Expression of Cbl-interacting protein of 85 kDa in MPTP mouse model of Parkinson's disease and 1-methyl-4-phenyl-pyridinium ion-treated dopaminergic SH-SY5Y cells

Alterations of thyroidal status in brain regions and hypothalamo-pituitary-blood-thyroid-axis associated with dopaminergic depletion in substantia nigra and ROS formation in different brain regions after MPTP treatment in adult male mice

MPTP produces oxidative stress, damages niagrostriatal dopaminergic neurons and develops Parkinsonism in rodents. Due to paucity of information, the thyroidal status in brain regions and peripheral tissues during different post-treatment days in MPTP-induced mice had been executed in the present study. MPTP depleted tyrosine hydroxylase protein expressions that signify the dopaminergic neuronal damage in substantia nigra. MPTP elevated ROS formation differentially in brain regions (cerebral cortex, hippocampus, substantia nigra) with maximal elevation at hippocampus. The changes in thyroid hormone (T₄ and T₃) levels indicate that brain regions might combat the adverse situation by keeping the levels of thyroid hormones either unchanged or in the elevated conditions in the latter phases (day-3 and day-7), apart from the depletion of thyroid hormones in certain brain regions (T₄ in SN and hippocampus, T₃ in hippocampus) as the immediate (day-1) effects after MPTP treatment. MPTP caused alterations of cellular morphology, RNA:Protein ratio and TPO protein expression, concomitantly depleted TPO mRNA expression and elevated TSH levels in the thyroid gland. Although T₄ levels changed differentially, T₃ levels remained unaltered in thyroid gland throughout the post-treatment days. Results have been discussed mentioning the putative role of T₄ and TSH in apoptosis and/or proliferation/differentiation of thyrocytes. In blood, T₄ levels remained unchanged while the changes in T₃ and TSH levels did not signify the clinical feature of hypo/hyperthyroidism of animals. In the pituitary, both T₄ and T₃ levels remained elevated where TSH differentially altered (elevated followed by depletion) during post-treatment days. Notably, T₄, T₃ and TSH levels did not alter in hypothalamus except initial (day-1) depletion of the T₄ level. Therefore, the feedback control mechanism of hypothalamo-pituitary-blood-thyroid-axis failed to occur after MPTP treatment. Overall, MPTP altered thyroidal status in the brain and peripheral tissues while both events might occur in isolation as well.

The Aβ Containing Brain Extracts Having Different Effects in Alzheimer's Disease Transgenic Caenorhabditis elegans and Mice

Background: The deposition of β-sheet rich amyloid in senile plaques is a pathological hallmark of Alzheimer's disease (AD), which is thought to cause neuronal dysfunction. Previous studies have strongly implicated that intracerebral infusion of brain extract containing aggregated β-amyloid (Aβ) is able to induce cerebral amyloidosis thus causing neuronal damage and clinical abnormalities in rodents and nonhuman primates, which are reminiscent of a prion-like mechanism. Prion disease has been documented in cases of prion-contaminated food consumption. Methods: We investigated whether cerebral transmission of Aβ was possible via oral administration of Aβ-rich brain extract in non-susceptible and susceptible host mice by immunohistochemistry, western blotting and behavior tests. Also brain extracts were supplied to AD transgenic Caenorhabditis elegans, and paralysis curve were conducted, following detection of Aβ amyloid. RNA sequencing of nematodes was applied then inhibitors for relevant dysregulated genes were used in the paralysis induction. Results: The oral treatment of AD brain extract or normal brain extract neither aggravated nor mitigated the Aβ load, glial activation or the abnormal behaviors in recipient Amyloid precursor protein/presenilin 1 (APP/PS1) mice. Whereas, a significant improvement of AD pathology was detected in worms treated with Aβ-rich or normal brain extracts, which was attributable to the heat-sensitive components of brain extracts. Transcriptome sequencing of CL4176 nematodes suggested that brain extracts could delay worm paralysis through multiple pathways, including ubiquitin mediated proteolysis and Transforming growth factor β (TGF-β) signaling pathway. Inhibitors of the ubiquitin proteasome system and the TGF-β signaling pathway significantly blocked the suppressive effects of brain extracts on worm paralysis. Conclusions: Our results suggest that systemic transmissible mechanisms of prion proteopathy may not apply to β amyloid, at least in terms of oral administration. However, brain extracts strongly ameliorated AD pathology in AD transgenic nematodes partially through TGF-β signaling pathway and ubiquitin mediated proteolysis, which indicated that some natural endogenous components in the mammalian tissues could resist Aβ toxicity.

Dynamic Changes in the Nigrostriatal Pathway in the MPTP Mouse Model of Parkinson's Disease

The characteristic brain pathology and motor and nonmotor symptoms of Parkinson's disease (PD) are well established. However, the details regarding the causes of the disease and its course are much less clear. Animal models have significantly enriched our current understanding of the progression of this disease. Among various neurotoxin-based models of PD, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model is the most commonly studied model. Here, we provide an overview of the dynamic changes in the nigrostriatal pathway in the MPTP mouse model of PD. Pathophysiological events, such as reductions in the striatal dopamine (DA) concentrations and levels of the tyrosine hydroxylase (TH) protein, depletion of TH-positive nerve fibers, a decrease in the number of TH-positive neurons in the substantia nigra pars compacta (SNpc), and glial activation, are addressed. This article will assist with the development of interventions or therapeutic strategies for PD.

Tiagabine Protects Dopaminergic Neurons against Neurotoxins by Inhibiting Microglial Activation

Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative disorders such as Parkinson's disease (PD). γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, has recently been shown to play an inhibitory role in the immune system. Tiagabine, a piperidine derivative, enhances GABAergic transmission by inhibiting GABA transporter 1 (GAT 1). In the present study, we found that tiagabine pretreatment attenuated microglial activation, provided partial protection to the nigrostriatal axis and improved motor deficits in a methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. The protective function of tiagabine was abolished in GAT 1 knockout mice that were challenged with MPTP. In an alternative PD model, induced by intranigral infusion of lipopolysaccharide (LPS), microglial suppression and subsequent neuroprotective effects of tiagabine were demonstrated. Furthermore, the LPS-induced inflammatory activation of BV-2 microglial cells and the toxicity of conditioned medium toward SH-SY5Y cells were inhibited by pretreatment with GABAergic drugs. The attenuation of the nuclear translocation of nuclear factor κB (NF-κB) and the inhibition of the generation of inflammatory mediators were the underlying mechanisms. Our results suggest that tiagabine acts as a brake for nigrostriatal microglial activation and that it might be a novel therapeutic approach for PD.

Parkin overexpression ameliorates hippocampal long-term potentiation and β-amyloid load in an Alzheimer's disease mouse model

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by a severe decline of memory performance. A widely studied AD mouse model is the APPswe/PSEN1ΔE9 (APP/PS1) strain, as mice exhibit amyloid plaques as well as impaired memory capacities. To test whether restoring synaptic plasticity and decreasing β-amyloid load by Parkin could represent a potential therapeutic target for AD, we crossed APP/PS1 transgenic mice with transgenic mice overexpressing the ubiquitin ligase Parkin and analyzed offspring properties. Overexpression of Parkin in APP/PS1 transgenic mice restored activity-dependent synaptic plasticity and rescued behavioral abnormalities. Moreover, overexpression of Parkin was associated with down-regulation of APP protein expression, decreased β-amyloid load and reduced inflammation. Our data suggest that Parkin could be a promising target for AD therapy.

Exogenous nerve growth factor supplementation elevates myocardial immunoreactivity and attenuates cardiac remodeling in pressure-overload rats

It is postulated that supplementation of exogenous nerve growth factor (NGF) might mediate improvement of the cardiac sympathetic nerve function in heart failure (HF). Local intramuscular injection of NGF near the cardiac sympathetic ganglia could influence the innervation pattern, norepinephrine transporter (NET) gene expression, and improve the cardiac remodeling in experimental HF animals. In this study, we injected NGF into the scalenus medius muscles of Sprague-Dawley rats with abdominal aortic constriction (AC). The nerve innervated pattern, left ventricular morphology, and function following injection in rats with AC were investigated respectively by immunohistochemistry and echocardiography. Levels of mRNA expression of NET, growth associated protein 43 (GAP 43), NGF and its receptors TrkA and p75(NTR), and brain natriuretic peptide (BNP) were measured by real-time polymerase chain reaction. The results showed that myocardial NGF mRNA levels were comparable in rats with AC. Short-term supplementation of exogenous NGF raised the myocardial NGF immunoreactivity, but did not cause hyperinnervation and NET mRNA upregulation in the AC rats. Furthermore, myocardial TrkA mRNA was found to be remarkably decreased and p75(NTR) mRNA was increased. Myocardial TrkA downregulation may play a beneficial effect for avoiding the hyperinnervation, and it is reasonable to postulate that p75(NTR) can function as an NGF receptor in the absence of TrkA. Interestingly, local NGF administration into the neck muscles near the ganglia could attenuate cardiac remodeling and downregulate BNP mRNA. These results suggest that exogenous NGF can reach the target tissue along the axons anterogradely, and improve the cardiac remodeling.

Sevoflurane exposure in 7-day-old rats affects neurogenesis, neurodegeneration and neurocognitive function

OBJECTIVE

Sevoflurane is widely used in pediatric anesthesia and former studies showed that it causes neurodegeneration in the developing brain. The present study was carried out to investigate the effects of sevoflurane on neurogenesis, neurodegeneration and behavior.

METHODS

We administered 5-bromodeoxyuridine, an S-phase marker, before, during, and after 4 h of sevoflurane given to rats on postnatal day 7 to assess dentate gyrus progenitor proliferation and Fluoro-Jade staining for degeneration. Spatial reference memory was tested 2 and 6 weeks after anesthesia.

RESULTS

Sevoflurane decreased progenitor proliferation and increased cell death until at least 4 days after anesthesia. Spatial reference memory was not affected at 2 weeks but was affected at 6 weeks after sevoflurane administration.

CONCLUSION

Sevoflurane reduces neurogenesis and increases the death of progenitor cells in developing brain. This might mediate the late-onset neurocognitive outcome after sevoflurane application.

NRSF/REST neuronal deficient mice are more vulnerable to the neurotoxin MPTP

Parkinson's disease (PD) is characterized by progressing loss of dopaminergic neurons in the midbrain. Abnormal gene expression plays a critical role in its pathogenesis. Neuron-restrictive silencer factor (NRSF)/neuronal repressor element-1 silencing transcription factor (REST), a member of the zinc finger transcription factors, inhibits the expression of neuron-specific genes in nonneuronal cells, and regulates neurogenesis. Our previous work showed that 1-methyl-4-phenyl-pyridinium ion triggers dynamic changes of messenger RNA and protein expression of NRSF in human dopaminergic SH-SY5Y cells, and alteration of NRSF expression exacerbates 1-methyl-4-phenyl-pyridinium ion-induced cell death. The purpose of this study was to explore the in vivo role of NRSF in the progress of PD by using NRSF/REST neuron-specific conditional knockout mice (cKO). 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was adopted to generate PD models in the cKO mice and wild type littermates. At 1, 3, 7, 14, 21, and 28 days after MPTP injection, behavioral tests were performed, and cKO mice displayed some impairments in locomotor activities. Also, the reduction of tyrosine hydroxylase protein in the striatum and the loss of dopaminergic neurons in the substantia nigra were more severe in the cKO mice. Meanwhile, the cKO mice exhibited a more dramatic depletion of striatal dopamine, accompanied by an increase in glial fibrillary acidic protein (GFAP) expression and sustained interleukin-1β transcription. These results suggested that NRSF/REST neuronal cKO mice are more vulnerable to the dopaminergic neurotoxin MPTP. Disturbance of the homeostasis of NRSF and its target genes, gliogenesis, and inflammation may contribute to the higher MPTP sensitivity in NRSF/REST neuronal cKO mice.

Overexpression of parkin ameliorates dopaminergic neurodegeneration induced by 1- methyl-4-phenyl-1,2,3,6-tetrahydropyridine in mice

Mutations in the parkin gene are currently thought to be the most common cause of recessive familial Parkinsonism. Parkin functions as an E3 ligase to regulate protein turnover, and its function in mitochondrial quality control has been reported recently. Overexpression of parkin has been found to prevent neuronal degeneration under various conditions both in vivo and in vitro. Here, we generated a transgenic mouse model in which expression of wild type parkin was driven by neuron-specific enolase (NSE) promoter. We reported that both young and old parkin transgenic mice exhibited less reduction of striatal TH protein and number of TH positive neurons in the substantia nigra induced by 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP), compared to wild type littermates. MPTP-induced mitochondrial impairment in the substantia nigra was improved in young parkin transgenic mice. Decreased striatal α-synuclein was demonstrated in old parkin transgenic mice. These results provide reliable evidence from the transgenic mouse model for parkin that overexpression of parkin may attenuate dopaminergic neurodegeneration induced by MPTP through protection of mitochondria and reduction of α-synuclein in the nigrostriatal pathway.

BAFF-R gene induced by IFN-γ in multiple myeloma cells is related to NF-κB signals

B-cell activating factor (BAFF) is a potent cell-survival factor expressed in many haematopoietic cells. BAFF regulates B-cell survival, differentiation and proliferation by binding to three tumour necrosis factor receptors: transmembrane activator, calcium modulator and cyclophilin ligand interactor; B-cell maturation antigen; and BAFF receptor (BAFF-R). Although BAFF-R is produced by interferon gamma (IFN-γ), the underlying mechanism remains elusive. In this study, we examined the effects of IFN-γ on BAFF-R expression in cultured human multiple myeloma cells (KM3) both at the transcriptional and posttranscriptional levels. Incubation of KM3 cells with IFN-γ elevated the expression of BAFF-R mRNA and protein levels. IFN-γ elicited marked enhancement of the human BAFF-R promoter activity and nuclear factor kappa B (NF-κB) DNA binding activity. NF-κB dependent on the human BAFF-R gene might be regulated via a transcriptional event through one putative NF-κB site on the BAFF-R gene promoter. These results provide a molecular mechanism for the increase in expression of the BAFF-R gene that is induced by proinflammatory cytokines in responsive cells.

Cold water stress attenuates dopaminergic neurotoxicity induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in mice

In the present study, we tested the effect of cold water stress (CWS) on dopaminergic neurons in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model, and found that CWS pretreatment elicited less MPTP neurotoxicity. To understand the molecular mechanism underlying this phenomenon, we detected the expression of heat shock protein 70 (Hsp70) in the striatum of the experimental mice, and found that CWS pretreatment could significantly increase striatal Hsp70 in MPTP-treated mice. Furthermore, in parallel with the induction of Hsp70, the MPTP-induced increase of striatal α-synuclein was inhibited in the CWS + MPTP-treated mice. CWS pretreatment also significantly inhibited the reduction of anti-apoptotic molecule Bcl-2 expression in the striatum and enhanced Bcl-2 transcription in the substantia nigra of MPTP-treated mice. Taken together, these data indicated that Hsp70 might be an important intermediate for the neuroprotective effect of CWS against MPTP-induced dopaminergic toxicity.

A role of both NF-κB pathways in expression and transcription regulation of BAFF-R gene in multiple myeloma cells

B-lymphocyte stimulator (BAFF) is a recently recognized member of the tumor necrosis factor ligand family (TNF) and a potent cell-survival factor expressed in many hematopoietic cells. BAFF regulates B-cell survival, differentiation, and proliferation by binding to three TNF receptors: TACI, BCMA, and BAFF-R. The mechanism involved in BAFF-R gene expression and regulation remains elusive. In this study, we examined BAFF-R gene expression, function, and regulation in multiple myeloma (KM3) cells. It was found that BAFF-BAFF-R induced cell survival by activating NF-κB1 pathway and NF-κB2 pathway. It was also found that NF-κB was an important transcription factor involved in regulating BAFF-R expression through one NF-κB binding site in the BAFF-R promoter, suggesting that inhibiting NF-κB could decrease the expression of BAFF-R mRNA and protein, and promote activity of BAFF-R gene. Our findings indicate that both NF-κB pathways are involved in the regulation of BAFF-R gene and the NF-κB-binding site of BAFF-R may be a new therapeutic target in this disease.

Ethanol-induced neurodegeneration in NRSF/REST neuronal conditional knockout mice

The transcription regulator, neuron-restrictive silencer factor (NRSF), also known as repressor element-1 silencing transcription factor (REST), plays an important role in neurogenesis and various neuronal diseases such as ischaemia, epilepsy, and Huntington's disease. In these disease processes, neuronal loss is associated with abnormal expression and/or localization of NRSF. Previous studies have demonstrated that NRSF regulates the effect of ethanol on neuronal cells in vitro, however, the role of NRSF in ethanol-induced neuronal cell death remains unclear. We generated nrsf conditional knockout mice using the Cre-loxP system to disrupt neuronal expression of nrsf and its truncated forms. At postnatal day 6, ethanol significantly increased the expression of REST4, a neuron-specific truncated form of NRSF, in the brains of wild type mice, and this effect was diminished in nrsf conditional knockout mice. The apoptotic effect of ethanol was pronounced in multiple brain regions of nrsf conditional mutant mice. These results indicate that NRSF, specifically REST4, may protect the developing brain from ethanol, and provide new evidence that NRSF can be a therapeutic target in foetal alcohol syndrome (FAS).

Requirement of regulated endocrine-specific protein-18 for development and expression of regulated endocrine-specific protein-18 isoform c in mice

Regulated endocrine-specific protein-18 (RESP18) is distributed mainly in the peripheral endocrine and neuroendocrine tissues. The expression of RESP18 protein is regulated by physiological factors, such as blood glucose or dopaminergic drugs, but its functions remain unclear. In this study, to explore the biological functions of RESP18 in vivo, we generated RESP18 heterozygous deficient mice, and further found RESP18 was essential for embryonic development. In addition, we cloned a new isoform of mouse RESP18 by reverse transcription-polymerase chain reaction (RT-PCR), and denominated it as RESP18-c. Mouse RESP18-c, by skipping exon4 (43 bp in length), encodes a shorter protein of 120 amino acid residues. The distribution of RESP18-c mRNA is similar with that of RESP18 mRNA in the peripheral tissues and brains of mice.

CIN85 regulates dopamine receptor endocytosis and governs behaviour in mice

Despite extensive investigations of Cbl-interacting protein of 85 kDa (CIN85) in receptor trafficking and cytoskeletal dynamics, little is known about its functions in vivo. Here, we report the study of a mouse deficient of the two CIN85 isoforms expressed in the central nervous system, exposing a function of CIN85 in dopamine receptor endocytosis. Mice lacking CIN85 exon 2 (CIN85(Deltaex2)) show hyperactivity phenotypes, characterized by increased physical activity and exploratory behaviour. Interestingly, CIN85(Deltaex2) animals display abnormally high levels of dopamine and D2 dopamine receptors (D2DRs) in the striatum, an important centre for the coordination of animal behaviour. Importantly, CIN85 localizes to the post-synaptic compartment of striatal neurons in which it co-clusters with D2DRs. Moreover, it interacts with endocytic regulators such as dynamin and endophilins in the striatum. Absence of striatal CIN85 causes insufficient complex formation of endophilins with D2DRs in the striatum and ultimately decreased D2DR endocytosis in striatal neurons in response to dopamine stimulation. These findings indicate an important function of CIN85 in the regulation of dopamine receptor functions and provide a molecular explanation for the hyperactive behaviour of CIN85(Deltaex2) mice.

Alteration of NRSF expression exacerbating 1-methyl-4-phenyl-pyridinium ion-induced cell death of SH-SY5Y cells

Neuron-restrictive silencer factor (NRSF)/neuronal repressor element-1 silencing transcription factor (REST) and its neuron-specific truncated form REST4 participates in the pathological processes of nervous system diseases, such as global ischemia, epilepsy, Huntington disease and so on. In this paper, we investigated the changes of NRSF and REST4 in a cellular model of Parkinson's disease (PD). Our results showed that neurotoxin 1-methyl-4-phenyl-pyridinium ion (MPP(+)) treatment triggered the mRNA and protein expression of NRSF and REST4, and caused both NRSF and REST4 proteins relocalized between the nucleus and cytoplasm in human dopaminergic SH-SY5Y cells. Redistribution of NRSF and REST4 derepressed the expression of target genes at late time points. Furthermore, alteration of NRSF and REST4 expression by overexpression or RNAi techniques elicited deleterious effects on cell viability of SH-SY5Y treated with toxic MPP(+).