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Expressions of extracellular matrix in kidney tissues. Expressions of fibronectin (A) and type IV collagen ( B) were detected by immunochemistry and western blot analysis. CTL: normal control mice (CTL), D: wild type diabetic mice (D), UTKO+D: diabetic mice with UII receptor knock out. *P<0.01 vs. CTL group; #P<0.05 vs. D group.
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Background/aims:
Urotensin II (UII) and its receptor are highly expressed in the kidney tissue of patients with diabetic nephropathy (DN). The aim of this study is to examine the roles of UII in the induction of endoplasmic reticulum stress (ER stress) and Epithelial-mesenchymal transition (EMT) in DN in vivo and in vitro.
Methods:
Kidney tissue...
Similar publications
Aim/introduction:
Urotensin II (UII) and autophagy have been considered as important components in the pathogenesis of diabetic nephropathy. The present study explores whether UII can regulate autophagy in kidney and its effect in diabetes.
Materials and methods:
Immunohistochemistry and western blot were conducted on the kidney tissues of diabe...
Citations
... Urotensin II(UII) is a novel vasoactive peptide. Studies have confirmed [12] that UII can induce EMT in renal tubular epithelial cells, but the specific mechanism remains unclear. Recently, studies have found that the expression of UII and its receptor increases significantly with the progression of CKD, and blocking UII can delay the progression of renal fibrosis [13]. ...
Objective
To explore the molecular mechanism of Astragaloside IV (AS-IV) in alleviating renal fibrosis by inhibiting Urotensin II-induced pyroptosis and epithelial-mesenchymal transition of renal tubular epithelial cells.
Methods
Forty SD rats were randomly divided into control group without operation: gavage with 5ml/kg/d water for injection and UUO model group: gavage with 5ml/kg/d water for injection; UUO+ AS-IV group (gavage with AS-IV 20mg/kg/d; and UUO+ losartan potassium group (gavage with losartan potassium 10.3mg/kg/d, with 10 rats in each group. After 2 weeks, Kidney pathology, serum Urotensin II, and cAMP concentration were detected, and the expressions of NLRP3, GSDMD-N, Caspase-1, and IL-1β were detected by immunohistochemistry. Rat renal tubular epithelial cells were cultured in vitro, and different concentrations of Urotensin II were used to intervene for 24h and 48h. Cell proliferation activity was detected using the CCK8 assay. Suitable concentrations of Urotensin II and intervention time were selected, and Urotensin II receptor antagonist (SB-611812), inhibitor of PKA(H-89), and AS-IV (15ug/ml) were simultaneously administered. After 24 hours, cells and cell supernatants from each group were collected. The cAMP concentration was detected using the ELISA kit, and the expression of PKA, α-SMA, FN, IL-1β, NLRP3, GSDMD-N, and Caspase-1 was detected using cell immunofluorescence, Western blotting, and RT-PCR.
Results
Renal tissue of UUO rats showed renal interstitial infiltration, tubule dilation and atrophy, renal interstitial collagen fiber hyperplasia, and serum Urotensin II and cAMP concentrations were significantly higher than those in the sham operation group (p <0.05). AS-IV and losartan potassium intervention could alleviate renal pathological changes, and decrease serum Urotensin II, cAMP concentration levels, and the expressions of NLRP3, GSDMD-N, Caspase-1, and IL-1β in renal tissues (p <0.05). Urotensin II at a concentration of 10⁻⁸ mol/L could lead to the decrease of cell proliferation, (p<0.05). Compared with the normal group, the cAMP level and the PKA expression were significantly increased (p<0.05). After intervention with AS-IV and Urotensin II receptor antagonist, the cAMP level and the expression of PKA were remarkably decreased (p<0.05). Compared with the normal group, the expression of IL-1β, NLRP3, GSDMD-N, and Caspase-1 in the Urotensin II group was increased (p<0.05), which decreased in the AS-IV and H-89 groups.
Conclusion
AS-IV can alleviate renal fibrosis by inhibiting Urotensin II-induced pyroptosis of renal tubular epithelial cells by regulating the cAMP/PKA signaling pathway.
... Recent publications supported the findings in cultured GMCs. UT knockout in mice attenuated streptozotocin-induced kidney endoplasmic reticulum stress, epithelial-mesenchymal transition (EMT), fibrosis, extracellular matrix production, glomerular lesion, and mesangial expansion (Pang et al., 2016;Peixoto-Neves et al., 2022). Findings from Clozel and colleagues indicated UT inhibition increased kidney perfusion and ameliorated proteinuria and kidney damage in diabetic rats (Clozel et al., 2006). ...
Chronic kidney disease (CKD) is a progressive and long-term condition marked by a gradual decline in kidney function. CKD is prevalent among those with conditions such as diabetes mellitus, hypertension, and glomerulonephritis. Affecting over 10% of the global population, CKD stands as a significant cause of morbidity and mortality. Despite substantial advances in understanding CKD pathophysiology and management, there is still a need to explore novel mechanisms and potential therapeutic targets. Urotensin II (UII), a potent vasoactive peptide, has garnered attention for its possible role in the development and progression of CKD. The UII system consists of endogenous ligands UII and UII-related peptide (URP) and their receptor, UT. URP pathophysiology is understudied, but alterations in tissue expression levels of UII and UT and blood or urinary UII concentrations have been linked to cardiovascular and kidney dysfunctions, including systemic hypertension, chronic heart failure, glomerulonephritis, and diabetes. UII gene polymorphisms are associated with increased risk of diabetes. Pharmacological inhibition or genetic ablation of UT mitigated kidney and cardiovascular disease in rodents, making the UII system a potential target for slowing CKD progression. However, a deeper understanding of the UII system's cellular mechanisms in renal and extrarenal organs is essential for comprehending its role in CKD pathophysiology. This review explores the evolving connections between the UII system and CKD, addressing potential mechanisms, therapeutic implications, controversies, and unexplored concepts.
... The UPR reactions were regulated by ATF6 inhibitors (PF-429242 and CEapinS-A7), Perk inhibitors (p58IPK, GSK2606414, GSK2656157, and AMG Perk 44), IRE1 inhibitors (4µ8C, Most of these studies have a small sample size considering ethical factors. However, it is more significant for the late pathological changes of ERS due to the strict enrollment requirements of renal biopsy as the gold standard [33][34][35][36][37][38][39]. The other is clinical DKD screening criteria based on glomerular filtration rate (eGFR) and urinary protein (UACR) [4]. ...
... The glucose metabolites AGEs/RAGE axis, methylated protein PRMT1 and histone H4 deacetylation can promote the occurrence of this condition [20,38,67], while Calbindin-D28K, TMBIM6, Sestrin2, and dapagliflozin could alleviate the above phenomena [17,19,20,68]. Renal tubular ERS markers, especially GRP78, can participate in autophagy and endocytosis [18,44], which promote inflammation [40,69], EMT and ECM [20,34,65,68] by regulating mitochondrial function and ROS production [18,69]. Moreover, IRE1α regulates TXNIP/NLRP3 mediated renal tubular pyroptosis [70]. ...
Diabetes kidney disease (DKD) is one of the common chronic microvascular complications of diabetes, which has become the most important cause of modern chronic kidney disease beyond chronic glomerulonephritis. The endoplasmic reticulum is one of the largest organelles, and endoplasmic reticulum stress (ERS) is the basic mechanism of metabolic disorder in all organs and tissues. Under the stimulation of stress-induced factors, the endoplasmic reticulum, as a trophic receptor, regulates adaptive and apoptotic ERS through molecular chaperones and three unfolded protein reaction (UPR) pathways, thereby regulating diabetic renal damage. Therefore, three pathway factors have different expressions in different sections of renal tissues. This study deeply discussed the specific reagents, animals, cells, and clinical models related to ERS in DKD, and reviewed ERS-related three pathways on DKD with glomerular filtration membrane, renal tubular reabsorption, and other pathological lesions of different renal tissues, as well as the molecular biological mechanisms related to the balance of adaption and apoptosis by searching and sorting out MeSH subject words from PubMed database.
... Therefore, while the detrimental effects of STZ are mediated by alpha cell dysfunction and beta-cell destruction, the beneficial effects of UT KO appear to be mediated through alpha cell protection. A study has shown that KO of UT protected against ER stress and extracellular matrix production in the kidneys of mice treated with a single intraperitoneal injection of STZ (Pang et al. 2016), consistent with our current findings. Given that the UII system is upregulated in the diabetic kidneys (Totsune et al. 2003, Langham et al. 2004, Dai et al. 2008, Suguro et al. 2008, Tian et al. 2008, Wang et al. 2009, Gruson et al. 2010), a combination of kidney and alpha cell protection may be involved in the mitigatory effect of UT KO in DKD (Fig. 8). ...
Plasma and urinary levels of UII, a potent vasoactive peptide, are elevated in diabetes mellitus (DM) patients. UII receptor (UT) expression levels are also increased in the kidneys of humans and animals with DM. Palosuran, an orally active UT antagonist, increased insulin levels and improved renal function in uninephrectomized streptozotocin (STZ)‐treated rats. However, human studies on the potential use of palosuran for kidney protection in diabetes were inconclusive. In addition to UT antagonism, palosuran can activate somatostatin receptors. Also, the reduced affinity of palosuran for UT in intact cells and tissues suggests that it may not be an optimal UT antagonist. Thus, using non‐selective and less potent UT antagonists constitutes a weakness in the scientific rigor of the prior attempts to dissect UT as a potential therapeutic target in DKD. Hence, studies using genetic animal models and highly selective and potent pharmacological antagonists are needed to fill the gaps of understanding on the pathophysiological significance of the UII system in DM. In the present study, we examine the development of hyperglycemia and DKD in the wild‐type (WT) and UT knockout (KO) mouse model of type 1 DM.
STZ‐treated mice showed increased blood glucose levels, glucosuria, decreased plasma insulin levels, and diabetic kidney disease (DKD), which UT KO attenuated. However, UT KO failed to reverse STZ‐induced insulin deficiency. To understand the underlying mechanism for alleviating hyperglycemia and DKD in UT KO despite the uncorrected insulin deficiency, we tested the role of the primary insulin counterregulatory hormone, glucagon. We found that STZ treatment increased plasma glucagon levels in WT mice but not in UT KO mice. This finding was supported by double immunohistochemistry of pancreatic islet sections, where STZ treatment reduced insulin and increased glucagon staining. UT KO reversed only the effect of STZ on glucagon staining. These findings suggest that UT KO protects the glucagon‐producing alpha cells but not the insulin‐producing beta cells.
UII increased glucagon secretion in a cultured pancreatic alpha cell line, which UT inhibition reversed. Next, to determine how UII triggers glucagon secretion, we performed membrane potential recordings in alpha cells using the perforated‐patch clamp technique. UII produced depolarization of alpha cells. This effect was abolished by UT inhibition. Calcium (Ca ²⁺ ) imaging demonstrated that UII stimulates intracellular Ca ²⁺ ([Ca ²⁺ ] i ) elevation in alpha cells, which T‐ and L‐type Ca ²⁺ channel blockers attenuated.
Taken together, the results of this study suggest that: (1) STZ‐treatment causes insulin deficiency, hyperglycemia, glucosuria, DKD, and hyperglucagonemia. (2) UT KO reverses STZ effects, except insulin deficiency. (3) UII increases glucagon secretion by alpha cells, mediated by UII‐induced membrane depolarization and Ca ²⁺ influx via T‐ and L‐type Ca ²⁺ channels. Therefore, the reversal of hyperglycemia, glucosuria, and DKD in UT KO might be linked to the reversal of hyperglucagonemia.
... Therefore, while the detrimental effects of STZ are mediated by alpha cell dysfunction and beta-cell destruction, the beneficial effects of UT KO appear to be mediated through alpha cell protection. A study has shown that KO of UT protected against ER stress and extracellular matrix production in the kidneys of mice treated with a single intraperitoneal injection of STZ (Pang et al, 2016), consistent with our current findings. Given that the UII system is upregulated in the diabetic kidneys (Dai et al., 2008;Gruson et al., 2010;Langham et al., 2004;Suguro et al., 2008;Tian et al., 2008;Totsune et al., 2003;Totsune et al., 2004;Wang et al., 2009), a combination of kidney and alpha cell protection may be involved in the mitigatory effect of UT KO in DKD (Fig. 8). ...
Beyond the central nervous, urotensin II (UII) and its receptor (UT) are functionally expressed in peripheral tissues of the endocrine, cardiovascular, and renal systems. The expression levels of UII and UT in the kidney and circulating UII levels are increased in diabetes. UII also promotes mesangial proliferation and matrix accumulation in vitro. Here, we evaluate the effect of UT deletion on the development of hyperglycemia and diabetic kidney disease (DKD) in streptozotocin (STZ)-treated mice. Ten‐week-old wild‐type and UT knockout (KO) mice were injected with STZ for 5 days to induce diabetes. Blood glucose levels were measured weekly, and necropsy was performed 12 weeks after STZ injection. UT ablation slowed hyperglycemia and glucosuria in STZ-treated mice. UT KO also ameliorated STZ-induced increase in HbA1c, but not STZ-induced decrease in plasma insulin levels. However, STZ-induced increases in plasma glucagon concentration and immunohistochemical staining for glucagon in pancreatic islets were lessened in UT KO mice. UT ablation also protected against STZ-induced kidney derangements, including albuminuria, mesangial expansion, glomerular lesions, and glomerular endoplasmic reticulum stress. UT is expressed in a cultured pancreatic alpha cell line, and its activation by UII triggered membrane depolarization, T- and L-type voltage-gated Ca2+ channel-dependent Ca2+ influx, and glucagon secretion. These findings suggest that apart from direct action on the kidneys to cause injury, UT activation by UII may result in DKD by promoting hyperglycemia via induction of glucagon secretion by pancreatic alpha cells.
... In rat proximal tubular epithelial cells, the advanced glycation end product (AGE) stimulates the increased expression of urotensin-II involved in the upregulation of TGFB1, FN1 and COL4A1, which promotes tubulointerstitial nephropathy in diabetes (Tian et al. 2016). In the diabetic nephropathy model, urotensin-II induces the upregulation of AIFM2, HSPA5, DDIT3, ESPL1, ACTA2, which induces ER stress and EMT in human renal proximal tubular epithelial cell line HK-2 cells (Pang et al. 2016). ...
Urotensin-II is a polypeptide ligand with neurohormone-like activity. It mediates downstream signaling pathways through G-protein-coupled receptor 14 (GPR14) also known as urotensin receptor (UTR). Urotensin-II is the most potent endogenous vasoconstrictor in mammals, promoting cardiovascular remodelling, cardiac fibrosis, and cardiomyocyte hypertrophy. It is also involved in other physiological and pathological activities, including neurosecretory effects, insulin resistance, atherosclerosis, kidney disease, and carcinogenic effects. Moreover, it is a notable player in the process of inflammatory injury, which leads to the development of inflammatory diseases. Urotensin-II/UTR expression stimulates the accumulation of monocytes and macrophages, which promote the adhesion molecules expression, chemokines activation and release of inflammatory cytokines at inflammatory injury sites. Therefore, urotensin-II turns out to be an important therapeutic target for the treatment options and management of associated diseases. The main downstream signaling pathways mediated through this urotensin-II /UTR system are RhoA/ROCK, MAPKs and PI3K/AKT. Due to the importance of urotensin-II systems in biomedicine, we consolidated a network map of urotensin-II /UTR signaling. The described signaling map comprises 33 activation/inhibition events, 31 catalysis events, 15 molecular associations, 40 gene regulation events, 60 types of protein expression, and 11 protein translocation events. The urotensin-II signaling pathway map is made freely accessible through the WikiPathways Database ( https://www.wikipathways.org/index.php/Pathway:WP5158 ). The availability of comprehensive urotensin-II signaling in the public resource will help understand the regulation and function of this pathway in normal and pathological conditions. We believe this resource will provide a platform to the scientific community in facilitating the identification of novel therapeutic drug targets for diseases associated with urotensin-II signaling.
... Urotensin II (UII) and its receptor are highly expressed in renal tissue in patients with DN [78]. Pang et al. [79] observed increased UII expression and ER stress in DN patients and diabetic mice, and UII induced epithelial-tomesenchymal transition (EMT) via the ER stress pathway in cultured HK2 cells. Additionally, a UII receptor antagonist and 4-PBA inhibited UII-induced ER stress and EMT. ...
Recent progress has been made in understanding the roles and mechanisms of endoplasmic reticulum (ER) stress in the development and pathogenesis of diabetic nephropathy (DN). Hyperglycemia induces ER stress and apoptosis in renal cells. The induction of ER stress can be cytoprotective or cytotoxic. Experimental treatment of animals with ER stress inhibitors alleviated renal damage. Considering these findings, the normalization of ER stress by pharmacological agents is a promising approach to prevent or arrest DN progression. The current article reviews the mechanisms, roles, and therapeutic aspects of these findings.
1. Introduction
Diabetic nephropathy (DN) is one of the common microvascular complications of diabetes. The main clinical manifestations are proteinuria, hyperglycemia, and impaired renal function. Additionally, mesangial hyperplasia, glomerular sclerosis, extracellular matrix accumulation, and tubulointerstitial fibrosis can be observed pathologically. Numerous studies have demonstrated the role of endoplasmic reticulum (ER) stress in the pathogenesis of DN [1–3].
... However, if stress persists or is too strong, the endoplasmic reticulum stressrelated apoptosis pathway is activated, and cell apoptosis is induced [26]. A previous study by our research group found that ERS participates in ECM accumulation and EMT in early type 1 diabetic mice and HK-2 cells, while ERS inhibitor 4-PBA can block the occurrence of EMT markers that increased expression and ECM accumulation [27]. Moon et al. also found that ER stress agonist tunicamycin induces EMT in HK2 cells, while ERS inhibitor 4-PBA weakens EMT in HK-2 cells induced by tunicamycin [28]. ...
The study is aimed at investigating the effects of Ginkgo biloba extract EGB761 on renal tubular damage and endoplasmic reticulum stress (ERS) in diabetic kidney disease (DKD). A total of 50 C57BL/6 N mice were randomly divided into the normal group, DKD group, DKD+EGB761 group (36 mg/kg), and DKD+4-phenylbutyrate (4-PBA) group (1 g/kg). The DKD model was replicated by high-fat diet combined with intraperitoneal injection of streptozotocin (STZ). Renal tubular epithelial cells (HK-2) were divided into the control group, high-glucose group (30 mmol/L), EGB761 group (40 mg/L, 20 mg/L, 10 mg/L), TM group, and TM+4-PBA group. After 8 weeks of administration, expressions of serum creatinine (Scr), blood urea nitrogen (BUN), 24 h urinary protein (24 h Pro), fasting blood glucose (FBG), β2-microglobulin (β2-MG), and retinol binding protein 4 (RBP4) of mice were tested. The pathological changes of renal tissue were observed. The expressions of extracellular matrix (ECM) accumulation and epithelial-mesenchymal transition (EMT) markers α-smooth muscle actin (α-SMA), E-cadherin, fibronectin, and collagen IV, as well as the ERS markers GRP78 and ATF6, were tested by Western blot, qPCR, immunohistochemistry, or immunofluorescence. EGB761 could decrease the Scr, BUN, 24 h Pro, and FBG levels in the DKD group, alleviate renal pathological injury, decrease urine β2-MG, RBP4 levels, and decrease the expression of α-SMA, collagen IV, fibronectin, and GRP78, as well as ATF6, while increase the expression of E-cadherin. These findings demonstrate that EGB761 can improve renal function, reduce tubular injury, and ameliorate ECM accumulation and EMT in DKD kidney tubules, and the mechanism may be related to the inhibition of ERS.
... Xu et al. [23] showed that ERS promoted RF, whereas SIRT1 reduced RF by inhibiting ERS in a UUO IF model [24]. Moreover, ERS inhibitors suppressed the α-SMA expression [25], suggesting that ERS inhibition can potentially prevent RF and delay AKI-CKD transition. ...
Endoplasmic reticulum stress (ERS) is strongly associated with acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Huaier extract (HE) protects against kidney injury; albeit, the underlying mechanism is unknown. We hypothesized that HE reduces kidney injury by inhibiting ERS. In this study, using an AKI-CKD mouse model of ischemia-reperfusion injury (IRI), we evaluated the effect of HE on AKI-CKD transition. We also explored the underlying molecular mechanisms in this animal model and in the HK-2 human kidney cell line. The results showed that HE treatment improved the renal function, demonstrated by a significant decrease in serum creatinine levels after IRI. HE appreciably reduced the degree of kidney injury and fibrosis and restored the expression of the microRNA miR-1271 after IRI. Furthermore, HE reduced the expression of ERS markers glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) and inhibited apoptosis in the IRI group. This in vivo effect was supported by in vitro results in which HE inhibited apoptosis and decreased the expression of CHOP and GRP78 induced by ERS. We demonstrated that CHOP is a target of miR-1271. In conclusion, HE reduces kidney injury, probably by inhibiting apoptosis and decreasing the expression of GRP78 and CHOP via miR-1271 upregulation.
... Urotensin II has also been implicated in pancreatic beta-cell dysfunction and in diabetic retinopathy. Marked elevated levels of urotensin II and urotensin II receptor, also known as GPR14 expression have been observed in renal biopsies of patients with DKD [115][116][117]. This finding was further supported in animal experiments suggesting urotensin II/GPR14 as a mediator of renal fibrosis [118]. ...
... The molecular mechanism by which urotensin II promotes DKD is not well understood. Urotensin II causes ER stress and promotes the production of ECM in kidney tubular epithelial cells from diabetic mice, which leads to kidney fibrosis in diabetic nephropathy [116]. Increasing urotensin II expression in the kidney is associated with a significant increase in the synthesis of the profibrotic factors transforming growth factor-β1 (TGFβ1), fibronectin, and type IV collagen. ...
The major clinical associations with the progression of diabetic kidney disease (DKD) are glycemic control and systemic hypertension. Recent studies have continued to emphasize vasoactive hormone pathways including aldosterone and endothelin which suggest a key role for vasoconstrictor pathways in promoting renal damage in diabetes. The role of glucose per se remains difficult to define in DKD but appears to involve key intermediates including reactive oxygen species (ROS) and dicarbonyls such as methylglyoxal which activate intracellular pathways to promote fibrosis and inflammation in the kidney. Recent studies have identified a novel molecular interaction between hemodynamic and metabolic pathways which could lead to new treatments for DKD. This should lead to a further improvement in the outlook of DKD building on positive results from RAAS blockade and more recently newer classes of glucose-lowering agents such as SGLT2 inhibitors and GLP1 receptor agonists.
