth factor (TGF)-ß receptors and platelet-derived growth factor (PDGF) receptors. However, its effect on peritoneal fibrosis is unknown. Here, we investigated its influence on epithelial-mesenchymal transition (EMT) of rat peritoneal mesothelial cells (PMCs) in vitro induced by a high-glucose (HG) culture solution. METHODS:: Rat PMCs were first cultured in a HG (2.5%) culture solution to observe the CF expression level (fluorescein isothiocyanate-lens culinaris agglutinin), we next established a knockdown model of rat PMCs in vitro with Fut8 small interfering RNA (siRNA) to observe whether inhibiting CF decreases the messenger RNA (mRNA) expression and protein expression of Fut8 and reverses EMT status. Rat PMCs were randomly divided into control group, mock group (transfected with scrambled siRNA), Fut8 siRNA group, HG group, HG + mock group, and HG + Fut8 siRNA group. Finally, we examined the activation of TGF-ß/Smad2/3 signaling and PDGF/extracellular signal-regulated kinase (ERK) signaling to observe the influence of CF on them. RESULTS:: CF, Fut8 mRNA, and protein expression were all significantly upregulated in HG- induced EMT model than those in the control rat PMCs (P < 0.05). Fut8 siRNA successfully blocked CF of TGF-ß receptors and PDGF receptors and attenuated the EMT status (E-cadherin and α-SMA and phenotypic changes) in HG-induced rat PMCs. In TGF-ß/Smad2/3 signaling, Fut8 siRNA did not suppress the protein expression of TGF-ß receptors and Smad2/3; however, it significantly suppressed the phosphorylation of Smad2/3 (relative expression folds of HG + Fut8 group vs. HG group: 7.6 ± 0.4 vs. 15.1 ± 0.6, respectively, P < 0.05). In PDGF/ERK signaling, Fut8 siRNA did not suppress the protein expression of PDGF receptors and ERK, but it significantly suppressed the phosphorylation of ERK (relative expression folds of HG + Fut8 group vs. HG group: 8.7 ± 0.9 vs. 15.6 ± 1.2, respectively, P < 0.05). Blocking CF inactivated the activities of TGF-ß and PDGF signaling pathways, and subsequently blocked EMT. CONCLUSIONS:: These results demonstrate that CF contributes to rat PMC EMT, and that blocking it attenuates EMT. CF regulation is a potential therapeutic target of peritoneal fibrosis.

Novel Mechanism of the Pericyte-Myofibroblast Transition in Renal Interstitial Fibrosis: Core Fucosylation Regulation.

Pericytes have been identified as a major source of myofibroblasts in renal interstitial fibrosis (RIF). The overactivation of several signaling pathways, mainly the TGF-ß and PDGF pathways, initiates the pericyte-myofibroblast transition during RIF. Key receptors in these two pathways have been shown to be modified by fucosyltransferase 8 (FUT8), the enzyme that catalyzes core fucosylation. This study postulated that core fucosylation might play an important role in regulating the pericyte transition in RIF. The data showed that core fucosylation increased with the extent of RIF in patients with IgA nephropathy (IgAN). Similarly, core fucosylation of pericytes increased in both a unilateral ureteral occlusion (UUO) mouse model and an in vitro model of pericyte transition. Inhibition of core fucosylation by adenoviral-mediated FUT8 shRNA in vivo and FUT8 siRNA in vitro significantly reduced pericyte transition and RIF. In addition, the activation of both the TGF-ß/Smad and PDGF/ERK pathways was blocked by core fucosylation inhibition. In conclusion, core fucosylation may regulate the pericyte transition in RIF by modifying both the TGF-ß/Smad and PDGF/ERK pathways. Glycosylation might be a novel "hub" target to prevent RIF.