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Neuroinflammation contributes to delayed secondary cell death following traumatic brain injury (TBI), has the potential to chronically exacerbate the initial insult, and represents a therapeutic target that has largely failed to translate into human efficacy. Thalidomide-like drugs have effectively mitigated neuroinflammation across cellular and animal models of TBI and neurodegeneration but are complicated by adverse actions in humans. We hence developed N-adamantyl phthalimidine (NAP) as a new thalidomide-like drug to mitigate inflammation without binding to cereblon, a key target associated with the antiproliferative, antiangiogenic, and teratogenic actions seen in this drug class. We utilized a phenotypic drug discovery approach that employed multiple cellular and animal models and ultimately examined immunohistochemical, biochemical, and behavioral measures following controlled cortical impact (CCI) TBI in mice. NAP mitigated LPS-induced inflammation across cellular and rodent models and reduced oligomeric α-synuclein and amyloid-β mediated inflammation. Following CCI TBI, NAP mitigated neuronal and synaptic loss, neuroinflammation, and behavioral deficits, and is unencumbered by cereblon binding, a key protein underpinning the teratogenic and adverse actions of thalidomide-like drugs in humans. In summary, NAP represents a new class of thalidomide-like drugs with anti-inflammatory actions for promising efficacy in the treatment of TBI and potentially longer-term neurodegenerative disorders.

Nurr1, a transcription factor belonging to the orphan nuclear receptor, has an essential role in the generation and maintenance of dopaminergic neurons and is important in the pathogenesis of Parkinson' disease (PD). In addition, Nurr1 has a non-neuronal function, and it is especially well known that Nurr1 has an anti-inflammatory function in the Parkinson's disease model. However, the molecular mechanisms of Nurr1 have not been elucidated. In this study, we describe a novel mechanism of Nurr1 function. To provide new insights into the molecular mechanisms of Nurr1 in the inflammatory response, we performed Chromatin immunoprecipitation sequencing (ChIP-Seq) on LPS-induced inflammation in BV2 cells and finally identified the RasGRP1 gene as a novel target of Nurr1. Here, we show that Nurr1 directly binds to the RasGRP1 intron to regulate its expression. Moreover, we also identified that RasGRP1 regulates the Ras-Raf-MEK-ERK signaling cascade in LPSinduced inflammation signaling. Finally, we conclude that RasGRP1 is a novel regulator of Nurr1's mediated inflammation signaling. Nurr1 (NR4A2) belongs to the nuclear receptor (NR)4 family of orphan nuclear receptors 1. NRs are ligand inducible transcription factors that bind to DNA and regulate the expression of target genes 2. Developing mesencephalic dopaminergic cells deficient in Nurr1 are unable to express tyrosine hydroxylase 3,4. Nurr1 deficiency in embryonic ventral midbrain cells causes them not to migrate normally, and they fail to innervate their striatal target areas 5. It has been suggested that the absence of Nurr1 may be a contributing factor in the pathogenesis of PD 6. Recently, two human mutations located in exon 1 of the Nurr1 gene were shown to result in a decreased expression of Nurr1 mRNA and were associated with familial PD 7. Additionally, recent studies have proposed that Nurr1 overexpression or modification of Nurr1 expression in stem cells (and neural stem cells) may have an impact on the future of cell therapy for PD 8-11. It is further supported by a link between altered Nurr1 expression and PD indicating that Nurr1 may have a protection role. Saijo et al. reported that Nurr1 protects dopaminergic neurons from inflammation-induced neurotoxicity through the inhibition of pro-inflammatory mediator expression in microglia and astrocytes 12. Nurr1 functions as a key component of a negative feedback loop in both microglia and astrocytes by recruiting CoREST corepressor complexes to NF-κB target genes 12. They found that a reduction of Nurr1 expression in itself does not affect the death of TH + dopaminergic neurons, but the expression of inflammatory mediators are enhanced, and the survival rate of TH + neurons are decreased in response to inflammatory stimuli in the Nurr1 deficiency condition 12. Moreover, they mentioned that astrocytes can act as amplifying agents of microglia-derived proinflammatory mediators in the production of neurotoxic factors 12-14. Collectively, the expression of LPS-induced pro-inflammatory genes in microglia lead to...

Astrocytes perform multiple essential functions in the developing and mature brain, including regulation of synapse formation, control of neurotransmitter release and uptake, and maintenance of extracellular ion balance. As a result, astrocytes have been implicated in the progression of neurodegenerative disorders such as Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease. Despite these critical functions, the study of human astrocytes can be difficult because standard differentiation protocols are time-consuming and technically challenging, but a differentiation protocol recently developed in our laboratory enables the efficient derivation of astrocytes from human embryonic stem cells. We used this protocol along with microarrays, luciferase, EMSA and ChIP assays to explore the genes involved in astrocyte differentiation. We demonstrate that paired-like homeodomain transcription factor 1 (PITX1) is critical for astrocyte differentiation. PITX1 overexpression induced early differentiation of astrocytes and its knockdown blocked astrocyte differentiation. PITX1 overexpression also increased and PITX1 knockdown decreased sex-determining region Y box 9 (SOX9), a known initiator of gliogenesis, expression during early astrocyte differentiation. Moreover, we determined that PITX1 activates the SOX9 promoter through a unique binding motif. Taken together, these findings indicate that PITX1 drives astrocyte differentiation by sustaining activation of the SOX9 promoter.

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