Upregulation of the stress-associated gene p8 in mouse models of demyelination and in multiple sclerosis tissues

Different Methods for Evaluating Microglial Activation Using Anti-Ionized Calcium-Binding Adaptor Protein-1 Immunohistochemistry in the Cuprizone Model

Microglia play an important role in the pathology of various central nervous system disorders, including multiple sclerosis (MS). While different methods exist to evaluate the extent of microglia activation, comparative studies investigating the sensitivity of these methods are missing for most models. In this study, we systematically evaluated which of the three commonly used histological methods (id est, quantification of microglia density, densitometrically evaluated staining intensity, or cellular morphology based on the determination of a ramification index, all measured in anti-ionized calcium-binding adaptor protein-1 (IBA1) immunohistochemical stains) is the most sensitive method to detect subtle changes in the microglia activation status in the context of MS. To this end, we used the toxin-induced cuprizone model which allows the experimental induction of a highly reproducible demyelination in several central nervous system regions, paralleled by early microglia activation. In this study, we showed that after 3 weeks of cuprizone intoxication, all methods reveal a significant microglia activation in the white matter corpus callosum. In contrast, in the affected neocortical grey matter, the evaluation of anti-IBA1 cell morphologies was the most sensitive method to detect subtle changes of microglial activation. The results of this study provide a useful guide for future immunohistochemical evaluations in the cuprizone and other neurodegenerative models.

Oncogenic Role of NUPR1 in Ovarian Cancer

Background

Nuclear protein 1 (NUPR1) plays a critical role in the development and progression of various types of human cancers. However, the role and mechanism of NUPR1 in ovarian cancer have not been elucidated. The purpose of this study was to investigate the effect of NUPR1 on ovarian cancer in vivo and in vitro.

Materials and Methods

Through the pretreatment of ovarian cancer cell lines, including A2780 and SKOV3 cells, the expression of NUPR1 was detected by RT-PCR and Western blot assays. When NUPR1 was overexpressed and knocked down in A2780 cells and overexpressed in SKOV3 cells, the MTT assays, colony formation assays and EdU assays were used to detect cell proliferation. Furthermore, cell invasion and migration ability were detected with the transwell assays. Cell cycle and apoptosis of A2780 cells after small interfering RNA-NUPR1 (siRNA-NUPR1) were detected by flow cytometry assays. Finally, the effect of NUPR1 gene silencing on the growth of ovarian cancer was evaluated by tumor xenograft experiment in vivo.

Results

The expression of NUPR1 protein in A2780 cells was significantly higher than that in ovarian surface epithelium (OSE) cells (P < 0.05). The results showed that downregulation of NUPR1 gene expression significantly inhibited the proliferation, migration and invasion ability of A2780 cells, and increased apoptosis of A2780 cells, which expressed relatively high levels of NUPR1. And the expression of apoptosis-related proteins caspase 3, caspase 9 and Bax was upregulated when NUPR1 was knocked out, while the expression of anti-apoptotic proteins of Bcl-2 and Bcl-xl was downregulated. At the same time, the opposite results were observed when NUPR1 was overexpressed in A2780 and SKOV3 cells. Notably, the effect of NUPR1 overexpression in A2780 cells could be partially or completely eliminated by treatment with the AKT inhibitor LY294002. In addition, NUPR1 knockdown could effectively inhibit tumor growth of mice in vivo.

Conclusion

In summary, NUPR1 has a carcinogenic effect in ovarian cancer, and the oncogenic effect of NUPR1 in ovarian cancer may be achieved by the AKT pathway.

Neuronal activity-dependent myelin repair promotes motor function recovery after contusion spinal cord injury

An increasing number of studies connect neuronal activity with developmental myelination but how neuronal activity regulates remyelination has not been clarified. In this study, we induced the demyelination of the dorsal corticospinal tract (dCST) by a mild contusion spinal cord injury (SCI) on the T10 segment, and manipulated the neuronal activity of the primary motor cortex (M1) using chemogenetic viruses to induce activity and to suppress it. We found that oligodendrocyte precursor cell (OPC) proliferation and oligodendrocyte maturity following remyelination was strengthened after 4-week of neuronal activity stimulation. Furthermore, hindlimb motor function was also found to be improved. Vice versa, suppression of neuronal activity attenuated these effects. These results indicate that bidirectional regulation of neuronal activity can effectively modulate the development of oligodendrocyte lineage cells and the remyelination process. Neuronal activity supports the proliferation of OPCs, improves oligodendrocyte maturation and amplifies the axonal remyelination process, even though leads to better motor function recovery. Manipulation of neuronal activity in a non-invasive manner is therefore a promising avenue for exploration towards the treatment of central nervous system (CNS) demyelination diseases.

Re-Examining the Role of TNF in MS Pathogenesis and Therapy

Multiple sclerosis (MS) is a common neurological disorder of putative autoimmune origin. Clinical and experimental studies delineate abnormal expression of specific cytokines over the course of the disease. One major cytokine that has been shown to play a pivotal role in MS is tumor necrosis factor (TNF). TNF is a pleiotropic cytokine regulating many physiological and pathological functions of both the immune system and the central nervous system (CNS). Convincing evidence from studies in human and experimental MS have demonstrated the involvement of TNF in various pathological hallmarks of MS, including immune dysregulation, demyelination, synaptopathy and neuroinflammation. However, due to the complexity of TNF signaling, which includes two-ligands (soluble and transmembrane TNF) and two receptors, namely TNF receptor type-1 (TNFR1) and type-2 (TNFR2), and due to its cell- and context-differential expression, targeting the TNF system in MS is an ongoing challenge. This review summarizes the evidence on the pathophysiological role of TNF in MS and in different MS animal models, with a special focus on pharmacological treatment aimed at controlling the dysregulated TNF signaling in this neurological disorder.

Cellular and molecular neuropathology of the cuprizone mouse model: clinical relevance for multiple sclerosis

The cuprizone mouse model allows the investigation of the complex molecular mechanisms behind nonautoimmune-mediated demyelination and spontaneous remyelination. While it is generally accepted that oligodendrocytes are specifically vulnerable to cuprizone intoxication due to their high metabolic demands, a comprehensive overview of the etiology of cuprizone-induced pathology is still missing to date. In this review we extensively describe the physico-chemical mode of action of cuprizone and discuss the molecular and enzymatic mechanisms by which cuprizone induces metabolic stress, oligodendrocyte apoptosis, myelin degeneration and eventually axonal and neuronal pathology. In addition, we describe the dual effector function of the immune system which tightly controls demyelination by effective induction of oligodendrocyte apoptosis, but in contrast also paves the way for fast and efficient remyelination by the secretion of neurotrophic factors and the clearance of cellular and myelinic debris. Finally, we discuss the many clinical symptoms that can be observed following cuprizone treatment, and how these strengthened the cuprizone model as a useful tool to study human multiple sclerosis, schizophrenia and epilepsy.

Expression and roles of As-NUPR1 protein from Artemia sinica during embryo development and in response to salinity stress

As-NUPR1, a stress-related protein, plays an important role in post-diapause during embryonic development in the brine shrimp Artemia sinica. In the present study, successful expression of As-NUPR1 from the cDNA sequence isolated from A. sinica was demonstrated using a prokaryotic expression system. The recombinant protein consisted of 132 amino acids with a molecular weight of 15 kDa, and a predicted isoelectric point of 7.17. As-NUPR1 polyclonal antibodies were prepared by immunization of Balb/c mice with purified recombinant As-NUPR1 protein as an antigen, and immunological studies were carried out. Expression of As-NUPR1 during different developmental stages of the embryo and in response to salinity stress was analyzed in A. sinica using Western blots. The experimental results showed that the expression of As-NUPR1 is widely distributed at different developmental stages in A. sinica, and there was no tissue or organ specificity. Expression of As-NUPR1 decreased gradually during the diapause termination stage of embryo development, after which there was a general increase in expression after breaking the shell. In addition, As-NUPR1 expression was highly upregulated under conditions of high salinity. These results suggest that the As-NUPR1 protein is a stress-related protein that plays a role in protecting embryos from high salt damage in different embryonic developmental stages, especially during the post-diapause period.

Expression and roles of NUPR1 in cholangiocarcinoma cells

Nuclear protein-1 (NUPR1) is a small nuclear protein that is responsive to various stress stimuli. Although NUPR1 has been associated with cancer development, its expression and roles in cholangiocarcinoma have not yet been described. In the present study, we found that NUPR1 was over-expressed in human cholangiocarcinoma tissues, using immunohistochemistry. The role of NUPR1 in cholangiocarcinoma was examined by its specific siRNA. NUPR1 siRNA decreased proliferation, migration and invasion of human cholangiocarcinoma cell lines (HuCCT1 and SNU1196 cells). From these results, we conclude that NUPR1 is over-expressed in cholangiocarcinoma and regulates the proliferation and motility of cancer cells.

Nupr1: the Swiss-knife of cancer

Nupr1 is a small, highly basic and loosely folded multifunctional protein whose expression is induced by several stresses. Its relation to cancer was first suggested by its overexpression in several human malignancies and the association of its expression with breast cancer metastasis. Accordingly, Nupr1 is structurally related to the high-mobility group (HMG) of transcriptional regulators, which play a key role in the stress response and in cancer progression. Nupr1 interacts with numerous partners to regulate cell cycle, programmed cell death, autophagy, chromatin accessibility, and transcription, and its expression is required for regulation of TGFβ activity. Pleiotropic functions accomplished by Nupr1 depend on its molecular partners, its location into the cell, its expression level and on the cell-type. Nupr1 might be a new drug-targetable protein whose blockade would prevent cancer progression and metastasis development.

Proteomic analysis of demyelinated and remyelinating brain tissue following dietary cuprizone administration

Cuprizone intoxication is a commonly used model of demyelination that allows the temporal separation of demyelination and remyelination. The underlying biochemical alterations leading to demyelination, using this model, remain unclear and may be multifold. Analysis of proteomic changes within the brains of cuprizone-exposed animals may help elucidate key cellular processes. In the current study, we report the results of the liquid chromatography tandem mass spectrometry analysis of total protein from the brain hemispheres of control and toxin-exposed mice at 6 weeks of exposure and after 3 and 6 weeks of recovery to identify protein changes during the remyelination phase. We found that at 6 weeks of cuprizone exposure, myelin proteins were reduced compared to controls and increased throughout the course of recovery, as expected. In contrast, other protein groups, such as proteins related to mitochondrial function, were increased at 6 weeks of treatment compared to untreated controls and returned toward control levels following withdrawal of toxin. These results suggest that a global proteomic analysis of the brain tissue of cuprizone-treated mice can identify changes related to the demyelination/remyelination process.

Luteolin triggers global changes in the microglial transcriptome leading to a unique anti-inflammatory and neuroprotective phenotype

Background

Luteolin, a plant derived flavonoid, exerts a variety of pharmacological activities and anti-oxidant properties associated with its capacity to scavenge oxygen and nitrogen species. Luteolin also shows potent anti-inflammatory activities by inhibiting nuclear factor kappa B (NFkB) signaling in immune cells. To better understand the immuno-modulatory effects of this important flavonoid, we performed a genome-wide expression analysis in pro-inflammatory challenged microglia treated with luteolin and conducted a phenotypic and functional characterization.

Methods

Resting and LPS-activated BV-2 microglia were treated with luteolin in various concentrations and mRNA levels of pro-inflammatory markers were determined. DNA microarray experiments and bioinformatic data mining were performed to capture global transcriptomic changes following luteolin stimulation of microglia. Extensive qRT-PCR analyses were carried out for an independent confirmation of newly identified luteolin-regulated transcripts. The activation state of luteolin-treated microglia was assessed by morphological characterization. Microglia-mediated neurotoxicity was assessed by quantifying secreted nitric oxide levels and apoptosis of 661W photoreceptors cultured in microglia-conditioned medium.

Results

Luteolin dose-dependently suppressed pro-inflammatory marker expression in LPS-activated microglia and triggered global changes in the microglial transcriptome with more than 50 differentially expressed transcripts. Pro-inflammatory and pro-apoptotic gene expression was effectively blocked by luteolin. In contrast, mRNA levels of genes related to anti-oxidant metabolism, phagocytic uptake, ramification, and chemotaxis were significantly induced. Luteolin treatment had a major effect on microglial morphology leading to ramification of formerly amoeboid cells associated with the formation of long filopodia. When co-incubated with luteolin, LPS-activated microglia showed strongly reduced NO secretion and significantly decreased neurotoxicity on 661W photoreceptor cultures.

Conclusions

Our findings confirm the inhibitory effects of luteolin on pro-inflammatory cytokine expression in microglia. Moreover, our transcriptomic data suggest that this flavonoid is a potent modulator of microglial activation and affects several signaling pathways leading to a unique phenotype with anti-inflammatory, anti-oxidative, and neuroprotective characteristics. With the identification of several novel luteolin-regulated genes, our findings provide a molecular basis to understand the versatile effects of luteolin on microglial homeostasis. The data also suggest that luteolin could be a promising candidate to develop immuno-modulatory and neuroprotective therapies for the treatment of neurodegenerative disorders.

Stress-inducible protein p8 is involved in several physiological and pathological processes

p8 (NUPR1 (nuclear protein-1), Com1 (candidate of metastasis-1)) is a protein related to the high mobility group of transcriptional regulators. It is a key player in the cellular stress response and is involved in metastasis. p8 was first identified as a gene induced in pancreatitis but has been since found overexpressed in several cancers and pathological conditions. Despite its small size and apparently simple structure, p8 functions in several biochemical and genetic pathways, and its expression is crucial for in vivo metastasis in mice, for cytokine induction of metalloproteases, and for stress-induced cardiomyocyte hypertrophy. Understanding p8 functions will provide new opportunities for developing more effective therapeutic approaches to cancer and cardiovascular diseases.

Impact of sex steroids on neuroinflammatory processes and experimental multiple sclerosis

Synthetic and natural estrogens as well as progestins modulate neuronal development and activity. Neurons and glia are endowed with high-affinity steroid receptors. Besides regulating brain physiology, both steroids conciliate neuroprotection against toxicity and neurodegeneration. The majority of data derive from in vitro studies, although more recently, animal models have proven the efficaciousness of steroids as neuroprotective factors. Indications for a safeguarding role also emerge from first clinical trials. Gender-specific prevalence of degenerative disorders might be associated with the loss of hormonal activity or steroid malfunctions. Our studies and evidence from the literature support the view that steroids attenuate neuroinflammation by reducing the pro-inflammatory property of astrocytes. This effect appears variable depending on the brain region and toxic condition. Both hormones can individually mediate protection, but they are more effective in cooperation. A second research line, using an animal model for multiple sclerosis, provides evidence that steroids achieve remyelination after demyelination. The underlying cellular mechanisms involve interactions with astroglia, insulin-like growth factor-1 responses, and the recruitment of oligodendrocytes.

A systems approach to prion disease

Prions cause transmissible neurodegenerative diseases and replicate by conformational conversion of normal benign forms of prion protein (PrP^C) to disease-causing PrP^Sc isoforms. A systems approach to disease postulates that disease arises from perturbation of biological networks in the relevant organ. We tracked global gene expression in the brains of eight distinct mouse strain–prion strain combinations throughout the progression of the disease to capture the effects of prion strain, host genetics, and PrP concentration on disease incubation time. Subtractive analyses exploiting various aspects of prion biology and infection identified a core of 333 differentially expressed genes (DEGs) that appeared central to prion disease. DEGs were mapped into functional pathways and networks reflecting defined neuropathological events and PrP^Sc replication and accumulation, enabling the identification of novel modules and modules that may be involved in genetic effects on incubation time and in prion strain specificity. Our systems analysis provides a comprehensive basis for developing models for prion replication and disease, and suggests some possible therapeutic approaches.

Transgenic inhibition of astroglial NF-kappa B improves functional outcome in experimental autoimmune encephalomyelitis by suppressing chronic central nervous system inflammation

In the CNS, the transcription factor NF-kappaB is a key regulator of inflammation and secondary injury processes. Following trauma or disease, the expression of NF-kappaB-dependent genes is activated, leading to both protective and detrimental effects. In this study, we show that transgenic inactivation of astroglial NF-kappaB (glial fibrillary acidic protein-IkappaB alpha-dominant-negative mice) resulted in reduced disease severity and improved functional recovery following experimental autoimmune encephalomyelitis. At the chronic stage of the disease, transgenic mice exhibited an overall higher presence of leukocytes in spinal cord and brain, and a markedly higher percentage of CD8(+)CD122(+) T regulatory cells compared with wild type, which correlated with the timing of clinical recovery. We also observed that expression of proinflammatory genes in both spinal cord and cerebellum was delayed and reduced, whereas the loss of neuronal-specific molecules essential for synaptic transmission was limited compared with wild-type mice. Furthermore, death of retinal ganglion cells in affected retinas was almost abolished, suggesting the activation of neuroprotective mechanisms. Our data indicate that inhibiting NF-kappaB in astrocytes results in neuroprotective effects following experimental autoimmune encephalomyelitis, directly implicating astrocytes in the pathophysiology of this disease.

Developmentally regulated synthesis of p8, a stress-associated transcription cofactor, in diapause-destined embryos of Artemia franciscana

Diapause-destined embryos of the crustacean Artemia franciscana arrest as gastrulae, acquire extreme stress tolerance, and enter profound metabolic dormancy. Among genes upregulated at 2 days postfertilization in these embryos is a homologue of p8, a stress-inducible transcription cofactor. Artemia p8 is smaller than vertebrate homologues but shares a basic helix-loop-helix domain and a bipartite nuclear localization signal. Probing of restriction digested DNA on Southern blots indicated a single Artemia p8 gene and 5'-RACE specified 2 transcription start sites. Several putative cis-acting regulatory sequences, including two heat shock elements, appeared upstream of the p8 transcription start site. Artemia p8 mRNA increased sharply at 1 day postfertilization in diapause-destined embryos and then declined, whereas p8 protein appeared 2 days postfertilization and remained relatively constant throughout development, indicating a stable protein. p8 was not detectable in nauplius-destined (nondiapause) Artemia embryos. Immunofluorescent staining revealed p8 within Artemia nuclei. The results support the idea that p8, a known stressresponsive transcription cofactor, mediates gene expression in diapause-destined Artemia embryos. p8 is the first diapause-related transcription factor identified in crustaceans and 1 of only a small number of such proteins identified in any organism undergoing diapause.

The murine p8 gene promoter is activated by activating transcription factor 4 (ATF4) in the gonadotrope-derived LbetaT2 cell line

The factor p8 is a high mobility group (HMG) A family member that is upregulated during the cellular stress response in numerous tissues. Because expression of this protein encourages cellular transformation, our goal is to characterize the mechanism by which the p8 gene is regulated. Using LbetaT2 cells as a model of a transformed cell in which p8 plays a role in tumor formation, we dissected the p8 promoter into its minimal functional units and found that activating transcription factor 4 (ATF4), a factor also upregulated during cellular stress responses, enhances p8 promoter activity in a dose-dependent manner. In addition, ATF4 binds in the highly conserved major activation domain of the p8 proximal promoter between -130 and -100 bp. Furthermore, we show that six of the nine base pairs that encompass the putative element are essential for ATF4 binding. These findings increase our knowledge of the mechanisms regulating the p8 gene in a genetically defined tumor model.