Protein phosphatase PPM1A inhibition attenuates osteoarthritis via regulating TGF-β/Smad2 signaling in chondrocytes

Protein phosphatase SCP4 regulates temporomandibular joint cartilage development via glucose metabolism

OBJECTIVE

Despite the growing evidence supporting the regulatory role of small carboxy-terminal domain (CTD) phosphatase 4 (SCP4) in metabolic pathways, limited knowledge exists concerning its involvement and molecular basis in temporomandibular joint (TMJ) cartilage growth, development, and homeostasis maintenance. Therefore, this study aims to investigate the role of SCP4 in chondrogenesis in condylar cartilage.

METHODS

We generated chondrocyte-specific SCP4 conditional knockout mice (SCP4Col2Cre). Whole skeletal staining, ABH/OG or HE staining, and immunohistochemistry were employed to compare chondrocyte differentiation and cartilage development between SCP4Col2Cre and Cre-negative mice during prenatal and postnatal periods. The impact of SCP4 on subchondral bone in mice was assessed using Micro-CT. Additionally, relevant biological functions were evaluated by KEGG and GO enrichment analysis, which further confirmed immunohistochemical staining, Western Blot, RT-PCR and Seahorse experiment.

RESULTS

Our findings demonstrated that the deficiency of SCP4 in chondrocytes resulted in defects in condylar chondrogenesis and impaired matrix production. Accordingly, the SCP4Col2Cre mice exhibited a significant decrease in bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), with an increase in trabecular separation (Tb.Sp). Furthermore, RNA-seq analysis showed the impact of SCP4 deficiency on glucose metabolism. Subsequently, we confirmed that the deficiency of SCP4 resulted in aberrant regulation of glucose transporter 1 (Glut1) and other glucose metabolism-related gene expression throughout prenatal and postnatal development in vivo and in vitro. We further demonstrated in vitro that the deletion of SCP4 led to increased ATP production and extracellular acidification rate (ECAR) levels, while concurrently reducing oxygen consumption rate (OCR) levels.

CONCLUSION

Our study emphasizes the crucial role of SCP4 in regulating prenatal and postnatal TMJ cartilage development, partly through aberrant upregulation of Glut1-mediated glucose metabolism.

MicroRNA-155 rs767649 polymorphism is associated with susceptibility to peri-implantitis

OBJECTIVE

To examine how the miR-155 rs767649 polymorphism affects miR-155 expression and to investigate its association with peri-implantitis susceptibility.

DESIGN

One hundred and eighty-seven peri-implantitis patients and 196 healthy implant subjects were enrolled. The expression level of miR-155 in the subjects' serum was tested using qRT-PCR. The rs767649 polymorphism was genotyped with the TaqMan SNP genotyping assay. The genotype and allele distributions of miR-155 rs767649 polymorphism were compared between the case and control groups. Target genes of miR-155 were predicted using four online databases (ENCORI, miRDB, miRWalk and TargetScan). Functions and pathways of these target genes were annotated through GO and KEGG enrichment.

RESULTS

The qRT-PCR results revealed that miR-155 was upregulated in patients with peri-implantitis (P < 0.001) based on Student's t test analysis. Carriers of the rs767649 TT genotype had higher levels of miR-155 expression in their serum (P < 0.001) and a greater risk of peri-implantitis compared to those with the TA/AA genotype according to the chi-square test results (P = 0.016). The downstream target genes of miR-155 may be involved in pathways such as Kaposi sarcoma-associated herpesvirus infection, ubiquitin-protein hydrolysis, and cell differentiation.

CONCLUSION

The results revealed a correlation between the miR-155 rs767649 polymorphism and susceptibility to peri-implantitis. The rs767649 TT genotype upregulates miR-155 expression, which regulates downstream signaling pathways and increases the chance of peri-implantitis.

Research progress of non-coding RNA regulating the role of PANoptosis in diabetes mellitus and its complications

Diabetes is a chronic metabolic disease that is endemic worldwide and is characterized by persistent hyperglycemia accompanied by multiple severe complications, including cardiovascular disease, kidney dysfunction, neuropathy, and retinopathy. The pathogenesis of diabetes mellitus and its complications is multifactorial, involving various molecular and cellular pathways. In recent years, research has indicated that mechanisms of cell death play a significant role in the advancement of diabetes and its complications. PANoptosis is a complex phenomenon caused by three cell death pathways: programmed apoptosis, necroptosis and pyroptosis. The contribution of PANoptosis to diabetes and its complications remains incompletely understood. Non-coding RNA, an important molecule in gene expression regulation, has shown significant regulatory functions in a variety of diseases. This paper reviews the underlying mechanisms of diverse types of non-coding RNAs (including lncRNA, miRNA and circRNA) in regulating PANoptosis and their specific contributions in diabetes, aiming to explore how non-coding RNAs influence PANoptosis and their effects in diabetes.

Sodium Hyaluronate-PDGF Repairs Cartilage and Subchondral Bone Microenvironment via HIF-1α-VEGF-Notch and SDF-1-CXCR4 Inhibition in Osteoarthritis

Chronic degenerative changes in cartilage and subchondral bone that lead to instability of the cartilage microenvironment are essential for the development of osteoarthritis (OA) in the old. Synchronous repair of cartilage and subchondral bone may be a key strategy for OA treatment. PDGF-BB effectively promoted chondrocyte regeneration and angiogenesis. However, the mechanisms by which PDGF-BB affects subchondral bone and the delivery of PDGF-BB to the joint cavity need to be further explored. In this study, we used sodium hyaluronate to deliver PDGF-BB (SH-PDGF) to the joint space and aimed to determine the mechanisms of SH-PDGF in repairing cartilage and subchondral bone and stabilising the cartilage microenvironment. In this research, we determined the pharmacokinetics of PDGF-BB and SH-PDGF in cartilage. Moreover, we investigated the effects of PDGF-BB and SH-PDGF on cartilage and the subchondral bone microenvironment by identifying changes in the HIF-VEGF-Notch axis and SDF-1-CXCR4 axis in an OA rat model. The results showed that PDGF-BB increased cell viability, decreased HIF-1α levels, inhibited inflammation and improved matrix metabolism in osteoarthritic chondrocytes under hyperoxic or hypoxic conditions. We also found that PDGF-BB and SH-PDGF showed similar effects on repairing cartilage and subchondral bone simultaneously. However, SH-PDGF had some advantages over PDGF-BB in prolonging the injection interval and decreasing the injection time. These protective effects were mediated by the inhibition of both the HIF-1α-VEGF-Notch axis and the SDF-1-CXCR4 axis. The underlying mechanisms include the inhibition of HIF-1α-VEGF-Notch-mediated vessel invasion and SDF-1-CXCR4 axis-mediated crosstalk between cartilage and subchondral tissue.

5-hydroxymethylfurfural attenuates osteoarthritis by upregulating of glucose metabolism in chondrocytes

INTRODUCTION

5-HMF (5-hydroxymethylfurfural), an active constituent found in Radix Rehmanniae Preparata, a widely utilized traditional Chinese medicine for osteoarthritis (OA) treatment, exhibits notable therapeutic benefits in countering the catabolic and inflammatory responses of OA chondrocytes. Despite these promising effects, the underlying mechanisms of 5-HMF's action remain elusive, thereby impeding its broader clinical application and development.

OBJECTIVE

To investigate the impact of 5-HMF on the progression of OA and elucidate its underlying mechanisms.

METHODS

In this study, Destabilization of the Medial Meniscus (DMM) was used to construct an OA model of C57BL/6 and transgenic mice in vivo, and interleukin -1β (IL-1β) was used to construct an OA model in vitro. Micro-CT and Alcnohistochemistry (IHC) and immunofluorescence (IF) were used to determine the eian Blue/Hematoxylin and Orange G (ABH/OG) staining were used to observe the morphological changes of joints. Western blot, Polymerase Chain Reaction (PCR), immuxpression levels of cartilage metabolic markers Collagen type II alpha 1 (Col2a1) and Matrix Metalloproteinase-13 (MMP13), as well as glucose transporter Glucose Transporter Type 1 (Glut1), glucose metabolic markers Hexokinase 1 (HK1) and Lactate Dehydrogenase A (LDHA). RNA-seq and Reactom analysis were used to predict the potential mechanism of 5-HMF in the treatment of OA.

RESULTS

5-HMF demonstrates effective alleviation of OA progression, improvement of subchondral sclerosis and cartilage degeneration, particularly in the realm of cartilage protection, which is equivalent to that of celebrex. The protective effect of 5-HMF on cartilage is primarily attributed to its regulatory role in cartilage matrix metabolism, suppress the activity of MMP13 and enhance the expression of Col2a1 to delay cartilage injury. Moreover, RNA sequencing results indicate that 5-HMF's therapeutic effect on OA is closely linked to metabolism, specifically glucose metabolism. Our in vivo and in vitro experiments validate these findings. 5-HMF can counteract the decline in glucose metabolism induced by OA through the Glut1/HK1/LDHA signaling pathway. Furthermore, our findings confirm that Glut1 knockout mice with a DMM-induced OA model do not respond to 5-HMF treatment.

CONCLUSION

Our data reveal for the first time that 5-HMF may play a role in cartilage protection in the treatment of osteoarthritis by regulating glycolysis driven by Glut1/HK1/LDHA.

β-Hydroxybutyrate ameliorates osteoarthritis through activation of the ERBB3 signaling pathway in mice

The ketogenic diet (KD) has demonstrated efficacy in ameliorating inflammation in rats with osteoarthritis (OA). However, the long-term safety of the KD and the underlying mechanism by which it delays OA remain unclear. We found that while long-term KD could ameliorate OA, it induced severe hepatic steatosis in mice. Consequently, we developed 2 versions of ketogenic-based diets: KD supplemented with vitamin D and intermittent KD. Both KD supplemented with vitamin D and intermittent KD effectively alleviated OA by significantly reducing the levels of inflammatory cytokines, cartilage loss, sensory nerve sprouting, and knee hyperalgesia without inducing hepatic steatosis. Furthermore, β-hydroxybutyrate (β-HB), a convenient energy carrier produced by adipocytes, could ameliorate OA without causing liver lesions. Mechanistically, β-HB enhanced chondrocyte autophagy and reduced apoptosis through the activation of Erb-B2 receptor tyrosine kinase 3 (ERBB3) signaling pathway; a pathway which was down-regulated in the articular chondrocytes from both OA patients and mice. Collectively, our findings highlighted the potential therapeutic value of β-HB and KD supplemented with vitamin D and intermittent KD approaches for managing OA.

Temporal progression of subchondral bone alterations in OA models involving induction of compromised meniscus integrity in mice and rats: A scoping review

OBJECTIVE

To categorize the temporal progression of subchondral bone alterations induced by compromising meniscus integrity in mouse and rat models of knee osteoarthritis (OA).

METHOD

Scoping review of investigations reporting subchondral bone changes with appropriate negative controls in the different mouse and rat models of OA induced by compromising meniscus integrity.

RESULTS

The available literature provides appropriate temporal detail on subchondral changes in these models, covering the entire spectrum of OA with an emphasis on early and mid-term time points. Microstructural changes of the subarticular spongiosa are comprehensively described; those of the subchondral bone plate are not. In mouse models, global subchondral bone alterations are unidirectional, involving an advancing sclerosis of the trabecular structure over time. In rats, biphasic subchondral bone alterations begin with an osteopenic degeneration and loss of subchondral trabeculae, progressing to a late sclerosis of the entire subchondral bone. Rat models, independently from the applied technique, relatively faithfully mirror the early bone loss detected in larger animals, and the late subchondral bone sclerosis observed in human advanced OA.

CONCLUSION

Mice and rats allow us to study the microstructural consequences of compromising meniscus integrity at high temporal detail. Thickening of the subchondral bone plate, an early loss of thinner subarticular trabecular elements, followed by a subsequent sclerosis of the entire subchondral bone are all important and reliable hallmarks that occur in parallel with the advancing articular cartilage degeneration. Thoughtful decisions on the study design, laterality, selection of controls and volumes of interest are crucial to obtain meaningful data.

Role of TRIM59 in regulating PPM1A in the pathogenesis of silicosis and the intervention effect of tanshinone IIA

This study examines the involvement of TRIM59 in silica-induced pulmonary fibrosis and explores the therapeutic efficacy of Tanshinone IIA (Tan IIA). In vivo experiments conducted on rats with silica-induced pulmonary fibrosis unveiled an increase in TRIM59 levels and a decrease in PPM1A levels. Subsequent investigations using in vitro silicosis cell models demonstrated that modulation of TRIM59 expression significantly impacts silicosis fibrosis, influencing the levels of PPM1A and activation of the Smad2/3 signaling pathway. Immunofluorescence and co-immunoprecipitation assays confirmed the interaction between TRIM59 and PPM1A in fibroblasts, wherein TRIM59 facilitated the degradation of PPM1A protein via proteasomal and ubiquitin-mediated pathways. Furthermore, employing a rat model of silica-induced pulmonary fibrosis, Tan IIA exhibited efficacy in mitigating lung tissue damage and fibrosis. Immunohistochemical analysis validated the upregulation of TRIM59 and downregulation of PPM1A in silica-induced pulmonary fibrosis, which Tan IIA alleviated. In vitro studies elucidated the mechanism by which Tan IIA regulates the Smad2/3 signaling pathway through TRIM59-mediated modulation of PPM1A. Treatment with Tan IIA in silica-induced fibrosis cell models resulted in concentration-dependent reductions in fibrotic markers and attenuation of relevant protein expressions. Tan IIA intervention in silica-induced fibrosis cell models mitigated the TRIM59-induced upregulation of fibrotic markers and enhanced PPM1A expression, thereby partially reversing Smad2/3 activation. Overall, the findings indicate that while overexpression of TRIM59 may activate the Smads pathway by suppressing PPM1A expression, treatment with Tan IIA holds promise in counteracting these effects by inhibiting TRIM59 expression.

Identification of Key lncRNAs, circRNAs, and mRNAs in Osteoarthritis via Bioinformatics Analysis

Osteoarthritis (OA) is a common degenerative joint disorder that adversely affects the quality of life of patients. Identification of novel diagnostic biomarkers is pivotal for the early detection and prevention of OA. Dataset GSE185059 was selected from Gene Expression Omnibus database to obtain differentially expressed lncRNAs (DE-lncRNAs), mRNAs (DE-mRNAs), and circRNAs (DE-circRNAs) between OA and normal samples. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses as well as protein-protein interaction (PPI) network construction of DE-mRNAs were conducted. Hub genes were identified from PPI networks and validated by RT-qPCR. starBase database was utilized for predicting miRNAs binding with hub genes, selected DE-lncRNAs and DE-circRNAs, respectively. The competing endogenous RNA (ceRNA) networks were constructed. A total of 818 DE-mRNAs, 191 DE-lncRNAs, and 2053 DE-circRNAs were identified. The DE-mRNAs were significantly enriched in several inflammation-related GO terms and KEGG pathways such as positive regulation of cell-cell adhesion, TNF-alpha signaling pathway and NF-kappa B signaling pathway. Thirteen hub genes were identified, which were CFTR, GART, SMAD2, NCK1, TJP1, UBE2D1, EFTUD2, PRKACB, IL10, SNRPG, CHD4, RPS24, and SRSF6. OA-related DE-lncRNA/circRNA-miRNA-hub gene networks were constructed. We identified 13 hub genes and constructed the ceRNA networks related to OA, providing a theoretical basis for further research.

Correlation between changes in serum YKL-40, LXRs, PPM1A, and TGF-β1 levels and airway remodeling and lung function in patients with bronchial asthma

OBJECTIVE

This study investigates the correlation between serum levels of YKL-40, LXRs, PPM1A, and TGF-β1 and airway remodeling and lung function in bronchial asthma patients.

METHODS

The study involved 80 bronchial asthma patients and 92 healthy individuals. Serum cytokines, airway remodeling, and lung function markers were compared across mild, moderate, and severe asthma cases using high-resolution CT, t-tests, ANOVA, and Pearson correlation analysis.

RESULTS

Asthmatic patients exhibited higher levels of serum YKL-40, LXRα, LXRβ, TGF-β1, airway wall thickness (T)/outer diameter (D), and WA% of total cross-sectional area compared to controls. Conversely, their serum PPM1A, Peak Expiratory Flow (PEF), and Forced Expiratory Volume in 1 s (FEV1) were lower. Serum YKL-40 and TGF-β1 levels were positively correlated with T/D and WA%, and negatively correlated with PEF and FEV1. PPM1A levels were strongly associated with T/D, WA%, PEF, and FEV1.

CONCLUSION

The severity of bronchial asthma is associated with increased serum levels of YKL-40, LXRα, LXRβ, and TGF-β1 and decreased PPM1A. The levels of YKL-40, PPM1A, and TGF-β1 have a significant correlation with airway remodeling and lung function.

Protein phosphatases regulate the formation of Müller glia-derived progenitor cells in the chick retina

Different kinase-dependent cell signaling pathways are known to play important roles in glia-mediated neuroprotection and reprogramming of Müller glia (MG) into Müller glia-derived progenitor cells (MGPCs) in the retina. However, very little is known about the phosphatases that regulate kinase-dependent signaling in MG. Using single-cell RNA-sequencing (scRNA-seq) databases, we investigated patterns of expression of Dual Specificity Phosphatases (DUSP1/6) and other protein phosphatases in normal and damaged chick retinas. We found that DUSP1, DUSP6, PPP3CB, PPP3R1 and PPPM1A/B/D/E/G are widely expressed by many types of retinal neurons and are dynamically expressed by MG and MGPCs in retinas during the process of reprogramming. We find that inhibition of DUSP1/6 and PP2C phosphatases enhances the formation of proliferating MGPCs in damaged retinas and in retinas treated with insulin and FGF2 in the absence of damage. By contrast, inhibition of PP2B phosphatases suppressed the formation of proliferating MGPCs, but increased numbers of proliferating MGPCs in undamaged retinas treated with insulin and FGF2. In damaged retinas, inhibition of DUSP1/6 increased levels of pERK1/2 and cFos in MG whereas inhibition of PP2B's decreased levels of pStat3 and pS6 in MG. Analyses of scRNA-seq libraries identified numerous differentially activated gene modules in MG in damaged retinas versus MG in retinas treated with insulin+FGF2 suggesting significant differences in kinase-dependent signaling pathways that converge on the formation of MGPCs. Inhibition of phosphatases had no significant effects upon numbers of dying cells in damaged retinas. We conclude that the activity of different protein phosphatases acting through retinal neurons and MG "fine-tune" the cell signaling responses of MG in damaged retinas and during the reprogramming of MG into MGPCs.

Osteoarthritis year in review 2023: Biology

Great progress continues to be made in our understanding of the multiple facets of osteoarthritis (OA) biology. Here, we review the major advances in this field and progress towards therapy development over the past year, highlighting a selection of relevant published literature from a PubMed search covering the year from the end of April 2022 to the end of April 2023. The selected articles have been arranged in themes. These include 1) molecular regulation of articular cartilage and implications for OA, 2) mechanisms of subchondral bone remodelling, 3) role of synovium and inflammation, 4) role of age-related changes including cartilage matrix stiffening, cellular senescence, mitochondrial dysfunction, metabolic dysfunction, and impaired autophagy, and 5) peripheral mechanisms of OA pain. Progress in the understanding of the cellular and molecular mechanisms responsible for the multiple aspects of OA biology is unravelling novel therapeutic targets for disease modification.

Osteoclast-derived exosomal miR-212-3p suppressed the anabolism and accelerated the catabolism of chondrocytes in osteoarthritis by targeting TGF-β1/Smad2 signaling

Osteoarthritis (OA) is a common aging-related disease affecting entire joint structures, encompassing articular cartilage and subchondral bone. Although senescence and dysfunction of chondrocytes are considered crucial factors in the occurrence of OA, the exact pathogenesis remains to be investigated. In our study, chondrocytes were incubated with a conditioned medium obtained from osteoclasts at different differentiation stages, suggesting that osteoclasts and osteoclast precursors suppressed anabolism and promoted the catabolism of chondrocytes in vitro. In contrast, the function of osteoclasts was more significant than osteoclast precursors. Further blocking of osteoclast exosome secretion by using GW4869 abolished the effect of osteoclasts on chondrocytes. Functionally, exosomal transfer of osteoclast-derived miR-212-3p inhibited Smad2 to mediate chondrocyte dysfunction, thus accelerating cartilage matrix degradation in OA via TGF-β1/Smad2 signaling. The mechanism was also confirmed within the articular cartilage in OA patients and surgery-induced OA mice. Our study provides new information on intercellular interactions in the bone microenvironment within articular cartilage and subchondral bone during OA progression. The miR-212-3p/Smad2 axis is a potential target for the prevention and therapy of OA.

Protein phosphatases regulate the formation of Müller glia-derived progenitor cells in the chick retina

Different kinase-dependent cell signaling pathways are known to play important roles in glia-mediated neuroprotection and reprogramming of Müller glia (MG) into Müller glia-derived progenitor cells (MGPCs) in the retina. However, very little is known about the phosphatases that regulate kinase-dependent signaling in MG. Using single-cell RNA-sequencing (scRNA-seq) databases, we investigated patterns of expression of Dual Specificity Phosphatases (DUSP1/6) and other protein phosphatases in normal and damaged chick retinas. We found that DUSP1, DUSP6, PPP3CB, PPP3R1 and PPPM1A/B/D/E/G are dynamically expressed by MG and MGPCs in retinas during the process of reprogramming. We find that inhibition of DUSP1/6 and PP2C phosphatases enhances the formation of proliferating MGPCs in damaged retinas and in retinas treated with insulin in FGF2 in the absence of damage. By contrast, inhibition of PP2B phosphatases suppressed the formation of proliferating MGPCs, but increased numbers of proliferating MGPCs in undamaged retinas treated with insulin and FGF2. In damaged retinas, inhibition of DUSP1/6 increased levels of pERK1/2 and cFos in MG whereas inhibition of PP2B's decreased levels of pStat3 and pS6 in MG. Analyses of scRNA-seq libraries identified numerous differentially activated gene modules in MG in damaged retinas versus MG in retinas treated with insulin+FGF2 suggesting significant differences in kinase-dependent signaling pathways that converge on the formation of MGPCs. Inhibition of phosphatases had no significant effects upon numbers of dying cells in damaged retinas. We conclude that the activity of different protein phosphatases "fine-tune" the cell signaling responses of MG in damaged retinas and during the reprogramming of MG into MGPCs.

Benzophenanthridine Alkaloid Chelerythrine Elicits Necroptosis of Gastric Cancer Cells via Selective Conjugation at the Redox Hyperreactive C-Terminal Sec498 Residue of Cytosolic Selenoprotein Thioredoxin Reductase

Targeting thioredoxin reductase (TXNRD) with low-weight molecules is emerging as a high-efficacy anti-cancer strategy in chemotherapy. Sanguinarine has been reported to inhibit the activity of TXNRD1, indicating that benzophenanthridine alkaloid is a fascinating chemical entity in the field of TXNRD1 inhibitors. In this study, the inhibition of three benzophenanthridine alkaloids, including chelerythrine, sanguinarine, and nitidine, on recombinant TXNRD1 was investigated, and their anti-cancer mechanisms were revealed using three gastric cancer cell lines. Chelerythrine and sanguinarine are more potent inhibitors of TXNRD1 than nitidine, and the inhibitory effects take place in a dose- and time-dependent manner. Site-directed mutagenesis of TXNRD1 and in vitro inhibition analysis proved that chelerythrine or sanguinarine is primarily bound to the Sec498 residue of the enzyme, but the neighboring Cys497 and remaining N-terminal redox-active cysteines could also be modified after the conjugation of Sec498. With high similarity to sanguinarine, chelerythrine exhibited cytotoxic effects on multiple gastric cancer cell lines and suppressed the proliferation of tumor spheroids derived from NCI-N87 cells. Chelerythrine elevated cellular levels of reactive oxygen species (ROS) and induced endoplasmic reticulum (ER) stress. Moreover, the ROS induced by chelerythrine could be completely suppressed by the addition of N-acetyl-L-cysteine (NAC), and the same is true for sanguinarine. Notably, Nec-1, an RIPK1 inhibitor, rescued the chelerythrine-induced rapid cell death, indicating that chelerythrine triggers necroptosis in gastric cancer cells. Taken together, this study demonstrates that chelerythrine is a novel inhibitor of TXNRD1 by targeting Sec498 and possessing high anti-tumor properties on multiple gastric cancer cell lines by eliciting necroptosis.