Dual roles of misshapen/NIK-related kinase (MINK1) in osteoarthritis subtypes through the activation of TGFβ signaling

MINK1 deficiency stimulates nucleus pulposus cell pyroptosis and exacerbates intervertebral disc degeneration

Intervertebral disc (IVD) degeneration, induced by aging and irregular mechanical strain, is highly prevalent in the elderly population, serving as a leading cause of chronic low back pain and disability. Evolving evidence has revealed the involvement of nucleus pulposus (NP) pyroptosis in the pathogenesis of IVD degeneration, while the precise regulatory mechanisms of NP pyroptosis remain obscure. Misshapen/Nck-interacting kinase (NIK)-related kinase 1 (MINK1), a serine-threonine protein kinase, has the potential to modulate the activation of NLRP3 inflammasome, indicating its pivotal role in governing pyroptosis. In this study, to assess the significance of MINK1 in NP pyroptosis and IVD degeneration, NP tissues from patients with varying degrees of IVD degeneration, and IVD tissues from both aging-induced and lumbar spine instability (LSI) surgery-induced IVD degeneration mouse models, with or without MINK1 ablation, were meticulously evaluated. Our findings indicated a notable decline in MINK1 expression in NP tissues of patients with IVD degeneration and both mouse models as degeneration progresses, accompanied by heightened matrix degradation and increased NP pyroptosis. Moreover, MINK1 ablation led to substantial activation of NP pyroptosis in both mouse models, and accelerating ECM degradation and intensifying the degeneration phenotype in mechanically stress-induced mice. Mechanistically, MINK1 deficiency triggered NF-κB signaling in NP tissues. Overall, our data illustrate an inverse correlation between MINK1 expression and severity of IVD degeneration, and the absence of MINK1 stimulates NP pyroptosis, exacerbating IVD degeneration by activating NF-κB signaling, highlighting a potential innovative therapeutic target in treating IVD degeneration.

The common marmoset as a translational model of age-related osteoarthritis

Age-related osteoarthritis (OA) is a degenerative joint disease characterized by pathological changes in nearly every intra- and peri-articular tissue that contributes to disability in older adults. Studying the etiology of age-related OA in humans is difficult due to an unpredictable onset and insidious nature. A barrier in developing OA modifying therapies is the lack of translational models that replicate human joint anatomy and age-related OA progression. The purpose of this study was to determine whether the common marmoset is a faithful model of human age-related knee OA. Semi-quantitative microCT scoring revealed greater radiographic OA in geriatric versus adult marmosets, and the age-related increase in OA prevalence was similar between marmosets and humans. Quantitative assessments indicate greater medial tibial cortical and trabecular bone thickness and heterogeneity in geriatric versus adult marmosets which is consistent with an age-related increase in focal subchondral bone sclerosis. Additionally, marmosets displayed an age-associated increase in synovitis and calcification of the meniscus and patella. Histological OA pathology in the medial tibial plateau was greater in geriatric versus adult marmosets driven by articular cartilage damage, proteoglycan loss, and altered chondrocyte cellularity. The age-associated increase in medial tibial cartilage OA pathology and meniscal calcification was greater in female versus male geriatric marmosets. Overall, marmosets largely replicate human OA as evident by similar 1) cartilage and skeletal morphology, 2) age-related progression in OA pathology, and 3) sex differences in OA pathology with increasing age. Collectively, these data suggest that the common marmoset is a highly translatable model of the naturally occurring, age-related OA seen in humans.

Identification of novel potential drugs for the treatment and prevention of osteoarthritis

Objectives

Osteoarthritis (OA) is characterized by a high prevalence, poor prognosis, and a propensity to lead to disability. Despite the availability of standard therapies, they are associated with potential side effects and don't provide a complete cure for patients. Consequently, there is an urgent demand for the development of novel drugs.

Method

The gene expression profiles (GSE64394, GSE178557 and GSE215039) of normal and OA chondrocytes samples were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified by the "LIMMA" R package. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment were conducted using the R package clusterProfiler. A protein-protein (PPI) interaction network was performed to identify hub genes by using the Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape. Small molecule compounds linked to OA were predicted through the NetworkAnalyst platform. Finally, molecular docking was conducted using AutoDock and Pymol software.

Results

We identified 98 DEGs primarily implicated in endochondral ossification, extracellular matrix degradation, and Wnt signaling pathways. 23 DEGs were closely associated with OA, and 10 hub genes were found to be potential drug targets for OA. Two new targeted compounds, tetrachlorodibenzodioxin (TCDD) and valproic acid (VPA), were screened. And they both exhibited strong binding affinity to their respective targets.

Conclusions

Reducing exposure to TCDD could be a crucial strategy in preventing OA, and VPA has gained recognition as a novel drug candidate for OA treatment.

Comprehensive analysis of senescence-related genes and immune infiltration in intervertebral disc degeneration: a meta-data approach utilizing bulk and single-cell RNA sequencing data

Objectives: This study aims to identify the key senescence genes and potential regulatory mechanisms that contribute to the etiology of intervertebral disc degeneration (IDD). Method: We analyzed GSE34095 and GSE70362 datasets, identifying key senescence-related differentially expressed genes (DEGs) in IDD using lasso regression. Risk scores classified patients into high- and low-risk groups. We compared pathways, functions, and immune infiltration between these groups. Diagnostic ability was assessed using ROC curves and a nomogram predicted IDD incidence. In single-cell dataset GSE165722, we evaluated expression of key senescence-related DEGs. Results: We identified 12 key senescence-related DEGs distinguishing high- and low-risk IDD patients. Enrichment analysis revealed cellular stress response, apoptotic signaling pathway, and protein kinase activation differences. Immune cell analysis showed elevated eosinophils in low-risk group and increased effector memory CD8 T, central memory CD4 T, myeloid-derived suppressor, natural killer, monocyte, Type 1 T helper, plasmacytoid dendritic, and natural killer T cells in high-risk group. A nomogram using AUC >0.75 genes (CXCL8, MAP4K4, MINK1, and TNIK) predicted IDD incidence with good diagnostic power. High senescence scores were observed in neutrophils. Conclusion: Our diagnostic model, based on key senescence-related DEGs and immune cell infiltration, offers new insights into IDD pathogenesis and immunotherapy strategies.

Phosphoproteomics reveals the BRAF-ERK1/2 axis as an important pathogenic signaling node in cartilage degeneration

OBJECTIVE

Osteoarthritis (OA) causes gradual cellular alterations, structural anomalies and joint dysfunction. Progressive decline of chondrocyte function plays a vital role on OA pathogenesis. Although protein phosphorylation controls cartilage metabolism, its regulation mechanism in OA remains unclear. Thus, proteomic methods were used to investigate phosphorylation changes in preserved and OA articular cartilage samples, and to explore the intervention targets of phosphorylated kinase.

METHODS

Preserved (control) and lesioned (OA) cartilage samples from OA cases were assessed by phosphoproteomics. Immobilized metal affinity chromatography was performed for phosphopeptide enrichment. Quantitated phosphosites were comparatively assessed in the cartilage sample pair. Kinase-substrate enrichment analyses were carried out for identifying OA-related kinases. BRAF expression in cartilage tissues was assessed by immunohistochemical staining. The effects of BRAF inhibitor on cartilage degeneration were examined in mouse chondrocytes and OA mouse model.

RESULTS

High-sensitivity mass spectrometry-based proteomics revealed 7,471 peptides and 4,375 phosphorylated peptides differing between preserved and lesioned cartilage samples, which represented the significant alteration of kinase hubs and transduction pathways. Phosphoproteomics identified BRAF may be involved in developing OA. BRAF regulated the downstream ERK signaling pathway. In addition, BRAF was upregulated in human OA cartilage as shown by immunohistochemistry. Remarkably, BRAF inhibition alleviated cartilage degradation in a mouse model of OA through its downstream of ERK pathway activation.

CONCLUSIONS

Jointly, these findings provide an overview of phosphoproteomic alterations occurring during cartilage degeneration, identifying the BRAF-ERK1/2 Axis signaling as a potential signaling pathway involved in OA.

Multi-Omic Investigations of a 17-19 Translocation Links MINK1 Disruption to Autism, Epilepsy and Osteoporosis

Balanced structural variants, such as reciprocal translocations, are sometimes hard to detect with sequencing, especially when the breakpoints are located in repetitive or insufficiently mapped regions of the genome. In such cases, long-range information is required to resolve the rearrangement, identify disrupted genes and, in symptomatic carriers, pinpoint the disease-causing mechanisms. Here, we report an individual with autism, epilepsy and osteoporosis and a de novo balanced reciprocal translocation: t(17;19) (p13;p11). The genomic DNA was analyzed by short-, linked- and long-read genome sequencing, as well as optical mapping. Transcriptional consequences were assessed by transcriptome sequencing of patient-specific neuroepithelial stem cells derived from induced pluripotent stem cells (iPSC). The translocation breakpoints were only detected by long-read sequencing, the first on 17p13, located between exon 1 and exon 2 of MINK1 (Misshapen-like kinase 1), and the second in the chromosome 19 centromere. Functional validation in induced neural cells showed that MINK1 expression was reduced by >50% in the patient’s cells compared to healthy control cells. Furthermore, pathway analysis revealed an enrichment of changed neural pathways in the patient’s cells. Altogether, our multi-omics experiments highlight MINK1 as a candidate monogenic disease gene and show the advantages of long-read genome sequencing in capturing centromeric translocations.

LncRNA SNHG14 contributes to proinflammatory cytokine production in rheumatoid arthritis via the regulation of the miR-17-5p/MINK1-JNK pathway

Rheumatoid arthritis (RA) is a widespread autoimmune disorder of the joints. Long noncoding RNAs (lncRNAs) have been reported to participate in the pathogenesis of RA by serving as competitive endogenous RNAs. LncRNA small nucleolar RNA host gene 14 (SNHG14) is involved in the development of various diseases. Here, we found that high expression of SNHG14 in RA was closely related to the disease activity. Functional assays indicated that SNHG14 knockdown obviously hampered phorbol myristate acetate-activated THP-1 (pTHP-1) cell proliferation and proinflammatory cytokines production. In mechanism, SNHG14 served as a sponge of microRNA-17-5p (miR-17-5p), and misshapen like kinase 1 (MINK1) was a target of miR-17-5p. SNHG14 depletion-induced inhibitory effects on cell proliferation and inflammatory response were reversed by MINK1 overexpression in macrophages. Moreover, SNHG14 promoted the jun N-terminal kinase (JNK) signaling via the miR-17-5p/MINK1 axis. Overall, SNHG14 boosted the process of RA by MINK1 activating the JNK pathway.

Roles and Mechanisms of Irisin in Attenuating Pathological Features of Osteoarthritis

To investigate the effects and mechanisms of irisin, a newly discovered myokine, in cartilage development, osteoarthritis (OA) pathophysiology and its therapeutic potential for treating OA we applied the following five strategical analyses using (1) murine joint tissues at different developmental stages; (2) human normal and OA pathological tissue samples; (3) experimental OA mouse model; (4) irisin gene knockout (KO) and knock in (KI) mouse lines and their cartilage cells; (5) in vitro mechanistic experiments. We found that Irisin was involved in all stages of cartilage development. Both human and mouse OA tissues showed a decreased expression of irisin. Intra-articular injection of irisin attenuated ACLT-induced OA progression. Irisin knockout mice developed severe OA while irisin overexpression in both irisin KI mice and intraarticular injection of irisin protein attenuated OA progression. Irisin inhibited inflammation and promoted anabolism in chondrogenic ADTC5 cells. Proliferative potential of primary chondrocytes from KI mice was found to be enhanced, while KO mice showed an inhibition under normal or inflammatory conditions. The primary chondrocytes from irisin KI mice showed reduced expression of inflammatory factors and the chondrocytes isolated from KO mice showed an opposite pattern. In conclusion, it is the first time to show that irisin is involved in cartilage development and OA pathogenesis. Irisin has the potential to ameliorate OA progression by decreasing cartilage degradation and inhibiting inflammation, which could lead to the development of a novel therapeutic target for treating bone and cartilage disorders including osteoarthritis.

Rapamycin-induced hyperglycemia is associated with exacerbated age-related osteoarthritis

BACKGROUND

The objective of this study was to determine if mechanistic target of rapamycin (mTOR) inhibition with or without AMP-activated protein kinase (AMPK) activation can protect against primary, age-related OA.

DESIGN

Dunkin-Hartley guinea pigs develop mild primary OA pathology by 5 months of age that progresses to moderate OA by 8 months of age. At 5 months, guinea pigs served as young control (n = 3) or were fed either a control diet (n = 8), a diet enriched with the mTOR-inhibitor rapamycin (Rap, 14 ppm, n = 8), or Rap with the AMPK-activator metformin (Rap+Met, 1000 ppm, n = 8) for 12 weeks. Knee joints were evaluated by OARSI scoring, micro-computed tomography, and immunohistochemistry. Glenohumeral articular cartilage was collected for western blotting.

RESULTS

Rap- and Rap+Met-treated guinea pigs displayed lower body weight than control. Rap and Rap+Met inhibited articular cartilage mTORC1 but not mTORC2 signaling. Rap+Met, but not Rap alone, stimulated AMPK. Despite lower body weight and articular cartilage mTORC1 inhibition, Rap- and Rap+Met-treated guinea pigs had greater OA severity in the medial tibial plateau due to articular cartilage structural damage and/or proteoglycan loss. Rap and Rap+Met increased plasma glucose compared to control. Plasma glucose concentration was positively correlated with proteoglycan loss, suggesting hyperglycemic stress after Rap treatment was related to worsened OA.

CONCLUSIONS

This is the first study to show that Rap induced increase in plasma glucose was associated with greater OA severity. Further, articular cartilage mTORC1 inhibition and bodyweight reduction by dietary Rap and Rap+Met did not appear to protect against primary OA during the prevailing hyperglycemia.

Identification of DNA methylation associated enrichment pathways in adults with non-specific chronic low back pain

Chronic low back pain (cLBP) that cannot be attributable to a specific pathoanatomical change is associated with high personal and societal costs. Still, the underlying mechanism that causes and sustains such a phenotype is largely unknown. Emerging evidence suggests that epigenetic changes play a role in chronic pain conditions. Using reduced representation bisulfite sequencing (RRBS), we evaluated DNA methylation profiles of adults with non-specific cLBP (n = 50) and pain-free controls (n = 48). We identified 28,325 hypermethylated and 36,936 hypomethylated CpG sites (p < 0.05). After correcting for multiple testing, we identified 159 DMRs (q < 0.01and methylation difference > 10%), the majority of which were located in CpG island (50%) and promoter regions (48%) on the associated genes. The genes associated with the differentially methylated regions were highly enriched in biological processes that have previously been implicated in immune signaling, endochondral ossification, and G-protein coupled transmissions. Our findings support inflammatory alterations and the role of bone maturation in cLBP. This study suggests that epigenetic regulation has an important role in the pathophysiology of non-specific cLBP and a basis for future studies in biomarker development and targeted interventions.

Genetic Variability in Molecular Pathways Implicated in Alzheimer's Disease: A Comprehensive Review

Alzheimer's disease (AD) is a complex neurodegenerative disease, affecting a significant part of the population. The majority of AD cases occur in the elderly with a typical age of onset of the disease above 65 years. AD presents a major burden for the healthcare system and since population is rapidly aging, the burden of the disease will increase in the future. However, no effective drug treatment for a full-blown disease has been developed to date. The genetic background of AD is extensively studied; numerous genome-wide association studies (GWAS) identified significant genes associated with increased risk of AD development. This review summarizes more than 100 risk loci. Many of them may serve as biomarkers of AD progression, even in the preclinical stage of the disease. Furthermore, we used GWAS data to identify key pathways of AD pathogenesis: cellular processes, metabolic processes, biological regulation, localization, transport, regulation of cellular processes, and neurological system processes. Gene clustering into molecular pathways can provide background for identification of novel molecular targets and may support the development of tailored and personalized treatment of AD.

OATargets: a knowledge base of genes associated with osteoarthritis joint damage in animals

Objectives

To collate the genes experimentally modulated in animal models of osteoarthritis (OA) and compare these data with OA transcriptomics data to identify potential therapeutic targets.

Methods

PubMed searches were conducted to identify publications describing gene modulations in animal models. Analysed gene expression data were retrieved from the SkeletalVis database of analysed skeletal microarray and RNA-Seq expression data. A network diffusion approach was used to predict new genes associated with OA joint damage.

Results

A total of 459 genes were identified as having been modulated in animal models of OA, with ageing and post-traumatic (surgical) models the most prominent. Ninety-eight of the 143 genes (69%) genetically modulated more than once had a consistent effect on OA joint damage severity. Several discrepancies between different studies were identified, providing lessons on interpretation of these data. We used the data collected along with OA gene expression data to expand existing annotations and prioritise the most promising therapeutic targets, which we validated using the latest reported associations. We constructed an online database OATargets to allow researchers to explore the collated data and integrate it with existing OA and skeletal gene expression data.

Conclusions

We present a comprehensive survey and online resource for understanding gene regulation of animal model OA pathogenesis.