Diabetic neuropathy (DN) is a common and severe complication of diabetes mellitus. There is still a lack of an effective treatment to DN because of its complex pathogenesis. Thioredoxin-interacting ...protein (TXNIP), an endogenous inhibitor of thioredoxin, has been shown to be associated with diabetic retinopathy and nephropathy. Herein, we aim to investigate the role of TXNIP in prediabetic neuropathy and therapeutic potential of verapamil which has been shown to inhibit TXNIP expression. The effects of mediating TXNIP on prediabetic neuropathy and its exact mechanism were performed using high-fat diet- (HFD-) induced diabetic mice and palmitate-treated neurons. Our results showed that TXNIP upregulation is associated with prediabetic neuropathy in HFD-fed mice. TXNIP knockdown improved DN in HFD-induced prediabetic mice. Mechanistically, increased TXNIP in dorsal root ganglion is transferred into the cytoplasm and shuttled to the mitochondria. In cytoplasm, TXNIP binding to TRX1 results in the increased oxidative stress and inflammation. In mitochondria, TXNIP binding to TRX2 induced mitochondria dysfunction and apoptosis. TXNIP isolated from TRX2 then shuttles to the cytoplasm and binds to NLRP3, resulting in further increased TXNIP-NLRP3 complex, which induced the release of IL-1β and the development of inflammation. Thus, apoptosis and inflammation of dorsal root ganglion neuron eventually cause neural dysfunction. In addition, we also showed that verapamil, a known inhibitor of calcium channels, improved prediabetic neuropathy in the HFD-fed mice by inhibiting the upregulation of TXNIP. Our finding suggests that TXNIP might be a potential target for the treatment of neuropathy in prediabetic patients with dyslipidemia.
MicroRNAs (miRNAs) play vital roles in the development of diabetic nephropathy. Here, we compared the protective efficacies of miR-26a and miR-30c in renal tubular epithelial cells (NRK-52E) and ...determined whether they demonstrated additive effects in the attenuation of renal fibrosis. TGFβ1 suppressed miR-26a and miR-30c expression but up-regulated pro-fibrotic markers in NRK-52E cells, and these changes were also found in the kidney cortex of 40-week-old diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats. Bioinformatic analyses and luciferase assays further demonstrated that both miR-26a and miR-30c targeted connective tissue growth factor (CTGF); additionally, Snail family zinc finger 1 (Snail1), a potent epithelial-to-mesenchymal transition (EMT) inducer, was targeted by miR-30c. Overexpression of miR-26a and miR-30c coordinately decreased CTGF protein levels and subsequently ameliorated TGFβ1-induced EMT in NRK-52E cells. Co-silencing of miR-26a and miR-30c exhibited the opposite effect. Moreover, miR-26a and miR-30c co-silenced CTGF to decrease ERK1/2 and p38 MAPK activation. Furthermore, miR-26a was up-regulated in urinary extracellular vesicles of diabetic nephropathy patients. Our study provides evidence for the cooperative roles of miR-26a and miR-30c in the pathogenesis of diabetic nephropathy, and the co-targeting of miR-26a and miR-30c could provide a new direction for diabetic nephropathy treatment.
Diabetic kidney disease (DKD) has become the most common cause of chronic kidney disease. Proteinuria is generally considered one of the clinical indicators of renal damage, and it is also closely ...related to the progression of DKD. Accumulating evidence indicates that proteinuria induces an upregulation of the expression levels of inflammatory cytokines and fibrosis markers in renal tubular epithelial cells, but the mechanism remains unclear. Previously, we showed that early growth response 1 (Egr1) played a key role in renal tubular injury. However, the upstream mechanism of Egr1 in the development of DKD is poorly understood. In this study, we found that albumin stimulation significantly increased the expression levels of Egr1, interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and fibronectin (FN) in HK-2 cells but decreased miR-23a-3p levels. We then identified that miR-23a-3p targeted the 3′ untranslated region (UTR) of Egr1 and directly suppressed the expression of Egr1. Moreover, we found that overexpression and inhibition of miR-23a-3p in HK-2 cells attenuated and promoted the expression of IL-6, TNF-α, and FN, respectively. Additionally, Egr1 silencing reversed the inflammation and fibrosis caused by the miR-23a-3p inhibitor. Thus, we conclude that miR-23a-3p attenuates the development of DKD through Egr1, suggesting that targeting miR-23a-3p may be a novel therapeutic approach for DKD.
In diabetic patients complicated with colorectal cancer (CRC), metformin treatment was reported to have diverse correlation with CRC-specific mortality. In laboratory studies, metformin was reported ...to affect the survival of cancer stem cells (CSCs) in breast and pancreatic cancers and glioblastoma. Although cscs play a critical role in the resistance to 5-fluorouracil (5-FU) chemotherapy in CRC patients, the effect of metformin on cscs in CRC patients and the synergistic effect of metformin in combination with 5-FU on cscs are not reported. In the present study pathological examinations were performed in 86 CRC patients complicated with type 2 DM who had been divided into a metformin group and a non-metformin group. Comparisons regarding pathological type, incidence of metastasis, expression of CD133 and β-catenin were conducted between the two groups. We explored the synergistic effects of metformin in combination with 5-FU on the proliferation, cell cycle, apoptosis and the proportion of CD133+ cscs of SW620 human colorectal cancer cell lines. The results show that metformin treatment had reverse correlations with the proportion of patients with poorly differentiated adenocarcinoma, the proportion of CD133+ cscs in CRC patients with type 2 DM. Metformin enhanced the antiproliferative effects of 5-FU on CD133+ cscs in SW620 cells. These findings provide an important complement to previous study. Inhibition of the proliferation of CD133+ cscs may be a potential mechanism responsible for the association of metformin use with improved CRC outcomes in CRC patients with type 2 diabetes.
Activation of brown adipose tissue (BAT) increases energy expenditure, which makes it an attractive therapeutic strategy for obesity. LncRNAs play an important role in adipocyte differentiation and ...regulation. Here we assessed the effect of lncRNA XIST on brown preadipocytes differentiation and metabolic regulation.
XIST expression levels were detected in human perirenal (peri-N) and subcutaneous adipose tissues (sub-Q), brown preadipocytes and 3T3-L1 preadipocytes. XIST overexpression and knockdown experiments were performed in brown preadipocytes. XIST overexpression mouse model was established by plasmid injection through tail vein.
In human adipose tissues, XIST expression was significantly higher in female than in male individuals. In vitro, XIST expression was significantly up-regulated during brown adipocyte differentiation. XIST knockdown inhibited differentiation of brown preadipocytes, while overexpression of XIST promotes brown preadipocytes to fully differentiation. RNA Binding Protein Immunoprecipitation (RIP) experiment revealed that XIST could directly bind to C/EBPα. In vivo, XIST overexpression prevents high-fat diet induced obesity and improves metabolic dysorder in male mice.
Our results suggest that XIST combats obesity through BAT activation at least partly by combination with transcription factor C/EBPα.
Adipose tissue is a major source of circulating microRNAs (miRNAs) that can regulate target genes in distant organs. However, the role of brown adipose tissue (BAT) in diabetic kidney disease (DKD) ...is still unknown. We studied the original BAT miR-30b targeting two key fibrotic regulators, Runt-related transcription factor 1 (Runx1) and snail family zinc finger 1 (Snail1), to combat DKD.
First, we transplanted healthy BAT from normal mouse donors into diabetic mice (induced by a high-fat diet and streptozotocin injection). In vitro, we observed extracellular vesicles (EVs) secreted from brown adipocytes. AgomiR-30b was directly administered to the BAT of diabetic mice twice weekly for 4 consecutive weeks. Next, the role of Runx1 in DKD was determined by using siRUNX1 or pCMV-RUNX1 in HK-2 cells and in diabetic mice treated with AAV9-U6-shRunx1 or AAV9-EF1a-Runx1.
BAT transplantation reactivated endogenous BAT activity in diabetic mice, increased circulating miR-30b levels and significantly ameliorated DKD. In TGFβ1-treated HK-2 cells, miR-30b expression was significantly suppressed. miR-30b overexpression markedly decreased fibronectin and downregulated Runx1 and Snail1 expression, while silencing of miR-30b had the opposite effects. Next, Runx1 knockdown and overexpression mimicked the above phenotype of miR-30b mimics and inhibitors, respectively, both in vitro and in vivo. Moreover, Runx1 promoted TGFβ1-induced fibrosis by upregulating the PI3K pathway.
BAT-derived miRNAs might be a promising target for kidney protection in diabetes mellitus.
•BAT transplantation improved systemic metabolism and attenuated DKD.•AMPK-SIRT1-PGC1α axis activation and circulating miRs such as miR-30b are correlated with BAT renoprotective effects.•BAT-derived miR-30b can target renal Runx1 and Snail to combat DKD.•Runx1 stimulates the fibrotic pathogenesis of DKD.
The dipeptidyl peptidase-4 inhibitor sitagliptin, a new anti-diabetic medicine, is effective in treating type 2 diabetes mellitus by increasing the activation and duration of action of glucagon-like ...peptide-1. Since atherosclerosis is the main pathological feature of diabetic cardiovascular complications, it is important to investigate the anti-atherosclerotic effect of sitagliptin and explore the relevant mechanisms.
Male apolipoprotein-E-knockout mice were randomly divided into two groups and fed either high-fat diet (HFD) or HFD plus sitagliptin at a concentration of 0.3% for 16 weeks. Body weight, food intake, blood glucose, serum lipids and adhesion molecules were measured. The atherosclerotic plaque area and its histological composition were analyzed using Sudan staining and immunohistochemistry. The expression of inflammatory cytokines (monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-6) and the activation of AMP-activated protein kinase (AMPK) and mitogen-activated protein kinase (MAPK) in the aortas were determined using quantitative polymerase chain reaction and western blot, respectively.
Mice treated with sitagliptin developed fewer atherosclerotic plaques than the control group (7.64 ± 1.98% vs 12.91 ± 1.15%, p < 0.001), particularly in the aortic arch and abdominal aorta, where plaques were decreased 1.92- and 2.74-fold, respectively (p < 0.05 and p < 0.01). Sitagliptin significantly reduced the content of collagen fiber in plaques 1.2-fold (p < 0.05). Moreover, sitagliptin significantly reduced the expression of monocyte chemoattractant protein-1 and interleukin-6 in the aorta (p < 0.01 and p < 0.05), as well as the serum levels of soluble vascular cell adhesion molecule-1 and P-selectin (both p < 0.05). In addition, Sitagliptin induced phosphorylation of AMPK and Akt (p < 0.05 and p < 0.01), while suppressed phosphorylation of p38 and extracellular signal-regulated kinase (Erk) 1/2 (p < 0.05 and p < 0.01) in aortas.
Our present study indicates that sitagliptin can reduce the area of the atherosclerotic lesion, possibly by regulating the AMPK and MAPK pathways and then reducing leukocyte -endothelial cell interaction and inflammation reactions. These actions are independent of weight loss and glucose-reducing effects.
Extracellular vesicles (EVs), which contain microRNA (miRNA), constitute a novel means of cell communication that may contribute to the inevitable expansion of renal fibrosis during diabetic kidney ...disease (DKD). Exendin-4 is effective for treating DKD through its action on GLP1R. However, the effect of exendin-4 on EV miRNA expression and renal cell communication during the development of DKD remains unknown. In this study, we found that EVs derived from HK-2 cells pre-treated with exendin-4 and high glucose (Ex-HG), which were taken up by normal HK-2 cells, resulted in decreased levels of FN and Col-I compared with EVs from HK-2 cells pre-treated with HG alone. Furthermore, we found that pretreatment with HG and exendin-4 may have contributed to a decrease in miR-192 in both HK-2 cells and EVs in a p53-dependent manner. Finally, we demonstrated that the amelioration of renal fibrosis by exendin-4 occurred through a miR-192-GLP1R pathway, indicating a new pathway by which exendin-4 regulates GLP1R. The results of this study suggest that exendin-4 inhibits the transfer of EV miR-192 from HG-induced renal tubular epithelial cells to normal cells, thus inhibiting GLP1R downregulation and protecting renal cells. This study reports a new mechanism by which exendin-4 exerts a protective effect against DKD.
It has been verified that adipose tissue was the major source of circulating microRNAs (miRNA), which could target downstream genes in distant organs such as liver. Here we show that brown adipose ...tissue (BAT) transplantation from healthy mice donor could reactivate endogenous BAT activity of diabetic mice induced by high fat diet (HFD) and streptozotocin (STZ) injection. BAT activation increased circulating miR-30b level and significantly improved diabetic nephropathy. In vitro, miR-30b was significantly downregulated by TGF β1 in HK-2 cells. In vivo, agomiR-30b was directly administered to the BAT of diabetic mice (0.25nmol/g body weight) twice per week for 4 consecutive weeks. Over-expressing miR-30b markedly decreased fibronectin expression, coupled with downregulated Runt-related transcription factor 1(Runx1) and snail family zinc finger 1 (Snail1) in the kidney of diabetic mice, while silencing of miR-30b displayed the opposite features. Next, knockdown or overpression of Runx1 both in vitro by using siRUNX1 or pCMV-RUNX1, and in vivo by AAV-U6-shRunx1 or AAV-EF1a-Runx1 respectively, could mimic the above phenotype of miR-30b mimic and inhibitor treatment respectively. Moreover, Runx1 promoted TGFβ1-induced fibrosis through upregulating PI3K pathway. These results suggest that BAT transplantation ameliorates diabetic nephropathy in mice through reactivating endogenous BAT and increasing circulating miR-30b level, which subsequently target renal Runx1 and Snail1, to improve renal fibrosis. BAT-original miRNAs might be a promising target for kidney protection in diabetes mellitus.
Disclosure
M. Guan: None.
Funding
National Natural Science Foundation of China (81870612, 81628004, 31400992, 81470047); Guangdong Science and Technology Project (2019A1515011997)
33 patients with active, moderate-severe Graves’ ophthalmopathy (GO) received 4.5 g methylprednisolone for 12 weeks and were divided by efficacy into two groups (responsive and unresponsive). All ...patients and 10 controls underwent orbital MRI examination at baseline. No significant difference was seen in baseline clinical characteristics between the two GO groups. The values of exophthalmos were higher in both GO groups than in the control and were higher in the responsive group versus the unresponsive group. Compared to the unresponsive group, the responsive group had a thicker inferior rectus as well as thinner orbital fat. The inferior rectus/fat ratio was significantly higher in the responsive group versus the unresponsive group. Multivariate logistic regression analysis showed that the exophthalmos value and inferior rectus/fat ratio were significantly associated with the response to glucocorticoid (GC). ROC analysis revealed that the cut-off points of the inferior rectus/fat ratio combined with the exophthalmos value to indicate efficacy were 1.42 and 20.78. For moderate-severe GO patients with CAS > 3, the combined inferior rectus/fat ratio and exophthalmos value in MRI may be a valuable indicator to predict the response to GC therapy.
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