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Neural crest migration is critical to its physiological function. Mechanisms controlling mammalian neural crest migration are comparatively unknown, due to difficulties accessing this cell population in vivo. Here we report requirements of glycogen synthase kinase 3 (GSK3) in regulating the neural crest in Xenopus and mouse models. We demonstrate that GSK3 is tyrosine phosphorylated (pY) in mouse neural crest cells and that loss of GSK3 leads to increased pFAK and misregulation of Rac1 and lamellipodin, key regulators of cell migration. Genetic reduction of GSK3 results in failure of migration. We find that pY-GSK3 phosphorylation depends on anaplastic lymphoma kinase (ALK), a protein associated with neuroblastoma. Consistent with this, neuroblastoma cells with increased ALK activity express high levels of pY-GSK3, and blockade of GSK3 or ALK can affect migration of these cells. Altogether, this work identifies a role for GSK3 in cell migration during neural crest development and cancer. Defects in neural crest development cause neurocristopathies and cancer, but what regulates this is unclear. Here, the authors show that glycogen synthase kinase 3 (GSK3) regulates migration of neural crest cells, as shown on genetic deletion of GSK3 in the mouse, and that this acts via anaplastic lymphoma kinase.

Glycogen synthase kinase‐3α/β (GSK3α/β) is a critical kinase for Tau hyperphosphorylation which contributes to neurodegeneration. Despite the termination of clinical trials for GSK3α/β inhibitors in Alzheimer's disease (AD) treatment, there is a pressing need for novel therapeutic strategies targeting GSK3α/β. Here, we identified the compound AS1842856 (AS), a specific forkhead box protein O1 (FOXO1) inhibitor, reduced intracellular GSK3α/β content in a FOXO1‐independent manner. Specifically, AS directly bound to GSK3α/β, promoting its translocation to the multivesicular bodies (MVBs) and accelerating exocytosis, ultimately decreasing intracellular GSK3α/β content. Expectedly, AS treatment effectively suppressed Tau hyperphosphorylation in cells exposed to okadaic acid or expressing the TauP301S mutant. Furthermore, AS was visualized to penetrate the blood–brain barrier (BBB) using an imaging mass microscope. Long‐term treatment of AS enhanced cognitive function in P301S transgenic mice by mitigating Tau hyperphosphorylation through downregulation of GSK3α/β expression in the brain. Altogether, AS represents a novel small‐molecule GSK3α/β inhibitor that facilitates GSK3α/β exocytosis, holding promise as a therapeutic agent for GSK3α/β hyperactivation‐associated disorders. AS1842856 (AS) inhibits Tauopathy via promoting glycogen synthase kinase‐3α/β (GSK3α/β) exocytosis. Upon entering the cell, AS binds to GSK3α/β and facilitates the translocation of GSK3α/β to early endosomes, which in turn promotes GSK3α/β accumulation in multivesicular bodies (MVBs) and subsequently reduces intracellular GSK3α/β contents via promoting GSK3α/β exocytosis. Reduced intracellular GSK3α/β inhibits Tau hyperphosphorylation and the formation of neurofibrillary tangles.

Glycogen synthase kinase‐3 (GSK3), consisting of GSK3α and GSK3β subtypes, is a complex protein kinase that regulates numerous substrates. Research has observed increased GSK3 expression in the brains of Alzheimer's disease (AD) patients and models. AD is a neurodegenerative disorder with diverse pathogenesis and notable cognitive impairments, characterized by Aβ aggregation and excessive tau phosphorylation. This article provides an overview of GSK3's structure and regulation, extensively analyzing its relationship with AD factors. GSK3 overactivation disrupts neural growth, development, and function. It directly promotes tau phosphorylation, regulates amyloid precursor protein (APP) cleavage, leading to Aβ formation, and directly or indirectly triggers neuroinflammation and oxidative damage. We also summarize preclinical research highlighting the inhibition of GSK3 activity as a primary therapeutic approach for AD. Finally, pending issues like the lack of highly specific and affinity‐driven GSK3 inhibitors, are raised and expected to be addressed in future research. In conclusion, GSK3 represents a target in AD treatment, filled with hope, challenges, opportunities, and obstacles. GSK3 signaling in Alzheimer's disease and targeted therapies.

Tumor cell invasion and resistance to therapy are the most intractable biological characteristics of cancer and, therefore, the most challenging for current cancer research and treatment paradigms. Refractory cancers, including pancreatic cancer and glioblastoma, show an inextricable association between the highly invasive behavior of tumor cells and their resistance to chemotherapy, radiotherapy and targeted therapies. These aggressive properties of cancer share distinct cellular pathways that are connected to each other by several molecular hubs. There is increasing evidence to show that glycogen synthase kinase (GSK)‐3β is aberrantly activated in various cancer types and this has emerged as a potential therapeutic target. In many but not all cancer types, aberrant GSK3β sustains the survival, immortalization, proliferation and invasion of tumor cells, while also rendering them insensitive or resistant to chemotherapeutic agents and radiation. Here we review studies that describe associations between therapeutic stimuli/resistance and the induction of pro‐invasive phenotypes in various cancer types. Such cancers are largely responsive to treatment that targets GSK3β. This review focuses on the role of GSK3β as a molecular hub that connects pathways responsible for tumor invasion and resistance to therapy, thus highlighting its potential as a major cancer therapeutic target. We also discuss the putative involvement of GSK3β in determining tumor cell stemness that underpins both tumor invasion and therapy resistance, leading to intractable and refractory cancer with dismal patient outcomes. Tumor invasion and therapy resistance are inextricably linked to each other in refractory cancer, thereby presenting challenges to current cancer treatment paradigms. Increasing evidence of an unexpected role for GSK3β in sustaining tumor cell survival and proliferation underpins the targeting of GSK3β as a novel cancer treatment. This review provides new insights into the unwanted association between cancer invasion and therapy resistance by focusing on previously unrecognized functions of GSK3β as a molecular hub that integrates distinct biological pathways.

The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) was initially identified as a key regulator of insulin-dependent glycogen synthesis. GSK-3 was subsequently shown to function in a wide range of cellular processes including differentiation, growth, motility and apoptosis. Aberrant regulation of GSK-3 has been implicated in a range of human pathologies including Alzheimer's disease, non-insulin-dependent diabetes mellitus (NIDDM) and cancer. As a consequence, the regulation of GSK-3 and the therapeutic potential of GSK-3 inhibitors have become key areas of investigation. This review will focus on the mechanisms of GSK-3 regulation, with emphasis on modulation by upstream signals, control of substrate specificity and GSK-3 localisation. The details of these mechanisms will be discussed in the context of specific signalling pathways.

The sensory cells that transduce the signals for hearing and balance are highly specialized mechanoreceptors called hair cells that together with supporting cells comprise the sensory epithelia of the inner ear. Loss of hair cells from toxin exposure and age can cause balance disorders and is essentially irreversible due to the inability of mammalian vestibular organs to regenerate physiologically active hair cells. Here, we show substantial regeneration of hair cells in a mouse model of vestibular damage by treatment with a combination of glycogen synthase kinase 3β and histone deacetylase inhibitors. The drugs stimulated supporting cell proliferation and differentiation into hair cells. The new hair cells were reinnervated by vestibular afferent neurons, rescuing otolith function by restoring head translation-evoked otolith afferent responses and vestibuloocular reflexes. Drugs that regenerate hair cells thus represent a potential therapeutic approach to the treatment of balance disorders.

Albuminuria affects millions of people, and is an independent risk factor for kidney failure, cardiovascular morbidity and death. The key cell that prevents albuminuria is the terminally differentiated glomerular podocyte. Here we report the evolutionary importance of the enzyme Glycogen Synthase Kinase 3 (GSK3) for maintaining podocyte function in mice and the equivalent nephrocyte cell in Drosophila . Developmental deletion of both GSK3 isoforms (α and β) in murine podocytes causes late neonatal death associated with massive albuminuria and renal failure. Similarly, silencing GSK3 in nephrocytes is developmentally lethal for this cell. Mature genetic or pharmacological podocyte/nephrocyte GSK3 inhibition is also detrimental; producing albuminuric kidney disease in mice and nephrocyte depletion in Drosophila . Mechanistically, GSK3 loss causes differentiated podocytes to re-enter the cell cycle and undergo mitotic catastrophe, modulated via the Hippo pathway but independent of Wnt-β-catenin. This work clearly identifies GSK3 as a critical regulator of podocyte and hence kidney function. Glycogen Synthase Kinase 3 (GSK3) has conserved functions across species but its role in the kidney is unclear. Here, the authors show that in the kidney podocyte cell of mice and related nephrocyte in Drosophila that GSK3 is a master regulator of function both during development and in maturity.

Two recent clinical studies support the feasibility of trials to evaluate the disease-modifying properties of lithium in Alzheimer's disease, although no benefits were obtained from short-term treatment. To evaluate the effect of long-term lithium treatment on cognitive and biological outcomes in people with amnestic mild cognitive impairment (aMCI). Forty-five participants with aMCI were randomised to receive lithium (0.25-0.5 mmol/l) (n = 24) or placebo (n = 21) in a 12-month, double-blind trial. Primary outcome measures were the modification of cognitive and functional test scores, and concentrations of cerebrospinal fluid (CSF) biomarkers (amyloid-beta peptide (Aβ(42)), total tau (T-tau), phosphorylated-tau) (P-tau). NCT01055392. Lithium treatment was associated with a significant decrease in CSF concentrations of P-tau (P = 0.03) and better perform-ance on the cognitive subscale of the Alzheimer's Disease Assessment Scale and in attention tasks. Overall tolerability of lithium was good and the adherence rate was 91%. The present data support the notion that lithium has disease-modifying properties with potential clinical implications in the prevention of Alzheimer's disease.

Alzheimer’s disease (AD), the most common cause of dementia and neurodegeneration in the elderly, is characterized by deterioration of memory and executive and motor functions. Neuropathologic hallmarks of AD include neurofibrillary tangles (NFTs), paired helical filaments, and amyloid plaques. Mutations in the microtubule-associated protein Tau, a major component of the NFTs, cause its hyperphosphorylation in AD. We have shown that signaling by the gaseous molecule hydrogen sulfide (H₂S) is dysregulated during aging. H₂S signals via a posttranslational modification termed sulfhydration/persulfidation, which participates in diverse cellular processes. Here we show that cystathionine γ-lyase (CSE), the biosynthetic enzyme for H₂S, binds wild type Tau, which enhances its catalytic activity. By contrast, CSE fails to bind Tau P301L, a mutant that is present in the 3xTg-AD mouse model of AD. We further show that CSE is depleted in 3xTg-AD mice as well as in human AD brains, and that H₂S prevents hyperphosphorylation of Tau by sulfhydrating its kinase, glycogen synthase kinase 3β (GSK3β). Finally, we demonstrate that sulfhydration is diminished in AD, while administering the H2S donor sodium GYY4137 (NaGYY) to 3xTg-AD mice ameliorates motor and cognitive deficits in AD.