The Osteoblast Transcriptome in Developing Zebrafish Reveals Key Roles for Extracellular Matrix Proteins Col10a1a and Fbln1 in Skeletal Development and Homeostasis.

Zebrafish are now widely used to study skeletal development and bone-related diseases. To that end, understanding osteoblast differentiation and function, the expression of essential transcription factors, signaling molecules, and extracellular matrix proteins is crucial. We isolated Sp7-expressing osteoblasts from 4-day-old larvae using a fluorescent reporter. We identified two distinct subpopulations and characterized their specific transcriptome as well as their structural, regulatory, and signaling profile. Based on their differential expression in these subpopulations, we generated mutants for the extracellular matrix protein genes col10a1a and fbln1 to study their functions. The col10a1a-/- mutant larvae display reduced chondrocranium size and decreased bone mineralization, while in adults a reduced vertebral thickness and tissue mineral density, and fusion of the caudal fin vertebrae were observed. In contrast, fbln1-/- mutants showed an increased mineralization of cranial elements and a reduced ceratohyal angle in larvae, while in adults a significantly increased vertebral centra thickness, length, volume, surface area, and tissue mineral density was observed. In addition, absence of the opercle specifically on the right side was observed. Transcriptomic analysis reveals up-regulation of genes involved in collagen biosynthesis and down-regulation of Fgf8 signaling in fbln1-/- mutants. Taken together, our results highlight the importance of bone extracellular matrix protein genes col10a1a and fbln1 in skeletal development and homeostasis.

M2 macrophage-derived exosomal miR-26b-5p regulates macrophage polarization and chondrocyte hypertrophy by targeting TLR3 and COL10A1 to alleviate osteoarthritis.

Osteoarthritis (OA) is one of the most prevalent chronic musculoskeletal diseases among the elderly population. In this study, macrophage-derived exosomes were isolated and identified. Exosomes were subjected to microRNA (miRNA) sequencing and bioinformatic analysis, and differentially expressed miRNAs were verified. miR-26b-5p target genes were confirmed through target-site mutation combined with a dual-luciferase reporter assay. The effects of miR-26b-5p on macrophage polarization and chondrocyte hypertrophy were assessed in vitro. miR-26b-5p agomir was applied to mice with OA induced by anterior cruciate ligament transection (ACLT). The therapeutic effects of miR-26b-5p were evaluated via pain behavior experiments and histological observations. In vitro, miR-26b-5p repolarized M1 macrophages to an anti-inflammatory M2 type by targeting the TLR3 signaling pathway. miR-26b-5p could target COL10A1, further inhibiting chondrocyte hypertrophy induced by M1 macrophage-conditioned medium (M1-CM). In vivo, miR-26b-5p agomir ameliorated gait abnormalities and mechanical allodynia in OA mice. miR-26b-5p treatment attenuated synovitis and cartilage degeneration, thereby delaying OA progression. In conclusion, M2 macrophage-derived exosomal miR-26b-5p could protect articular cartilage and ameliorate gait abnormalities in OA mice by targeting TLR3 and COL10A1. miR-26b-5p further affected macrophage polarization and chondrocyte hypertrophy. Thus, this exosomal miR-26b-5p-based strategy might be a potential method for OA treatment.

Experimental validation and pan-cancer analysis identified COL10A1 as a novel oncogene and potential therapeutic target in prostate cancer.

BACKGROUND: Type X collagen (COL10) is a homologous trimeric non-fibrillar collagen found in the extracellular matrix of human tissues, and it exhibits a distinctive white appearance. Type X collagen α1 chain (COL10A1) is a specific cleaved fragment of type X collagen. However, the expression, prognostic significance, clinicopathological attributes and immune-related associations of COL10A1 in prostate cancer as well as in pan-cancer contexts remain poorly understood. METHODS: Using bioinformatic analysis of data from the most recent databases (TCGA, GTEx and GEO databases), we have extensively elucidated the role played by COL10A1 in terms of its expression patterns, prognostic implications, and immune efficacy across a pan-cancer spectrum. Subsequently, the biological functions of COL10A1 in prostate cancer were elucidated by experimental validation. RESULTS: Our findings have confirmed that COL10A1 was highly expressed in most cancers and was associated with poorer prognosis in cancer patients. Immune correlation analysis of COL10A1 in various cancers showed its significant correlation with Tumor mutational burden (TMB), microsatellite instability (MSI) and immune cell infiltration. In addition, knockdown of COL10A1 in prostate cancer resulted in a substantial reduction in the proliferation, migration, and invasive potential of prostate cancer cells. CONCLUSION: Our pan-cancer analysis of COL10A1 gene provided novel insights into its pivotal role in cancer initiation, progression, and therapeutic implications, underscoring its potential significance in prognosis and immunotherapeutic interventions for cancer, particularly prostate cancer.

COL10A1 is a novel factor in the development of choroidal neovascularization.

With the dramatic rise in the aging population, researching age-related macular degeneration (AMD), especially the severe form neovascular AMD (nAMD), has become more important than ever. In this study, we found that collagen type X was increased in retina-choroid tissue of mice with laser-induced choroidal neovascularization (CNV) based on immunohistofluorescence. RNA sequencing and bioinformatic analyses were performed to compare the retina-choroid tissue complex of the CNV mouse model to normal controls. Collagen type X alpha 1 chain (Col10a1) was among the most significantly upregulated genes, and the results were validated with an animal model at the mRNA and protein levels by quantitative real-time polymerase chain reaction (qPCR) and western blotting, respectively. COL10A1 was also upregulated in human retinal microvascular endothelial cells (HRMECs), human umbilical vein endothelial cells (HUVECs), RPE19 cells and RF/6A cells under hypoxic conditions. Next, in vitro and in vivo experiments were performed to study the effect of COL10A1 on neovascularization. siRNA knockdown of COL10A1 suppressed the proliferation and tube formation ability of HRMECs under hypoxic conditions. Snail family transcriptional repressor 1 (SNAIL1) and angiopoietin-2 (ANGPT2) were downregulated in COL10A1 knockdown HRMECs under hypoxic conditions and thus were potential downstream genes. Significant decreases in CNV leakage and CNV lesion area, as assessed by fundus fluorescein angiography (FFA) and immunofluorescence of choroidal flat mounts, respectively, were observed in a mouse model intravitreally injected with anti-collagen X monoclonal antibody (mAb) compared to the controls. In conclusion, COL10A1 promotes CNV formation and may represent a new candidate target for the treatment and diagnosis of nAMD and other neovascular diseases.

Combining stretching and gallic acid to decrease inflammation indices and promote extracellular matrix production in osteoarthritic human articular chondrocytes.

Osteoarthritis (OA) patients undergo cartilage degradation and experience painful joint swelling. OA symptoms are caused by inflammatory molecules and the upregulation of catabolic genes leading to the breakdown of cartilage extracellular matrix (ECM). Here, we investigate the effects of gallic acid (GA) and mechanical stretching on the expression of anabolic and catabolic genes and restoring ECM production by osteoarthritic human articular chondrocytes (hAChs) cultured in monolayers. hAChs were seeded onto conventional plates or silicone chambers with or without 100 µM GA. A 5% cyclic tensile strain (CTS) was applied to the silicone chambers and the deposition of collagen and glycosaminoglycan, and gene expressions of collagen types II (COL2A1), XI (COL11A2), I (COL1A1), and X (COL10A1), and matrix metalloproteinases (MMP-1 and MMP-13) as inflammation markers, were quantified. CTS and GA acted synergistically to promote the deposition of collagen and glycosaminoglycan in the ECM by 14- and 7-fold, respectively. Furthermore, the synergistic stimuli selectively upregulated the expression of cartilage-specific proteins, COL11A2 by 7-fold, and COL2A1 by 47-fold, and, in contrast, downregulated the expression of MMP-1 by 2.5-fold and MMP-13 by 125-fold. GA supplementation with CTS is a promising approach for restoring osteoarthritic hAChs ECM production ability making them suitable for complex tissue engineering applications.

Identification of a novel COL10A1: c.1952 G>T variant in a family with Schmid metaphyseal chondrodysplasia and development of a noninvasive prenatal testing method.

BACKGROUND: The collagen alpha-1(X) chain gene (COL10A1) is a known causative gene for Schmid metaphyseal chondrodysplasia (SMCD). This study clinically examined a Chinese family (n = 42) for SMCD and inheritance pattern. Fifteen individuals were diagnosed with SMCD based on characteristic skeletal phenotypes with autosomal dominant inheritance mode. METHODS: Four clinically diagnosed patients and three healthy relatives were selected for subsequent genetic tests. Trio-whole exome sequencing (Trio-WES) followed by Sanger sequencing and familial co-segregation analysis were performed to identify SMCD-associated variants. RESULTS: COL10A1 (NM_000493.4):c.1952 G>T(p.Trp651Leu) variant was detected only in the four patients and not in the three healthy relatives. The variant was evaluated as "likely pathogenic" according to the American College of Medical Genetics and Genomics variation classification guidelines with evidence of PM2, PM5, PP1, and PP3. To test the presence of the target variant in proband's fetal offspring, we developed a noninvasive prenatal testing method by extracting cell-free fetal DNA in maternal plasma followed by high-depth sequencing. The variant was also detected in the fetus and later confirmed by amniocentesis. CONCLUSION: We identified a new disease-causing variant in COL10A1. Cell-free fetal DNA in maternal peripheral blood can be used as the rapid and noninvasive prenatal diagnostic method to detect the pathogenic/or likely pathogenic variant.

Downregulation of miR-1-3p expression inhibits the hypertrophy and mineralization of chondrocytes in DDH.

BACKGROUND: Developmental dysplasia of the hip (DDH) is a highly prevalent hip disease among children. However, its pathogenesis remains unclear. MicroRNAs (miRNA) are important regulators of cartilage development. In a previous study, high-throughput miRNA sequencing of tissue samples from an animal model of DDH showed a low level of miR-1-3p in the cartilage of the acetabular roof (ARC), but its role in DDH pathogenesis was not addressed. Therefore, our aim here was to investigate the effects of miR-1-3p in the ARC. METHODS: The diagnosis of acetabular dysplasia was confirmed with X-ray examination, while imaging and HE staining were conducted to further evaluate the ARC thickness in each animal model. FISH was employed to verify miR-1-3p expression in the ARC and chondrocytes. The miR-1-3p target genes were predicted by a bioinformatics database. A dual-luciferase reporter assay was used to confirm the targeting relationship between miR-1-3p and SOX9. The gene expression of miR-1-3p, SOX9, RUNX2 and collagen type X was evaluated by qPCR analysis. The protein expression of SOX9, RUNX2 and collagen type X was detected by western blot analysis. The levels of SOX9, RUNX2, and collagen type X in the ARC were further assessed via immunohistochemistry analysis. Finally, Alizarin Red S staining was used to observe the mineralized nodules produced by the chondrocytes. RESULTS: We observed low expression of miR-1-3p in the ARC of animals with DDH. SOX9 is a miR-1-3p target gene. Using miR-1-3p silencing technology in vitro, we demonstrated significantly reduced chondrocyte-generated mineralized nodules compared to those of the control. We also confirmed that with miR-1-3p silencing, SOX9 expression was upregulated, whereas the expression of genes associated with endochondral osteogenesis such as RUNX2 and collagen type X was downregulated. To confirm the involvement of miR-1-3p silencing in abnormal ossification through SOX9, we also performed a rescue experiment in which SOX9 silencing restored the low expression of RUNX2 and collagen type X produced by downregulated miR-1-3p expression. Finally, the elevated SOX9 levels and reduced RUNX2 and collagen type X levels in the ARC of rabbits with DDH were also verified using immunohistochemistry, RT-PCR, and western blots. CONCLUSION: The relatively low expression of miR-1-3p in the ARC may be the cause of abnormal endochondral ossification in the acetabular roof of animals with DDH.

Characterization of a novel COL10A1 variant associated with Schmid-type metaphyseal chondrodysplasia and a literature review.

BACKGROUND: Schmid-type metaphyseal chondrodysplasia (SMCD) is a rare autosomal dominant skeletal dysplasia caused by heterozygous mutations in COL10A1, the gene which encodes collagen type X alpha 1 chain. However, its genotype-phenotype relationship has not been fully determined. Subjects and Methods The proband is a 2-year-old boy, born of non-consanguineous Chinese parents. We conducted a systematic analysis of the clinical and radiological characteristics and a follow-up study of the proband. Whole-exome sequencing was applied for the genetic analysis, together with bioinformatic analysis of predicted consequences of the identified variant. A homotrimer model was built to visualize the affected region and predict possible outcomes of this variant. Furthermore, a literature review and genotype-phenotype analysis were performed by online searching all cases with SMCD. RESULTS: A novel heterozygous variant (NM_000493.4: c.1863_1866delAATG, NP_000484.2: p.(Met622 Thrfs*54)) was identified in COL10A1 gene in the affected child. And it was predicted to be pathogenic by in silico analysis. Protein modeling revealed that the variant was located in the NC1 domain, which was predicted to produce truncated collagen and impair the trimerization of collagen type X alpha 1 chain and combination with molecules in the matrix. Moreover, genotype-phenotype correlation analysis demonstrated that patients with truncating variants or variants in NC1 domain often presented earlier onset and severer symptoms compared with those with non-truncating or variants in non-NC1 domains. CONCLUSION: The NC1 domain of COL10A1 was proved to be the hotspot region underlying SMCD, patients with variants in NC1 domain were more likely to present severer manifestations at an earlier age.

Collagen Type X Alpha 1 (COL10A1) Contributes to Cell Proliferation, Migration, and Invasion by Targeting Prolyl 4-Hydroxylase Beta Polypeptide (P4HB) in Breast Cancer.

BACKGROUND Breast cancer, a common malignant tumor, has been considered as the leading cause of cancer-related death in women. Collagen type X alpha 1 (COL10A1) is overexpressed in breast cancer. The current study was designed to determine the functional involvement and regulatory mechanism of COL10A1 on the growth and metastasis of breast cancer. MATERIAL AND METHODS COL10A1 and Prolyl 4-hydroxylase beta polypeptide (P4HB) expressions in normal tissues and tumor tissues of breast cancer patients were obtained from the GEPIA dataset. COL10A1 and P4HB levels in breast cancer cell lines were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Furthermore, the interaction between COL10A1 and P4HB was confirmed by co-immunoprecipitation (Co-IP) assay. Cell Counting Kit-8 (CCK-8) and colony formation assay were applied to evaluate cell proliferation and clone-forming abilities of breast cancer cells. In addition, wound healing assay and transwell assay were performed to measure cell migration and invasion capabilities, respectively, in breast cancer. RESULTS The GEPIA dataset presented overexpressed COL10A1 and P4HB in tumor tissues of breast cancer patients. COL10A1 and P4HB expression levels were greatly upregulated in breast cancer cell lines. In addition, COL10A1 could directly interact with P4HB. Functionally, overexpressed COL10A1 boosted the proliferation and metastasis of breast cancer cells and silenced COL10A1 impeded the progression of breast cancer. More importantly, knockdown of P4HB weakened the promoting effects of overexpressed COL10A1 on cell proliferation, migration, and invasion in breast cancer. CONCLUSIONS COL10A1 promotes the malignant progression of breast cancer by upregulating P4HB expression, indicating that COL10A1 functions as an oncogene in breast cancer.

Differentiation of Hypertrophic Chondrocytes from Human iPSCs for the In Vitro Modeling of Chondrodysplasias.

Chondrodysplasias are hereditary diseases caused by mutations in the components of growth cartilage. Although the unfolded protein response (UPR) has been identified as a key disease mechanism in mouse models, no suitable in vitro system has been reported to analyze the pathology in humans. Here, we developed a three-dimensional culture protocol to differentiate hypertrophic chondrocytes from induced pluripotent stem cells (iPSCs) and examine the phenotype caused by MATN3 and COL10A1 mutations. Intracellular MATN3 or COL10 retention resulted in increased ER stress markers and ER size in most mutants, but activation of the UPR was dependent on the mutation. Transcriptome analysis confirmed a UPR with wide-ranging changes in bone homeostasis, extracellular matrix composition, and lipid metabolism in the MATN3 T120M mutant, which further showed altered cellular morphology in iPSC-derived growth-plate-like structures in vivo. We then applied our in vitro model to drug testing, whereby trimethylamine N-oxide led to a reduction of ER stress and intracellular MATN3.

Analysis of Collagen type X alpha 1 (COL10A1) expression and prognostic significance in gastric cancer based on bioinformatics.

Collagen type X alpha 1 (COL10A1) is a member of the collagen family and the main matrix component. However, COL10A1 expression and prognosis relationship remains unclear in gastric cancer (GC). Through the analysis of database of Oncomine, the Cancer Genome Atlas (TCGA) as well as the Gene Expression Omnibus (GEO), in contrast to the tissue of normal gastric, COL10A1 in gastric cancer, had been upregulated. The high expression of COL10A1 was obviously related to T stage (P = 0.025) and lymph node metastasis (P = 0.025). It has been illustrated by the analysis of logistic regression that COL10A1's heightened expression in gastric cancer had been essentially linked with pathological stage, tumor differentiation, and T classification. The Kaplan-Meier curve in the Kaplan-Meier plotter database (P = 0.0371) and GSE84437 (P = 0.002) indicate that patients with high COL10A1 expression possess poor prognosis, specifically GC patients with lymph node metastasis have it. TCGA's Multivariate analysis (P = 0.025) and GSE84437 dataset (P = 0.034) show that high expression COL10A1 is a key independent predictor of poor overall survival. Searching KEGG pathway enrichment by GSEA, the results suggested that 29 pathways were enriched. qRT-PCR technique was used for verification of the COL10A1's high expression in gastric cancer in contrast to the normal gastric tissues. In conclusion, COL10A1 is of great importance in predicting the survival rate of GC patients.

Histone deacetylase 4 deletion results in abnormal chondrocyte hypertrophy and premature ossification from collagen type 2α1­expressing cells.

Histone deacetylase 4 (HDAC4) plays a vital role in chondrocyte hypertrophy and bone formation. To investigate the function of HDAC4 in postnatal skeletal development, the present study developed lineage­specific HDAC4­knockout mice [collagen type 2α1 (Col2α1)­Cre, HDAC4d/d mice] by crossing transgenic mice expressing Cre recombinase. Thus, a specific ablation of HDAC4 was performed in Col2α1­expressing mice cells. The knee joints of HDAC4fl/fl and Col2α1­Cre, HDAC4d/d mice were analyzed at postnatal day (P)2­P21 using an in vivo bromodeoxyuridine (BrdU) assay, and Safranin O, Von Kossa and whole­body staining were used to evaluate the developmental growth plate, hypertrophic differentiation, mineralization and skeletal mineralization patterns. The trabecular bone was analyzed using microcomputed tomography. The expressions of BrdU, proliferating cell nuclear antigen (PCNA), matrix metalloproteinase (MMP)­13, runt­related transcription factor (Runx)­2, osteoprotegerin (OPG), CD34, type X collagen (ColX), osteocalcin and Wnt5a were determined using immunohistochemistry, in situ hybridization (ISH) and reverse transcription­quantitative (RT­q)PCR. The results demonstrated that HDAC4­null mice (HDAC4d/d mice) were severely runted; these mice had a shortened hypertrophic zone (histopathological evaluation), accelerated vascular invasion and articular mineralization (Von Kossa staining), elevated expressions of MMP­13, Runx2, OPG and CD34 (RT­qPCR and immunohistochemistry), downregulated expression of the proliferative marker BrdU and PCNA (immunohistochemistry), increased expression of ColX and decreased expression of Wnt5a (ISH). In conclusion, chondrocyte­derived HDAC4 was responsible for regulating chondrocyte proliferation and differentiation as well as endochondral bone formation.

Different types of cartilage neotissue fabricated from collagen hydrogels and mesenchymal stromal cells via SOX9, TGFB1 or BMP2 gene transfer.

OBJECTIVE: As native cartilage consists of different phenotypical zones, this study aims to fabricate different types of neocartilage constructs from collagen hydrogels and human mesenchymal stromal cells (MSCs) genetically modified to express different chondrogenic factors. DESIGN: Human MSCs derived from bone-marrow of osteoarthritis (OA) hips were genetically modified using adenoviral vectors encoding sex-determining region Y-type high-mobility-group-box (SOX) 9, transforming growth factor beta (TGFB) 1 or bone morphogenetic protein (BMP) 2 cDNA, placed in type I collagen hydrogels and maintained in serum-free chondrogenic media for three weeks. Control constructs contained unmodified MSCs or MSCs expressing GFP. The respective constructs were analyzed histologically, immunohistochemically, biochemically, and by qRT-PCR for chondrogenesis and hypertrophy. RESULTS: Chondrogenesis in MSCs was consistently and strongly induced in collagen I hydrogels by the transgenes SOX9, TGFB1 and BMP2 as evidenced by positive staining for proteoglycans, chondroitin-4-sulfate (CS4) and collagen (COL) type II, increased levels of glycosaminoglycan (GAG) synthesis, and expression of mRNAs associated with chondrogenesis. The control groups were entirely non-chondrogenic. The levels of hypertrophy, as judged by expression of alkaline phosphatase (ALP) and COL X on both the protein and mRNA levels revealed different stages of hypertrophy within the chondrogenic groups (BMP2>TGFB1>SOX9). CONCLUSIONS: Different types of neocartilage with varying levels of hypertrophy could be generated from human MSCs in collagen hydrogels by transfer of genes encoding the chondrogenic factors SOX9, TGFB1 and BMP2. This technology may be harnessed for regeneration of specific zones of native cartilage upon damage.

Anti-inflammatory capacity of Apremilast in human chondrocytes is dependent on SOX-9.

BACKGROUND AND PURPOSE: Osteoarthritis (OA) impacts the quality of life in middle-aged and elderly people by inducing immobility. The severe inflammation in chondrocytes is reported to be related to the development and process of OA. The present study aims to investigate the protective effects of Apremilast on injured chondrocytes induced by interleukin-1α (IL-1α) and the underlying mechanism. METHODS: 10 ng/mL IL-1α was used to induce the in vitro injured chondrocytes. QRT-PCR was used to evaluate the expression level of Sry-type high-mobility-group box 9 (SOX-9), collagen type II alpha-1 gene (COL2A1), Aggrecan (ACAN) and collagen type X alpha 1 chain (COL10A1). SiRNA technology was utilized to knock down the expression of SOX-9 in the chondrocytes. The expression of SOX-9 was determined by Western Blot assay and/or immunofluorescence assay. Western Blot was used to evaluate the expression level of phosphorylated cyclic AMP response element binding (CREB). RESULTS: SOX9, Col2a1 and Acan were significantly up-regulated and Col10a1 was significantly down-regulated in the chondrocytes by Apremilast in a dose-dependent manner. IL-1α induced the injured chondrocytes by decreasing the expression of SOX9, Col2a1, Acan and increasing the expression of Col10a1, which were greatly reversed by Apremilast. By silencing SOX-9, the effects of Apremilast on SOX9 and marker genes were abolished. Phosphorylated CREB was up-regulated by Apremilast in a time-dependent manner. The up-regulated SOX-9 by Apremilast was reversed by the protein kinase A (PKA)/CREB pathway inhibitor H89. CONCLUSION: Apremilast may protect chondrocytes from inflammation by up-regulating SOX9.

3D spheroid culture models for chondrocytes using polyethylene glycol-coated microfabricated chip.

As chondrocytes fail to retain their chondrogenic potential in two-dimensional monolayer cultures, several three-dimensional culture systems have been employed for investigating the physiology and pathophysiology in articular cartilage tissues. In this study, we introduced a polyethylene glycol-coated microfabricated chip that enables spheroid formation from ATDC5 cell line, commonly used as a model for in vitro chondrocyte research. ATDC5 cells cultured in our devices aggregated immediately and generated a single spheroid per well within 24 h. Most cells in spheroids cultured in differentiation medium were viable and the circular shape and smooth surface of the spheroid were maintained up to 14 d in culture. We also detected potent hypoxia conditions, a key factor in chondrogenesis, in whole lesions of ATDC5 spheroids. Expression of chondrogenesis-related genes and type X collagen protein was significantly increased in ATDC5 spheroids grown in differentiation medium, compared with monolayer-cultured ATDC5 cells. We also demonstrated that the differentiation medium-induced Akt protein phosphorylation was upregulated in ATDC5 cells cultured in our spheroid device, suggesting that enhancement of chondrogenic potential in ATDC5 spheroids results from PI3/Akt signaling activation. These results indicated that our spheroid culture system could constitute a high-throughput strategy approach towards elucidating the molecular mechanisms that regulate chondrogenesis.

Involvement of Bmal1 and circadian clock signaling in chondrogenic differentiation of ATDC5 cells by fluoride.

Skeletal fluorosis causes growth plate impairment and growth retardation during bone development. However, the mechanism of how fluoride impairs chondrocyte is unclear. To explore the effect of fluoride on chondrocyte differentiation and the regulation of circadian clock signaling pathway during chondrogenesis, we treated ATDC5 cells with fluoride and carried out a series of experiments. 10-3 M fluoride inhibited cell viability and significantly decreased the expression of Sox9 and Col2a1 (P < 0.05). Fluoride inhibited proteoglycan synthesis and decreased significantly the expression of Aggrecan, Ihh and Col10a1 (P < 0.05). Meanwhile, fluoride significantly inhibited the expression of Bmal1 and disrupted circadian clock signaling pathway (P < 0.05). Furthermore, fluoride disrupted the time-dependent expression of circadian clock molecules and stage-specific differentiation markers. Overexpression of Bmal1 by lentivirus reversed the adverse effects of fluoride on chondrogenesis. These results suggested that fluoride inhibited chondrocyte viability and delayed chondrocyte differentiation. Fluoride delayed chondrogenesis partly via interfering with Bmal1 and circadian clock signaling pathway. Nevertheless, the specific mechanism of circadian clock in fluoride-induced cartilage damage needs to be further studied.

Screening and identification of key biomarkers in alimentary tract cancers: A bioinformatic analysis.

BACKGROUND: Alimentary tract cancers (ATCs) are the most malignant cancers in the world. Numerous studies have revealed the tumorigenesis, diagnosis and treatment of ATCs, but many mechanisms remain to be explored. METHODS: To identify the key genes of ATCs, microarray datasets of oesophageal cancer, gastric cancer and colorectal cancer were obtained from the Gene Expression Omnibus (GEO) database. In total, 207 differentially expressed genes (DEGs) were screened. KEGG and GO function enrichment analyses were conducted, and a protein-protein interaction (PPI) network was generated and gene modules analysis was performed using STRING and Cytoscape. RESULTS: Five hub genes were screened, and the associated biological processes indicated that these genes were mainly enriched in cellular processes, protein binding and metabolic processes. Clinical survival analysis showed that COL10A1 and KIF14 may be significantly associated with the tumorigenesis or pathology grade of ATCs. In addition, relative human ATC cell lines along with blood samples and tumour tissues of ATC patients were obtained. The data proved that high expression of COL10A1 and KIF14 was associated with tumorigenesis and could be detected in blood. CONCLUSION: In conclusion, the identification of hub genes in the present study helped us to elucidate the molecular mechanisms of tumorigenesis and identify potential diagnostic indicators and targeted treatment for ATCs.

Upregulated miR-101 inhibits acute kidney injury-chronic kidney disease transition by regulating epithelial-mesenchymal transition.

Acute kidney injury (AKI) is an independent risk factor for chronic kidney disease (CKD). However, the role and mechanism of microRNA (miRNA, miR) in AKI-CKD transition are elusive. In this study, a murine model of renal ischemia/reperfusion was established to investigate the repairing effect and mechanism of miR-101a-3p on renal injury. The pathological damage of renal tissue was observed by hematoxylin and eosin and Masson staining. The levels of miR-101, profibrotic cytokines, and epithelial-mesenchymal transition (EMT) markers were analyzed using Western blotting, real-time polymerase chain reaction, and/or immunofluorescence. MiR-101 overexpression caused the downregulation of α-smooth muscle actin, collagen-1, and vimentin, as well as upregulation of E-cadherin, thereby alleviating the degree of renal tissue damage. MiR-101 overexpression mitigated hypoxic HK-2 cell damage. Collagen, type X, alpha 1 and transforming growth factor ß receptor 1 levels were downregulated in hypoxic cells transfected with miR-101 mimic. Our study indicates that miR-101 is an anti-EMT miRNA, which provides a novel therapeutic strategy for AKI-CKD transition.

C-type natriuretic peptide stimulates osteoblastic proliferation and collagen-X expression but suppresses fibroblast growth factor-23 expression in vitro.

BACKGROUND: The effects of C-type natriuretic peptide (CNP) and fibroblast growth factor (FGF)-23 appear to oppose each other during the process of bone formation, whereas few studies exist on the interaction between CNP and FGF-23. The main objective of the present study is to probe whether CNP is directly responsible for the regulation of osteoblast or via antagonizing FGF-23. METHODS: Osteoblasts were cultured in the absence or presence of CNP (0, 10, and 100 pmol/L) for 24 h, 48 h and 72 h, respectively. RESULTS: The findings of the present study indicated that: (1) CNP significantly stimulated osteoblastic proliferation and collagen (Col)-X expression; (2) both osteoblastic (osteocalcin, procollagen type I carboxy-terminal propeptide, total alkaline phosphatase and bone-specific alkaline phosphatase) and osteolytic (tartrate-resistant acid phosphatase and cross-linked carboxyterminal telopeptide of type I collagen) bone turnover biomarkers were up-regulated by CNP in osteoblasts; (3) FGF-23 mRNA and protein were significantly down-regulated at 24 h by CNP in osteoblasts, but the expression of FGF receptor-1/Klotho had no significant change. CONCLUSIONS: CNP stimulates osteoblastic proliferation and Col-X expression via the down-regulation of FGF-23 possibly in vitro. However, the specific mechanisms of the interaction between CNP and FGF-23 in osteoblasts are still unclear according to our findings. A further study on osteoblasts cultured with CNP and FGF-23 inhibitor will be undertaken in our laboratory.

Zebrafish models of skeletal dysplasia induced by cholesterol biosynthesis deficiency.

Human disorders of the post-squalene cholesterol biosynthesis pathway frequently result in skeletal abnormalities, yet our understanding of the mechanisms involved is limited. In a forward-genetic approach, we have found that a late-onset skeletal mutant, named kolibernu7 , is the result of a cis-acting regulatory mutation leading to loss of methylsterol monooxygenase 1 (msmo1) expression within pre-hypertrophic chondrocytes. Generated msmo1nu81 knockdown mutation resulted in lethality at larval stage. We demonstrated that this is a result of both cholesterol deprivation and sterol intermediate accumulation by creating a mutation eliminating activity of Lanosterol synthase (Lss). Our results indicate that double lssnu60;msmo1nu81 and single lssnu60 mutants survive significantly longer than msmo1nu81 homozygotes. Liver-specific restoration of either Msmo1 or Lss in corresponding mutant backgrounds suppresses larval lethality. Rescued mutants develop dramatic skeletal abnormalities, with a loss of Msmo1 activity resulting in a more-severe patterning defect of a near-complete loss of hypertrophic chondrocytes marked by col10a1a expression. Our analysis suggests that hypertrophic chondrocytes depend on endogenous cholesterol synthesis, and blocking C4 demethylation exacerbates the cholesterol deficiency phenotype. Our findings offer new insight into the genetic control of bone development and provide new zebrafish models for human disorders of the cholesterol biosynthesis pathway.