Regulation of Osteoblast Migration Involving Receptor Activator of Nuclear Factor-kappa B (RANK) Signaling

RANK in cancer-associated fibroblasts: A valuable prognostic determinant for metastasis in early-stage breast cancer patients

BACKGROUND

The molecular system of receptor activator of nuclear factor kappa-β (RANK) and its ligand (RANKL) plays a role in a variety of physiological and pathological processes. These encompass the regulation of bone metabolism, mammary gland development, immune function, as well as their involvement and tumorigenesis. Nevertheless, limited knowledge exists regarding their function within the tumor microenvironment.

METHODS AND RESULTS

We explored the significance of RANK expression in cancer-associated fibroblasts (CAFs) as a prognostic biomarker in early breast cancer patients (BCPs) by immunohistochemistry. Results reveal a significant correlation between high RANK expression in CAFs and an increased risk of metastasis (p= 0.006), shorter metastasis-free survival (MFS) [p= 0.007, OR (95%CI) = 2.290 (1.259-4.156)], and lower overall survival (OS) [p= 0.004, OR (95%CI) = 2.469 (1.343-4.541)]. Upon analyzing the phenotype of CD34(-) CAFs isolated from primary tumors in BCPs, we observed co-expression of RANK with CD105 marker by immunofluorescence and flow cytometry, characteristic of mesenchymal stem/stromal cells (MSCs), suggesting the possible cellular origin. Also RANKL-RANK system increase the OCT-4, SOX-2 and DKK-1 (dickkopf 1) gene expression in CD34(-) CAFs by RT-PCR. Moreover, this system plays a crucial role in the migration of these CD34(-) CAFs.

CONCLUSIONS

These results support the clinical relevance of RANK in CAFs and propose its potential as a future therapeutic target in the treatment of early BCPs.

The OSR9 Regimen: A New Augmentation Strategy for Osteosarcoma Treatment Using Nine Older Drugs from General Medicine to Inhibit Growth Drive

As things stand in 2023, metastatic osteosarcoma commonly results in death. There has been little treatment progress in recent decades. To redress the poor prognosis of metastatic osteosarcoma, the present regimen, OSR9, uses nine already marketed drugs as adjuncts to current treatments. The nine drugs in OSR9 are: (1) the antinausea drug aprepitant, (2) the analgesic drug celecoxib, (3) the anti-malaria drug chloroquine, (4) the antibiotic dapsone, (5) the alcoholism treatment drug disulfiram, (6) the antifungal drug itraconazole, (7) the diabetes treatment drug linagliptin, (8) the hypertension drug propranolol, and (9) the psychiatric drug quetiapine. Although none are traditionally used to treat cancer, all nine have attributes that have been shown to inhibit growth-promoting physiological systems active in osteosarcoma. In their general medicinal uses, all nine drugs in OSR9 have low side-effect risks. The current paper reviews the collected data supporting the role of OSR9.

Uncovering the potential role of oxidative stress in the development of periodontitis and establishing a stable diagnostic model via combining single-cell and machine learning analysis

BACKGROUND

The primary pathogenic cause of tooth loss in adults is periodontitis, although few reliable diagnostic methods are available in the early stages. One pathological factor that defines periodontitis pathology has previously been believed to be the equilibrium between inflammatory defense mechanisms and oxidative stress. Therefore, it is necessary to construct a model of oxidative stress-related periodontitis diagnostic markers through machine learning and bioinformatic analysis.

METHODS

We used LASSO, SVM-RFE, and Random Forest techniques to screen for periodontitis-related oxidative stress variables and construct a diagnostic model by logistic regression, followed by a biological approach to build a Protein-Protein interaction network (PPI) based on modelled genes while using modelled genes. Unsupervised clustering analysis was performed to screen for oxidative stress subtypes of periodontitis. we used WGCNA to explore the pathways correlated with oxidative stress in periodontitis patients. Networks. Finally, we used single-cell data to screen the cellular subpopulations with the highest correlation by scoring oxidative stress genes and performed a proposed temporal analysis of the subpopulations.

RESULTS

We discovered 3 periodontitis-associated genes (CASP3, IL-1β, and TXN). A characteristic line graph based on these genes can be helpful for patients. The primary hub gene screened by the PPI was constructed, where immune-related and cellular metabolism-related pathways were significantly enriched. Consistent clustering analysis found two oxidative stress categories, with the C2 subtype showing higher immune cell infiltration and immune function ratings. Therefore, we hypothesized that the high expression of oxidative stress genes was correlated with the formation of the immune environment in patients with periodontitis. Using the WGCNA approach, we examined the co-expressed gene modules related to the various subtypes of oxidative stress. Finally, we selected monocytes for mimetic time series analysis and analyzed the expression changes of oxidative stress genes with the mimetic time series axis, in which the expression of JUN, TXN, and IL-1β differed with the change of cell status.

CONCLUSION

This study identifies a diagnostic model of 3-OSRGs from which patients can benefit and explores the importance of oxidative stress genes in building an immune environment in patients with periodontitis.

Hyponatremia elicits gene expression changes driving osteoclast differentiation and functions

Growing evidence indicates that chronic hyponatremia represents a significant risk for bone loss, osteoporosis, and fractures in our aging population. Our prior studies on a rat model of the syndrome of inappropriate antidiuretic hormone secretion indicated that chronic hyponatremia causes osteoporosis by increasing osteoclastic bone resorption, thereby liberating stored sodium from bone. Moreover, studies in RAW264.7 pre-osteoclastic cells showed increased osteoclast formation and resorptive activity in response to low extracellular fluid sodium ion concentration (low [Na+]). These studies implicated a direct stimulatory effect of low [Na+] rather than the low osmolality on cultured osteoclastic cells. In the present cellular studies, we explored gene expression changes triggered by low [Na+] using RNA sequencing and gene ontology analysis. Results were confirmed by mouse whole genome microarray, and quantitative RT-PCR. Findings confirmed gene expression changes supporting osteoclast growth and differentiation through stimulation of receptor activator of nuclear factor kappa-B ligand (RANKL), and PI3K/Akt pathways, and revealed additional pathways. New findings on low [Na+]-induced upregulation of lysosomal genes, mitochondrial energy production, MMP-9 expression, and osteoclast motility have supported the significance of osteoclast transcriptomic responses. Functional assays demonstrated that RANL and low [Na+] independently enhance osteoclast functions. Understanding the molecular mechanisms of hyponatremia-induced osteoporosis provides the basis for future studies identifying sodium-sensing mechanisms in osteoclasts, and potentially other bone cells, and developing strategies for treatment of bone fragility in the vulnerable aging population most affected by both chronic hyponatremia and osteoporosis. ISSUE SECTIONS: Signaling Pathways; Parathyroid, Bone, and Mineral Metabolism.

The Role of NR4A1 in the Pathophysiology of Osteosarcoma: A Comprehensive Bioinformatics Analysis of the Single-Cell RNA Sequencing Dataset

Osteosarcoma is a kind of aggressive human malignancy, and the prognosis of the patients with osteosarcoma remains low. Studies have demonstrated that the tumor microenvironment plays a key role in regulating osteosarcoma progression. Recent studies have also shown that scRNA-seq plays an essential role in understanding the tumor heterogeneity and distinct subpopulations of tumors. In order to further understand the scRNA-seq data of osteosarcoma tissues, the present study further analyzed the scRNA-seq dataset (GSE152048) and explored the potential role of nuclear receptor-related genes in the pathophysiology of osteosarcoma. In our analysis, we identified 11 cell types in all the osteosarcoma tissues and nuclear receptors (NRs) were distributed in all types of cells. Further stratification analysis showed that NRs were mainly detected in “TIL” and “Osteoblastic” of the metastasis osteosarcoma, in “TIL”, “Myoblast”, “Endothelial”, and “Myeloid” of the primary osteosarcoma, and in “Chondroblastic”, “Osteoblast”, and “Pericyte” of the recurrent osteosarcoma. The NRs were also differentially expressed in different cell types among the metastasis, primary, and recurrent osteosarcoma. Furthermore, several NRs such as NR4A2, NR4A1, and NR3C1 have been found to be differentially expressed in most types of DEGs among metastasis, primary, and recurrent osteosarcoma. A high expression of NR4A1 in the osteosarcoma tissues was significantly correlated with a shorter 5-year overall survival of patients with osteosarcoma. On the other hand, there was no significant association between NR4A2 expression and the 5-year overall survival of patients with osteosarcoma. The expression of NR4A1 was significantly higher in the metastasis osteosarcoma tissues than in the primary osteosarcoma tissues as validated from GSE32981 and GSE154540. The expression of NR4A1 was significantly higher in osteosarcoma tissues from patients with poor chemosensitivity than that from patients with good chemosensitivity as validated from GSE154540. Further analysis of the scRNA-seq data revealed that the percentage of osteoblasts with a high NR4A1 expression was higher in the recurrent osteosarcoma tissues than that with a low NR4A1 expression. In conclusion, the present study may suggest that NR4A1 may be an important prognostic biomarker for osteosarcoma progression. However, further validation studies should be performed to confirm our findings.

A missense mutation sheds light on a novel structure-function relationship of RANKL

The tumor necrosis factor (TNF)-like core domain of receptor activator of nuclear factor-κB ligand (RANKL) is a functional domain critical for osteoclast differentiation. One of the missense mutations identified in patients with osteoclast-poor autosomal recessive osteopetrosis (ARO) is located in residue methionine 199 that is replaced with lysine (M199K) amid the TNF-like core domain. However, the structure-function relationship of this mutation is not clear. Sequence-based alignment revealed that the fragment containing human M199 is highly conserved and equivalent to M200 in rat. Using site-directed mutagenesis, we generated three recombinant RANKL mutants M200K/A/E (M200s) by replacing the methionine 200 with lysine (M200K), alanine (M200A), and glutamic acid (M200E), representative of distinct physical properties. TRAcP staining and bone pit assay showed that M200s failed to support osteoclast formation and bone resorption, accompanied by impaired osteoclast-related signal transduction. However, no antagonistic effect was found in M200s against wild-type rat RANKL. Analysis of the crystal structure of RANKL predicted that this methionine residue is located within the hydrophobic core of the protein, thus, likely to be crucial for protein folding and stability. Consistently, differential scanning fluorimetry analysis suggested that M200s were less stable. Western blot analysis analyses further revealed impaired RANKL trimerization by M200s. Furthermore, receptor-ligand binding assay displayed interrupted interaction of M200s to its intrinsic receptors. Collectively, our studies revealed the molecular basis of human M199-induced ARO and elucidated the indispensable role of rodent residue M200 (equivalent to human M199) for the RANKL function.

A Retrospective Analysis: A Novel Index Predicts Survival and Risk-Stratification for Bone Destruction in 419 Newly Diagnosed Multiple Myelomas

Objective

Multiple myeloma (MM) patients with bone destruction are difficult to restore, so it is of great clinical significance to further explore the factors affecting MM bone destruction.

Methods and results

This study retrospectively analyzed 419 cases with MM. Multiple linear regression analysis showed that those MM patients with a higher concentration of Ca²⁺ in serum, higher positive rate of CD138 immuno-phenotype and advanced in stage with 13q34 deletion in cytogenetics would be more prone to bone destruction, while total bile acid (TBA) and kappa chain isotope negatively correlated with bone destruction in MM patients. The Kaplan-Meier analysis indicated that Ca²⁺, serum β2-microglobulin (β2-MG), hemoglobin (HGB), creatinine (CREA), uric acid (UA) and age correlated with the survival of bone destruction in MM patients. Cox regression analysis further showed that the independent prognostic factors of β2-MG and CREA had a higher risk for early mortality in bone destruction patients. Moreover, an index was calculated based on β2-MG and globulin (GLB) to white blood cell (WBC) ratio to predict the poor survival of bone destruction patients.

Conclusion

We provide a novel marker to predict the prognosis of myeloma patients using routine examination method instead of bone marrow aspiration, and provide a reference for clinical evaluation.

S-amlodipine improves endothelial dysfunction via the RANK/RANKL/OPG system by regulating microRNA-155 in hypertension

S-amlodipine has been broadly used to treat hypertension, but its protective effects and underlying mechanism remain controversial. The purpose of our study was to investigate the mechanism by which S-amlodipine improves endothelial dysfunction. Specifically, we investigated if S-amlodipine regulates RANK/RANKL/OPG and micro-RNA 155 (miR-155) levels. Spontaneous hypertensive rats (SHR) were randomly divided into two groups: SHR (n = 12) and S-amlodipine (n = 12). We found that left ventricular ejection fraction (LVEF) increased significantly in the S-amlodipine group compared to the SHR group. After 10 weeks of S-amlodipine treatment, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were significantly lower and eNOS and NO production was significantly higher in the S-amlodipine group compared to the SHR group. In human umbilical vein endothelial cells (HUVECs), miR-155, RANK, and RANKL levels were significantly decreased, while OPG mRNA levels were significantly increased in the S-amlodipine group. HUVECs were transfected with miR-155 mimics or an inhibitor to determine the relationship between miR-155 and RANK/RANKL/OPG and NF-κB signaling. OPG mRNA levels following miR-155 inhibition were significantly higher compared to levels following treatment with miR-155 mimics. S-amlodipine significantly inhibited RANKL expression and NF-κB phosphorylation, and there were no significant differences in response to the NF-κB inhibitor (Bay110785). RANKL expression and NF-κB phosphorylation significantly decreased in the miR-155 inhibitor group. Furthermore, OPG protein expression significantly increased in response to miR-155 inhibition and S-amlodipine treatment (all p < 0.05). Our results indicate that S-amlodipine inhibits inflammation and protects against endothelial dysfunction, likely via regulating the RANK/RANKL/OPG pathway, which appears to be downstream of miR-155.

Autocrine production of reproductive axis neuropeptides affects proliferation of canine osteosarcoma in vitro

Background

Osteosarcoma strikes hundreds of people each year, of both advanced and younger ages, and is often terminal. Like many tumor types, these bone tumors will frequently undergo a neuroendocrine transition, utilizing autocrine and/or paracrine hormones as growth factors and/or promoters of angiogenesis to facilitate progression and metastasis. While many of these factors and their actions on tumor growth are characterized, some tumor-derived neuropeptides remain unexplored.

Methods

Using validated canine osteosarcoma cell lines in vitro, as well as cells derived from spontaneous tumors in dogs, we explored the autocrine production of two neuropeptides typically found in the hypothalamus, and most closely associated with reproduction: gonadotropin-releasing hormone (GnRH) and kisspeptin (Kiss-1). We evaluated gene expression and protein secretion of these hormones using quantitative RT-PCR and a sensitive radioimmunoassay, and explored changes in cell proliferation determined by MTS cell viability assays.

Results

Our current studies reveal that several canine osteosarcoma cell lines (COS, POS, HMPOS, D17, C4) synthesize and secrete GnRH and express the GnRH receptor, while COS and POS also express kiss1 and its cognate receptor. We have further found that GnRH and kisspeptin, exogenously applied to these tumor cells, exert significant effects on both gene expression and proliferation. Of particular interest, kisspeptin exposure stimulated GnRH secretion from COS, similarly to the functional relationship observed within the neuroendocrine reproductive axis. Additionally, GnRH and kisspeptin treatment both increased COS proliferation, which additionally manifested in increased expression of the bone remodeling ligand rankl within these cells. These effects were blocked by treatment with a specific GnRH receptor inhibitor. Both neuropeptides were found to increase expression of the specific serotonin (5HT) receptor htr2a, the activation of which has previously been associated with cellular proliferation, suggesting that production of these factors by osteosarcoma cells may act to sensitize tumors to circulating 5HT of local and/or enteric origin.

Conclusions

Here we report that kisspeptin and GnRH act as autocrine growth factors in canine osteosarcoma cells in vitro, modulating RANKL and serotonin receptor expression in a manner consistent with pro-proliferative effects. Pharmacological targeting of these hormones may represent new avenues of osteosarcoma treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5363-4) contains supplementary material, which is available to authorized users.

RANKL signaling in bone marrow mesenchymal stem cells negatively regulates osteoblastic bone formation

RANKL signaling is essential for osteoclastogenesis. Its role in osteoblastic differentiation and bone formation is unknown. Here we demonstrate that RANK is expressed at an early stage of bone marrow mesenchymal stem cells (BMSCs) during osteogenic differentiation in both mice and human and decreased rapidly. RANKL signaling inhibits osteogenesis by promoting β-catenin degradation and inhibiting its synthesis. In contrast, RANKL signaling has no significant effects on adipogenesis of BMSCs. Interestingly, conditional knockout of rank in BMSCs with Prx1-Cre mice leads to a higher bone mass and increased trabecular bone formation independent of osteoclasts. In addition, rank^flox/flox: Prx1-Cre mice show resistance to ovariectomy-(OVX) induced bone loss. Thus, our results reveal that RANKL signaling regulates both osteoclasts and osteoblasts by inhibition of osteogenic differentiation of BMSCs and promotion of osteoclastogenesis.

Researchers in China have shown that a gene known for breaking bones down is also involved in making new bone. Bones are constantly repaired and reshaped by cells which break down bone tissue, osteoclasts, and those which create new bone, osteoblasts. The RANKL gene is known to play an important role in osteoclast development, but Jiacan Su of the Second Military Medical University has shown that it is also important for osteoblasts. Su’s team detected high expression of RANKL and its receptor, RANK, in bone marrow stem cells, and the levels decreased as the stem cells differentiated into osteoblasts. Artificially increasing RANK expression decreased osteoblast differentiation, while reducing its expression increased osteoblast differentiation and bone mass. By showing that RANKL regulates osteoblasts as well as osteoclasts, these findings open new avenues for understanding bones development.

Mesenchymal Stem Cell Migration during Bone Formation and Bone Diseases Therapy

During bone modeling, remodeling, and bone fracture repair, mesenchymal stem cells (MSCs) differentiate into chondrocyte or osteoblast to comply bone formation and regeneration. As multipotent stem cells, MSCs were used to treat bone diseases during the past several decades. However, most of these implications just focused on promoting MSC differentiation. Furthermore, cell migration is also a key issue for bone formation and bone diseases treatment. Abnormal MSC migration could cause different kinds of bone diseases, including osteoporosis. Additionally, for bone disease treatment, the migration of endogenous or exogenous MSCs to bone injury sites is required. Recently, researchers have paid more and more attention to two critical points. One is how to apply MSC migration to bone disease therapy. The other is how to enhance MSC migration to improve the therapeutic efficacy of bone diseases. Some considerable outcomes showed that enhancing MSC migration might be a novel trick for reversing bone loss and other bone diseases, such as osteoporosis, fracture, and osteoarthritis (OA). Although plenty of challenges need to be conquered, application of endogenous and exogenous MSC migration and developing different strategies to improve therapeutic efficacy through enhancing MSC migration to target tissue might be the trend in the future for bone disease treatment.

Importance and regulation of adult stem cell migration

Cell migration is an essential process throughout the life of vertebrates, beginning during embryonic development and continuing throughout adulthood. Stem cells have an inherent ability to migrate, that is as important as their capacity for self‐renewal and differentiation, enabling them to maintain tissue homoeostasis and mediate repair and regeneration. Adult stem cells reside in specific tissue niches, where they remain in a quiescent state until called upon and activated by tissue environmental signals. Cell migration is a highly regulated process that involves the integration of intrinsic signals from the niche and extrinsic factors. Studies using three‐dimensional in vitro models have revealed the astonishing plasticity of cells in terms of the migration modes employed in response to changes in the microenvironment. These same properties can, however, be subverted during the development of some pathologies such as cancer. In this review, we describe the response of adult stem cells to migratory stimuli and the mechanisms by which they sense and transduce intracellular signals involved in migratory processes. Understanding the molecular events underlying migration may help develop therapeutic strategies for regenerative medicine and to treat diseases with a cell migration component.

Dynamic Tracking of Osteoblastic Cell Traction Force during Guided Migration

Introduction

Continuous development of cell traction force can regulate cell migration on various extracellular matrixes in vivo. However, the topographical effect on traction force is still not fully understood.

Methods

Micropost sensors with parallel guiding gratings were fabricated in polydimethylsiloxane to track the cell traction force during topographical guidance in real time. The force distributions along MC3T3-E1 mouse osteoblasts were captured every minute. The traction force in the leading, middle, and trailing regions was monitored during forward and reversed cell migration.

Results

The traction force showed periodic changes during cell migration when the cell changed from elongated to contracted shape. For cell migration without guiding pattern, the leading region showed the largest traction force among the three regions, typically 5.8 ± 0.8 nanonewton (nN) when the cell contracted and 7.1 ± 0.5 nN when it elongated. During guided cell migration, a lower traction force was obtained. When a cell contracted, the trailing traction force was 4.1 ± 0.4 for non-guided migration and 2.2 ± 0.2 nN for guided migration. As a cell became elongated, the trailing traction force was 6.0 ± 0.5 nN during non-guided migration and 4.8 ± 0.3 nN under guidance. When a cell reversed its migration direction, the magnitudes of the traction force from the leading to the trailing regions also flipped.

Conclusion

The cell traction force is continuously influenced by topographical guidance, which determines cell migration speed and direction. These results of cell traction force development on various topographies could lead to better cell migration control using topotaxis.

Osteoblast migration in vertebrate bone

Bone formation, for example during bone remodelling or fracture repair, requires mature osteoblasts to deposit bone with remarkable spatial precision. As osteoblast precursors derive either from circulation or resident stem cell pools, they and their progeny are required to migrate within the three-dimensional bone space and to navigate to their destination, i.e. to the site of bone formation. An understanding of this process is emerging based on in vitro and in vivo studies of several vertebrate species. Receptors on the osteoblast surface mediate cell adhesion and polarization, which induces osteoblast migration. Osteoblast migration is then facilitated along gradients of chemoattractants. The latter are secreted or released proteolytically by several cell types interacting with osteoblasts, including osteoclasts and vascular endothelial cells. The positions of these cellular sources of chemoattractants in relation to the position of the osteoblasts provide the migrating osteoblasts with tracks to their destination, and osteoblasts possess the means to follow a track marked by multiple chemoattractant gradients. In addition to chemotactic cues, osteoblasts sense other classes of signals and utilize them as landmarks for navigation. The composition of the osseous surface guides adhesion and hence migration efficiency and can also provide steering through haptotaxis. Further, it is likely that signals received from surface interactions modulate chemotaxis. Besides the nature of the surface, mechanical signals such as fluid flow may also serve as navigation signals for osteoblasts. Alterations in osteoblast migration and navigation might play a role in metabolic bone diseases such as osteoporosis.

RANK-RANKL signalling in cancer

Oncogenic events combined with a favourable environment are the two main factors in the oncological process. The tumour microenvironment is composed of a complex, interconnected network of protagonists, including soluble factors such as cytokines, extracellular matrix components, interacting with fibroblasts, endothelial cells, immune cells and various specific cell types depending on the location of the cancer cells (e.g. pulmonary epithelium, osteoblasts). This diversity defines specific "niches" (e.g. vascular, immune, bone niches) involved in tumour growth and the metastatic process. These actors communicate together by direct intercellular communications and/or in an autocrine/paracrine/endocrine manner involving cytokines and growth factors. Among these glycoproteins, RANKL (receptor activator nuclear factor-κB ligand) and its receptor RANK (receptor activator nuclear factor), members of the TNF and TNFR superfamilies, have stimulated the interest of the scientific community. RANK is frequently expressed by cancer cells in contrast with RANKL which is frequently detected in the tumour microenvironment and together they participate in every step in cancer development. Their activities are markedly regulated by osteoprotegerin (OPG, a soluble decoy receptor) and its ligands, and by LGR4, a membrane receptor able to bind RANKL. The aim of the present review is to provide an overview of the functional implication of the RANK/RANKL system in cancer development, and to underline the most recent clinical studies.

Cyclopropanyldehydrocostunolide LJ attenuates high glucose-induced podocyte injury by suppressing RANKL/RANK-mediated NF-κB and MAPK signaling pathways

AIMS

The aim of this research was to investigate the effects of cyclopropanyldehydrocostunolide (also named LJ), a derivative of sesquiterpene lactones (SLs), on high glucose (HG)-induced podocyte injury and the associated molecular mechanisms.

METHODS

Differentiated mouse podocytes were incubated in different treatments. The migration and albumin filtration of podocytes were examined by Transwell filters. The protein and mRNA levels of MCP-1 were measured using enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR (q-PCR). Protein expression and phosphorylation were detected by western blot, and the nuclear translocation of NF-κB was performed with a confocal microscope. The gene expression of the receptor activator for NF-κB (RANK) was silenced by small interfering RNA (siRNA).

RESULTS

Our results showed that HG enhanced migration, albumin filtration and MCP-1 expression in podocytes. At the molecular level, HG promoted the phosphorylation of NF-κB/p65, IKKβ, IκBα, mitogen-activated protein kinase (MAPK) and the nuclear translocation of p65. LJ reversed the effects of HG in a dose-dependent manner. Furthermore, our data provided the first demonstration that the receptor activator for NF-κB ligand (RANKL) and its cognate receptor RANK were overexpressed in HG-induced podocytes and were downregulated by LJ. RANK siRNA also attenuated HG-induced podocyte injury and markedly inhibited the activation of NF-κB and MAPK signaling pathways.

CONCLUSIONS

LJ attenuates HG-induced podocyte injury by suppressing RANKL/RANK-mediated NF-κB and MAPK signaling pathways.