Article

Unlocking mechanisms in interleukin-1β-induced changes in hippocampal neurogenesis—a role for GSK-3β and TLX

Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
Translational Psychiatry (Impact Factor: 4.36). 11/2012; 2(11):e194. DOI: 10.1038/tp.2012.117
Source: PubMed

ABSTRACT Glycogen synthase kinase-3β (GSK-3β) and the orphan nuclear receptor tailless homolog (TLX) are key regulators of hippocampal neurogenesis, which has been reported to be dysregulated in both neurodegenerative and psychiatric disorders. Inflammation is also implicated in the neuropathology of these disorders because of increased levels of the pro-inflammatory cytokine interleukin-1β (IL-1β) in the brain. At elevated levels, IL-1β signaling through the IL-1 receptor type 1 has been shown to be detrimental to hippocampal neurogenesis. TLX is required to maintain neural stem/progenitor cells (NSPCs) in an undifferentiated state and is involved in NSPC fate determination, while GSK-3β negatively regulates Wnt signaling, a vital pathway promoting neurogenesis. This study shows that GSK-3β inhibition using a small-molecule inhibitor and the mood stabilizer lithium restores the IL-1β-induced decrease in NSPC proliferation and neuronal differentiation of embryonic rat hippocampal NSPCs to control levels. The IL-1β-induced effect on NSPCs is paralleled by a decrease in TLX expression that can be prevented by GSK-3β inhibition. The present results suggest that GSK-3β ameliorates the anti-proliferative and pro-gliogenic effects of IL-1β, and that TLX is vulnerable to inflammatory insult. Strategies to reduce GSK-3β activity or to increase TLX expression may facilitate the restoration of hippocampal neurogenesis in neuroinflammatory conditions where neurogenesis is impaired.

Download full-text

Full-text

Available from: Yvonne Nolan, Feb 03, 2014
0 Followers
 · 
89 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Protein kinase B (AKT) and glycogen synthase kinase 3 beta (GSK3β) are two protein kinases involved in dopaminergic signaling. Dopamine-associated neuropsychiatric illnesses such as schizophrenia and bipolar disorder seem to be characterized by impairments in the AKT/GSK3β network. Here, we sought evidence for the presence of molecular and functional changes in the AKT/GSK3β pathway using an established infection-based mouse model of developmental neuropsychiatric disease that is based on prenatal administration of the viral mimetic poly(I:C) (=polyriboinosinic-polyribocytidilic acid). We found that adult offspring of poly(I:C)-exposed mothers displayed decreased total levels of AKT protein and reduced phosphorylation at AKT threonine residues in the medial prefrontal cortex. Prenatally immune challenged offspring also exhibited increased GSK3β protein expression and activation status, the latter of which was evidenced by a decrease in the ratio between phosphorylated and total GSK3β protein in the medial prefrontal cortex. These molecular changes were not associated with overt signs of inflammatory processes in the adult brain. We further found that acute pre-treatment with the selective GSK3β inhibitor TDZD-8 dose-dependently normalized aberrant behavior typically emerging following prenatal immune activation, including deficient spontaneous alternation in the Y-maze and increased locomotor responses to systemic amphetamine treatment. Taken together, the present mouse model demonstrates that prenatal exposure to viral-like immune activation leads to long-term alterations in GSK3β signaling, some of which are critically implicated in schizophrenia and bipolar disorder.
    Neuropharmacology 05/2013; 73. DOI:10.1016/j.neuropharm.2013.05.012 · 4.82 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Differentiation of neural progenitor cells (NPCs) is important for protecting neural cells and brain tissue during inflammation. Interleukin-1 beta (IL-1β) is the most common pro- inflammatory cytokine in brain inflammation, and increased IL-1β levels can decrease the proliferation of NPCs. We aimed to investigate whether agmatine (Agm), a primary polyamine that protects neural cells, could trigger differentiation of NPCs by activating IL-1β in vitro. The cortex of ICR mouse embryos (E14) was dissociated to culture NPCs. NPCs were stimulated by lipopolysaccharide (LPS). After 6 days, protein expression of stem cell markers and differentiation signal factors was confirmed by using western blot analysis. Also, immunocytochemistry was used to confirm the cell fate. Agm treatment activated NPC differentiation significantly more than in the control group, which was evident by the increased expression of a neuronal marker, MAP2, in the LPS-induced, Agm-treated group. Differentiation of LPS-induced, Agm-treated NPCs was regulated by the MAPK pathway and is thought to be related to IL-1β activation and decreased expression of TLX, a transcription factor that regulates NPC differentiation. Our results reveal that Agm can promote NPC differentiation to neural stem cells by modulating IL-1β expression under inflammatory condition, and they suggest that Agm may be a novel therapeutic strategy for neuroinflammatory diseases.
    12/2013; 22(4):268-76. DOI:10.5607/en.2013.22.4.268
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: While the detrimental impact of inflammation on adult hippocampal neurogenesis and associated behaviors has recently gained credence, the effects of inflammation on the developing brain is an area of research which is quickly gaining momentum, and a growing number of research articles on this topic have been published in recent years. Indeed, we now know that pro-inflammatory mediators negatively influence both hippocampal neurogenesis and neuronal cytoarchitecture during brain development. Here we present a comprehensive review of the current literature on inflammation-induced changes in hippocampal neurogenesis during early life and the consequent behavioral deficits which may ensue in later life. We also offer insights into the cellular and molecular mechanisms underlying the hippocampal-dependant behavioral changes observed in neurodevelopmental disorders, particularly in those where cognitive dysfunction plays a major role. We further consider whether early-life inflammation-induced changes in hippocampal neurogenesis may contribute to the onset of mood and cognitive deficits in later life.
    Neuroscience & Biobehavioral Reviews 01/2014; 40. DOI:10.1016/j.neubiorev.2014.01.004 · 10.28 Impact Factor
Show more