The relationship between obstructive sleep apnea and osteoarthritis: evidence from an observational and Mendelian randomization study.

Objectives: Obstructive sleep apnea (OSA) and osteoarthritis (OA) are common comorbidities that significantly impact individuals' quality of life. However, the relationship between OSA and OA remains unclear. This study aims to explore the connection between OSA and OA and evaluate causality using Mendelian randomization (MR). Methods: A total of 12,454 participants from the National Health and Nutrition Examination Survey (2009-2012) were included. OSA participants were identified based on self-reported interviews. The association between OA and OSA was assessed through multivariable logistic regression analysis. A two-sample MR was employed to investigate the relationship between OSA and OA, specifically hip OA and knee OA, utilizing the inverse variance-weighted (IVW) approach. Results: Based on the observational study, individuals with OSA exhibited a higher risk of OA (OR = 1.67, 95% CI = 1.40-1.98). IVW demonstrated that the risk of OA (OR = 1.13, 95% CI: 1.05-1.21, p = 0.001), hip OA (OR = 1.11, 95% CI: 1.04-1.18, p = 0.002), and knee OA (OR = 1.08, 95% CI: 1.02-1.14, p = 0.005) was significantly associated with OSA. Reverse MR analyses indicated no effect of OA on OSA. Additionally, body mass index (BMI) was found to mediate 36.9% (95% CI, 4.64-73.2%, p = 0.026) of the OSA effects on OA risk. Conclusion: The cross-sectional observational analysis unveiled noteworthy associations between OSA and OA. Meanwhile, findings from the MR study provide support for a causal role.

Hsa_circ_0020378 targets miR-556-5p/MAPK1 to regulate osteosarcoma cell proliferation and migration.

Osteosarcoma (OS) is still a disorder threatening children life. A growing number of evidences highlights the role of circular RNAs (circRNAs) during OS malignancy. Herein, we aimed to address the pathological contribution of the unrecognized circ_0020378 to OS progression. Analysis of the expression of circ_0020378, miR-556-5p, and MAPK1 in OS tissues and cells was performed using RT-qPCR or western blotting. CCK8, colony formation assays, and Tranwell migration assays were adopted to assess the OS cell viability, clone formation ability and migration. Tumor xenograft mouse model was used to assess the in vivo function of circ_0020378. The relationship between miR-556-5p and circ_0020378 or MAPK1 was discovered using luciferase reporter assays and RNA binding protein immunoprecipitation tests. In OS tissues and cells, circ_0020378 and MAPK1 were significantly elevated, although miR-556-5p expression exhibited a different pattern. Circ_0020378 silence attenuated OS cell proliferation, colony formation ability and migration in vitro, and retarded tumor growth in vivo. MiR-556-5p was targeted by circ_0020378. Furthermore, miR-556-5p inhibitor promoted the OS cell proliferation and migration, while this promoted malignant actions of OS cells were abrogated by circ_0020378 silence. Additionally, miR-556-5p directly bound to MAPK1, and MAPK1 silence exerted its inhibitory effect on OS cell proliferation and migration, and yet the inhibition was offset by miR-556-5p inhibitor. Circ_0020378 acts as a novel tumor promoter that controls OS growth by miR-556-5p/MAPK1 axis, suggesting circ_0020378/miR-556-5p/MAPK1 might be a novel target for OS intervention.

Biosensors of protein kinase action: from in vitro assays to living cells.

Protein kinases, and the signal transduction pathways in which they participate, are now recognized to be medicinally attractive targets of opportunity. Inhibitors of the protein kinase family not only hold great promise as therapeutic agents, but are also of profound utility in the characterization of signaling pathways. The direct visualization of protein kinase activity in living cells provides a genuine assessment of the efficacy and selectivity of these inhibitors in a physiological setting. In addition, the ability to visualize the activity of a protein kinase in real time furnishes a direct measurement of the activation of specific signaling pathways in response to extracellular stimuli. We have developed two series of fluorescent substrates for protein kinase C (PKC) using a strategy that positions the reporter-group directly on the residue undergoing phosphorylation. The first series of PKC substrates is based, in part, on the Ca(+2) indicators developed by Tsien and his collaborators during the 1980s. In this case, phosphorylation of the substrate creates a divalent metal ion binding site. Upon metal ion coordination, a fluorescence change transpires via a mechanism analogous to that described for the Ca(+2) indicators. The second series of PKC sensors was identified via the preparation and subsequent screen of a library of fluorescently-labeled PKC peptide substrates. The lead derivative displays a phosphorylation-induced fluorescence change that allows the visualization of real-time PKC activity in both cell lysates and living cells. Furthermore, immunodepletion experiments demonstrate that the fluorescently-tagged peptide is selectively, if not exclusively, phosphorylated by the conventional PKCs. Both of the protein kinase biosensor strategies take advantage of the ease with which peptides can be modified to create libraries of structurally altered analogs. However, the inherent synthetic mutability of peptides is not just limited to library construction. For example, it may ultimately be possible to simultaneously monitor multiple protein kinases by affixing fluorophores with distinct photophysical properties to appropriately designed active site-directed peptides.

Oncology drug discovery applications using the FMAT 8100 HTS system.

High-throughput screening (HTS) for potential anticancer agents requires a broad portfolio of assay platforms that may include kinase enzyme assays, protein-protein binding assays, and functional cell-based apoptosis assays. The authors have explored the use of fluorometric microvolume assay technology (the FMAT 8100 HTS System) in three distinct homogeneous HTS assays: (1). a Src tyrosine kinase enzyme assay, (2). a Grb2-SH2 protein-peptide interaction assay, and (3). an annexin V binding apoptosis assay. Data obtained from all three assays suggest that the FMAT system should facilitate the implementation of homogeneous assays for a wide variety of molecular targeted and cell-based screens.

Real time visualization of protein kinase activity in living cells.

A library of fluorescently labeled protein kinase C (PKC) peptide substrates was prepared to identify a phosphorylation-induced reporter of protein kinase activity. The lead PKC substrate displays a 2.5-fold change in fluorescence intensity upon phosphorylation. PKC activity is readily sampled in cell lysates containing the activated PKCs. Immunodepletion of conventional PKCs from the cell lysate eliminates the fluorescence response, suggesting that this peptide substrate is selectively phosphorylated by PKCalpha, beta, and gamma. Finally, living cells microinjected with the peptide substrate exhibit a 2-fold increase in fluorescence intensity upon exposure to a PKC activator. These results suggest that peptide-based protein kinase biosensors may be useful in monitoring the temporal and spatial dynamics of PKC activity in living cells.