ASPN Synergizes with HAPLN1 to Inhibit the Osteogenic Differentiation of Bone Marrow Mesenchymal Stromal Cells and Extracellular Matrix Mineralization of Osteoblasts

OBJECTIVE

Bone marrow mesenchymal stromal cells (BMSCs) are major sources of osteogenic precursor cells in bone remodeling, which directly participate in osteoporosis (OP) progression. However, the involved specific mechanisms of BMSCs in OP warrant mass investigations. Initially, our bioinformatics analysis uncovered the prominent up-regulation of Asporin (ASPN) and proteoglycan link protein 1 (HAPLN1) in osteoblasts (OBs) of OP patients and their possible protein interaction. Hence, this study aimed to explore the effects of ASPN and HAPLN1 on osteogenic differentiation of BMSCs, extracellular matrix (ECM) mineralization of OBs, and osteoclastogenesis, hoping to offer research basis for OP treatment.

METHODS

GSE156508 dataset was used for analysis and screening to acquire the differentially expressed genes in OBs of OP patients, followed by the predicative analysis via STRING. OP mouse models were induced by ovariectomy (OVX), and ASPN and HAPLN1 expression was determined. BMSCs and bone marrow macrophages (BMMs) were isolated from OVX mice and induced for osteogenic differentiation and osteoclastogenesis, respectively. After knockdown experiments, we assessed adipogenic differentiation and osteogenic differentiation in BMSCs. Osteogenic (OPN, OCN, and COL1A1) and osteoclast (Nfatc1 and c-Fos) marker protein expression was determined. The binding of ASPN to HAPLN1 was analyzed.

RESULTS

High expression of ASPN and HAPLN1 and their protein interaction were observed in OBs of OP patients via bioinformatics and in bone tissues of OVX mice. ASPN interacted with HAPLN1 in BMSCs of OVX mice. ASPN/HAPLN1 knockdown increased ALP, OPN, OCN, and COL1A1 protein expression and ECM mineralization in BMSCs while decreasing Nfatc1 and c-Fos expression in BMMs. These effects were aggravated by the simultaneous knockdown of ASPN and HAPLN1.

CONCLUSION

Our results indicate that ASPN synergises with HAPLN1 to suppress the osteogenic differentiation of BMSCs and ECM mineralization of OBs and promote the osteoclastogenesis in OP.

Processing and interpretation of core-electron XPS spectra of complex plasma-treated polyethylene-based surfaces using a theoretical peak model

Interpretation of X-ray photoelectron spectroscopy (XPS) spectra of complex material surfaces, such as those obtained after surface plasma treatment of polymers, is confined by the available references. The limited understanding of the chemical surface composition may impact the ability to determine suitable coupling chemistries used for surface decoration or assess surface-related properties like biocompatibility. In this work, XPS is used to investigate the chemical composition of various ultra-high-molecular-weight polyethylene (UHMWPE) surfaces. UHMWPE doped with α-tocopherol or functionalised by active screen plasma nitriding (ASPN) was investigated as a model system. Subsequently, a more complex combined system obtained by ASPN treatment of α-tocopherol doped UHMWPE was investigated. Through ab initio orbital calculations and by employing Koopmans' theorem, the core-electron binding energies (CEBEs) were evaluated for a substantial number of possible chemical functionalities positioned on PE-based model structures. The calculated ΔCEBEs showed to be in reasonable agreement with experimental reference data. The calculated ΔCEBEs were used to develop a material-specific peak model suitable for the interpretation of merged high-resolution C 1 s, N 1 s and O 1 s XPS spectra of PE-based materials. In contrast to conventional peak fitting, the presented approach allowed the distinction of functionality positioning (i.e. centred or end-chain) and evaluation of the long-range effects of the chemical functionalities on the PE carbon backbone. Altogether, a more detailed interpretation of the modified UHMWPE surfaces was achieved whilst reducing the need for manual input and personal bias introduced by the spectral analyst.

ASPN Is a Potential Biomarker and Associated with Immune Infiltration in Endometriosis

Objective: Endometriosis is a benign gynecological disease characterized by distant metastasis. Previous studies have discovered abnormal numbers and function of immune cells in endometriotic lesions. We aimed to find potential biomarkers of endometriosis and to explore the relationship between ASPN and the immune microenvironment of endometriosis. Methods: We obtained the GSE141549 and GSE7305 datasets containing endometriosis and normal endometrial samples from the Gene Expression Omnibus database (GEO). In the GSE141549 dataset, differentially expressed genes (DEGs) were found. The Least Absolute Shrinkage and Selection Operator (Lasso) regression and generalized linear models (GLMs) were used to screen new biomarkers. The expression levels and diagnostic utility of biomarkers were assessed in GSE7305, and biomarker expression levels were further validated using qRT-PCR and western blot. We identified DEGs between high and low expression groups of key biomarkers. Enrichment analysis was carried out to discover the target gene’s biological function. We analyzed the relationship between key biomarker expression and patient clinical features. Finally, the immune cells that infiltrate endometriosis were assessed using the Microenvironment Cell Population-Counter (MCP-counter), and the correlation of biomarker expression with immune cell infiltration and immune checkpoints genes was studied. Results: There were a total of 38 DEGs discovered. Two machine learning techniques were used to identify 10 genes. Six biomarkers (SCG2, ASPN, SLIT2, GEM, EGR1, and FOS) had good diagnostic efficiency (AUC > 0.7) by internal and external validation. We excluded previously reported related genes (SLIT2, EGR1, and FOS). ASPN was the most significantly differentially expressed biomarker between normal and ectopic endometrial tissues, as verified by qPCR. The western blot assay revealed a significant upregulation of ASPN expression in endometriotic tissues. The investigation for DEGs in the ASPN high- and low-expression groups revealed that the DEGs were particularly enriched in extracellular matrix tissue, vascular smooth muscle contraction, cytokine interactions, the calcium signaling pathway, and the chemokine signaling pathway. High ASPN expression was related to r-AFS stage (p = 0.006), age (p = 0.03), and lesion location (p < 0.001). Univariate and multivariate logistic regression analysis showed that ASPN expression was an independent influencing factor in patients with endometriosis. Immune cell infiltration analysis revealed a significant increase in T-cell, B-cell, and fibroblast infiltration in endometriosis lesions; cytotoxic lymphocyte, NK-cell, and endothelial cell infiltration were reduced. Additionally, the percentage of T cells, B cells, fibroblasts, and endothelial cells was favorably connected with ASPN expression, while the percentage of cytotoxic lymphocytes and NK cells was negatively correlated. Immune checkpoint gene (CTLA4, LAG3, CD27, CD40, and ICOS) expression and ASPN expression were positively associated. Conclusions: Increased expression of ASPN is associated with immune infiltration in endometriosis, and ASPN can be used as a diagnostic biomarker as well as a potential immunotherapeutic target in endometriosis.

Asporin Promotes TGF-β-induced Lung Myofibroblast Differentiation by Facilitating Rab11-dependent Recycling of TβRI

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive fibrotic lung disease with high mortality and morbidity. Asporin (ASPN), a member of the small leucine-rich proteoglycan (SLRP) family, plays crucial roles in tissue injury and regeneration. However, the precise pathophysiological role of ASPN and its molecular mechanisms in IPF remain unknown. We sought to investigate the role of ASPN during the development of pulmonary fibrosis and the therapeutic potential of targeting ASPN-related signaling pathways. In our study, three microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database, and differentially expressed genes (DEGs) were screened out by bioinformatic analysis. Hub genes were selected from the protein-protein interaction network. ASPN was examined in lung tissues from pulmonary fibrosis mouse models and the role of ASPN in TGF-β/Smad signaling was determined by transfection with ASPN shRNA vectors in vitro. Biotinylation assays were conducted to measure plasma membrane TβRI and TβRI recycling after ASPN knockdown. The results showed ASPN expression was increased in the lungs of pulmonary fibrosis mouse models, and ASPN was primarily localized in α-SMA+ myofibroblasts. In vitro experiments proved that ASPN knockdown inhibited TGF-β/Smad signaling and myofibroblast differentiation by regulating the stability of TβRI. Further molecular mechanisms revealed that ASPN knockdown inhibited TGF-β/Smad signaling by suppressing recycling of TβRI to the cell surface in a Rab11-dependent manner and facilitated lysosome-mediated degradation of TβRI. In conclusion, our findings provide important evidence for the use of ASPN as a novel pharmacological target for treating pulmonary fibrosis.

Asporin inhibits collagen matrix-mediated intercellular mechanocommunications between fibroblasts during keloid progression

Keloids are fibrotic lesions that grow unceasingly and invasively and are driven by local mechanical stimuli. Unlike other fibrotic diseases and normal wound healing, keloids exhibit little transformation of dermal fibroblasts into α-SMA⁺ myofibroblasts. This study showed that asporin is the most strongly expressed gene in keloids and its gene-ontology terms relate strongly to ECM metabolism/organization. Experiments with human dermal cells (HDFs) showed that asporin overexpression/treatment abrogated the HDF ability to adopt a perpendicular orientation when subjected to stretching tension. It also induced calcification of the surrounding 3D collagen matrix. Asporin overexpression/treatment also prevented the HDFs from remodeling the surrounding 3D collagen matrix, leading to a disorganized network of thick, wavy collagen fibers that resembled keloid collagen architecture. This in turn impaired the ability of the HDFs to contract the collagen matrix. Asporin treatment also made the fibroblasts impervious to the fibrous collagen contraction of α-SMA⁺ myofibroblasts, which normally activates fibroblasts. Thus, by calcifying collagen, asporin prevents fibroblasts from linearly rearranging the surrounding collagen; this reduces both their mechanosensitivity and mechanosignaling to each other through the collagen network. This blocks fibroblast activation and differentiation into the mature myofibroblasts that efficiently remodel the extracellular matrix. Consequently, the fibroblasts remain immature, highly proliferative, and continue laying down abundant extracellular matrix, causing keloid growth and invasion. Notably, dermal injection of asporin-overexpressing HDFs into murine wounds recapitulated keloid collagen histopathological characteristics. Thus, disrupted interfibroblast mechanocommunication may promote keloid progression. Asporin may be a new diagnostic biomarker and therapeutic target for keloids.

A distinct repertoire of cancer-associated fibroblasts is enriched in cribriform prostate cancer

Outcomes for men with localized prostate cancer vary widely, with some men effectively managed without treatment on active surveillance, while other men rapidly progress to metastatic disease despite curative-intent therapies. One of the strongest prognostic indicators of outcome is grade groups based on the Gleason grading system. Gleason grade 4 prostate cancer with cribriform morphology is associated with adverse outcomes and can be utilized clinically to improve risk stratification. The underpinnings of disease aggressiveness associated with cribriform architecture are not fully understood. Most studies have focused on genetic and molecular alterations in cribriform tumor cells; however, less is known about the tumor microenvironment in cribriform prostate cancer. Cancer-associated fibroblasts (CAFs) are a heterogeneous population of fibroblasts in the tumor microenvironment that impact cancer aggressiveness. The overall goal of this study was to determine if cribriform prostate cancers are associated with a unique repertoire of CAFs. Radical prostatectomy whole-tissue sections were analyzed for the expression of fibroblast markers (ASPN in combination with FAP, THY1, ENG, NT5E, TNC, and PDGFRβ) in stroma adjacent to benign glands and in Gleason grade 3, Gleason grade 4 cribriform, and Gleason grade 4 noncribriform prostate cancer by RNAscope®. Halo® Software was used to quantify percent positive stromal cells and expression per positive cell. The fibroblast subtypes enriched in prostate cancer were highly heterogeneous. Both overlapping and distinct populations of low abundant fibroblast subtypes in benign prostate stroma were enriched in Gleason grade 4 prostate cancer with cribriform morphology compared to Gleason grade 4 prostate cancer with noncribriform morphology and Gleason grade 3 prostate cancer. In addition, gene expression was distinctly altered in CAF subtypes adjacent to cribriform prostate cancer. Overall, these studies suggest that cribriform prostate cancer has a unique tumor microenvironment that may distinguish it from other Gleason grade 4 morphologies and lower Gleason grades.

Advocacy in pediatric neurosurgery: results from a 2017 survey of the American Society of Pediatric Neurosurgeons

OBJECTIVE

Pediatric neurosurgeons are unswerving advocates for public health-related issues in children, with most providers participating in local, regional, national, or international efforts. Collective advocacy efforts by organized pediatric neurosurgeons have not been undertaken to date.

METHODS

A 10-item survey was administered to members of the American Society of Pediatric Neurosurgeons (ASPN) in order to evaluate attitudes and opinions regarding the development of a formal advocacy effort by the organization.

RESULTS

Seventy-nine of 178 registered members of the ASPN (44.38%) participated in the survey. Participants were 82.61% male, with age, stage of career, and practice type varied. Although there was unequivocal support for participation in organized advocacy, respondents were divided on methods and topics for advocacy. In this survey, the ASPN membership prioritized public health and clinical issues over economic issues that affected children.

CONCLUSIONS

Most respondents favored the drafting of position statements on key issues and partnerships with larger organizations to pursue an advocacy agenda. The survey provides data regarding pediatric neurosurgeons' attitudes that may assist with the design of a successful advocacy program.

Synovial tissue quantitative proteomics analysis reveals paeoniflorin decreases LIFR and ASPN proteins in experimental rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a common worldwide public health problem, which causes a chronic, systemic inflammatory disorder of synovial joints. Paeoniflorin (PA) has achieved positive results to some extent for the treatment of RA.

Purpose

This study aimed to reveal the potential druggable targets of PA in an experimental RA model using quantitative proteomics analysis.

Study design and methods

Thirty Sprague-Dawley rats were randomly divided into a normal group, model group and PA group. PA (1 mg/kg) was used to treat collagen-induced arthritis (CIA) rats for 42 days. We used isobaric tags for relative and absolute quantitation-based quantitative proteomics to analyze the synovial tissue of rats. Ingenuity pathway analysis (IPA) software was applied to process the data. The proteins that were targeted via IPA software were verified by Western blots.

Results

We found that PA caused 86 differentially expressed proteins (≥1.2-fold or ≤0.84-fold) compared with the CIA group. Of these varied proteins, 20 significantly changed (p<0.05) proteins referred to 41 CIA-relative top pathways after IPA pathway analysis. Thirteen of the PA-regulated pathways were anchored, which intervened in 24 biological functions. Next, network analysis revealed that leukemia inhibitory factor receptor (LIFR) and asporin (ASPN), which participate in two significant networks, contributed the most to the efficacy of PA treatment. Additionally, Western blots confirmed the aforementioned druggable targets of PA for the treatment of RA.

Conclusion

The results reveal that PA may treat RA by decreasing two key proteins, LIFR and ASPN. Our research helps to identify potential agents for RA treatment.

Association study of candidate genes for susceptibility to Kashin-Beck disease in a Tibetan population

Background

Many osteoarthritis (OA) susceptibility genes have been identified in recent years. Given the overlap in the phenotype of joint inflammation between OA and Kashin-Beck disease (KBD), the aim of this study is to explore whether the reported OA susceptibility genes and two genes that may link to OA pathophysiology are associated with KBD in the Tibetan population.

Method

Fifteen single-nucleotide polymorphisms (SNPs) in 12 candidate genes previously reported as OA susceptibility loci were selected for investigation. Genotyping was performed using the SNaPshot method for these SNPs in a Tibetan population composed of 849 KBD patients and 565 normal controls. Meanwhile, the coding regions of two genes, COL10A1 and HABP2, which may involve in the pathological mechanism of OA/KBD, were sequenced by Sanger sequencing to identify susceptibility coding variants for KBD in the Tibetan population.

Results

The two arthritis-susceptible candidate SNPs, rs7775 (p.Arg324Gly) in the FRZB gene and rs7033979 in the ASPN gene, showed associations with KBD (OR = 1.568, P = 4 × 10⁻³ and OR = 0.744, P = 8 × 10⁻³, respectively). The coding variants rs142463796 (p.Asp128Asn) and rs2228547 (p.Gly545Arg) in the COL10A1 gene (OR = 9.832 and P = 6 × 10⁻³ and OR = 1.242, P = 0.043, respectively) and rs548354451 (p.Asp272Glu) in the HABP2 gene (OR = 2.813, P = 0.010) were associated with KBD patients.

Conclusion

These finding suggested that rs7775 in the FRZB gene may increase susceptibility to KBD, while rs7033979 in the ASPN gene may play a protective role in susceptibility to KBD in Tibetans. Moreover, genetic variants in chondrogenesis-related genes COL10A1 and HABP2 may play a role in the risk of developing KBD in the Tibetan population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-017-0423-6) contains supplementary material, which is available to authorized users.

The small leucine-rich repeat secreted protein Asporin induces eyes in Xenopus embryos through the IGF signalling pathway

Small leucine-rich repeat proteoglycan (SLRP) family proteins play important roles in a number of biological events. Here, we demonstrate that the SLRP family member Asporin (ASPN) plays a crucial role in the early stages of eye development in Xenopus embryos. During embryogenesis, ASPN is broadly expressed in the neuroectoderm of the embryo. Overexpression of ASPN causes the induction of ectopic eyes. By contrast, blocking ASPN function with a morpholino oligonucleotide (ASPN-MO) inhibits eye formation, indicating that ASPN is an essential factor for eye development. Detailed molecular analyses revealed that ASPN interacts with insulin growth factor receptor (IGFR) and is essential for activating the IGF receptor-mediated intracellular signalling pathway. Moreover, ASPN perturbed the Wnt, BMP and Activin signalling pathways, suggesting that ASPN thereby creates a favourable environment in which the IGF signal can dominate. ASPN is thus a novel secreted molecule essential for eye induction through the coordination of multiple signalling pathways.

High-resolution molecular validation of self-renewal and spontaneous differentiation in clinical-grade adipose-tissue derived human mesenchymal stem cells

Improving the effectiveness of adipose-tissue derived human mesenchymal stromal/stem cells (AMSCs) for skeletal therapies requires a detailed characterization of mechanisms supporting cell proliferation and multi-potency. We investigated the molecular phenotype of AMSCs that were either actively proliferating in platelet lysate or in a basal non-proliferative state. Flow cytometry combined with high-throughput RNA sequencing (RNASeq) and RT-qPCR analyses validate that AMSCs express classic mesenchymal cell surface markers (e.g., CD44, CD73/NT5E, CD90/THY1, and CD105/ENG). Expression of CD90 is selectively elevated at confluence. Self-renewing AMSCs express a standard cell cycle program that successively mediates DNA replication, chromatin packaging, cyto-architectural enlargement, and mitotic division. Confluent AMSCs preferentially express genes involved in extracellular matrix (ECM) formation and cellular communication. For example, cell cycle-related biomarkers (e.g., cyclins E2 and B2, transcription factor E2F1) and histone-related genes (e.g., H4, HINFP, NPAT) are elevated in proliferating AMSCs, while ECM genes are strongly upregulated (>10-fold) in quiescent AMSCs. AMSCs also express pluripotency genes (e.g., POU5F1, NANOG, KLF4) and early mesenchymal markers (e.g., NES, ACTA2) consistent with their multipotent phenotype. Strikingly, AMSCs modulate expression of WNT signaling components and switch production of WNT ligands (from WNT5A/WNT5B/WNT7B to WNT2/WNT2B), while upregulating WNT-related genes (WISP2, SFRP2, and SFRP4). Furthermore, post-proliferative AMSCs spontaneously express fibroblastic, osteogenic, chondrogenic, and adipogenic biomarkers when maintained in confluent cultures. Our findings validate the biological properties of self-renewing and multi-potent AMSCs by providing high-resolution quality control data that support their clinical versatility.

Integrated regulatory mechanisms of miRNAs and targeted genes involved in colorectal cancer

PURPOSE

CRC (Colorectal cancer) is a lethal cancer for death worldwide and the underlying pathological mechanisms for CRC progression remain unclear. We aimed to explore the regulatory mechanism of CRC and provide novel biomarkers for CRC screening.

METHODS

Downloading from GEO (Gene Expression Omnibus) database, Microarray data GSE44861 were consisted of 111 colon tissues samples including 55 from adjacent noncancerous tissues and 56 from tumors tissues. After data pre-processing, up- and down regulated DEGs (differentially expressed genes) were identified using Bayes moderated t-test. Then DIVAD (Database for Annotation, Visualization and Integrated Discovery) was recruited to perform functional analysis for DEGs. Thereafter, PPI (protein-protein interaction) network was constructed by mapping DEGs into STRING (Search Tool for the Retrieval of Interacting Genes) database. Further, PPI modules were constructed and the protein domains of DEGs in the modules were analyzed. Moreover, miRNA regulatory network was established through GSEA (gene set enrichment analysis) method.

RESULTS

In summary, 96 up- and 212 down-regulated DEGs were identified. Totally, ten DEGs with high degrees in the constructed PPI network were selected, in which COLL1A1, PTGS2 and ASPN were also identified as crucial genes in PPI modules. Furthermore, COLL1A1 was predicted to be targeted by miR-29, while PTGS2 and ASPN were both predicted to be regulated by miR-101 and miR-26.

CONCLUSION

COL11A1 might involve in the progression of CRC via being targeted by miR-29, whereas PTGS2 and ASPN were both regulated by miR-101 and miR-26. Moreover, ASPN may be supposed as a novel biomarker for CRC detection and prevention.

Cartilage Intermediate Layer Protein and Asporin Polymorphisms Are Independent Risk Factors of Lumbar Disc Degeneration in Male Collegiate Athletes

OBJECTIVE

Lumbar disc degeneration (LDDG), recently reported to have strong genetic determinants, is a major cause of discopathy and lower back pain. However, most studies have only evaluated the effects of a single susceptibility polymorphism. Our purpose was to examine the effect of two susceptibility polymorphism for LDDG in Japanese collegiate athletes.

DESIGN

We investigated two susceptibility genes for LDDG-cartilage intermediate layer protein (CILP) and asporin (ASPN)-in 516 collegiate athletes and genotyped the risk allele of CILP (1184T/C) and ASPN (D14). LDDG was evaluated using T2-weighted magnetic resonance imaging.

RESULTS

By using logistic regression analysis, we found that the ASPN D14 allele and CILP genotype were associated with an increased risk of LDDG in male but not female athletes (CILP CT: odds ratios [OR] = 1.77, 95% confidence interval [CI] = 1.07-2.93; CILP CC: OR = 4.38, 95% CI = 1.42-13.54; ASPN D14: OR = 2.17, 95% CI = 1.10-4.28]. We also found that CILP C and ASPN D14 were independent variables. The ORs with more than two risk alleles were largely increased.

CONCLUSIONS

The CILP and ASPN polymorphisms are independent genetic risk factors for LDDG in male but not female Japanese collegiate athletes.

ASPN and GJB2 Are Implicated in the Mechanisms of Invasion of Ductal Breast Carcinomas

The mechanism of progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) remains largely unknown. We compared gene expression in tumors with simultaneous DCIS and IDC to decipher how diverse proteins participate in the local invasive process.

Twenty frozen tumor specimens with concurrent, but separated, DCIS and IDC were microdissected and evaluated. Total RNA was extracted and microarray analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST Arrays. Microarray data were validated by quantitative real time reverse transcription-PCR (qRT-PCR) and immunohistochemistry. Controls included seven pure in situ carcinomas, eight fragments from normal breast tissue, and a series of mouse breast carcinomas (MMTV-PyMT).

Fifty-six genes were differentially expressed between DCIS and IDC samples. The genes upregulated in IDC samples, and probably associated with invasion, were related to the epithelial-mesenchymal transition (ASPN, THBS2, FN1, SPARC, and COL11A1), cellular adhesion (GJB2), cell motility and progression (PLAUR, PLAU, BGN, ADAMTS16, and ENPP2), extracellular matrix degradation (MMP11, MMP13, and MMP14), and growth/proliferation (ST6GAL2). qRT-PCR confirmed the expression patterns of ASPN, GJB2, ENPP2, ST6GAL2, and TMBS10. Expression of the ASPN and GJB2 gene products was detected by immunohistochemistry in invasive carcinoma foci. The association of GJB2 protein expression with invasion was confirmed by qRT-PCR in mouse tumors (P < 0.05).

Conclusions: The upregulation of ASPN and GJB2 may play important roles in local invasion of breast ductal carcinomas.