ADR3, a next generation i-body to human RANKL, inhibits osteoclast formation and bone resorption.

Osteoporosis is a chronic skeletal condition characterized by low bone mass and deteriorated microarchitecture of bone tissue and puts tens of millions of people at high risk of fractures. New therapeutic agents like i-bodies, a class of next-generation single-domain antibodies, are needed to overcome some limitations of conventional treatments. An i-body is a human immunoglobulin scaffold with two long binding loops that mimic the shape and position of those found in shark antibodies, the variable new antigen receptors of sharks. Its small size (∼12 kDa) and long binding loops provide access to drug targets, which are considered undruggable by traditional monoclonal antibodies. Here, we have successfully identified a human receptor activator of nuclear factor-κB ligand (RANKL) i-body, ADR3, which demonstrates a high binding affinity to human RANKL (hRANKL) with no adverse effect on the survival or proliferation of bone marrow-derived macrophages. Differential scanning fluorimetry suggested that ADR3 is stable and able to tolerate a wide range of physical environments (including both temperature and pH). In addition, in vitro studies showed a dose-dependent inhibitory effect of ADR3 on osteoclast differentiation, podosome belt formation, and bone resorption activity. Further investigation on the mechanism of action of ADR3 revealed that it can inhibit hRANKL-mediated signaling pathways, supporting the in vitro functional observations. These clues collectively indicate that hRANKL antagonist ADR3 attenuates osteoclast differentiation and bone resorption, with the potential to serve as a novel therapeutic to protect against bone loss.

A systematic review and meta-analysis of acupuncture for De Quervain's tenosynovitis treatment.

BACKGROUND: De Quervain's tenosynovitis (DQt) is a prevalent chronic inflammatory musculoskeletal disorder predominantly affecting the radial aspect of the wrist. This study conducted a comprehensive review of the efficacy of acupuncture in treating De Quervain's tenosynovitis (DQt). Although there is evidence suggesting that acupuncture can alleviate symptoms of DQt-characterized by pain, swelling, and functional impairment-higher-level evidence is still required to further substantiate its efficacy and safety. This study conducted a comprehensive review of the efficacy of acupuncture in treating De Quervain's tenosynovitis (DQt). METHODS: By systematically searching databases such as PubMed, Science Direct, Web of Science, Google Scholar, EMbase, PEDro, China National Knowledge Infrastructure Database (CNKI), Wanfang Database, and Chongqing VIP China Science, Technology Journal Database (VIP), we retrieved randomized controlled trial (RCT) literature on acupuncture for DQt, with the search period extending to November 1, 2023. After extracting and assessing data from the included literature, we performed Meta-analysis using RevMan 5.4.1 software. RESULTS: The results encompassed 14 RCT papers, involving 851 patients. The Meta-analysis findings indicated that, when compared to topical analgesics, acupuncture demonstrated a significant increase in treatment effectiveness (RR = 1.24; 95% CI = 1.11, 1.39, P = 0.0002) and a notable reduction in VAS pain scores (MD = -1.06; 95% CI = -1.51, -0.61, P < 0.00001). However, no statistically significant difference was observed in conney wrist joint scores. Furthermore, acupuncture was found to reduce VAS pain scores compared to the waiting list group. In comparison to corticosteroid injections (CSI), acupuncture did not show statistical significance in VAS, effectiveness rate, and conney wrist scores. CONCLUSION: Acupuncture exhibited a promising trend in alleviating pain associated with DQt and enhancing treatment effectiveness. Nonetheless, due to limitations in the quantity and quality of the included studies, these findings warrant further validation through additional research.

Transcriptome analysis reveals potential key immune genes of Hong Kong oyster (Crassostrea hongkongensis) against Vibrio parahaemolyticus infection.

Hong Kong oyster (Crassostrea hongkongensis) is one of the main species of economic shellfish cultivated in the coastal areas of southern China. The cultivation of this shellfish may be adversely impacted by Vibrio parahaemolyticus, a harmful pathogenic bacterium for many mariculture species, as it usually exists on the surface of Hong Kong oysters. Although previous studies have discovered that oysters rely on non-specific immune system to fight pathogen invasion, the genes corresponding to the complex immune system against Vibrio is still not fully elucidated. Therefore, we conducted a transcriptome analysis on the gill from Hong Kong oysters at two time points (i.e., 12 h and 24 h after V. parahaemolyticus or PBS challenge) to identify potential immune genes against V. parahaemolyticus infection. A total of 61779 unigenes with the average length of 1221 bp were obtained, and the annotation information of 39917 unigenes were obtained from Nr, SwissProt, KEGG and COG/KOG. After a pairwise comparison between V. parahaemolyticus or PBS challenge at the two time points, three groups of differentially expressed genes induced by V. parahaemolyticus were captured and analyzed. GO and KEGG analyses showed that multiple immune-related genes played an important role in pathogen infection, including HSP70, PCDP3 and TLR4. Furthermore, genes annotation indicated that LITAF, TNFSF10, Duox2 and big defensin family are also involved in immune regulation. Our study provides a reference for further exploration the molecular mechanism that defenses the pathogen infection regarding the identified immune-related genes in Hong Kong oysters.

Expressions of melanopsins in telencephalon imply their function in synchronizing semilunar spawning rhythm in the mudskipper Boleophthalmus pectinirostris.

The mudskipper Boleophthalmus pectinirostris inhabits intertidal mudflats, exhibiting semilunar reproductive rhythms. To investigate whether melanopsin is possibly involved in the synchronization of the semilunar spawning rhythm in the female mudskipper, we first cloned all four melanopsin subtypes (opn4m1, opn4m3, opn4x1, opn4x2) in B. pectinirostris. Results from RTq-PCR showed that significantly higher transcription levels of all four melanopsin subtypes were observed in the eyes rather than other tissues. In brain, all four melanopsin subtypes were also detectable in different regions, including the telencephalon, in which the expression of melanopsin has not been reported in other teleosts. The transcription levels of opn4m3 and opn4x1 in the telencephalon exhibited a daily fluctuation pattern. When females entered the spawning season, opn4m1 and opn4x1 transcript levels increased significantly in the telencephalon. During the spawning season, the transcript levels of opn4m3 and opn4x1 in the telencephalon appeared to have a cyclic pattern associated with semilunar periodicity, exhibiting two cycles with a peak around the first or the last lunar quarters. Results from ISH showed that, opn4x1 mRNA was localized in the medial of dorsal telencephalic area, dorsal nucleus of ventral telencephalic area (Vd), ventral nucleus of ventral telencephalic area (Vv), anterior part of parvocellular preoptic nucleus, magnocellular part of the magnocellular preoptic nucleus (PMmc), habenular and ventral zone of hypothalamus. Intriguingly, gnrh3 mRNA was also located in Vd, Vv and PMmc. Taken together, our results suggested that melanopsins, e.g. opn4x1, expressed in the telencephalon might mediate semilunar spawning activity in the female mudskipper.

The molecular structure and function of sorting nexin 10 in skeletal disorders, cancers, and other pathological conditions.

SNX10 is a member of the phox homology domain-containing family of phosphoinositide-binding proteins. Intracellularly, SNX10 localizes to endosomes where it mediates intracellular trafficking, endosome organization, and protein localization to the centrosome and cilium. It is highly expressed in bone and the gut where it participates in bone mineral and calcium homeostasis through the regulation of osteoclastic bone resorption and gastric acid secretion, respectively. Not surprisingly, patients harboring mutations in SNX10 mutation manifest a phenotype of autosomal recessive osteopetrosis or malignant infantile osteopetrosis, which is clinically characterized by dense bones with increased cortical bone into the medullary space with bone marrow occlusion or depletion, bone marrow failure, and anemia. Accordingly, SNX10 mutant osteoclasts exhibit impaired bone resorptive capacity. Beyond the skeleton, there is emerging evidence implicating SNX10 in cancer development, metabolic disorders, inflammation, and chaperone-mediated autophagy. Understanding the structural basis through which SNX10 exerts its diverse biological functions in both cell and tissue-specific manners may therefore inform new therapeutic opportunities toward the treatment and management of SNX10-related diseases.

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.

Carnosol suppresses RANKL-induced osteoclastogenesis and attenuates titanium particles-induced osteolysis.

Osteolysis is a common medical condition characterized by excessive activity of osteoclasts and bone resorption, leading to severe poor quality of life. It is essential to identify the medications that can effectively suppress the excessive differentiation and function of osteoclasts to prevent and reduce the osteolytic conditions. It has been reported that Carnosol (Car), isolated from rosemary and salvia, has anti-inflammatory, antioxidative, and anticancer effects, but its activity on osteolysis has not been determined. In this study, we found that Car has a strong inhibitory effect on the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation dose-dependently without any observable cytotoxicity. Moreover, Car can inhibit the RANKL-induced osteoclastogenesis and resorptive function via suppressing NFATc1, which is a result of affecting MAPK, NF-κB and Ca2+ signaling pathways. Moreover, the particle-induced osteolysis mouse model confirmed that Car could be effective for the treatment of bone loss in vivo. Taken together, by suppressing the formation and function of RANKL-induced osteoclast, Car, may be a therapeutic supplementary in the prevention or the treatment of osteolysis.

The effect of Chinese herbal medicine on digestive system and liver functions should not be neglected in COVID-19: An updated systematic review and meta-analysis.

Gastrointestinal symptoms and liver injury are common in patients with coronavirus disease 2019 (COVID-19). However, profiles of different pharmaceutical interventions used are relatively underexplored. Chinese herbal medicine (CHM) has been increasingly used for patients with COVID-19, but the efficacy of CHM used in COVID-19 on gastrointestinal symptoms and liver functions has not been well studied with definitive results based on the updated studies. The present study aimed at testing the efficacy of CHM on digestive symptoms and liver function (primary outcomes), the aggravation of COVID-19, and the time to viral assay conversion (secondary outcomes), among patients with COVID-19, compared with standard pharmacotherapy. The literature search was undertaken in 11 electronic databases from December 1, 2019 up to November 8, 2020. Appraisal of the evidence was conducted with Cochrane risk of bias tool or Newcastle Ottawa Scale. A random-effects model or subgroup analysis was conducted when significant heterogeneity was identified in the meta-analysis. The certainty of the evidence was assessed with the grading of recommendations assessment, development, and evaluation approach. Forty-eight included trials involving 4,704 participants were included. Meta-analyses favored CHM plus standard pharmacotherapy for COVID-19 on reducing the aggravation of COVID-19 and the time to viral assay conversion compared with standard pharmacotherapy. However, the present CHM as a complementary therapy for treating COVID-19 may not be beneficial for improving most gastrointestinal symptoms and liver function based on the current evidence. More well-conducted trials are warranted to confirm the potential efficacy of CHM furtherly.

Reliability and validity of Healthy Fitness Measurement Scale Version1.0 (HFMS V1.0) in Chinese elderly people.

PURPOSE: We examined the reliability and validity of the Healthy Fitness Measurement Scale Version 1.0 (HFMS V1.0) specifically on elderly people in China. METHODS: We carried out a cross-sectional study in December 2020 and enrolled 800 elderly people through stratified sampling technique, including 777 valid samples (with a mean age of 71.81 ± 8.36 years), of which 382 cases (49.2%) were women. The level of healthy fitness was measured using the HFMS V1.0. The Cronbach's alpha coefficient, split-half reliability, test-retest reliability, convergent and discriminant validity, exploratory factor and confirmatory factor were calculated for assessing the reliability and validity of HFMS V1.0. RESULTS: HFMS V1.0 consists of 8 dimensions and 38 items. The scale had acceptable reliability (Cronbach's alpha = 0.920, split-half = 0.946, test-retest = 0.878). Exploratory factor analysis showed KMO value =0.927, and uncovered 10 factors with the cumulative contribution rate of 65.71% and all factor loads over 0.40. The item distribution was consistent with the initial expectation of the scale. The confirmatory factor analysis indicated good fit: CMIN/DF = 2.796, RMSEA = 0.048, IFI =0.914, TLI = 0.902, CFI = 0.913. CONCLUSION: HFMS V1.0 was shown to have acceptable reliability and validity indices for this sample. Collectively, HFMS V1.0 is reliable and efficient to measure the healthy fitness of elderly people. It is recommended to use it among the elderly in other Chinese cities in the future to ensure uniformity and objectivity. This scale can be carried out to evaluate of the effectiveness of public health measures in improving the healthy fitness level of the elderly and optimizing public health policies.

The emerging roles of hnRNPK.

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an DNA/RNA-binding protein and regulates a wide range of biological processes and disease pathogenesis. It contains 3 K-homologous (KH) domains, which are conserved in other RNA-binding proteins, mediate nucleic acid binding activity, and function as an enhancer or repressor of gene transcription. Phosphorylation of the protein alters its regulatory function, which also enables the protein to serve as a docking platform for the signal transduction proteins. In terms of the function of hnRNPK, it is central to many cellular events, including long noncoding RNA (lncRNA) regulation, cancer development and bone homoeostasis. Many studies have identified hnRNPK as an oncogene, where it is overexpressed in cancer tissues compared with the nonneoplastic tissues and its expression level is related to the prognosis of different types of host malignancies. However, hnRNPK has also been identified as a tumour suppressor, as it is important for the activation of the p53/p21 pathway. Recently, the protein is also found to be exclusively related to the regulation of paraspeckles and lncRNAs such as Neat1, Lncenc1 and Xist. Interestingly, hnRNPK has been found to associate with the Kabuki-like syndrome and Au-Kline syndrome with prominent skeletal abnormalities. In vitro study revealed that the hnRNPK protein is essential for the formation of osteoclast, in line with its importance in the skeletal system.

Arctiin abrogates osteoclastogenesis and bone resorption via suppressing RANKL-induced ROS and NFATc1 activation.

Osteoporosis, characterized by disrupted bone resorption and formation, is viewed as a global health challenge. Arctiin (ARC) is a main component of Arctium lappa L, which exerts chemopreventive effects against various tumor cells. However, the role of ARC in bone remodeling is still unclear. Here, we first demonstrated that ARC inhibits osteoclast formation and bone resorption function induced by the receptor activator of nuclear factor-κB ligand (RANKL) in a dose- and time-dependent manner without exerting cytotoxic effects. Mechanistic analysis revealed that ARC not only suppresses RANKL-induced mitogen-activated protein kinase (MAPK) and calcium signaling pathways, but also enhances the expression of cytoprotective enzymes that are involved in scavenging reactive oxygen species (ROS). Further, ARC inhibits the activation of the major transcription factor nuclear factor of activated T cells 1 (NFATc1) during RANKL-induced osteoclast formation. Preclinical studies showed that ARC protects bone loss in an ovariectomy (OVX) mouse model. Conclusively, our data confirmed that ARC could potentially inhibit osteoclastogenesis by abrogating RANKL-induced MAPK, calcium, and NFATc1 signaling pathway, as well as by promoting the expression of ROS scavenging enzymes in Nrf2/Keap1/ARE signaling pathway, thereby2 preventing OVX-induced bone loss. Thus, ARC may serve as a novel therapeutic agent for the treatment of osteoporosis.

Chondromodulin-1 in health, osteoarthritis, cancer, and heart disease.

The human chondromodulin-1 (Chm-1, Chm-I, CNMD, or Lect1) gene encodes a 334 amino acid type II transmembrane glycoprotein protein with characteristics of a furin cleavage site and a putative glycosylation site. Chm-1 is expressed most predominantly in healthy and developing avascular cartilage, and healthy cardiac valves. Chm-1 plays a vital role during endochondral ossification by the regulation of angiogenesis. The anti-angiogenic and chondrogenic properties of Chm-1 are attributed to its role in tissue development, homeostasis, repair and regeneration, and disease prevention. Chm-1 promotes chondrocyte differentiation, and is regulated by versatile transcription factors, such as Sox9, Sp3, YY1, p300, Pax1, and Nkx3.2. Decreased expression of Chm-1 is implicated in the onset and progression of osteoarthritis and infective endocarditis. Chm-1 appears to attenuate osteoarthritis progression by inhibiting catabolic activity, and to mediate anti-inflammatory effects. In this review, we present the molecular structure and expression profiling of Chm-1. In addition, we bring a summary to the potential role of Chm-1 in cartilage development and homeostasis, osteoarthritis onset and progression, and to the pathogenic role of Chm-1 in infective endocarditis and cancers. To date, knowledge of the Chm-1 receptor, cellular signalling, and the molecular mechanisms of Chm-1 is rudimentary. Advancing our understanding the role of Chm-1 and its mechanisms of action will pave the way for the development of Chm-1 as a therapeutic target for the treatment of diseases, such as osteoarthritis, infective endocarditis, and cancer, and for potential tissue regenerative bioengineering applications.

Asperpyrone A attenuates RANKL-induced osteoclast formation through inhibiting NFATc1, Ca2+ signalling and oxidative stress.

Imbalance of osteoblast and osteoclast in adult leads to a variety of bone-related diseases, including osteoporosis. Thus, suppressing the activity of osteoclastic bone resorption becomes the main therapeutic strategy for osteoporosis. Asperpyrone A is a natural compound isolated from Aspergillus niger with various biological activities of antitumour, antimicrobial and antioxidant. The present study was designed to investigate the effects of Asperpyrone A on osteoclastogenesis and to explore its underlining mechanism. We found that Asperpyrone A inhibited RANKL-induced osteoclastogenesis in a dose-dependent manner when the concentration reached 1 µm, and with no cytotoxicity until the concentration reached to 10 µm. In addition, Asperpyrone A down-regulated the mRNA and protein expression of NFATc1, c-fos and V-ATPase-d2, as well as the mRNA expression of TRAcP and Ctsk. Furthermore, Asperpyrone A strongly attenuated the RNAKL-induced intracellular Ca2+ oscillations and ROS (reactive oxygen species) production in the process of osteoclastogenesis and suppressed the activation of MAPK and NF-κB signalling pathways. Collectively, Asperpyrone A attenuates RANKL-induced osteoclast formation via suppressing NFATc1, Ca2+ signalling and oxidative stress, as well as MAPK and NF-κB signalling pathways, indicating that this compound may become a potential candidate drug for the prevention or treatment of osteoporosis.

Astilbin prevents bone loss in ovariectomized mice through the inhibition of RANKL-induced osteoclastogenesis.

Osteoporosis is the most common osteolytic disease characterized by excessive osteoclast formation and resultant bone loss, which afflicts millions of patients around the world. Astilbin, a traditional herb, is known to have anti-inflammatory, antioxidant and antihepatic properties, but its role in osteoporosis treatment has not yet been confirmed. In our study, astilbin was found to have an inhibitory effect on the RANKL-induced formation and function of OCs in a dose-dependent manner without cytotoxicity. These effects were attributed to its ability to suppress the activity of two transcription factors (NFATc1 and c-Fos) indispensable for osteoclast formation, followed by inhibition of the expression of bone resorption-related genes and proteins (Acp5/TRAcP, CTSK, V-ATPase-d2 and integrin ß3). Furthermore, we examined the underlying mechanisms and found that astilbin repressed osteoclastogenesis by blocking Ca2+ oscillations and the NF-κB and MAPK pathways. In addition, the therapeutic effect of MA on preventing bone loss in vivo was further confirmed in an ovariectomized mouse model. Therefore, considering its ability to inhibit RANKL-mediated osteoclastogenesis and the underlying mechanisms, astilbin might be a potential candidate for treating osteolytic bone diseases.

Miniaturization of the Whole Process of Protein Crystallographic Analysis by a Microfluidic Droplet Robot: From Nanoliter-Scale Purified Proteins to Diffraction-Quality Crystals.

To obtain diffraction-quality crystals is one of the largest barriers to analyze the protein structure using X-ray crystallography. Here we describe a microfluidic droplet robot that enables successful miniaturization of the whole process of crystallization experiments including large-scale initial crystallization screening, crystallization optimization, and crystal harvesting. The combination of the state-of-the-art droplet-based microfluidic technique with the microbatch crystallization mode dramatically reduces the volumes of droplet crystallization reactors to tens nanoliter range, allowing large-scale initial screening of 1536 crystallization conditions and multifactor crystallization condition optimization with extremely low protein consumption, and on-chip harvesting of diffraction-quality crystals directly from the droplet reactors. We applied the droplet robot in miniaturized crystallization experiments of seven soluble proteins and two membrane proteins, and on-chip crystal harvesting of six proteins. The X-ray diffraction data sets of these crystals were collected using synchrotron radiation for analyzing the structures with similar diffraction qualities as conventional crystallization methods.

Cistanche deserticola polysaccharide attenuates osteoclastogenesis and bone resorption via inhibiting RANKL signaling and reactive oxygen species production.

Osteoporosis is a metabolic disease characterized by osteopenia and bone microstructural deterioration. Osteoclasts are the primary effector cells that degrade bone matrix and their abnormal function leads to the development of osteoporosis. Reactive oxygen species (ROS) accumulation during cellular metabolism promotes osteoclast proliferation and differentiation, therefore, playing an important role in osteoporosis. Cistanche deserticola polysaccharide (CDP) possesses antitumor, anti-inflammatory, and antioxidant activity. However, the impact of CDP on osteoclasts is unclear. In this study, tartrate-resistant acid phosphatase staining, immunofluorescence, reverse transcription-polymerase chain reaction, and western blot analysis were utilized to demonstrate that CDP inhibited osteoclastogenesis and hydroxyapatite resorption. In addition, CDP also inhibited the expression of osteoclast maker genes including Ctsk, Mmp9, and Acp5 and had no effect on receptor activator of nuclear factor κB (RANK) expression. Mechanistic analyses revealed that CDP increases the expression of antioxidant enzymes to attenuate RANKL-mediated ROS production in osteoclasts and inhibits nuclear factor of activated T cells and mitogen-activated protein kinase activation. These results suggest that CDP may represent a candidate drug for the treatment of osteoporosis caused by excessive osteoclast activity.

The emerging role of NPNT in tissue injury repair and bone homeostasis.

Nephronectin (NPNT), a highly conserved extracellular matrix protein, plays an important role in regulating cell adhesion, differentiation, spreading, and survival. NPNT protein belongs to the epidermal growth factor (EGF)-like superfamily and exhibits several common structural determinants; including EGF-like repeat domains, MAM domain (Meprin, A5 Protein, and Receptor Protein-Tyrosine Phosphatase µ), RGD motif (Arg-Gly-Asp) and a coiled-coil domain. It regulates integrins-mediated signaling pathways via the interaction of its RGD motif with integrin α8ß1. Recent studies revealed that NPNT is involved in kidney development, renal injury repair, atrioventricular canal differentiation, pulmonary function, and muscle cell niche maintenance. Moreover, NPNT regulates osteoblast differentiation and mineralization, as well as osteogenic angiogenesis. Altered expression of NPNT has been linked with the progression of certain types of cancers, such as spontaneous breast tumor metastasis and malignant melanoma. Interestingly, NPNT gene expression can be regulated by a range of external factors such as tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-ß), oncostatin M (OSM), bone morphogenic protein 2 (BMP2), Wnt3a, Vitamin D3 , and microRNA-378 (miR378). Further understanding the cellular and molecular mechanisms by which NPNT regulates tissue homeostasis in an organ-specific manner is critical in exploring NPNT as a therapeutic target for tissue regeneration and tissue engineering.

EGFL7: Master regulator of cancer pathogenesis, angiogenesis and an emerging mediator of bone homeostasis.

Epidermal growth factor-like domain-containing protein 7 (EGFL7), a member of the epidermal growth factor (EGF)-like protein family, is a potent angiogenic factor expressed in many different cell types. EGFL7 plays a vital role in controlling vascular angiogenesis during embryogenesis, organogenesis, and maintaining skeletal homeostasis. It regulates cellular functions by mediating the main signaling pathways (Notch, integrin) and EGF receptor cascades. Accumulating evidence suggests that Egfl7 plays a crucial role in cancer biology by modulating tumor angiogenesis, metastasis, and invasion. Dysregulation of Egfl7 has been frequently found in several types of cancers, such as malignant glioma, colorectal carcinoma, oral and oesophageal cancers, gastric cancer, hepatocellular carcinoma, pancreatic cancer, breast cancer, lung cancer, osteosarcoma, and acute myeloid leukemia. In addition, altered expression of miR-126, a microRNA associated with Egfl7, was found to play an important role in oncogenesis. More recently, our study has shown that EGFL7 is expressed in both the osteoclast and osteoblast lineages and promotes endothelial cell activities via extracellular signal-regulated kinase (ERK), signal transducer and activator of transcription 3 (STAT3), and integrin signaling cascades, indicative of its angiogenic regulation in the bone microenvironment. Thus, understanding the role of EGFL7 may provide novel insights into the development of improved diagnostics and therapeutic treatment for cancers and skeletal pathological disorders, such as ischemic osteonecrosis and bone fracture healing.

Modulating calcium-mediated NFATc1 and mitogen-activated protein kinase deactivation underlies the inhibitory effects of kavain on osteoclastogenesis and bone resorption.

Osteoclasts are responsible for bone resorption during the process of bone remodeling. Increased osteoclast numbers and bone resorption activity are the main factors contributing to bone loss-related diseases such as osteoporosis. Therefore, modulating the formation and function of osteoclasts is critical for the effective treatment of osteolysis and osteoporosis. Kavain is the active ingredient extracted from the root of the kava plant, which possesses known anti-inflammatory properties. However, the effects of kavain on osteoclastogenesis and bone resorption remain unclear. In this study, we found that kavain inhibits receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and fusion using tartrate-resistant acid phosphatase staining and immunofluorescence. Furthermore, kavain inhibited bone resorption performed by osteoclasts. Using reverse transcription-polymerase chain reaction and western blot analysis, we found that kavain downregulates the expression of osteoclast marker genes, such as nuclear factor of activated T cells, cytoplasmic 1 (Nfatc1), v-atpase d2 (Atp6v0d2), dendrocyte expressed seven transmembrane protein (Dcstamp), matrix metallopeptidase 9 (Mmp9), cathepsin K (Ctsk), and Acp5. Additionally, kavain repressed RANKL-induced calcium oscillations, nuclear factor of activated T cells activation, and mitogen-activated protein kinase phosphorylation, while leaving NF-κB unaffected. We found no effects of kavain on either osteoblast proliferation or differentiation. Besides, kavain inhibited bone loss in ovariectomized mice by suppressing osteoclastogenesis. Collectively, these data suggest a potential use for kavain as a candidate drug for the treatment of osteolytic diseases.

Lumichrome inhibits osteoclastogenesis and bone resorption through suppressing RANKL-induced NFAT activation and calcium signaling.

The dynamic balance between bone resorption and bone formation is crucial to maintain bone mass. Osteoclasts are key cells that perform bone resorption while osteoblasts and osteocytes function in bone formation. Osteoporosis, a bone metabolism disease characterized by bone loss and degradation of bone microstructure, occurs when osteoclastic bone resorption outstrips osteoblastic bone synthesis. The interaction between receptor activator of nuclear factor κB ligand (RANKL) and RANK on the surface of bone marrow macrophages promotes osteoclast differentiation and activation. In this study, we found that lumichrome, a photodegradation product of riboflavin, inhibits RANKL-induced osteoclastogenesis and bone resorption as determined by tartrate-resistant acid phosphatase staining, immunofluorescence, reverse transcription-polymerase chain reaction, and western blot. Our results showed that lumichrome represses the expression of osteoclast marker genes, including cathepsin K (Ctsk) and Nfatc1. In addition, lumichrome suppressed RANKL-induced calcium oscillations, NFATc1, NF-κB, and MAPK signaling activation. Moreover, lumichrome promoted osteoblast differentiation at an early stage, as demonstrated by upregulated expression of osteoblast marker genes Alp, Runx2, and Col1a1. We also found that lumichrome reduces bone loss in ovariectomized mice by inhibiting osteoclastogenesis. In summary, our data suggest the potential of lumichrome as a therapeutic drug for osteolytic diseases.