miR-433-3p suppresses bone formation and mRNAs critical for osteoblast function in mice

Changing landscape of hematopoietic and mesenchymal cells and their interactions during aging and in age-related skeletal pathologies

Aging profoundly impacts mesenchymal and hematopoietic lineage cells, including their progenitors-the skeletal stem cells (SSCs) and hematopoietic stem cells (HSCs), respectively. SSCs are crucial for skeletal development, homeostasis, and regeneration, maintaining bone integrity by differentiating into osteoblasts, adipocytes, and other lineages that contribute to the bone marrow (BM) microenvironment. Meanwhile, HSCs sustain hematopoiesis and immune function. With aging, SSCs and HSCs undergo significant functional decline, partly driven by cellular senescence-a hallmark of aging characterized by irreversible growth arrest, secretion of pro-inflammatory factors (senescence associated secretory phenotype, SASP), and impaired regenerative potential. In SSCs, senescence skews lineage commitment toward adipogenesis at the expense of osteogenesis, contributing to increased bone marrow adiposity (BMAd), reduced bone quality, and osteoporosis. Similarly, aged HSCs exhibit diminished self-renewal, biased differentiation, and heightened inflammation, compromising hematopoietic output and immune function. In this review, we examine the age-related cellular and molecular changes in SSCs and HSCs, their lineage decisions in the aging microenvironment, and the interplay between skeletal and hematopoietic compartments. We also discuss the role of senescence-driven alterations in BM homeostasis and how targeting cellular aging mechanisms may offer therapeutic strategies for mitigating age-related skeletal and hematopoietic decline.

Decreasing miR-433-3p Activity in the Osteoblast Lineage Blunts Glucocorticoid-mediated Bone Loss

Glucocorticoid excess causes bone loss due to decreased bone formation and increased bone resorption; miR-433-3p is a microRNA (miRNA) that negatively regulates bone formation in male mice by targeting Runx2 as well as RNAs involved in Wnt, protein kinase A, and endogenous glucocorticoid signaling. To examine the impact of miR-433-3p on glucocorticoid-mediated bone loss, transgenic mice expressing a miR-433-3p tough decoy inhibitor in the osteoblast lineage were administered prednisolone via slow-release pellets. Bone loss was greater in control mice treated with prednisolone compared with miR-433-3p tough decoy mice due to higher osteoclast activity in the controls. In whole femurs, Rankl was significantly higher in prednisolone-treated controls compared with miR-433-3p tough decoy mice. Surprisingly, negative regulators of Wnt signaling Sost and Dkk1 were higher in miR-433-3p tough decoy mice and were unaffected by prednisolone. Luciferase- 3'-untranslated region reporter assays demonstrated that Sost is a novel miR-433-3p target, whereas Dkk1 is a previously validated miR-433-3p target. miR-433-3p levels are lower in matrix-synthesizing osteoblasts than in more osteocytic cells; thus the impact of miR-433-3p on the osteoblast lineage may be dependent on cell context: it is a negative regulator in matrix-depositing osteoblasts by targeting RNAs important for differentiation and function but a positive regulator in osteocytes, due to its ability to target prominently expressed negative regulators of Wnt signaling, Sost and Dkk1. The mechanisms by which miR-433-3p indirectly regulates glucocorticoid-mediated osteoclastogenesis remain unknown. However, we speculate that this regulation may be mediated by miR-433-3p activity in osteocytes, which play an important role in controlling osteoclastogenesis.

Advances in the roles and mechanisms of mesenchymal stem cell derived microRNAs on periodontal tissue regeneration

Periodontitis is one of the most prevalent oral diseases leading to tooth loss in adults, and is characterized by the destruction of periodontal supporting structures. Traditional therapies for periodontitis cannot achieve ideal regeneration of the periodontal tissue. Mesenchymal stem cells (MSCs) represent a promising approach to periodontal tissue regeneration. Recently, the prominent role of MSCs in this context has been attributed to microRNAs (miRNAs), which participate in post-transcriptional regulation and are crucial for various physiological and pathological processes. Additionally, they function as indispensable elements in extracellular vesicles, which protect them from degradation. In periodontitis, MSCs-derived miRNAs play a pivotal role in cellular proliferation and differentiation, angiogenesis of periodontal tissues, regulating autophagy, providing anti-apoptotic effects, and mediating the inflammatory microenvironment. As a cell-free strategy, their small size and ability to target related sets of genes and regulate signaling networks predispose miRNAs to become ideal candidates for periodontal tissue regeneration. This review aims to introduce and summarize the potential functions and mechanisms of MSCs-derived miRNAs in periodontal tissue repair and regeneration.

Natural Compounds for Bone Remodeling: Targeting osteoblasts and relevant signaling pathways

In the process of bone metabolism and bone remodeling, bone marrow mesenchymal stem cells (BM-MSCs) differentiate into osteoblasts (OBs) under certain conditions to enable the formation of new bone, and normal bone reconstruction and pathological bone alteration are closely related to the differentiation and proliferation functions of OBs. Osteogenic differentiation of BM-MSCs involves multiple signaling pathways, which function individually but interconnect intricately to form a complex signaling regulatory network. Natural compounds have fewer adverse effects than chemically synthesized drugs, optimize bone health, and are more suitable for long-term use. In this paper, we focus on OBs, summarize the current research progress of signaling pathways related to OBs differentiation, and review the molecular mechanisms by which chemically synthesized drugs with potential anti-osteoporosis properties regulate OBs-mediated bone formation.

Molecular Signaling Pathways and MicroRNAs in Bone Remodeling: A Narrative Review

Bone remodeling is an intricate process executed throughout one's whole life via the cross-talk of several cellular events, progenitor cells and signaling pathways. It is an imperative mechanism for regaining bone loss, recovering damaged tissue and repairing fractures. To achieve this, molecular signaling pathways play a central role in regulating pathological and causal mechanisms in different diseases. Similarly, microRNAs (miRNAs) have shown promising results in disease management by mediating mRNA targeted gene expression and post-transcriptional gene function. However, the role and relevance of these miRNAs in signaling processes, which regulate the delicate balance between bone formation and bone resorption, are unclear. This review aims to summarize current knowledge of bone remodeling from two perspectives: firstly, we outline the modus operandi of five major molecular signaling pathways, i.e.,the receptor activator of nuclear factor kappa-B (RANK)-osteoprotegrin (OPG) and RANK ligand (RANK-OPG-RANKL), macrophage colony-stimulating factor (M-CSF), Wnt/β-catenin, Jagged/Notch and bone morphogenetic protein (BMP) pathways in regards to bone cell formation and function; and secondly, the miRNAs that participate in these pathways are introduced. Probing the miRNA-mediated regulation of these pathways may help in preparing the foundation for developing targeted strategies in bone remodeling, repair and regeneration.

The role of miR-433-3p in vascular calcification in type 2 diabetic patients: targeting WNT/β-Catenin and RANKL/RANK/OPG signaling pathways

BACKGROUND

Vascular calcification (VC) is a major predictor of cardiovascular diseases that represent the principal cause of mortality among type-2 diabetic patients. Accumulating data suggest the vital role of some microRNAs on vascular calcification as an epigenetic regulator. Thus, we assessed herein, the role of serum miR-433-3p in vascular calcification in type-2 diabetic patients.

METHODS

Twenty healthy subjects (control group) and forty diabetic patients (20 without VC and 20 with VC) were involved in the study. miR-433-3p gene expression was measured. Runx2, Dickkopf-1 (DKK1), β-catenin, Receptor activator of nuclear factor kappa-B ligand (RANKL), and osteoprotegerin (OPG) levels in serum were assessed by ELISA technique.

RESULTS

Diabetes patients had significantly lower levels of miR-433-3p expression in comparison to the control group, with the lowest levels being found in diabetic patients with VC. Furthermore, Runx2, β-catenin, and RANKL levels were significantly increased with concomitant lower DKK1 and OPG levels detected in the two diabetic groups especially those with VC.

CONCLUSION

Collectively, the study documented that down-regulation of miR-433-3p may contribute to the development of VC through activating WNT/β-Catenin and RANKL/RANK/OPG signaling pathways.

Osteoblast-Derived Matrix Vesicles Exhibit Exosomal Traits and a Unique Subset of microRNA: Their Caveolae-Dependent Endocytosis Results in Reduced Osteogenic Differentiation

Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellular matrix (ECM). In addition to playing a role in biomineralization, osteoblast-derived MVs were recently suggested to have regulatory duties. The aims of this study were to establish the characteristics of osteoblast-derived MVs in the context of extracellular vesicles like exosomes, assess their role in modulating osteoblast differentiation, and examine their mechanism of uptake. MVs were isolated from the ECM of MG63 human osteoblast-like cell cultures and characterized via enzyme activity, transmission electron microscopy, nanoparticle tracking analysis, Western blot, and small RNA sequencing. Osteoblasts were treated with MVs from two different culture conditions (growth media [GM]; osteogenic media [OM]) to evaluate their effects on the differentiation and production of inflammatory markers and on macrophage polarization. MV endocytosis was assessed using a lipophilic, fluorescent dye and confocal microscopy with the role of caveolae determined using methyl-β-cyclodextrin. MVs exhibited a four-fold enrichment in alkaline phosphatase specific activity compared to plasma membranes; were 50-150 nm in diameter; possessed exosomal markers CD63, CD81, and CD9 and endosomal markers ALIX, TSG101, and HSP70; and were selectively enriched in microRNA linked to an anti-osteogenic effect and to M2 macrophage polarization. Treatment with GM or OM MVs decreased osteoblast differentiation. Osteoblasts endocytosed MVs using a mechanism that involves caveolae. These results support the hypothesis that osteoblasts produce MVs that participate in the regulation of osteogenesis.

SMSCs-derived sEV overexpressing miR-433-3p inhibits angiogenesis induced by sEV released from synoviocytes under triggering of ferroptosis

BACKGROUND

Ferroptosis is characterized by accumulation of lipid peroxides that leads to oxidative stress. In progressive rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) suffered from oxidative stress induced by generation of excess reactive oxygen species (ROS) and survived from elevated lipid oxidation. However the phenomenon of abnormal synovial fibroblasts proliferation under ferroptotic stress remain to be explained and the effects of this event on disease progression of RA need to be investigated.

METHODS

FLS from RA patients (RA-FLS) were stimulated with LPS as an inflammatory model in vitro, and simultaneously treated with ferroptosis inducer Erastin/RSL3 or inhibitor ferrostatin-1. Besides, small extracellular vesicles (sEV) from the supernatant of RA-FLS culture under Erastin/RSL3 management were isolated. The degree of ferroptosis in cells were evaluated by Lipid-ROS detection via flowcytometry and ferroptosis marker protein expression determined by western bloting. The expression of core component of ESCRT-III CHMP4A and CHMP5 was determined by western bloting, and knockdown of CHMP4A was further performed to detect the influence of ESCRT-III complex on ferroptosis as well as LPS/Erastin induced sEV (LPS/Erastin-sEV) releasing. Moreover, miR-433-3p level in the isolated sEV was evaluated by RT-qPCR and interaction of miR-433-3p with FOXO1/VEGF axis were evaluated. MiR-433-3p was overexpressed in synovial mesenchymal stem cells (SMSCs) via miR-433-3p mimics transfection. RA-FLS was co-cultured with human dermal microvascular endothelial cells (HDMECs). LPS/Erastin-sEV or sEV derived from miR-433-3p-overexpressing SMSCs (miR-433-3p-SMSCs-sEV) were added to the co-culture system, and supernatants from co-culture without sEV were given to HDMECs. Angiogenic activity of HDMECs were identified by transwell test and endothelial tube formation analysis. Erastin-sEV and miR-433-3p-SMSCs-sEV were also administrated in collagen-induced arthritis (CIA) mouse model respectively, and progression of arthritis were evaluated.

RESULTS

Ferroptosis of RA-FLS was triggered by LPS/Erastin and accompanied with increased expression of ESCRT-III core components as well as elevated release of sEV from RA-FLS. HDMECs' migration and tube formation in vitro was significantly induced/suppressed by supernatants from co-culture under management of Erastin-sEV/miR-433-3p-SMSCs-sEV due to varied VEGF expression regulated by miR-433-3p targeting FOXO1. MiR-433-3p-SMSCs-sEV could inhibit the Erastin-sEV promoted VEGF expression and mitigated arthritis severity.

CONCLUSION

Erastin-sEV could aggravate synovial angiogenesis and promote arthritis progression. Administration of miR-433-3p-SMSCs-sEV may be a potential novel therapeutic method as significant antagonism to Erastin-sEV for RA treatment.

Circadian clock genes as promising therapeutic targets for bone loss

The circadian clock regulates many key physiological processes such as the sleep-wake cycle, hormone release, cardiovascular health, glucose metabolism and body temperature. Recent evidence has suggested a critical role of the circadian system in controlling bone metabolism. Here we review the connection between bone metabolism and the biological clock, and the roles of these mechanisms in bone loss. We also analyze the regulatory effects of clock-related genes on signaling pathways and transcription factors in osteoblasts and osteoclasts. Additionally, osteocytes and endothelial cells (ECs) regulated by the circadian clock are also discussed in our review. Furthermore, we also summarize the regulation of circadian clock genes by some novel modulators, which provides us with a new insight into a potential strategy to prevent and treat bone diseases such as osteoporosis by targeting circadian genes.

MicroRNA-101a enhances trabecular bone accrual in male mice

High-throughput microRNA sequencing was performed during differentiation of MC3T3-E1 osteoblasts to develop working hypotheses for specific microRNAs that control osteogenesis. The expression data show that miR-101a, which targets the mRNAs for the epigenetic enzyme Ezh2 and many other proteins, is highly upregulated during osteoblast differentiation and robustly expressed in mouse calvaria. Transient elevation of miR-101a suppresses Ezh2 levels, reduces tri-methylation of lysine 27 in histone 3 (H3K27me3; a heterochromatic mark catalyzed by Ezh2), and accelerates mineralization of MC3T3-E1 osteoblasts. We also examined skeletal phenotypes of an inducible miR-101a transgene under direct control of doxycycline administration. Experimental controls and mir-101a over-expressing mice were exposed to doxycycline in utero and postnatally (up to 8 weeks of age) to maximize penetrance of skeletal phenotypes. Male mice that over-express miR-101a have increased total body weight and longer femora. MicroCT analysis indicate that these mice have increased trabecular bone volume fraction, trabecular number and trabecular thickness with reduced trabecular spacing as compared to controls. Histomorphometric analysis demonstrates a significant reduction in osteoid volume to bone volume and osteoid surface to bone surface. Remarkably, while female mice also exhibit a significant increase in bone length, no significant changes were noted by microCT (trabecular bone parameters) and histomorphometry (osteoid parameters). Hence, miR-101a upregulation during osteoblast maturation and the concomitant reduction in Ezh2 mediated H3K27me3 levels may contribute to the enhanced trabecular bone parameters in male mice. However, the sex-specific effect of miR-101a indicates that more intricate epigenetic mechanisms mediate physiological control of bone formation and homeostasis.

RNA-Seq reveals miRNA role in thermogenic regulation in brown adipose tissues of goats

BACKGROUND

MicroRNAs (miRNAs) are a family of short non-coding RNA molecules and play important roles in various biological processes. However, knowledge of the expression profiles and function of miRNAs on the regulation of brown adipose tissue (BAT) thermogenesis remains largely unknown.

RESULTS

In this study, we found that brown adipose tissue (BAT) existed within the perirenal fat at 1 day after birth (D1) and transferred into white adipose tissue (WAT) at 30 days after birth (D30) by UCP1 protein expression and immunohistochemistry analysis. After that, we performed RNA sequencing on six libraries of goat BAT and WAT. A total of 238 known miRNAs and 1834 goat novel miRNAs were identified. Moreover, 395 differentially expressed miRNAs including 167 up-regulated and 228 down-regulated miRNAs were obtained in BAT. For the known BAT enriched miRNA, 30 miRNAs were enriched in goat BAT but not in mouse BAT. In addition, miR-433 was enriched in goat BAT but not in mouse BAT. Gain- and loss-of-function experiments reveal that miR-433 reduced the lipid accumulation of brown adipocytes and decreased the expression of BAT marker and mitochondrial related genes. However, miR-433 had no effect on lipid accumulation and thermogenesis in white adipocytes. In addition, miR-433 inhibited the expression of MAPK8 by targeting to the 3'UTR of MAPK8 gene. These data demonstrate that miR-433 acts as a negative regulator in controlling brown adipocytes differentiation and thermogenesis.

CONCLUSION

The present study provides a detailed miRNAs expression landscape in BAT and WAT. Furthermore, we found that miR-433, which was highly expressed on BAT had a negative regulatory function on the thermogenesis and adipogenesis in goat brown adipocytes. This study provides evidence for understanding the role of miRNAs in regulating BAT thermogenesis and energy expenditure in goats.

N-myc downstream regulated gene 1 suppresses osteoblast differentiation through inactivating Wnt/β-catenin signaling

Background

N-myc downstream regulated gene 1 (NDRG1) plays a role in a variety of biological processes including differentiation of osteoclasts. However, it is not known if and how NDRG1 regulates osteogenic differentiation of marrow stromal progenitor cells.

Methods

Gene expression profiling analysis was performed to study the expression level of Ndrg1 during osteogenic and adipogenic differentiation. Gain-of-function and/or loss-of function experiments were carried out to study the role of NDRG1 in the proliferation and differentiation of marrow stromal progenitor cells and the mechanism underlying the function was investigated. Finally, in vivo transfection of Ndrg1 siRNA was done and its effect on osteogenic and adipogenic differentiation in mice was explored.

Results

Gene expression profiling analysis revealed that NDRG1 level was regulated during osteogenic and adipogenic differentiation of progenitor cells. The functional experiments demonstrated that NDRG1 negatively regulated the cell growth, and reciprocally modulated the osteogenic and adipogenic commitment of marrow stromal progenitor cells, driving the cells to differentiate toward adipocytes at the expense of osteoblast differentiation. Moreover, NDRG1 interacted with low-density lipoprotein receptor-related protein 6 (LRP6) in the stromal progenitor cells and inactivated the canonical Wnt/β-catenin signaling cascade. Furthermore, the impaired differentiation of progenitor cells induced by Ndrg1 siRNA could be attenuated when β-catenin was simultaneously silenced. Finally, in vivo transfection of Ndrg1 siRNA to the marrow of mice prevented the inactivation of canonical Wnt signaling in the BMSCs of ovariectomized mice, and ameliorated the reduction of osteoblasts on the trabeculae and increase of fat accumulation in the marrow observed in the ovariectomized mice.

Conclusion

This study has provided evidences that NDRG1 plays a role in reciprocally modulating osteogenic and adipogenic commitment of marrow stromal progenitor cells through inactivating canonical Wnt signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02714-5.