Opposing Roles of GSK3α and GSK3β Phosphorylation in Platelet Function and Thrombosis

APIP regulated by YAP propels methionine cycle and metastasis in head and neck squamous cell carcinoma

The Yes-associated protein (YAP) plays a vital role in tumor progression and metabolic regulation. However, the involvement of YAP in metabolic reprogramming of head and neck squamous cell carcinoma remains unclear. Using RNA sequencing and ultra-high-performance liquid chromatography-tandem mass spectrometry, we observed that YAP increased the levels of the main metabolites and enzymes involved in methionine metabolism. APIP, an enzyme involved in the methionine salvage pathway, was transcriptionally activated by YAP. Further experiments showed that APIP promotes HNSCC cells migration and invasion in vitro and tumor metastasis in adjacent lymph nodes and distant organs in vivo. APIP also increases the levels of metabolites in the methionine cycle. We further found that methionine reversed the inhibition of HNSCC migration and invasion by APIP knockdown. In vivo experiments demonstrated that methionine addition promoted tumor metastasis. Mechanistically, the methionine cycle phosphorylated and inactivated GSK3β, then induced the epithelial mesenchymal transition pathway. Increased APIP expression was detected in patients with HNSCC, especially in tumors with lymph node metastasis. Metabolites of methionine cycle were also elevated in HNSCC patients. Our findings revealed that APIP, a novel target of YAP, promotes the methionine cycle and HNSCC metastasis through GSK3β phosphorylation.

Platelet Activation Pathways Controlling Reversible Integrin αIIbβ3 Activation

Background  Agonist-induced platelet activation, with the integrin αIIbβ3 conformational change, is required for fibrinogen binding. This is considered reversible under specific conditions, allowing a second phase of platelet aggregation. The signaling pathways that differentiate between a permanent or transient activation state of platelets are poorly elucidated. Objective  To explore platelet signaling mechanisms induced by the collagen receptor glycoprotein VI (GPVI) or by protease-activated receptors (PAR) for thrombin that regulate time-dependent αIIbβ3 activation. Methods  Platelets were activated with collagen-related peptide (CRP, stimulating GPVI), thrombin receptor-activating peptides, or thrombin (stimulating PAR1 and/or 4). Integrin αIIbβ3 activation and P-selectin expression was assessed by two-color flow cytometry. Signaling pathway inhibitors were applied before or after agonist addition. Reversibility of platelet spreading was studied by microscopy. Results  Platelet pretreatment with pharmacological inhibitors decreased GPVI- and PAR-induced integrin αIIbβ3 activation and P-selectin expression in the target order of protein kinase C (PKC) > glycogen synthase kinase 3 > β-arrestin > phosphatidylinositol-3-kinase. Posttreatment revealed secondary αIIbβ3 inactivation (not P-selectin expression), in the same order, but this reversibility was confined to CRP and PAR1 agonist. Combined inhibition of conventional and novel PKC isoforms was most effective for integrin closure. Pre- and posttreatment with ticagrelor, blocking the P2Y 12 adenosine diphosphate (ADP) receptor, enhanced αIIbβ3 inactivation. Spreading assays showed that PKC or P2Y 12 inhibition provoked a partial conversion from filopodia to a more discoid platelet shape. Conclusion  PKC and autocrine ADP signaling contribute to persistent integrin αIIbβ3 activation in the order of PAR1/GPVI > PAR4 stimulation and hence to stabilized platelet aggregation. These findings are relevant for optimization of effective antiplatelet treatment.

Anemoside B4 alleviates arthritis pain via suppressing ferroptosis-mediated inflammation

Chronic pain is the key manifestations of rheumatoid arthritis. Neuroinflammation in the spinal cord drives central sensitization and chronic pain. Ferroptosis has potentially important roles in the occurrence of neuroinflammation and chronic pain. In the current study, mouse model of collagen-induced arthritis was established by intradermal injection of type II collagen in complete Freund's adjuvant (CFA) solution. CFA inducement resulted in swollen paw and ankle, mechanical and spontaneous pain, and impaired motor coordination. The spinal inflammation was triggered, astrocytes were activated, and increased NLRP3-mediated inflammatory signal was found in CFA spinal cord. Oxidative stress and ferroptosis in the spinal cord were manifested. Meanwhile, enhancive spinal GSK-3β activity and abnormal phosphorylated Drp1 were observed. To investigate the potential therapeutic options for arthritic pain, mice were intraperitoneally injected with AB4 for three consecutive days. AB4 treatment reduced pain sensitivity and increased the motor coordination. In the spinal cord, AB4 treatment inhibited NLRP3 inflammasome-mediated inflammatory response, increased antioxidation, decreased mitochondrial reactive oxygen species and ferroptosis. Furthermore, AB4 decreased GSK-3β activity by binding with GSK-3β through five electrovalent bonds. Our findings indicated that AB treatment relieves arthritis pain by inhibiting GSK-3β activation, increasing antioxidant capability, reducing Drp1-mediated mitochondrial dysfunction and suppressing neuroinflammation.

New insights into the role of GSK-3β in the brain: from neurodegenerative disease to tumorigenesis

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase widely expressed in various tissues and organs. Unlike other kinases, GSK-3 is active under resting conditions and is inactivated upon stimulation. In mammals, GSK-3 includes GSK-3 α and GSK-3β isoforms encoded by two homologous genes, namely, GSK3A and GSK3B. GSK-3β is essential for the control of glucose metabolism, signal transduction, and tissue homeostasis. As more than 100 known proteins have been identified as GSK-3β substrates, it is sometimes referred to as a moonlighting kinase. Previous studies have elucidated the regulation modes of GSK-3β. GSK-3β is involved in almost all aspects of brain functions, such as neuronal morphology, synapse formation, neuroinflammation, and neurological disorders. Recently, several comparatively specific small molecules have facilitated the chemical manipulation of this enzyme within cellular systems, leading to the discovery of novel inhibitors for GSK-3β. Despite these advancements, the therapeutic significance of GSK-3β as a drug target is still complicated by uncertainties surrounding the potential of inhibitors to stimulate tumorigenesis. This review provides a comprehensive overview of the intricate mechanisms of this enzyme and evaluates the existing evidence regarding the therapeutic potential of GSK-3β in brain diseases, including Alzheimer's disease, Parkinson's disease, mood disorders, and glioblastoma.

The Inhibitory Effects of Protaetia brevitarsis seulensis Larvae Extract on Human Platelet Aggregation and Glycoprotein IIb/IIIa Expression

The white-spotted flower chafer, Protaetia brevitarsis seulensis, is used as a traditional remedy against liver cirrhosis, hepatitis, and hepatic cancer. In this study, we investigated if P. brevitarsis extract (PBE) inhibited platelet aggregation via integrin αIIb/β3 regulation. We observed that PBE inhibited αIIb/β3 activation by regulating the cyclic nucleotides, cyclic adenosine monophosphate and cyclic guanosine monophosphate. Additionally, PBE affected phosphatidylinositol-3 kinase, Akt, SYK, glycogen synthase kinase-3α/β, cytosolic phospholipase A2, and p38 expression, which are signal transduction molecules expressed by platelets, and consequently suppressed αIIbβ3 activity and thromboxane A2 generation. Taken together, PBE showed strong antiplatelet effects and may be used to block thrombosis- and platelet-mediated cardiovascular diseases.

3-Arylidene-2-oxindoles as GSK3β inhibitors and anti-thrombotic agents

Development of novel agents that prevent thrombotic events is an urgent task considering increasing incidence of cardiovascular diseases and coagulopathies that accompany cancer and COVID-19. Enzymatic assay identified novel GSK3β inhibitors in a series of 3-arylidene-2-oxindole derivatives. Considering the putative role of GSK3β in platelet activation, the most active compounds were evaluated for antiplatelet activity and antithrombotic activity. It was found that GSK3β inhibition by 2-oxindoles correlates with inhibition of platelet activation only for compounds 1b and 5a. Albeit, in vitro antiplatelet activity matched well with in vivo anti-thrombosis activity. The most active GSK3β inhibitor 5a exceeds antiplatelet activity of acetylsalicylic acid in vitro by 10.3 times and antithrombotic activity in vivo by 18.7 times (ED₅₀ 7.3 mg/kg). These results support the promising role of GSK3β inhibitors for development of novel antithrombotic agents.