Protein repertoire impact of Ubiquitin-Proteasome System impairment: insight into the protective role of beta-estradiol

17-β-estradiol potentiates the neurotrophic and neuroprotective effects mediated by the dopamine D3/acetylcholine nicotinic receptor heteromer in dopaminergic neurons

Dopaminergic neurons express a heteromer composed of the dopamine D3 receptor and the α4β2 nicotinic acetylcholine receptor, the D3R-nAChR heteromer, activated by both nicotine and dopamine D2 and D3 receptors agonists, such as quinpirole, and crucial for dopaminergic neuron homeostasis. We now report that D3R-nAChR heteromer activity is potentiated by 17-β-estradiol which acts as a positive allosteric modulator by binding a specific domain on the α4 subunit of the nicotinic receptor protomer. In mouse dopaminergic neurons, in fact, 17-β-estradiol significantly increased the ability of nicotine and quinpirole in promoting neuron dendritic remodeling and in protecting neurons against the accumulation of α-synuclein induced by deprivation of glucose, with a mechanism that does not involve the classical estrogen receptors. The potentiation induced by 17-β-estradiol required the D3R-nAChR heteromer since either nicotinic receptor or dopamine D3 receptor antagonists and interfering TAT-peptides, but not the estrogen receptor antagonist fulvestrant, specifically prevented 17-β-estradiol effects. Evidence of estrogens neuroprotection, mainly mediated by genomic mechanisms, have been provided, which is in line with epidemiological data reporting that females are less likely to develop Parkinson's Disease than males. Therefore, potentiation of D3R-nAChR heteromer activity may represent a further mechanism by which 17-β-estradiol reduces dopaminergic neuron vulnerability.

Neuroactive steroids and Parkinson's disease: Review of human and animal studies

The greater prevalence and incidence of Parkinson's disease (PD) in men suggest a beneficial effect of sex hormones. Neuroactive steroids have neuroprotective activities thus offering interesting option for disease-modifying therapy for PD. Neuroactive steroids are also neuromodulators of neurotransmitter systems and may thus help to control PD symptoms and side effect of dopamine medication. Here, we review the effect on sex hormones (estrogen, androgen, progesterone and its metabolites) as well as androstenediol, pregnenolone and dehydroepiandrosterone) in human studies and in animal models of PD. The effect of neuroactive steroids is reviewed by considering sex and hormonal status to help identify specifically for women and men with PD what might be a preventive approach or a symptomatic treatment. PD is a complex disease and the pathogenesis likely involves multiple cellular processes. Thus it might be useful to target different cellular mechanisms that contribute to neuronal loss and neuroactive steroids provide therapeutics options as they have multiple mechanisms of action.

Impact of Pharmacological Inhibition of Hydrogen Sulphide Production in the SOD1G93A-ALS Mouse Model

A number of factors can trigger amyotrophic lateral sclerosis (ALS), although its precise pathogenesis is still uncertain. In a previous study done by us, poisonous liquoral levels of hydrogen sulphide (H₂S) in sporadic ALS patients were reported. In the same study very high concentrations of H₂S in the cerebral tissues of the familial ALS (fALS) model of the SOD1G93A mouse, were measured. The objective of this study was to test whether decreasing the levels of H₂S in the fALS mouse could be beneficial. Amino-oxyacetic acid (AOA)—a systemic dual inhibitor of cystathionine-β-synthase and cystathionine-γ lyase (two key enzymes in the production of H₂S)—was administered to fALS mice. AOA treatment decreased the content of H₂S in the cerebral tissues, and the lifespan of female mice increased by approximately ten days, while disease progression in male mice was not affected. The histological evaluation of the spinal cord of the females revealed a significant increase in GFAP positivity and a significant decrease in IBA1 positivity. In conclusion, the results of the study indicate that, in the animal model, the inhibition of H₂S production is more effective in females. The findings reinforce the need to adequately consider sex as a relevant factor in ALS.

Repurposing sex steroids and related drugs as potential treatment for Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder for which a greater prevalence and incidence is described in men. This suggests a protective effect of sex hormones in the brain. Therefore, steroids and drugs to treat endocrine conditions could have additional application for PD. Here, we review the protective effect of sex hormones, particularly estrogens, progesterone, androgens and dehydroepiandrosterone, in animal models of PD and also in human studies. Data also support that drugs affecting estrogen neurotransmission such as selective estrogen receptor modulators or affecting steroid metabolism with 5α-reductase inhibitors could be repositioned for treatment of PD. Sex steroids are also modulator of neurotransmission, thus they could repurposed to treat PD motor symptoms and to modulate the response to PD medication. No drug is yet available to limit PD progression. PD is a complex disease implicating multiple pathological processes and a therapeutic strategy using drugs with several mechanisms of action, such as sex steroids and endocrine drugs are interesting repositioning options for symptomatic treatment and disease-modifying activity for PD. This article is part of the Special Issue entitled 'Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders'.

Resveratrol protects neuronal-like cells expressing mutant Huntingtin from dopamine toxicity by rescuing ATG4-mediated autophagosome formation

Parkinsonian-like motor deficits in Huntington's Disease (HD) patients are associated with abnormal dopamine neurotransmission in the striatum. Dopamine metabolism leads to the formation of oxidized dopamine quinones that exacerbates mitochondrial dysfunction with production of reactive oxygen species (ROS) that eventually lead to neuronal cell death. We have previously shown that dopamine-induced oxidative stress triggers apoptotic cell death in dopaminergic neuroblastoma SH-SY5Y cells hyper-expressing the mutant polyQ Huntingtin (polyQ-Htt) protein. Dopamine toxicity was paralleled by impaired autophagy clearance of the polyQ-Htt aggregates. In this study, we found that Dopamine affects the stability and function of ATG4, a redox-sensitive cysteine-protein involved in the processing of LC3, a key step in the formation of autophagosomes. Resveratrol, a dietary polyphenol with anti-oxidant and pro-autophagic properties, has shown neuroprotective potential in HD. Yet the molecular mechanism through which Resveratrol can protect HD cells against DA is not known. Here, we show that Resveratrol prevents the generation of ROS, restores the level of ATG4, allows the lipidation of LC3, facilitates the degradation of polyQ-Htt aggregates and protects the cells from Dopamine toxicity. The present findings provide a mechanistic explanation of the neuroprotective activity of Resveratrol and support its inclusion in a therapeutic regimen to slow down HD progression.

Cellular effects induced by 17-β-estradiol to reduce the survival of renal cell carcinoma cells

Background

Renal cell carcinoma (RCC) is an adult malignancy with 2:1 men-to-women ratio, which implies the possible role of sex hormones in RCC carcinogenesis. One of the predominant sex hormones in women before menopause, 17-β-estradiol (or E2), may regulate RCC growth by cellular mechanisms that are still not fully understood.

Methods

The expression levels of E2 receptors (ER1 and ER2) were determined in different RCC cell lines. The DNA damage response induced by E2 was determined by a DNA double-strand break marker γH2AX. To study the possible effect of E2 on oxidative stress response, RCC cells were stained with 2,7-dichlorofluorescein diacetate and analyzed by flow cytometry. Upregulation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) ser40 phosphorylation in response to oxidative stress was detected by immunoblotting. Finally, annexin V/propidium iodide (PI) double staining assay was used to determine E2-induced cellular apoptosis.

Results

Variable expression of ER1 and ER2 were found in the RCC cell lines studied (786-O, A498, and ACHN), in which ACHN and A498 showed highest and lowest ER expression, respectively. In A498 cells, E2 induced DNA double-strand breaks with positive staining of γH2AX. On the other hand, the level of reactive oxidative species were elevated in ACHN cells after E2 treatment. The E2-induced oxidative stress also induced the Ser40 phosphorylation and nuclear translocation of Nrf2. Finally, we also demonstrated that E2 induced apoptosis as revealed by annexin V/PI double staining.

Conclusions

In this study, we demonstrated the cellular effects of E2 on DNA repair, ROS production as well as Nrf2 activation, and apoptosis in RCC cell lines. Together these cellular alterations may contribute to the reduced viability of RCC cells following E2 treatment.

Cooperation of Genomic and Rapid Nongenomic Actions of Estrogens in Synaptic Plasticity

Neuroplasticity refers to the changes in the molecular and cellular processes of neural circuits that occur in response to environmental experiences. Clinical and experimental studies have increasingly shown that estrogens participate in the neuroplasticity involved in cognition, behavior, and memory. It is generally accepted that estrogens exert their effects through genomic actions that occur over a period of hours to days. However, emerging evidence indicates that estrogens also rapidly influence the neural circuitry through nongenomic actions. In this review, we provide an overview of the genomic and nongenomic actions of estrogens and discuss how these actions may cooperate in synaptic plasticity. We then summarize the role of epigenetic modifications, synaptic protein synthesis, and posttranslational modifications, and the splice variants of estrogen receptors in the complicated network of estrogens. The combination of genomic and nongenomic mechanisms endows estrogens with considerable diversity in modulating neural functions including synaptic plasticity.

17beta-estradiol counteracts neuropathic pain: a behavioural, immunohistochemical, and proteomic investigation on sex-related differences in mice

Sex differences play a role in pain sensitivity, efficacy of analgesic drugs and prevalence of neuropathic pain, even if the underlying mechanisms are far from being understood. We demonstrate that male and female mice react differently to structural and functional changes induced by sciatic nerve ligature, used as model of neuropathic pain. Male mice show a gradual decrease of allodynia and a complete recovery while, in females, allodynia and gliosis are still present four months after neuropathy induction. Administration of 17β-estradiol is able to significantly attenuate this difference, reducing allodynia and inducing a complete recovery also in female mice. Parallel to pain attenuation, 17β-estradiol treated-mice show a functional improvement of the injured limb, a faster regenerative process of the peripheral nerve and a decreased neuropathy-induced gliosis. These results indicate beneficial effects of 17β-estradiol on neuropathic pain and neuronal regeneration and focuses on the importance of considering gonadal hormones also in clinical studies.

Liver protein profiles in insulin receptor-knockout mice reveal novel molecules involved in the diabetes pathophysiology

Liver has a principal role in glucose regulation and lipids homeostasis. It is under a complex control by substrates such as hormones, nutrients, and neuronal impulses. Insulin promotes glycogen synthesis, lipogenesis, and lipoprotein synthesis and inhibits gluconeogenesis, glycogenolysis, and VLDL secretion by modifying the expression and enzymatic activity of specific molecules. To understand the pathophysiological mechanisms leading to metabolic liver disease, we analyzed liver protein patterns expressed in a mouse model of diabetes by proteomic approaches. We used insulin receptor-knockout (IR(-/-)) and heterozygous (IR(+/-)) mice as a murine model of liver metabolic dysfunction associated with diabetic ketoacidosis and insulin resistance. We evaluated liver fatty acid levels by microscopic examination and protein expression profiles by orthogonal experimental strategies using protein 2-DE MALDI-TOF/TOF and peptic nLC-MS/MS shotgun profiling. Identified proteins were then loaded into Ingenuity Pathways Analysis to find possible molecular networks. Twenty-eight proteins identified by 2-DE analysis and 24 identified by nLC-MS/MS shotgun were differentially expressed among the three genotypes. Bioinformatic analysis revealed a central role of high-mobility group box 1/2 and huntigtin never reported before in association with metabolic and related liver disease. A different modulation of these proteins in both blood and hepatic tissue further suggests their role in these processes. These results provide new insight into pathophysiology of insulin resistance and hepatic steatosis and could be useful in identifying novel biomarkers to predict risk for diabetes and its complications.

p63 isoforms regulate metabolism of cancer stem cells

p63 is an important regulator of epithelial development expressed in different variants containing (TA) or lacking (ΔN) the N-terminal transactivation domain. The different isoforms regulate stem-cell renewal and differentiation as well as cell senescence. Several studies indicate that p63 isoforms also play a role in cancer development; however, very little is known about the role played by p63 in regulating the cancer stem phenotype. Here we investigate the cellular signals regulated by TAp63 and ΔNp63 in a model of epithelial cancer stem cells. To this end, we used colon cancer stem cells, overexpressing either TAp63 or ΔNp63 isoforms, to carry out a proteomic study by chemical-labeling approach coupled to network analysis. Our results indicate that p63 is implicated in a wide range of biological processes, including metabolism. This was further investigated by a targeted strategy at both protein and metabolite levels. The overall data show that TAp63 overexpressing cells are more glycolytic-active than ΔNp63 cells, indicating that the two isoforms may regulate the key steps of glycolysis in an opposite manner. The mass-spectrometry proteomics data of the study have been deposited to the ProteomeXchange Consortium ( http://proteomecentral.proteomexchange.org ) via the PRIDE partner repository with data set identifiers PXD000769 and PXD000768.

Proteomic profiling of ATM kinase proficient and deficient cell lines upon blockage of proteasome activity

Ataxia Telangiectasia Mutated (ATM) protein kinase is a key effector in the modulation of the functionality of some important stress responses, including DNA damage and oxidative stress response, and its deficiency is the hallmark of Ataxia Telangiectasia (A-T), a rare genetic disorder. ATM modulates the activity of hundreds of target proteins, essential for the correct balance between proliferation and cell death. The aim of this study is to evaluate the phenotypic adaptation at the protein level both in basal condition and in presence of proteasome blockage in order to identify the molecules whose level and stability are modulated through ATM expression. We pursued a comparative analysis of ATM deficient and proficient lymphoblastoid cells by label-free shotgun proteomic experiments comparing the panel of proteins differentially expressed. Through a non-supervised comparative bioinformatic analysis these data provided an insight on the functional role of ATM deficiency in cellular carbohydrate metabolism's regulation. This hypothesis has been demonstrated by targeted metabolic fingerprint analysis SRM (Selected Reaction Monitoring) on specific thermodynamic checkpoints of glycolysis. This article is part of a Special Issue entitled: Translational Proteomics.