Glycogen synthase kinase-3β inhibition decreases inflammation and relieves cancer induced bone pain via reducing Drp1-mediated mitochondrial damage

Study on the Mechanisms of Glrα3 in Pain Sensitization of Endometriosis

Endometriosis, often associated with chronic pelvic pain, can lead to anxiety and depression. This study investigates the role and mechanism of Glycine receptor alpha 3 (Glrα3) in the central sensitization of pain in endometriosis, aiming to identify new therapeutic targets. Using a Glrα3 knockout mouse model of endometriosis, we employed behavioral tests, qPCR, immunofluorescence, Nissl staining, MRI, and Western blot to assess the involvement of Glrα3 in central pain sensitization. Our results indicate that endometriosis-induced hyperalgesia and anxiety-depressive-like behaviors are linked to increased Glrα3 expression. Chronic pain in endometriosis leads to gray matter changes in the sensory and insular cortices, with Glrα3 playing a significant role. The inhibition of Glrα3 alleviates pain, reduces neuronal abnormalities, and decreases glial cell activation. The absence of Glrα3 effectively regulates the central sensitization of pain in endometriosis by inhibiting glial cell activation and maintaining neuronal stability. This study offers new therapeutic avenues for the clinical treatment of endometriosis-related pain.

Alleviating effect of lycorine on CFA‑induced arthritic pain via inhibition of spinal inflammation and oxidative stress

Chronic pain is the primary symptom of osteoarthritis affecting a patient's quality of life. Neuroinflammation and oxidative stress in the spinal cord contribute to arthritic pain and represent ideal targets for pain management. In the present study, a model of arthritis was established by intra-articular injection of complete Freund's adjuvant (CFA) into the left knee joint in mice. After CFA inducement, knee width and pain hypersensitivity in the mice were increased, motor disability was impaired, spinal inflammatory reaction was induced, spinal astrocytes were activated, antioxidant responses were decreased, and glycogen synthase kinase 3β (GSK-3β) activity was inhibited. To explore the potential therapeutic options for arthritic pain, lycorine was intraperitoneally injected for 3 days in the CFA mice. Lycorine treatment significantly reduced mechanical pain sensitivity, suppressed spontaneous pain, and recovered motor coordination in the CFA-induced mice. Additionally, in the spinal cord, lycorine treatment decreased the inflammatory score, reduced NOD-like receptor protein 3 inflammasome (NLRP3) activity and IL-1β expression, suppressed astrocytic activation, downregulated NF-κB levels, increased nuclear factor erythroid 2-related factor 2 expression and superoxide dismutase activity. Furthermore, lycorine was shown to bind to GSK-3β through three electrovalent bonds, to inhibit GSK-3β activity. In summary, lycorine treatment inhibited GSK-3β activity, suppressed NLRP3 inflammasome activation, increased the antioxidant response, reduced spinal inflammation, and relieved arthritic pain.

Tris(1,3-dichloro-2-propyl) Phosphate Inhibits Early Embryonic Development by Binding to Gsk-3β Protein in Zebrafish

Recently, several studies have reported that exposure to tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) results in abnormal development of zebrafish embryos in blastocyst and gastrula stages, but molecular mechanisms are still not clear. This lacking strongly affects the interspecific extrapolation of embryonic toxicity induced by TDCIPP and hazard evaluation. In this study, zebrafish embryos were exposed to 100, 500 or 1000 μg/L TDCIPP, and 6-bromoindirubin-3'-oxime (BIO, 35.62 μg/L) was used as a positive control. Results demonstrated that treatment with TDCIPP or BIO caused an abnormal stacking of blastomere cells in mid blastula transition (MBT) stage, and subsequently resulted in epiboly delay of zebrafish embryos. TDCIPP and BIO up-regulated the expression of β-catenin protein and increased its accumulation in nuclei of embryonic cells. This accumulation was considered as a driver for early embryonic developmental toxicity of TDCIPP. Furthermore, TDCIPP and BIO partly shared the same modes of action, and both of them could bind to Gsk-3β protein, and then decreased the phosphorylation level of Gsk-3β in TYR·216 site and lastly inhibited the activity of Gsk-3β kinase, which was responsible for the increased concentrations of β-catenin protein in embryonic cells and accumulation in nuclei. Our findings provide new mechanisms for clarifying the early embryonic developmental toxicity of TDCIPP in zebrafish.

Mn-SOD alleviates methotrexate-related hepatocellular injury via GSK-3β affecting anti-oxidative stress of HO-1 and Drp1

OBJECTIVES

Methotrexate (MTX) is the most common therapeutic agent that may have the risk of drug-induced liver injury. Its pathogenic mechanism is related to oxidative stress caused by mitochondrial dysfunction. Superoxide dismutase (SOD), including manganese-containing SOD (Mn-SOD), can exert its effect of anti-oxidative stress by scavenging superoxide free radicals. Accordingly, this study is performed to explore the underlying molecular mechanism via observing whether Mn-SOD could affect the damage of MTX to hepatocytes.

METHODS

Human hepatocyte cell line L-02 was cultured in vitro and divided into 4 groups, including a blank group with the addition of the same volume of serum-free medium, a MTX group (40 μg/well MTX drug-treatment), a MTX+NC group (40 μg/well MTX drug-treatment+blank plasmid), and a MTX+SOD group (40 μg/well MTX drug-treatment+Mn-SOD plasmid). The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and microRNA-122 (miR-122) in the supernatant of cell culture were respectively detected by automatic biochemical analytical instrument and real-time RT-PCR to evaluate the degree of hepatocyte damage in each group. MitoSOX fluorescent probe was used to label intracellular superoxide in each group, and cell apoptosis was detected by flow cytometry. Meanwhile, the contents of glycogen synthase kinase-3 beta (GSK-3β), hemeoxygenase-1 (HO-1), mitochondrial fission-mediated protein of dynamin-related protein 1 (Drp1), and Mn-SOD were detected by Western blotting.

RESULTS

Compared with the blank group, the levels of ALT, AST, and miR-122 in the supernatant of hepatocyte culture of the MTX group and MTX+NC group were significantly elevated (all P <0.05), and that in the MTX+SOD group were significantly decreased ( P <0.05) and equivalent to that in the blank group. MitoSOX staining revealed that the MTX group and MTX+NC had the most abundant superoxide; and the amount was significantly reduced in the MTX+SOD group, without a significant difference when compared with the blank group. Furthermore, the results of flow cytometry indicated that compared with the blank group, the MTX group and MTX+NC group showed significantly increased cell apoptosis ( P <0.05); while there was obviously reduced cell apoptosis in the MTX+SOD group than that in the MTX group and MTX+NC group ( P <0.05). According to the results of Western blotting, the blank group and MTX+SOD group had higher expressions of Mn-SOD, p-GSK-3β, and HO-1; while the MTX group and MTX+NC group exhibited remarkably lower levels of Mn-SOD, p-GSK-3β, and HO-1 than those in the blank group ( P <0.05). Besides, a completely opposite trend was found in the expression of Drp1, which was highly expressed in the MTX group and MTX+NC group, but lowly expressed in the blank group and the MTX+SOD group.

CONCLUSIONS

MTX may induce hepatocyte damage, and one of the mechanisms may be due to the decrease of intracellular Mn-SOD level, which can cause the accumulation of superoxide, affect the levels of HO-1 and Drp1 through GSK-3β leading to mitochondrial damage and cell apoptosis. High expression of Mn-SOD intracellularly through exogenous introduction can scavenge drug-produced superoxide, affect HO-1 and Drp1 levels through GSK-3β, activate mitochondria, protect cells against damage from oxidative stress, and inhibit hepatocyte apoptosis eventually. So exogenous introduction of SOD may be a potential therapeutic approach to block or reverse MTX-related hepatocyte injury.

Glycogen synthase kinase-3β inhibition decreases inflammation and relieves cancer induced bone pain via reducing Drp1-mediated mitochondrial damage

Bone is the preferential site of metastasis for breast cancer. Invasion of cancer cells induces the destruction of bone tissue and damnification of peripheral nerves and consequently induced central sensitization which contributes to severe pain. Herein, cancer induced bone pain (CIBP) rats exhibited destruction of tibia, mechanical allodynia and spinal inflammation. Inflammatory response mainly mediated by astrocyte and microglia in central nervous system. Our immunofluorescence analysis revealed activation of spinal astrocytes and microglia in CIBP rats. Transmission electron microscopy (TEM) observations of mitochondrial outer membrane disruption and cristae damage in spinal mitochondria of CIBP rats. Proteomics analysis identified abnormal expression of proteins related to mitochondrial organization and function. Intrathecally, injection of GSK‐3β activity inhibitor TDZD‐8 significantly attenuated Drp1‐mediated mitochondrial fission and recovered mitochondrial function. Inhibition of GSK‐3β activity also suppressed NLRP3 inflammasome cascade and consequently decreased mechanical pain sensitivity of CIBP rats. For cell research, TDZD‐8 treatment significantly reversed TNF‐α induced mitochondrial membrane potential (MMP) deficiency and high mitochondrial reactive oxygen species level. Taken together, GSK‐3β inhibition by TDZD‐8 decreases spinal inflammation and relieves cancer induced bone pain via reducing Drp1‐mediated mitochondrial damage.