Tescalcin modulates bone marrow-derived mesenchymal stem cells osteogenic differentiation via the Wnt/β-catenin signaling pathway

BACKGROUND

Bone mesenchymal stem cells (BMSCs) are recognized for their intrinsic capacity for self-renewal and differentiation into osteoblasts, adipocytes, and chondrocytes, making them pivotal entities within the field of bone research. Tescalcin (TESC) is known to play a role in specific cellular processes related to proliferation and differentiation. However, the precise involvement of TESC in the regulation of BMSCs remains unclear. The present study was designed to verify the functional implications of TESC in BMSCs.

METHODS

An adenovirus vector was engineered to downregulate TESC expression, and the Wnt/β-catenin signaling pathway was activated using BML-284. The assessment of mRNA was conducted by quantitative real-time polymerase chain reaction (qRT-PCR). The assessment of protein expression was conducted by Western blotting and immunofluorescence techniques (IF), respectively. Alkaline phosphatase (ALP) staining and activity assays were performed to verify ALP changes, while Alizarin Red S (ARS) staining and quantitative analysis were employed to assess mineralization capacity.

RESULTS

Initially, we observed an upregulation of TESC expression during osteogenic differentiation. Subsequently, TESC knockdown was demonstrated to decrease the osteogenic-related genes expression and diminish BMSCs mineralization. Concomitantly, we identified the inhibition of Wnt/β-catenin signaling following the TESC knockdown. Furthermore, the administration of BML-284 effectively activated the Wnt/β-catenin pathway, successfully rescuing the compromised TESC-mediated osteogenic differentiation.

CONCLUSION

Our findings indicate that TESC knockdown exerts an inhibitory effect on the osteogenic differentiation of BMSCs through the modulation of the Wnt/β-catenin signaling pathway. This study unveils a novel target with potential applications for enhancing the regenerative potential of BMSCs in the realm of regenerative medicine.

The Bcr-Abl inhibitor DCC-2036 inhibits necroptosis and ameliorates osteoarthritis by targeting RIPK1 and RIPK3 kinases

Osteoarthritis (OA) is a chronic progressive degenerative joint disease. Owing to its complex pathogenesis, OA treatment is typically challenging. Necroptosis is a form of programmed cell death mainly mediated by the serine/threonine kinases, RIPK1 and RIPK3, and mixed lineage kinase-like domain (MLKL). In this study, we found that the multi-targeted kinase inhibitor DCC-2036 can inhibit TSZ (TNF-α, Smac mimetic, and z-VAD-FMK)-induced necroptosis of chondrocytes and synovial fibroblast cells (SFs). In addition, we found that oral DCC-2036 inhibited chondrocyte damage in a rat model of OA induced by intra-articular injection of monosodium iodoacetate (MIA). A mechanistic study showed that DCC-2036 directly inhibited the activities of RIPK1 and RIPK3 kinases to block necroptosis, inhibiting the inflammatory response and protecting chondrocytes. In summary, our research suggests that DCC-2036, a new necroptosis inhibitor targeting RIPK1 and RIPK3 kinase activity, may be useful for the clinical treatment of OA and provides a new direction for the research and treatment of OA.

Exercise induced meteorin-like protects chondrocytes against inflammation and pyroptosis in osteoarthritis by inhibiting PI3K/Akt/NF-κB and NLRP3/caspase-1/GSDMD signaling

The production of metrnl, a novel adipomyokine, is induced upon exercise in adipose tissue and skeletal muscle. In this study, we investigated the anti-inflammatory and antipyroptotic effects of exercise-induced metrnl producted in rats in vitro and in vivo. Forty Sprague-Dawley rats were divided randomly into five groups: control (CG), osteoarthritis (OA) with sedentary lifestyle (OAG), OA with low intensity exercise (OAL), OA with moderate intensity exercise (OAM), and OA with high intensity exercise (OAH). The correlation between the level of metrnl and OA degree was detected using ELISA, X-ray imaging, histology, and immunohistochemistry in vivo. Primary chondrocytes were preincubated with recombinant metrnl before interleukin-1β administration to verify the anti-inflammatory and antipyroptotic effects of metrnl. Western blotting and quantitative reverse transcription (qRT)-PCR were used to evaluate the differences in protein and mRNA expression between groups, respectively. Reactive oxygen species (ROS) assay, immunofluorescence, transmission electron microscopy (TEM), and flow cytometry were used to evaluate morphological changes and pyroptosis in chondrocytes. In the moderate-intensity treadmill exercise group, the severity of OA showed maximum relief and the metrnl levels had the most significant increase. Metrnl exerted its anti-inflammatory effect through the suppression of the PI3K/Akt/NF-κB pathway in IL-1β-induced OA chondrocytes, which was accompanied with the recovery of collagen II expression and the attenuation of MMP13 and ADAMTS5. Moreover, metrnl ameliorated chondrocyte pyroptosis by inhibiting the activation of the nod-like receptor protein-3/caspase-1/gasdermin D cascade. In conclusion, moderate-intensity exercise improves inflammation and pyroptosis by increasing metrnl release, which inhibits the PI3K/Akt/NF-κB and further NLRP3/caspase-1/GSDMD signaling pathways.

Overexpression of SMS in the tumor microenvironment is associated with immunosuppression in hepatocellular carcinoma

Disorders of polyamine metabolism may contribute to the development of hepatocellular carcinoma (HCC), but the precise mechanism remains unknown. This study reports that spermine synthase (SMS), an enzyme involved in polyamine biosynthesis, is overexpressed in HCC and not associated with hepatitis virus infection in HCC patients. The results of analyzing the clinical data of HCC patients showed that SMS level as a categorical dependent variable was related to clinicopathological features of poor prognosis. Furthermore, the Kaplan-Meier survival analysis and ROC curve indicated that increased SMS level is associated with poor survival rate in HCC and may be a potential biomarker to discriminate HCC tissues. However, SMS overexpression limited the therapeutic effect of immune checkpoint blockade (ICB), which seemed to be related to the immunosuppressive effect of the HCC immune microenvironment formed by higher mRNA transcript levels of immune checkpoints and higher infiltration levels of immunosuppressive cells. In samples with high and low SMS expression, functional enrichment analysis of the differentially expressed genes (DEGs) showed that SMS may be linked to the occurrence and development of HCC by affecting a variety of immune-related pathways, such as Intestinal immune network for IgA production, Fc gamma R-mediated phagocytosis, Antigen processing and presentation, Th1 and Th2 cell differentiation. Subsequently, analysis of the co-expression network of SMS in the liver hepatocellular carcinoma (LIHC) cohort revealed that SMS has a broad impact on multiple important immune- and metabolic-related processes in HCC. In summary, SMS is a promising biomarker to differentiate the prognosis, immune characteristics, and holds promise as a potential target for ICB therapy to improve HCC.

Curcumin exerts chondroprotective effects against osteoarthritis by promoting AMPK/PINK1/Parkin-mediated mitophagy

Osteoarthritis (OA), a chronic degenerative disease with heterogeneous properties, is difficult to cure due to its complex pathogenesis. Curcumin possesses excellent anti-inflammatory and antioxidant properties and may have potential therapeutic value in OA. In this study, we investigated the action targets of curcumin and identified potential anti-OA targets for curcumin. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analyses were performed to evaluate these targets. Furthermore, we established a sodium monoiodoacetate-induced rat knee OA model and IL-1β induced OA chondrocyte model to verify the effect and mechanism of curcumin against OA. The GO and KEGG analyses screened seven hub genes involved in metabolic processes and the AMPK signaling pathway. Curcumin can significantly attenuate OA characteristics according to Osteoarthritis Research Society International (OARSI) and Mankin scores in OA rats. Additionally, curcumin is notably employed as an activator of mitophagy in maintaining mitochondrial homeostasis (ROS, Ca²⁺, ATP production, and mitochondrial membrane potential). The expression levels of mitophagy-related proteins were increased not only in articular cartilage but also in chondrocytes with curcumin intervention. Combining validation experiments and network pharmacology, we identified the importance of mitophagy in the curcumin treatment of OA. The chondroprotective effects of curcumin against OA are mediated by the AMPK/PINK1/Parkin pathway, and curcumin may serve as a potential novel drug for OA management.

Lysosomes involved in the cellular toxicity of nano-alumina: combined effects of particle size and chemical composition

Nowadays, manufactured nano-particles of aluminum oxide (nano-alumina) have been widely used in many fields with the rapidly developed nano-technology, but their basic toxic data are scarce. It is believed that the smaller nano-particles are able to easily cross the bio-membrane and quickly reach cellular compartments rather than micro-size particles, thus showing more toxic effects. The aim of this study was to compare the toxicity of nano- and micro- particles of alumina for detecting particle size related toxicity, and to compare the toxicity of nano-alumina and nano-carbon with the same particle size for determining chemical composition related toxicity. The present study revealed that nano-particles of alumina were much toxic than micro-alumina particles, indicating a particle size related toxicity; and were much more toxic than nano-carbon particles as well, manifesting a chemical related toxicity. The mechanism might be concerned with the involvement of the lysosomes. In conclusion, toxicity of nano-alumina is a combination of the toxic effects of its particle size and chemical composition.

MAC-CCD system: a novel lymphocyte microwell-array chip system equipped with CCD scanner to generate human monoclonal antibodies against influenza virus

We previously developed a lymphocyte microwell-array system, which effectively detects antigen-specific B-cells by monitoring intracellular Ca(2+) mobilization at the single-cell level with a fluorescent Ca(2+) indicator, fluo-4. However, it is difficult for the system to perform time-lapse monitoring. Here, we developed a novel method, a lymphocyte microwell-array chip system equipped with a charge-coupled device (CCD) time-lapse scanner (MAC-CCD system), for monitoring intracellular Ca(2+) mobilization. The MAC-CCD system is able to monitor intracellular Ca(2+) mobilization of more than 15,000-20,000 individual live B-cells every 10 s. In addition, we adopted a correlation method in a MAC-CCD system, which enabled us to detect B-cells with a frequency of as few as 0.046%. Furthermore, we succeeded in obtaining six influenza nucleoprotein-specific human monoclonal antibodies from the peripheral blood of influenza-vaccinated volunteers. These results demonstrate that the MAC-CCD system with a correlation method could detect very rare antigen-specific B-cells.

Caspase-8 has an essential role in resveratrol-induced apoptosis of rheumatoid fibroblast-like synoviocytes

OBJECTIVE

Resveratrol is a naturally occurring polyphenol, which possesses chemotherapeutic potential through its ability to trigger apoptosis. The objective of this study was to investigate the major determinant for the apoptotic cell death induction by resveratrol in fibroblast-like synoviocytes (FLS) derived from patients with RA.

METHODS

The effect of resveratrol on apoptotic cell death was quantified in a population of subG1 in RA FLS by flow cytometry. The underlying signalling mechanism for apoptotic death was examined by analysing mitochondrial membrane potential, activation of the caspase cascade and translocation of Bid.

RESULTS

We show that activation of caspase-8 is essential for triggering resveratrol-induced apoptotic signalling via the involvement of the mitochondrial pathway in RA FLS. Our findings also suggest that this enhanced apoptosis caused by resveratrol occurred in RA FLS irrespective of p53 status. Exposure to resveratrol caused extensive apoptotic cell death, along with a caspase-dependent (activation of caspase-9 and -3, poly ADPribose polymerase (PARP) cleavage and mitochondrial cytochrome c release) or caspase-independent [translocation of apoptosis-inducing factor (AIF) to the nucleus] signalling pathway. Analysis of upstream signalling events affected by resveratrol revealed that the activated caspase-8 triggered mitochondrial apoptotic events by inducing Bid cleavage without any alteration in the levels of Bax, Bcl-xL or Bcl2. The caspase-8 inhibitor or over-expression of crmA abrogated cell death induced by resveratrol and prevented processing of the downstream cascade.

CONCLUSION

The results suggest that resveratrol causes activation of caspase-8, which in turn results in modulation of mitochondrial apoptotic machinery to promote apoptosis of RA FLS.

Lentivirus-mediated carboxyl-terminal modulator protein gene transfection via aerosol in lungs of K-ras null mice

The low efficiency of conventional therapies in achieving long-term survival of lung cancer patients calls for development of novel options. Aerosol gene delivery may provide the alternative for safe and effective treatment for lung cancer. Therefore, current study was performed to elucidate the potential effects of C-terminal modulator protein (CTMP) via aerosol on lung tumorigenesis. Lentiviral vector-CTMP was delivered into K-ras null lung cancer mice through the nose-only inhalation system for 30 min. After 48 h, the potential effects of CTMP on Akt1-related signals and cell cycle regulation in the lungs were evaluated by western blot, immunohistochemistry and zymography. Lentivirus-based CTMP delivery inhibited the Akt1 activity through selective suppression of Akt1 phosphorylation at Ser473. Aerosol delivery of CTMP inhibited proteins important for Akt1 signals, cell cycle and tumor metastasis in lungs of K-ras null mice. Together, our results suggest that lentivirus-mediated aerosol delivery of CTMP may be compatible with noninvasive in vivo gene therapy. Our results emphasize the importance of noninvasive-targeted delivery of CTMP for lung cancer therapy in the future. While the studies are conducted in mice, it is envisioned that noninvasive targeting the specific genes responsible for cancer progression is an attractive strategy for effective anticancer therapeutics.

Increment of calcium-activated and delayed rectifier potassium current by hyposmotic swelling in gastric antral circular myocytes of guinea pig

AIM

To observe the effect of hyposmotic swelling on calcium-activated potassium current [IKCa] and delayed rectifier potassium current [IKV] in gastric antral circular myocytes of guinea pig.

METHODS

The whole cell patch-clamp technique was used, and the myocytes were isolated by collagenase. Cells were swelled by the hyposmotic solution (200 Osmmol/kg).

RESULTS

The hyposmotic solution markedly increased IKCa and IKV. The increase of IKCa was markedly inhibited by tetrathylammonium (TEA) 4 mmol/L and charybdotoxin (ChTX) 200 nmol/L. The increase of IKV was incompletely blocked by TEA and completely blocked by 4-aminopyridine (4-AP) 10 mmol/L. There was no significant difference between the amplitudes of the increase of IKCa and IKV (P < 0.05). IKCa increased (17.0 +/- 4.8) s after the cells were perfused with the hyposmotic solution, whereas IKV increased (30.7 +/- 13.7) s after the cells exposed to the hyposmotic solution. There was significant difference between the latency of IKCa and IKV (P < 0.05).

CONCLUSION

Hyposmotic swelling increased both IKCa and IKV, and the increment was likely related to the cell volume regulation.

The involvement of calcium mobilization in the calcium-activated potassium currents activated by hyposmotic swelling in gastric antral circular myocytes of the guinea-pig

In our study of the effects of hyposmotic swelling on the Ca(2+)-activated potassium currents [I(K(Ca))] and its mechanism, we employed the whole-cell patch clamp technique using the gastric antral circular myocytes of the guinea-pig. Hyposmotic swelling efficiently increased I(K(Ca)), and the extent of changes in I(K(Ca)) was sharply dependent on the osmolarity of the perfusion solutions. When the calcium-free solution (EGTA 10 microM added in calcium-free solution) was superfused, I(K(Ca)) was not increased by the hyposmotic swelling. Gadolinium (Gd(3+)) 100 nM, a blocker of the stretch-activated nonselective cation channel, blocked the activation of I(K(Ca)) induced by hyposmotic swelling, but nicardipine 5 microM (the L-type calcium channel blocker) did not. Heparin 3 mg/ml, a potent inhibitor of inositol triphosphate receptor (InsP(3)R), did not inhibit the response, and caffeine 1 mM (the agonist for calcium-induced calcium release [CICR]) imitated the effect of hyposmotic swelling. Ryanodine (15 microM), markedly inhibited the effect. These results suggest that hyposmotic swelling activates I(K(Ca)), and the activation is associated with CICR, which is triggered by extracellular calcium influx through the stretch-activated channel (SA channel).