Wnt-Signaling Regulated by Glucocorticoid-Induced miRNAs

Fufang Zhenshu Tiaozhi capsule enhances bone formation and safeguards against glucocorticoid-induced osteoporosis through innovative Mekk2-mediated β-catenin deubiquitination

INTRODUCTION

Bone homeostasis depends on the regulation of β-catenin in osteoblasts. Glucocorticoids (GCs) are known to diminish β-catenin activity via Wnt pathway signaling, leading to osteoporosis. Conversely, activating β-catenin in osteoblasts through mitogen-activated protein kinase kinase kinase 2 (Mekk2) offers an innovative approach to combat GC-induced osteoporosis (GIOP). Fufang Zhenshu Tiaozhi (FTZ) capsules have shown effectiveness in treating GIOP, but the mechanisms behind this are still unclear.

MATERIALS AND METHODS

In this study, Mekk2 knockout mice (Mekk2-/-) was generated by CRISPR/Cas9. These mice were then subjected to Alcian Blue-Alizarin Red staining and immunofluorescence to assess their bone and cartilage development. To establish models of GIOP, both Mekk2-/- and wild-type (WT) mice were treated with dexamethasone (DXMS) and subsequently given FTZ capsules. We analyzed the resulting phenotypic changes in these mice using Micro-CT scans and histomorphological studies. Primary osteoblasts, isolated from both Mekk2-/- and WT mice, underwent qRT-PCR to measure key osteogenesis markers, including Runx2, Sp7, Bgalp, Col1a1 and Alp. Cells were then exposed to treatments with either FTZ or Wnt3a and the phosphorylation levels of β-catenin and Mekk2, along with the protein expression of Runx2, were evaluated using Western blotting and immunoprecipitation. Additionally, C3H10T1/2 cells transfected with TOPflash-luciferase and Renilla luciferase reporters were treated with FTZ and Wnt3a to measure β-catenin activity.

RESULTS

In our study, administering FTZ in vivo effectively prevented bone loss typically induced by GCs. However, it's important to note that this protective effect was substantially reduced in mice lacking Mekk2. Additionally, FTZ showed a significant ability to enhance osteogenic differentiation in primary osteoblasts, doing so by altering the expression of Mekk2. Intriguingly, the impact of FTZ on Mekk2 appears to function through a pathway separate from the traditional Wnt signaling route. Furthermore, our findings indicate that FTZ also promotes the deubiquitination of β-catenin, contributing further to its positive effects on bone health.

CONCLUSIONS

This study suggests that FTZ plays a significant role in protecting bone mass in cases of GIOP. The mechanism through which FTZ confers this benefit involves the activation of Mekk2/β-catenin signaling pathways, which represents a promising alternative strategy to counteract the deleterious effects of GIOP by augmenting osteoblastogenesis.

MiRNA-21a, miRNA-145, and miRNA-221 Expression and Their Correlations with WNT Proteins in Patients with Obstructive and Non-Obstructive Coronary Artery Disease

MicroRNAs and the WNT signaling cascade regulate the pathogenetic mechanisms of atherosclerotic coronary artery disease (CAD) development.

OBJECTIVE

To evaluate the expression of microRNAs (miR-21a, miR-145, and miR-221) and the role of the WNT signaling cascade (WNT1, WNT3a, WNT4, and WNT5a) in obstructive CAD and ischemia with no obstructive coronary arteries (INOCA).

METHOD

The cross-sectional observational study comprised 94 subjects. The expression of miR-21a, miR-145, miR-221 (RT-PCR) and the protein levels of WNT1, WNT3a, WNT4, WNT5a, LRP6, and SIRT1 (ELISA) were estimated in the plasma of 20 patients with INOCA (66.5 [62.8; 71.2] years; 25% men), 44 patients with obstructive CAD (64.0 [56.5; 71,0] years; 63.6% men), and 30 healthy volunteers without risk factors for cardiovascular diseases (CVD).

RESULTS

Higher levels of WNT1 (0.189 [0.184; 0.193] ng/mL vs. 0.15 [0.15-0.16] ng/mL, p < 0.001) and WNT3a (0.227 [0.181; 0.252] vs. 0.115 [0.07; 0.16] p < 0.001) were found in plasma samples from patients with obstructive CAD, whereas the INOCA group was characterized by higher concentrations of WNT4 (0.345 [0.278; 0.492] ng/mL vs. 0.203 [0.112; 0.378] ng/mL, p = 0.025) and WNT5a (0.17 [0.16; 0.17] ng/mL vs. 0.01 [0.007; 0.018] ng/mL, p < 0.001). MiR-221 expression level was higher in all CAD groups compared to the control group (p < 0.001), whereas miR-21a was more highly expressed in the control group than in the obstructive (p = 0.012) and INOCA (p = 0.003) groups. Correlation analysis revealed associations of miR-21a expression with WNT1 (r = -0.32; p = 0.028) and SIRT1 (r = 0.399; p = 0.005) protein levels in all CAD groups. A positive correlation between miR-145 expression and the WNT4 protein level was observed in patients with obstructive CAD (r = 0.436; p = 0.016). Based on multivariate regression analysis, a mathematical model was constructed that predicts the type of coronary lesion. WNT3a and LRP6 were the independent predictors of INOCA (p < 0.001 and p = 0.002, respectively).

CONCLUSIONS

Activation of the canonical cascade of WNT-β-catenin prevailed in patients with obstructive CAD, whereas in the INOCA and control groups, the activity of the non-canonical pathway was higher. It can be assumed that miR-21a has a negative effect on the formation of atherosclerotic CAD. Alternatively, miR-145 could be involved in the development of coronary artery obstruction, presumably through the regulation of the WNT4 protein. A mathematical model with WNT3a and LRP6 as predictors allows for the prediction of the type of coronary artery lesion.

Glucocorticoid Signaling Pathway: From Bench to Bedside

Glucocorticoids were named by Hans Hugo Bruno Selye, the modern father of stress concepts, for their important role in glucose metabolism [...].

Apoptosis Evaluation in Circulating CD34+-Enriched Hematopoietic Stem and Progenitor Cells in Patients with Abnormally Increased Production of Endogenous Glucocorticoids in Course of Cushing's Syndrome

Abnormalities in hematological parameters of peripheral blood have been noted in patients with endogenous Cushing's Syndrome (CS) in the corticotropin (ACTH)-dependent and ACTH-independent forms. Nevertheless, the exact mechanism of glucocorticoids (GCs) action on human hematopoiesis is still not entirely clear. The aim of the study was to determine whether endogenous excessive production of GCs could affect apoptosis of CD34+ cells enriched in hematopoietic stem and progenitor cells (HSPCs) collected from the peripheral blood of newly diagnosed CS patients. Flow cytometry, Annexin-V enzyme-linked immunosorbent assay, TUNEL assay, real-time quantitative PCR, and microarray RNA/miRNA techniques were used to characterize CS patients' HSPCs. We found that the glucocorticoid receptor (GR) protein expression levels in CS were higher than in healthy controls. A complex analysis of apoptotic status of CS patients' HSPC cells showed that GCs significantly augmented apoptosis in peripheral blood-derived CD34+ cells and results obtained using different methods to detect early and late apoptosis in analyzed cell population were consistent. CS was also associated with significant upregulation in several members of the BCL-2 superfamily and other genes associated with apoptosis control. Furthermore, global gene expression analysis revealed significantly higher expression of genes associated with programmed cell death control in HSPCs from CS patients. These findings suggest that human endogenous GCs have a direct pro-apoptotic activity in hematopoietic CD34+ cells derived from CS subjects before treatment.

Coaxially Fabricated Dual-Drug Loading Electrospinning Fibrous Mat with Programmed Releasing Behavior to Boost Vascularized Bone Regeneration

In clinical treatment, the bone regeneration of critical-size defects is desiderated to be solved, and the regeneration of large bone segment defects depends on early vascularization. Therefore, overcoming insufficient vascularization in artificial bone grafts may be a promising strategy for critical-size bone regeneration. Herein, a novel dual-drug programmed releasing electrospinning fibrous mat (EFM) with a deferoxamine (DFO)-loaded shell layer and a dexamethasone (DEX)-loaded core layer is fabricated using coaxial electrospinning technology, considering the temporal sequence of vascularization and bone repair. DFO acts as an angiogenesis promoter and DEX is used as an osteogenesis inducer. The results demonstrate that the early and rapid release of DFO promotes angiogenesis in human umbilical vascular endothelial cells and the sustained release of DEX enhances the osteogenic differentiation of rat bone mesenchymal stem cells. DFO and DEX exert synergetic effects on osteogenic differentiation via the Wnt/β-catenin signaling pathway, and the dual-drug programmed releasing EFM acquired perfect vascularized bone regeneration ability in a rat calvarial defect model. Overall, the study suggests a low-cost strategy to enhance vascularized bone regeneration by adjusting the behavior of angiogenesis and osteogenesis in time dimension.

Characterization of Adrenal miRNA-Based Dysregulations in Cushing's Syndrome

MiRNAs are important epigenetic players with tissue- and disease-specific effects. In this study, our aim was to investigate the putative differential expression of miRNAs in adrenal tissues from different forms of Cushing’s syndrome (CS). For this, miRNA-based next-generation sequencing was performed in adrenal tissues taken from patients with ACTH-independent cortisol-producing adrenocortical adenomas (CPA), from patients with ACTH-dependent pituitary Cushing’s disease (CD) after bilateral adrenalectomy, and from control subjects. A confirmatory QPCR was also performed in adrenals from patients with other CS subtypes, such as primary bilateral macronodular hyperplasia and ectopic CS. Sequencing revealed significant differences in the miRNA profiles of CD and CPA. QPCR revealed the upregulated expression of miR-1247-5p in CPA and PBMAH (log2 fold change > 2.5, p < 0.05). MiR-379-5p was found to be upregulated in PBMAH and CD (log2 fold change > 1.8, p < 0.05). Analyses of miR-1247-5p and miR-379-5p expression in the adrenals of mice which had been exposed to short-term ACTH stimulation showed no influence on the adrenal miRNA expression profiles. For miRNA-specific target prediction, RNA-seq data from the adrenals of CPA, PBMAH, and control samples were analyzed with different bioinformatic platforms. The analyses revealed that both miR-1247-5p and miR-379-5p target specific genes in the WNT signaling pathway. In conclusion, this study identified distinct adrenal miRNAs as being associated with CS subtypes.

Mechanisms behind context-dependent role of glucocorticoids in breast cancer progression

Glucocorticoids (GCs), mostly dexamethasone (dex), are routinely administered as adjuvant therapy to manage side effects in breast cancer. However, recently, it has been revealed that dex triggers different effects and correlates with opposite outcomes depending on the breast cancer molecular subtype. This has raised new concerns regarding the generalized use of GC and suggested that the context-dependent effects of GCs can be taken into potential consideration during treatment design. Based on this, attention has recently been drawn to the role of the glucocorticoid receptor (GR) in development and progression of breast cancer. Therefore, in this comprehensive review, we aimed to summarize the different mechanisms behind different context-dependent GC actions in breast cancer by applying a multilevel examination, starting from the association of variants of the GR-encoding gene to expression at the mRNA and protein level of the receptor, and its interactions with other factors influencing GC action in breast cancer. The role of GCs in chemosensitivity and chemoresistance observed during breast cancer therapy is discussed. In addition, experiences using GC targeting therapeutic options (already used and investigated in preclinical and clinical trials), such as classic GC dexamethasone, selective glucocorticoid receptor agonists and modulators, the GC antagonist mifepristone, and GR coregulators, are also summarized. Evidence presented can aid a better understanding of the biology of context-dependent GC action that can lead to further advances in the personalized therapy of breast cancer by the evaluation of GR along with the conventional estrogen receptor (ER) and progesterone receptor (PR) in the routine diagnostic procedure.