RCAN1.4 attenuates renal fibrosis through inhibiting calcineurin-mediated nuclear translocation of NFAT2

Multi-parameter magnetic resonance imaging of zebularine in liver fibrosis treatment and calcineurin/NFAT3 mechanism

BACKGROUND

Hepatic stellate cell (HSC) activation is key to liver fibrosis. Targeting DNA methylation shows promise. Zebularine, a methylation inhibitor, may suppress HSC activation via the calcineurin (CaN)/NFAT3 pathway. Magnetic resonance imaging (MRI) is a noninvasive tool for evaluating liver fibrosis evaluation tool, but multiparametric MRI for zebularine’s effects in liver fibrosis mouse models has not been studied.

AIM

To clarify the anti-fibrosis mechanism and MRI-evaluated efficacy of zebularine.

METHODS

In vitro, transforming growth factor (TGF)-β1-stimulated human HSCs (LX-2) were treated with zebularine. α-smooth muscle actin, fibrotic and anti-fibrotic gene levels, and regulator of calcineurin1 (RCAN1) regulation were measured. In vivo, carbon tetrachloride (CCl₄)-induced liver fibrosis in mice was treated with zebularine, and fibrosis was evaluated using various biochemical, histopathological, and MRI methods.

RESULTS

Zebularine upregulated RCAN1.4 protein (P < 0.01) and inhibited the CaN/NFAT3 pathway (P < 0.05). In HSCs, TGF-β1 reduced anti-fibrotic gene massage RNA (mRNA) and increased fibrotic mRNA (P < 0.05), whereas zebularine had the opposite effects (P < 0.01, P < 0.05). CCl₄-treated mice exhibited increases in various fibrosis-related indices, all of which were reversed by zebularine treatment (P < 0.05).

CONCLUSION

Zebularine may reduce LX-2 activation and extracellular matrix deposition via RCAN1.4 and CaN/NFAT3 pathways. Multiparametric MRI can assess its efficacy, suggesting zebularine’s potential as a liver fibrosis treatment.

Trametinib ameliorated Adriamycin-induced podocyte injury by inhibiting METTL3 modified m6A RCAN1 RNA methylation

N6-methyladenosine (m6A) plays a crucial role in kidney diseases. Methyltransferase-like 3 (METTL3) as a key m6A writer can be regulated by trametinib. However, the epigenetic regulation of trametinib in focal segmental glomerulosclerosis (FSGS) remains unclear. We investigated whether trametinib protects podocytes by modulating METTL3-methylated target RNAs. Regulator of calcineurin 1 (RCAN1) was predicted as a target binding RNA of METTL3 by THEW database. Immunostaining of METTL3 and RCAN1 with podocyte marker Wilm's tumor-1 (WT-1) confirmed their localization within podocytes in renal biopsy from FSGS patients. Transfection METTL3 to human podocytes reduced WT-1, synaptopodin (SYNPO), and RCAN1 protein levels. Total m6A, m6A methylated RNA of RCAN1 increased and total RCAN1 mRNA decreased. Inhibition of METTL3 using siRNA or trametinib reversed these changes and attenuated the ADR-induced downregulation of WT-1 and SYNPO in vitro. In ADR-induced FSGS mice, trametinib ameliorated proteinuria, hypoalbuminemia, renal dysfunction, glomerulosclerosis and podocyte foot process effacement. Additionally, trametinib preserved podocyte function assessed by WT-1 and SYNPO as well as delayed renal fibrosis assessed by α-smooth muscle actin and fibronectin. Consistent with results in vitro, trametinib also decreased the ADR-induced upregulation of METTL3 and reversed the changed levels of total m6A, m6A methylated Rcan1 and total Rcan1 in FSGS mice. In conclusion, trametinib may serve as a renal protective agent for FSGS by regulating METTL3-dependent RCAN1 methylation levels.

Pinocembrin alleviates renal ischemia-reperfusion injury/unilateral ureteral obstruction (UUO)-generated renal fibrosis by targeting the CYP1B1/ROS/MAPK axis

In our research, we constructed models of renal ischemia-reperfusion (I/R)-exposed acute kidney injury (AKI) and unilateral ureteral obstruction (UUO)-stimulated renal fibrosis (RF) in C57BL/6 mice and HK-2 cells. We firstly authenticated that oral pinocembrin (PIN) administration obviously mitigated tissue damage and renal dysfunction induced by I/R injury, and PIN attenuated UUO-caused RF, as confirmed by the reduced expression of fibrotic markers as well as hematoxylin-eosin (H&E), Sirius red, immunohistochemistry, and Masson staining. Meanwhile, the beneficial role of PIN was again demonstrated in HK-2 cells with hypoxia-reoxygenation (H/R) or transforming growth factor beta-1 (TGF-β1) treatment. Importantly, the "ingredient-target-pathway-disease" network was established through bioinformatics analysis and molecular docking, which showed that PIN may target cytochrome P450 1B1 (CYP1B1) and modulate the mitogen-activated protein kinase (MAPK) pathway to exert its impact during injury. Furthermore, experiments confirmed that PIN usage remarkably constrained CYP1B1 expression, reactive oxygen species (ROS) production, MAPK-pathway-associated inflammation, or apoptosis during I/R injury or UUO exposure. PIN also ameliorated the elevated protein phosphorylation of MAPK pathway components [p38, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase 1 (JNK ERK and JNK)], which validated the PIN-induced inhibition of the MAPK signaling pathway in renal I/R or UUO injury. Moreover, the AAV9 (adeno-associated virus 9)-packed CYP1B1 or pcDNA-CYP1B1 overexpression plasmid was utilized to treat C57BL/6 mice or HK-2 cells to overexpress CYP1B1, respectively. Notably, CYP1B1 overexpression considerably abolished PIN's restriction impact on ROS generation and MAPK pathway activation. In conclusion, via bioinformatics analysis, molecular docking, animal model, and cellular experiments, we proved that PIN alleviates renal I/R injury/UUO-generated renal fibrosis through regulating the CYP1B1/ROS/MAPK axis.

Sulforaphane alleviates renal fibrosis through dual regulation on mTOR-mediated autophagy pathway

Renal fibrosis is a common pathological process of progressive chronic kidney disease (CKD). However, effective therapy is constrained currently. Autophagy is an important mechanism in kidney injury and repairment but its exact role in renal fibrosis was discrepant according to previous studies. Sulforaphane (SFN), a natural plant compound, has been explored as a promising nutritional therapy for a variety of diseases. But the salutary effect and underlying mechanism of SFN on CKD have not been fully elucidated. In this study, we investigated the effect of SFN on renal fibrosis in unilateral ureteral obstruction (UUO) mice. Then we examined the regulatory effect of SFN on autophagy-related proteins in renal fibroblasts and renal tubular epithelial cells. Our results showed that sulforaphane could significantly alleviate renal fibrosis in UUO mice. In vitro, the expression levels of autophagy-related protein showed that SFN could upregulate the autophagy activity of renal interstitial fibroblasts and downregulate the autophagy activity of renal tubular epithelial cells. Furthermore, we found that phosphorylated mTOR protein levels was reduced in renal fibroblasts and increased in renal tubular epithelial cells after SFN treatment. Our results strongly suggested that SFN could alleviate renal fibrosis through dual regulation of mTOR-mediated autophagy pathway. This finding may provide a new perspective on the renal salutary effect of SFN and provide a preclinical rationale for exploring the therapeutic potential of SFN to slow down renal fibrosis.

Unlocking the therapeutic potential of the NFAT pathway in kidney diseases

The nuclear factor of activated T cells (NFAT) is a novel renoprotective transcription factor in an inactive form in the cytoplasm and an active form in the nucleus. NFAT is expressed in T cells, heart, kidney and lymphocytes. NFAT plays an essential role in inducing apoptosis of renal tubular epithelial cells. NFAT levels have been observed to increase significantly during kidney diseases. Further, downregulation or silencing of endogenous NFAT mitigates kidney diseases. NFAT regulation depends upon the intricate interplay between calcium ions and calcineurin (CaN), thus orchestrating the NFAT/calcineurin signalling pathway. When CaN is activated, it induces dephosphorylation of NFAT and localises the active NFAT into the nucleus, which ultimately leads to inflammation, fibrosis and apoptosis of kidney cells. Further, the global incidence (> 800 million) due to kidney disease imposes a significant economic burden on the healthcare system. Therefore, it is crucial to comprehend the pathways involved in the pathophysiology of kidney diseases to develop targeted interventions. Ongoing studies indicate potential therapies, including anandamide, 11R-VIVIT and maxacalcitol to regulate NFAT levels in kidney disease. The present review discusses the role and regulation of NFAT in the pathogenesis of kidney diseases. This is focused on various preclinical studies that have shown NFAT downregulation as a potential therapeutic strategy against kidney disease setting the foundation for future clinical investigations.

Identification of RCAN1's role in hepatocellular carcinoma using single-cell analysis

BACKGROUND

The regulator of calcineurin 1 (RCAN1) is expressed in multiple organs, including the heart, liver, brain, and kidney, and is closely linked to the pathogenesis of cardiovascular diseases, Down syndrome, and Alzheimer's disease. It is also implicated in the development of various organ tumors; however, its potential role in hepatocellular carcinoma (HCC) remains poorly understood. Therefore, the objective of this study was to investigate the potential mechanisms of RCAN1 in HCC through bioinformatics analysis.

METHODS

We conducted a joint analysis based on the NCBI and TCGA databases, integrating both bulk transcriptome and single-cell analyses to examine the principal biological functions of RCAN1 in HCC, as well as its roles related to phenotype, metabolism, and cell communication. Subsequently, an RCAN1-overexpressing cell line was established, and the effects of RCAN1 on tumor cells were validated through in vitro experiments. Moreover, we endeavored to identify potential related drugs using molecular docking and molecular dynamics simulations.

RESULTS

The expression of RCAN1 was found to be downregulated in 19 types of cancer tissues and upregulated in 11 types of cancer tissues. Higher levels of RCAN1 expression were associated with improved patient survival. RCAN1 was predominantly expressed in hepatocytes, macrophages, endothelial cells, and monocytes, and its high expression not only closely correlated with the distribution of cells related to the HCC phenotype but also with the distribution of HCC cells themselves. Additionally, Rcan1 may directly or indirectly participate in metabolic pathways such as alanine, aspartate, and glutamate metabolism, as well as butanoate metabolism, thereby influencing tumor cell proliferation and migration. In vitro experiments confirmed that RCAN1 overexpression promoted apoptosis while inhibiting proliferation and invasion of HCC cells. Through molecular docking of 1615 drugs, we screened brompheniramine as a potential target drug and verified our results by molecular dynamics.

CONCLUSION

In this study, we revealed the relationship between RCAN1 and HCC through bioinformatics methods, verified that RCAN1 can affect the progress of the disease through experiments, and finally identified potential therapeutic drugs through drug molecular docking and molecular dynamics.

Targeted delivery of type I TGF-β receptor-mimicking peptide to fibrotic kidney for improving kidney fibrosis therapy via enhancing the inhibition of TGF-β1/Smad and p38 MAPK pathways

Renal fibrosis is a representative pathological feature of various chronic kidney diseases, and efficient treatment is needed. Interstitial myofibroblasts are a key driver of kidney fibrosis, which is dependent on the binding of TGF-β1 to type I TGF-β receptor (TβRI) and TGF-β1-related signaling pathways. Therefore, attenuating TGF-β1 activity by competing with TGF-β1 in myofibroblasts is an ideal strategy for treating kidney fibrosis. Recently, a novel TβRI-mimicking peptide RIPΔ demonstrated a high affinity for TGF-β1. Thus, it could be speculated that RIPΔ may be used for anti-fibrosis therapy. Platelet-derived growth factor β receptor (PDGFβR) is highly expressed in fibrotic kidney. In this study, we found that target peptide Z-RIPΔ, which is RIPΔ modified with PDGFβR-specific affibody ZPDGFβR, was specifically and highly taken up by TGF-β1-activated NIH3T3 fibroblasts. Moreover, Z-RIPΔ effectively inhibited the myofibroblast proliferation, migration and fibrosis response in vitro. In vivo and ex vivo experiments showed that Z-RIPΔ specifically targeted fibrotic kidney, improved the damaged renal function, and ameliorated kidney histopathology and renal fibrosis in UUO mice. Mechanistic studies showed that Z-RIPΔ hold the stronger inhibition of the TGF-β1/Smad and TGF-β1/p38 pathways than unmodified RIPΔ in vitro and in vivo. Furthermore, systemic administration of Z-RIPΔ to UUO mice led to minimal toxicity to major organs. Taken together, RIPΔ modified with ZPDGFβR increased its therapeutic efficacy and reduced its systemic toxicity, making it a potential candidate for targeted therapy for kidney fibrosis.

Artificial intelligence-assisted repurposing of lubiprostone alleviates tubulointerstitial fibrosis

Tubulointerstitial fibrosis (TIF) is the most prominent cause which leads to chronic kidney disease (CKD) and end-stage renal failure. Despite extensive research, there have been many clinical trial failures, and there is currently no effective treatment to cure renal fibrosis. This demonstrates the necessity of more effective therapies and better preclinical models to screen potential drugs for TIF. In this study, we investigated the antifibrotic effect of the machine learning-based repurposed drug, lubiprostone, validated through an advanced proximal tubule on a chip system and in vivo UUO mice model. Lubiprostone significantly downregulated TIF biomarkers including connective tissue growth factor (CTGF), extracellular matrix deposition (Fibronectin and collagen), transforming growth factor (TGF-β) downstream signaling markers especially, Smad-2/3, matrix metalloproteinase (MMP2/9), plasminogen activator inhibitor-1 (PAI-1), EMT and JAK/STAT-3 pathway expression in the proximal tubule on a chip model and UUO model compared to the conventional 2D culture. These findings suggest that the proximal tubule on a chip model is a more physiologically relevant model for studying and identifying potential biomarkers for fibrosis compared to conventional in vitro 2D culture and alternative of an animal model. In conclusion, the high throughput Proximal tubule-on-chip system shows improved in vivo-like function and indicates the potential utility for renal fibrosis drug screening. Additionally, repurposed Lubiprostone shows an effective potency to treat TIF via inhibiting 3 major profibrotic signaling pathways such as TGFβ/Smad, JAK/STAT, and epithelial-mesenchymal transition (EMT), and restores kidney function.

Nephroprotective Effects of Cardamonin on Renal Ischemia Reperfusion Injury/UUO-Induced Renal Fibrosis

Acute kidney injury and chronic renal fibrosis are intractable pathological processes to resolve, yet limited strategies are able to effectively address them. Cardamonin (CAD) is a flavonoid with talented antioxidant, anti-inflammatory capacity, and satisfactory biosafety. In our study, animal and cellular models of renal ischemia/reperfusion (I/R) and unilateral ureteral obstruction (UUO) were successfully constructed to confirm whether CAD confers protective effects and underlying mechanisms. Animal experiments demonstrated that CAD application (100 mg/kg) distinctly ameliorated tissue damage and improved renal function. Meanwhile, the continuous oral administration of CAD after UUO surgery efficiently inhibited renal fibrosis as confirmed by hematoxylin-eosin (H&E), Sirius red, and Masson staining as well as the downregulated mRNA and protein expression of collagen I, α-smooth muscle actin (α-SMA), collagen III, and fibronectin. Interestingly, in transforming growth factor β1 (TGF-β1)-stimulated and hypoxia/reoxygenation (H/R)-exposed human kidney-2 (HK-2) cells, protective effects of CAD were again authenticated. Meanwhile, we performed bioinformatics analysis and constructed the "ingredient-target-pathway-disease" network to conclude that the potential mechanisms of CAD protection may be through the regulation of oxidative stress, inflammation, apoptosis, and mitogen-activated protein kinase (MAPK) pathway. Furthermore, experimental data validated that CAD evidently decreased the reactive oxygen species (ROS) production and malondialdehyde (MDA) content while depressing the mRNA and protein expression of inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and Il-1β) and inhibiting apoptosis as evidenced by decreased levels of P53, BAX, cleaved caspase-3, and apoptotic rate in renal I/R and UUO models. In addition, the impact of CAD on restraining oxidative stress and inflammation was attributed to its ability to elevate antioxidant enzyme activities including catalase, superoxide dismutase 1 (SOD1), and superoxide dismutase 2 (SOD2) and to inhibit the inflammation-associated MARK/nuclear factor-κB (MAPK/NF-κB) signaling pathway. In conclusion, cardamonin restored the antioxidative capacity to block oxidative stress and suppressed the MAPK/NF-κB signaling pathway to alleviate inflammatory response, thus mitigating I/R-generated acute kidney injury/UUO-induced renal fibrosis in vivo and in vitro, which indicated the potential therapeutic advantage of cardamonin in attenuating acute and chronic kidney injuries.

Calcineurin Is a Universal Regulator of Vessel Function-Focus on Vascular Smooth Muscle Cells

Calcineurin, a serine/threonine phosphatase regulating transcription factors like NFaT and CREB, is well known for its immune modulatory effects and role in cardiac hypertrophy. Results from experiments with calcineurin knockout animals and calcineurin inhibitors indicate that calcineurin also plays a crucial role in vascular function, especially in vascular smooth muscle cells (VSMCs). In the aorta, calcineurin stimulates the proliferation and migration of VSMCs in response to vascular injury or angiotensin II administration, leading to pathological vessel wall thickening. In the heart, calcineurin mediates coronary artery formation and VSMC differentiation, which are crucial for proper heart development. In pulmonary VSMCs, calcineurin/NFaT signaling regulates the release of Ca2+, resulting in increased vascular tone followed by pulmonary arterial hypertension. In renal VSMCs, calcineurin regulates extracellular matrix secretion promoting fibrosis development. In the mesenteric and cerebral arteries, calcineurin mediates a phenotypic switch of VSMCs leading to altered cell function. Gaining deeper insights into the underlying mechanisms of calcineurin signaling will help researchers to understand developmental and pathogenetical aspects of the vasculature. In this review, we provide an overview of the physiological function and pathophysiology of calcineurin in the vascular system with a focus on vascular smooth muscle cells in different organs. Overall, there are indications that under certain pathological settings reduced calcineurin activity seems to be beneficial for cardiovascular health.

Disruption of RCAN1.4 expression mediated by YY1/HDAC2 modulates chronic renal allograft interstitial fibrosis

Chronic allograft dysfunction (CAD) is a major factor that hinders kidney transplant survival in the long run. Epithelial-mesenchymal transition (EMT) has been confirmed to significantly contribute to interstitial fibrosis/tubular atrophy (IF/TA), which is the main histopathological feature of CAD. Aberrant expression of the regulator of calcineurin 1 (RCAN1), recognized as an endogenous inhibitor of the calcineurin phosphatase, has been shown to be extensively involved in various kidney diseases. However, it remains unclear how RCAN1.4 regulates IF/TA formation in CAD patients. Herein, an in vivo mouse renal transplantation model and an in vitro model of human renal tubular epithelial cells (HK-2) treated with tumor necrosis factor-α (TNF-α) were employed. Our results proved that RCAN1.4 expression was decreased in vivo and in vitro, in addition to the up-regulation of Yin Yang 1 (YY1), a transcription factor that has been reported to convey multiple functions in chronic kidney disease (CKD). Knocking in of RCAN1.4 efficiently attenuated chronic renal allograft interstitial fibrosis in vivo and inhibited TNF-α-induced EMT in vitro through regulating anti-oxidative stress and the calcineurin/nuclear factor of activated T cells cytoplasmic 1 (NFATc1) signaling pathway. In addition, suppression of YY1 mediated by shRNA or siRNA alleviated TNF-α-induced EMT through abolishing reactive species partly in an RCAN1.4-dependent manner. Notably, we confirmed that YY1 negatively regulated RCAN1.4 transcription by directly interacting with the RCAN1.4 promoter. In addition, histone deacetylase 2 (HDAC2) interacted with YY1 to form a multi-molecular complex, which was involved in TNF-α-induced RCAN1.4 transcriptional repression. Therefore, RCAN1.4 is suggested to be modulated by the YY1/HDAC2 transcription repressor complex in an epigenetic manner, which is a mediated nephroprotective effect partly through modulating O2⋅- generation and the calcineurin/NFATc1 signaling pathway. Thus, the YY1-RCAN1.4 axis constitutes an innovative target for IF/TA treatment in CAD patients.

Inhibitory Effects of Rhein on Renal Interstitial Fibrosis via the SHH-Gli1 Signal Pathway

Background. Rhein is the main extract of Rheum palmatum L., which has been proved to improve the renal function of chronic kidney disease, but its mechanism is not clear. Therefore, this experiment explored the potential pharmacological effect of rhein on renal interstitial fibrosis rats. Methods. This study explores the potential pharmacological action of rhein. In this work, we investigate the potential pharmacological action of rhein in unilateral urethral obstruction (UUO) rats. Thirty Sprague Dawley rats were randomly divided into three groups: sham, UUO, and rhein (rhein-treated UUO rats) groups. The left ureters of the UUO group rats were exposed and bluntly dissected. The rhein group rats were administered an intragastric gavage of rhein (2 mg·kg−1·d−1) for 14 d. Kidney function-related indicators were monitored in these rats, while indexes of pathologic aspects were determined histologically. The expression of α-SMA, TGF-β1, SHH, Gli1, and Snail was quantified using real-time polymerase chain reaction and western blotting. The NRK-49F cells were incubated with and without SHH (100 ng·ml−1) for 48 hours. The SHH-activated NRK-49F cells were incubated with cyclopamine (CNP, 20 umol L−1) or rhein (1 ng·ml−1). The Gli1 and Snail mRNA and protein level were detected. Results. In the in vivo experiment, the results exhibited that UUO caused renal pathological damages. However, these changes could be significantly reversed by the administration of rhein. Compared with the untreated UUO group, the rhein group showed reduced kidney tubular atrophy and necrosis, interstitial fibrosis, hyperplasia, and abnormal deposition of extracellular matrix. Rhein reduced the RNA and protein expression of SHH, Gli1, and Snail of the UUO rats. In the in vitro experiment, CNP or rhein treatment decreased the expression of Gli1 and Snail on mRNA and protein levels in SHH-induced NRK-49F cells, suggesting that CNP or rhein suppresses SHH-induced NRK-49F activation. Taken together, these results demonstrated that rhein suppresses SHH-Gli1-Snail signal pathway activation, with potential implications for the treatment of renal fibrosis. Conclusions. Treatment with rhein remarkably ameliorated renal interstitial fibrosis in UUO rats by regulating the SHH-Gli1-Snail signal pathway.