Ectopic localization of FOXO3a protein in Lewy bodies in Lewy body dementia and Parkinson's disease

Functional Implications of Protein Arginine Methyltransferases (PRMTs) in Neurodegenerative Diseases

During the aging of the global population, the prevalence of neurodegenerative diseases will be continuously growing. Although each disorder is characterized by disease-specific protein accumulations, several common pathophysiological mechanisms encompassing both genetic and environmental factors have been detected. Among them, protein arginine methyltransferases (PRMTs), which catalyze the methylation of arginine of various substrates, have been revealed to regulate several cellular mechanisms, including neuronal cell survival and excitability, axonal transport, synaptic maturation, and myelination. Emerging evidence highlights their critical involvement in the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia-amyotrophic lateral sclerosis (FTD-ALS) spectrum, Huntington's disease (HD), spinal muscular atrophy (SMA) and spinal and bulbar muscular atrophy (SBMA). Underlying mechanisms include the regulation of gene transcription and RNA splicing, as well as their implication in various signaling pathways related to oxidative stress responses, apoptosis, neuroinflammation, vacuole degeneration, abnormal protein accumulation and neurotransmission. The targeting of PRMTs is a therapeutic approach initially developed against various forms of cancer but currently presents a novel potential strategy for neurodegenerative diseases. In this review, we discuss the accumulating evidence on the role of PRMTs in the pathophysiology of neurodegenerative diseases, enlightening their pathogenesis and stimulating future research.

FoxO3 and oxidative stress: a multifaceted role in cellular adaptation

Oxidative stress is a major cause of morbidity and mortality in human health and disease. In this review, we focus on the Forkhead Box (Fox) subclass O3 (FoxO3), an extensively studied transcription factor that plays a pleiotropic role in a wide range of physiological and pathological processes by regulating multiple gene regulatory networks involved in the modulation of numerous aspects of cellular metabolism, including fuel metabolism, cell death, and stress resistance. This review will also focus on regulatory mechanisms of FoxO3 expression and activity, such as crucial post-translational modifications and non-coding RNAs. Moreover, this work discusses and evidences some pathways to how this transcription factor and reactive oxygen species regulate each other, which may lead to the pathogenesis of various types of diseases. Therefore, in addition to being a promising therapeutic target, the FoxO3-regulated signaling pathways can also be used as reliable diagnostic and prognostic biomarkers and indicators for drug responsiveness.

FOXO3 gene hypermethylation and its marked downregulation in breast cancer cases: A study on female patients

Background

FOXO3, a member of the FOX transcription factor family, is frequently described as being deregulated in cancer. Additionally, notable role of FOXO3 can be easily recognized in the process of ageing and survival. Even though various studies have been done to acknowledge the tumour-suppressive or oncogenic role of FOXO3 in cancer, still there exist a lack of understanding in terms of cancer prognosis and treatment. Therefore, to provide better insight, our study aims to evaluate the role and function of FOXO3 in breast cancer in Indian female patients. We examined the FOXO3 expression levels in breast cancer samples by analyzing mRNA and protein expression along with its clinicopathological parameters.

Results

A total of 127 cases of breast cancer with equal normal cases (n=127) were assessed with methylation (MS-PCR), Immunohistochemistry (IHC), mRNA expression using Real-time PCR was analysed and 66.14% cases at mRNA level were found to be downregulated, while 81.10% of cases had little or very little protein expression. Our data state, the promoter hypermethylation of the FOXO3 gene and the downregulated protein expression are significantly correlated (p=0.0004). Additionally, we found a significant correlation between the level of FOXO3 mRNA with ER (p=0.04) and status of lymph node (p=0.01) along with this.

Conclusion

Data suggests the prognostic significance and the tumour-suppressive role of FOXO3 in breast cancer cases studied in India. However, there is a need for the extended research targeting FOXO3 to measure its clinical potential and develop well-defined therapeutic strategies.

Unraveling Parkinson's Disease Neurodegeneration: Does Aging Hold the Clues?

Aging is the greatest risk factor for Parkinson's disease (PD), suggesting that mechanisms driving the aging process promote PD neurodegeneration. Several lines of evidence support a role for aging in PD. First, hallmarks of brain aging such as mitochondrial dysfunction and oxidative stress, loss of protein homeostasis, and neuroinflammation are centrally implicated in PD development. Second, mutations that cause monogenic PD are present from conception, yet typically only cause disease following a period of aging. Third, lifespan-extending genetic, dietary, or pharmacological interventions frequently attenuate PD-related neurodegeneration. These observations support a central role for aging in disease development and suggest that new discoveries in the biology of aging could be leveraged to elucidate novel mechanisms of PD pathophysiology. A recent rapid growth in our understanding of conserved molecular pathways that govern model organism lifespan and healthspan has highlighted a key role for metabolism and nutrient sensing pathways. Uncovering how metabolic pathways involving NAD+ consumption, insulin, and mTOR signaling link to the development of PD is underway and implicates metabolism in disease etiology. Here, we assess areas of convergence between nervous system aging and PD, evaluate the link between metabolism, aging, and PD and address the potential of metabolic interventions to slow or halt the onset of PD-related neurodegeneration drawing on evidence from cellular and animal models.

The Role of miRNA-182 and FOXO3 Expression in Breast Cancer

OBJECTIVE

evaluating the role of FOXO3 mRNA and mi RNA 182-5P expression levels in BC patients.

METHOD

25 Samples of breast cancer and paired samples of non-cancerous tissues from the same resected breast were obtained from 25 female patients suffering from breast cancer and examined and analyzed by real time PCR to detect the expression levels of FOXO3 mRNA and mi RNA 182-5P. Patients' data were collected from patients medical records.

RESULTS

Foxo3 m RNA expression was down regulated in BC tissues (1.37± 1.96) as compared to control group (23.62 ± 54.39) and decreased FOXO3 expression was associated with larger tumor size (p= 0.046), late histopathological grading (p= 0.002), late TNM staging (<0.001) and increased miR-182 expression (p= 0.025). We found that expression level of miR-182 was significantly higher among breast cancer group (1.10±1.15) as compared to the control group (0.58±0.96 ) with p value = 0.017. We noted a significant increased expression associated with larger tumor size (p= 0.002), late histopathological grading (p= 0.008), late TNM staging (p= 0.002) and decreased FOXO3 expression (p= 0.025). A significant negative correlation between miR-182 and FOXO3 mRNA fold expression with r = - 0.447, and a p value of 0.025, this could be attributed to miRNA targeting FOXO gene.

COCLUSION

Down regulation of FOXO3 and up regulation of miR-182 expression was associated with advanced breast cancer. The negative correlation between miR-182 and FOXO3 mRNA could be attributed to miRNA targeting FOXO gene.

FOXO and related transcription factors binding elements in the regulation of neurodegenerative disorders

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and others, are characterized by progressive loss of neuronal cells, which causes memory impairment and cognitive decline. Mounting evidence demonstrated the possible implications of diverse biological processes, namely oxidative stress, mitochondrial dysfunction, aberrant cell cycle re-entry, post-translational modifications, protein aggregation, impaired proteasome dysfunction, autophagy, and many others that cause neuronal cell death. The condition worsens as there is no effective treatment for such diseases due to their complex pathogenesis and mechanism. Mounting evidence demonstrated the role of regulatory transcription factors, such as NFκβ, FoxO, Myc, CREB, and others that regulate the biological processes and diminish the disease progression and pathogenesis. Studies demonstrated that forkhead box O (FoxO) transcription factors had been implicated in the regulation of aging and longevity. Further, the functions of FoxO proteins are regulated by different post-translational modifications (PTMs), namely acetylation, and ubiquitination. Various studies concluded that FoxO proteins exert both neuroprotective and neurotoxic properties depending on their regulation mechanism and activity in the brain. Thus, understanding the nature of FoxO expression and activity in the brain will help develop effective therapeutic strategies. Herein, firstly, we discuss the role of FoxO protein in cell cycle regulation and cell proliferation, followed by the regulation of FoxO proteins through acetylation and ubiquitination. We also briefly explain the activity and expression pattern of FoxO proteins in the neuronal cells and explain the mechanism through which FoxO proteins are rescued from oxidative stress-induced neurotoxicity. Later on, we present a detailed view of the implication of FoxO proteins in neurodegenerative disease and FoxO proteins as an effective therapeutic target.

The Role of Exosomal microRNAs and Oxidative Stress in Neurodegenerative Diseases

Neurodegenerative diseases including Alzheimer's disease and Parkinson's disease are aging-associated diseases with irreversible damage of brain tissue. Oxidative stress is commonly detected in neurodegenerative diseases and related to neuronal injury and pathological progress. Exosome, one of the extracellular vesicles, is demonstrated to carry microRNAs (miRNAs) and build up a cell-cell communication in neurons. Recent research has found that exosomal miRNAs regulate the activity of multiple physiological pathways, including the oxidative stress response, in neurodegenerative diseases. Here, we review the role of exosomal miRNAs and oxidative stress in neurodegenerative diseases. Firstly, we explore the relationship between oxidative stress and neurodegenerative diseases. Secondly, we introduce the characteristics of exosomes and roles of exosome-related miRNAs. Thirdly, we summarized the crosstalk between exosomal miRNAs and oxidative stress in neurodegenerative diseases. Fourthly, we discuss the potential of exosomes to be a biomarker in neurodegenerative diseases. Finally, we summarize the advantages of exosome-based delivery and present situation of research on exosome-based delivery of therapeutic miRNA. Our work is aimed at probing and reinforcing the recognition of the pathomechanism of neurodegenerative diseases and providing the basis for novel strategies of clinical diagnosis and treatment.

Systematic Surveys of Iron Homeostasis Mechanisms Reveal Ferritin Superfamily and Nucleotide Surveillance Regulation to be Modified by PINK1 Absence

Iron deprivation activates mitophagy and extends lifespan in nematodes. In patients suffering from Parkinson’s disease (PD), PINK1-PRKN mutations via deficient mitophagy trigger iron accumulation and reduce lifespan. To evaluate molecular effects of iron chelator drugs as a potential PD therapy, we assessed fibroblasts by global proteome profiles and targeted transcript analyses. In mouse cells, iron shortage decreased protein abundance for iron-binding nucleotide metabolism enzymes (prominently XDH and ferritin homolog RRM2). It also decreased the expression of factors with a role for nucleotide surveillance, which associate with iron-sulfur-clusters (ISC), and are important for growth and survival. This widespread effect included prominently Nthl1-Ppat-Bdh2, but also mitochondrial Glrx5-Nfu1-Bola1, cytosolic Aco1-Abce1-Tyw5, and nuclear Dna2-Elp3-Pold1-Prim2. Incidentally, upregulated Pink1-Prkn levels explained mitophagy induction, the downregulated expression of Slc25a28 suggested it to function in iron export. The impact of PINK1 mutations in mouse and patient cells was pronounced only after iron overload, causing hyperreactive expression of ribosomal surveillance factor Abce1 and of ferritin, despite ferritin translation being repressed by IRP1. This misregulation might be explained by the deficiency of the ISC-biogenesis factor GLRX5. Our systematic survey suggests mitochondrial ISC-biogenesis and post-transcriptional iron regulation to be important in the decision, whether organisms undergo PD pathogenesis or healthy aging.

FOXO3a from the Nucleus to the Mitochondria: A Round Trip in Cellular Stress Response

Cellular stress response is a universal mechanism that ensures the survival or negative selection of cells in challenging conditions. The transcription factor Forkhead box protein O3 (FOXO3a) is a core regulator of cellular homeostasis, stress response, and longevity since it can modulate a variety of stress responses upon nutrient shortage, oxidative stress, hypoxia, heat shock, and DNA damage. FOXO3a activity is regulated by post-translational modifications that drive its shuttling between different cellular compartments, thereby determining its inactivation (cytoplasm) or activation (nucleus and mitochondria). Depending on the stress stimulus and subcellular context, activated FOXO3a can induce specific sets of nuclear genes, including cell cycle inhibitors, pro-apoptotic genes, reactive oxygen species (ROS) scavengers, autophagy effectors, gluconeogenic enzymes, and others. On the other hand, upon glucose restriction, 5′-AMP-activated protein kinase (AMPK) and mitogen activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) -dependent FOXO3a mitochondrial translocation allows the transcription of oxidative phosphorylation (OXPHOS) genes, restoring cellular ATP levels, while in cancer cells, mitochondrial FOXO3a mediates survival upon genotoxic stress induced by chemotherapy. Interestingly, these target genes and their related pathways are diverse and sometimes antagonistic, suggesting that FOXO3a is an adaptable player in the dynamic homeostasis of normal and stressed cells. In this review, we describe the multiple roles of FOXO3a in cellular stress response, with a focus on both its nuclear and mitochondrial functions.

14-3-3 Proteins Are on the Crossroads of Cancer, Aging, and Age-Related Neurodegenerative Disease

14-3-3 proteins are a family of conserved regulatory adaptor molecules which are expressed in all eukaryotic cells. These proteins participate in a variety of intracellular processes by recognizing specific phosphorylation motifs and interacting with hundreds of target proteins. Also, 14-3-3 proteins act as molecular chaperones, preventing the aggregation of unfolded proteins under conditions of cellular stress. Furthermore, 14-3-3 proteins have been shown to have similar expression patterns in tumors, aging, and neurodegenerative diseases. Therefore, we put forward the idea that the adaptor activity and chaperone-like activity of 14-3-3 proteins might play a substantial role in the above-mentioned conditions. Interestingly, 14-3-3 proteins are considered to be standing at the crossroads of cancer, aging, and age-related neurodegenerative diseases. There are great possibilities to improve the above-mentioned diseases and conditions through intervention in the activity of the 14-3-3 protein family.

Exosomes in Parkinson's Disease: Current Perspectives and Future Challenges

Exosomes, which are lipid bilayer membrane vesicles, have been implicated as carriers of biological macromolecules. In recent years, the functions of exosomes in the spreading of pathological conversion of proteins among neurons have drawn particular attention in Parkinson's disease research. Extracellular α-synuclein is proven to be associated with exosomes in vivo and in vitro. The contents of these exosomes may be altered during the pathological and clinical processes, serving as a potential target for biomarker development in Parkinson's disease. This Review highlights the current understanding of biogenesis and pathophysiological roles of exosomes. Meanwhile, exosomes are promising delivery vehicles. Artificial exosomes can be loaded with defined therapeutically active molecules, such as drugs, small interfering RNAs, long noncoding RNAs, and proteins to the brain, ensuring the site-specific targeting strategy to the recipient cells. Therefore, we will also discuss the potential applications of exosomes in developing modified exosome-based drug carrier systems to halt the pathologic propagation of Parkinson's disease.

Role of FOXO3 Activated by HIV-1 Tat in HIV-Associated Neurocognitive Disorder Neuronal Apoptosis

There are numerous types of pathological changes in human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND), including apoptosis of neurons. HIV-1 transactivator of transcription (Tat) protein, which is encoded by HIV-1, may promote apoptosis in HAND. Forkhead box O3 (FOXO3) is a multispecific transcription factor that has roles in many biological processes, including cellular apoptosis. The aim of this study was to determine whether FOXO3 is activated by HIV-1 Tat and to investigate its role in neuronal apoptosis in HAND. We employed tissue staining and related molecular biological experimental methods to confirm our hypothesis. The in vivo experimental results demonstrated that the expression of nuclear FOXO3 increased in the apoptotic neurons of the cerebral cortexes of rhesus macaques infected with simian human immunodeficiency virus (SHIV). The in vitro investigation showed that HIV-1 Tat activated FOXO3, causing it to move from the cytoplasm to the nucleus via the c-Jun N-terminal kinase (JNK) signaling pathway in SH-SY5Y cells. Moreover, FOXO3 down-regulated expression of the anti-apoptosis gene B-cell lymphoma 2 (Bcl-2) and up-regulated the expression of the pro-apoptosis gene Bcl-2-like 11 (Bim) after entering the nucleus, eventually causing cellular apoptosis. Finally, reduction of nuclear FOXO3 reversed cellular apoptosis. Our results suggest that HIV-1 Tat induces FOXO3 to translocate from the cytoplasm to the nucleus via the JNK signaling pathway, leading to neuronal apoptosis. Agents targeting FOXO3 may provide approaches for restoring neuronal function in HAND.

Increased Foxo3a Nuclear Translocation and Activity is an Early Neuronal Response to βγ-Secretase-Mediated Processing of the Amyloid-β Protein Precursor: Utility of an AβPP-GAL4 Reporter Assay

Sequential cleavage of the amyloid-β protein precursor (AβPP) by BACE1 (β-secretase) followed by theγ-secretase complex, is strongly implicated in Alzheimer's disease (AD) but the initial cellular responses to these cleavage events are not fully defined. β-secretase-mediated AβPP processing yields an extracellular domain (sAβPPβ) and a C-terminal fragment of AβPP of 99 amino acids (C99). Subsequent cleavage by γ-secretase produces amyloid-β (Aβ) and an AβPP intracellular domain (AICD). A cellular screen based on the generation of AICD from an AβPP-Gal4 fusion protein was adapted by introducing familial AD (FAD) mutations into the AβPP sequence and linking the assay to Gal4-UAS driven luciferase and GFP expression, to identify responses immediately downstream of AβPP processing in neurons with a focus on the transcription factor Foxo3a which has been implicated in neurodegeneration. The K670N/M671L, E682K, E693G, and V717I FAD mutations and the A673T protective mutation, were introduced into the AβPP sequence by site directed mutagenesis. When expressed in mouse cortical neurons, AβPP-Gal4-UAS driven luciferase and GFP expression was substantially reduced by γ-secretase inhibitors, lowered by β-secretase inhibitors, and enhanced by α-secretase inhibitors suggesting that AICD is a product of the βγ-secretase pathway. AβPP-Gal4-UAS driven GFP expression was exploited to identify individual neurons undergoing amyloidogenic AβPP processing, revealing increased nuclear localization of Foxo3a and enhanced Foxo3a-mediated transcription downstream of AICD production. Foxo3a translocation was not driven by AICD directly but correlated with reduced Akt phosphorylation. Collectively this suggests that βγ-secretase-mediated AβPP processing couples to Foxo3a which could be an early neuronal signaling response in AD.

Dysregulation of Transcription Factors: A Key Culprit Behind Neurodegenerative Disorders

Neurodegenerative diseases (NDs) are considered heterogeneous disorders characterized by progressive pathological changes in neuronal systems. Transcription factors are protein molecules that are important in regulating the expression of genes. Although the clinical manifestations of NDs vary, the pathological processes appear similar with regard to neuroinflammation, oxidative stress, and proteostasis, to which, as numerous studies have discovered, transcription factors are closely linked. In this review, we summarized and reviewed the roles of transcription factors in NDs, and then we elucidated their functions during pathological processes, and finally we discussed their therapeutic values in NDs.

Critical role of FOXO3a in carcinogenesis

FOXO3a is a member of the FOXO subfamily of forkhead transcription factors that mediate a variety of cellular processes including apoptosis, proliferation, cell cycle progression, DNA damage and tumorigenesis. It also responds to several cellular stresses such as UV irradiation and oxidative stress. The function of FOXO3a is regulated by a complex network of processes, including post-transcriptional suppression by microRNAs (miRNAs), post-translational modifications (PTMs) and protein–protein interactions. FOXO3a is widely implicated in a variety of diseases, particularly in malignancy of breast, liver, colon, prostate, bladder, and nasopharyngeal cancers. Emerging evidences indicate that FOXO3a acts as a tumor suppressor in cancer. FOXO3a is frequently inactivated in cancer cell lines by mutation of the FOXO3a gene or cytoplasmic sequestration of FOXO3a protein. And its inactivation is associated with the initiation and progression of cancer. In experimental studies, overexpression of FOXO3a inhibits the proliferation, tumorigenic potential, and invasiveness of cancer cells, while silencing of FOXO3a results in marked attenuation in protection against tumorigenesis. The role of FOXO3a in both normal physiology as well as in cancer development have presented a great challenge to formulating an effective therapeutic strategy for cancer. In this review, we summarize the recent findings and overview of the current understanding of the influence of FOXO3a in cancer development and progression.

Levels of α- and β-synuclein regulate cellular susceptibility to toxicity from α-synuclein oligomers

α-Synuclein (α-syn) is associated with a range of diseases, including Parkinson disease. In disease, α-syn is known to aggregate and has the potential to be neurotoxic. The association between copper and α-syn results in the formation of stellate toxic oligomers that are highly toxic to cultured neurons. We further investigated the mechanism of toxicity of α-syn oligomers. Cells that overexpress α-syn showed increased susceptibility to the toxicity of the oligomers, while those that overexpressed β-syn showed increased resistance to the toxic oligomers. Elevated α-syn expression caused an increase in expression of the transcription factor Forkhead box O3a (FoxO3a). Inhibition of FoxO3a activity by the overexpression of DNA binding domain of FoxO3a resulted in significant protection from α-syn oligomer toxicity. Increased FoxO3a expression in cells was shown to be caused by increased ferrireductase activity and Fe(II) levels. These results suggest that α-syn increases FoxO3a expression as a result of its intrinsic ferrireductase activity. The results also suggest that FoxO3a plays a pivotal role in the toxicity of both Fe(II) and toxic α-syn species to neuronal cells.-Angelova, D. M., Jones, H. B. L., Brown, D. R. Levels of α- and β-synuclein regulate cellular susceptibility to toxicity from α-synuclein oligomers.

Does Vitamin C Influence Neurodegenerative Diseases and Psychiatric Disorders?

Vitamin C (Vit C) is considered to be a vital antioxidant molecule in the brain. Intracellular Vit C helps maintain integrity and function of several processes in the central nervous system (CNS), including neuronal maturation and differentiation, myelin formation, synthesis of catecholamine, modulation of neurotransmission and antioxidant protection. The importance of Vit C for CNS function has been proven by the fact that targeted deletion of the sodium-vitamin C co-transporter in mice results in widespread cerebral hemorrhage and death on post-natal day one. Since neurological diseases are characterized by increased free radical generation and the highest concentrations of Vit C in the body are found in the brain and neuroendocrine tissues, it is suggested that Vit C may change the course of neurological diseases and display potential therapeutic roles. The aim of this review is to update the current state of knowledge of the role of vitamin C on neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis and amyotrophic sclerosis, as well as psychiatric disorders including depression, anxiety and schizophrenia. The particular attention is attributed to understanding of the mechanisms underlying possible therapeutic properties of ascorbic acid in the presented disorders.

Sirtuins and Their Roles in Brain Aging and Neurodegenerative Disorders

Sirtuins (SIRT1-SIRT7) are unique histone deacetylases (HDACs) whose activity depends on NAD⁺ levels and thus on the cellular metabolic status. SIRTs regulate energy metabolism and mitochondrial function. They orchestrate the stress response and damage repair. Through these functions sirtuins modulate the course of aging and affect neurodegenerative diseases. SIRTSs interact with multiple signaling proteins, transcription factors (TFs) and poly(ADP-ribose) polymerases (PARPs) another class of NAD⁺-dependent post-translational protein modifiers. The cross-talk between SIRTs TFs and PARPs is a highly promising research target in a number of brain pathologies. This review describes updated results on sirtuins in brain aging/neurodegeneration. It focuses on SIRT1 but also on the roles of mitochondrial SIRTs (SIRT3, 4, 5) and on SIRT6 and SIRT2 localized in the nucleus and in cytosol, respectively. The involvement of SIRTs in regulation of insulin-like growth factor signaling in the brain during aging and in Alzheimer's disease was also focused. Moreover, we analyze the mechanism(s) and potential significance of interactions between SIRTs and several TFs in the regulation of cell survival and death. A critical view is given on the application of SIRT activators/modulators in therapy of neurodegenerative diseases.

The neuroprotective role of ferrostatin-1 under rotenone-induced oxidative stress in dopaminergic neuroblastoma cells

Endoplasmic reticulum (ER) proteins including protein disulfide isomerase (PDI) are playing crucial roles in maintaining appropriate protein folding. Under nitrosative stress, an excess of nitric oxide (NO) radical species induced the S-nitrosylation of PDI cysteines which eliminate its isomerase and oxidoreductase capabilities. In addition, the S-nitrosylation-PDI complex is the cause of aggregation especially of the α-synuclein (α-syn) protein (accumulation of Lewy-body aggregates). We recently identified a potent antioxidant small molecule, Ferrostatin-1 (Fer-1), that was able to inhibit a non-apoptotic cell death named ferroptosis. Ferroptosis cell death involved the generation of oxidative stress particularly lipid peroxide. In this work, we reported the neuroprotective role of ferrostatin-1 under rotenone-induced oxidative stress in dopaminergic neuroblastoma cells (SH-SY5Y). We first synthesized the Fer-1 and confirmed that it is not toxic toward the SH-SY5Y cells at concentrations up to 12.5 μM. Second, we showed that Fer-1 compound quenched the commercially available stable radical, the 2,2-diphenyl-1-picrylhydrazyl (DPPH), in non-cellular assay at 82 %. Third, Fer-1 inhibited the ROS/RNS generated under rotenone insult in SH-SY5Y cells. Fourth, we revealed the effective role of Fer-1 in ER stress mediated activation of apoptotic pathway. Finally, we reported that Fer-1 mitigated rotenone-induced α-syn aggregation.

Enhanced phosphatidylinositol 3-kinase (PI3K)/Akt signaling has pleiotropic targets in hippocampal neurons exposed to iron-induced oxidative stress

The PI3K/Akt pathway is a key component in synaptic plasticity and neuronal survival. The aim of this work was to investigate the participation of the PI3K/Akt pathway and its outcome on different molecular targets such as glycogen synthase kinase 3β (GSK3β) and Forkhead box-O (FoxO) transcription factors during mild oxidative stress triggered by iron overload. The exposure of mouse hippocampal neurons (HT22) to different concentrations of Fe(2+) (25-200 μm) for 24 h led us to define a mild oxidative injury status (50 μm Fe(2+)) in which cell morphology showed changes typical of neuronal damage with increased lipid peroxidation and cellular oxidant levels but no alteration of cellular viability. There was a simultaneous increase in both Akt and GSK3β phosphorylation. Levels of phospho-FoxO3a (inactive form) increased in the cytosolic fraction of cells treated with iron in a PI3K-dependent manner. Moreover, PI3K and Akt translocated to the nucleus in response to oxidative stress. Iron-overloaded cells harboring a constitutively active form of Akt showed decreased oxidants levels. Indeed, GSH synthesis under oxidative stress conditions was regulated by activated Akt. Our results show that activation of the PI3K/Akt pathway during iron-induced neurotoxicity regulates multiple targets such as GSK3β, FoxO transcriptional activity, and glutathione metabolism, thus modulating the neuronal response to oxidative stress.

Engulfment adaptor phosphotyrosine-binding-domain-containing 1 (GULP1) is a nucleocytoplasmic shuttling protein and is transactivationally active together with low-density lipoprotein receptor-related protein 1 (LRP1)

APP (amyloid precursor protein) and LRP1 (low-density lipoprotein receptor-related protein 1) have been implicated in the pathogenesis of AD (Alzheimer's disease). They are functionally linked by Fe65, a PTB (phosphotyrosine-binding)-domain-containing adaptor protein that binds to intracellular NPxY-motifs of APP and LRP1, thereby influencing expression levels, cellular trafficking and processing. Additionally, Fe65 has been reported to mediate nuclear signalling in combination with intracellular domains of APP and LRP1. We have previously identified another adaptor protein, GULP1 (engulfment adaptor PTB-domain-containing 1). In the present study we characterize and compare nuclear trafficking and transactivation of GULP1 and Fe65 together with APP and LRP1 and report differential nuclear trafficking of adaptors when APP or LRP1 are co-expressed. The observed effects were additionally supported by a reporter-plasmid-based transactivation assay. The results from the present study indicate that Fe65 might have signalling properties together with APP and LRP1, whereas GULP1 only mediates LRP1 transactivation.

Neuroprotective effects of phenolic antioxidant tBHQ associate with inhibition of FoxO3a nuclear translocation and activity

The Forkhead transcription factor, FoxO3a induces genomic death responses in neurones following translocation from the cytosol to the nucleus. Nuclear translocation of FoxO3a is triggered by trophic factor withdrawal, oxidative stress and the stimulation of extrasynaptic NMDA receptors. Receptor activation of phosphatidylinositol 3-kinase (PI3K)-Akt signalling pathways retains FoxO3a in the cytoplasm, thereby inhibiting the transcriptional activation of death-promoting genes. We hypothesized that phenolic antioxidants such as tert-Butylhydroquinone (tBHQ), which is known to stimulate PI3K-Akt signalling, would inhibit FoxO3a translocation and activity. Treatment of cultured cortical neurones with NMDA increased the nuclear localization of FoxO3a, reduced the phosphorylation of FoxO3a, increased caspase activity and up-regulated Fas ligand expression. In contrast the phenolic antioxidant, tBHQ, caused retention of FoxO3a in the cytosol coincident with enhanced PI3K- dependent phosphorylation of FoxO3a. tBHQ-induced nuclear exclusion of FoxO3a was associated with reduced FoxO-mediated transcriptional activity. Exposure of neurones to tBHQ inhibited NMDA-induced nuclear translocation of FoxO3a, prevented NMDA-induced up-regulation of FoxO-mediated transcriptional activity, blocked caspase activation and protected neurones from NMDA-induced excitotoxic death. Collectively, these data suggest that phenolic antioxidants such as tBHQ oppose stress-induced activation of FoxO3a and therefore have potential neuroprotective utility in neurodegeneration.

Combined exposure to Maneb and Paraquat alters transcriptional regulation of neurogenesis-related genes in mice models of Parkinson's disease

Background

Parkinson's disease (PD) is a multifactorial disease where environmental factors act on genetically predisposed individuals. Although only 5% of PD manifestations are associated with specific mutations, majority of PD cases are of idiopathic origin, where environment plays a prominent role. Concurrent exposure to Paraquat (PQ) and Maneb (MB) in rural workers increases the risk for PD and exposure of adult mice to MB/PQ results in dopamine fiber loss and decreased locomotor activity. While PD is characterized by neuronal loss in the substantia nigra, we previously showed that accumulation of α-synuclein in the limbic system contributes to neurodegeneration by interfering with adult neurogenesis.

Results

We investigated the effect of pesticides on adult hippocampal neurogenesis in two transgenic models: Line 61, expressing the human wild type SNCA gene and Line LRRK2(G2019S), expressing the human LRRK2 gene with the mutation G2019S. Combined exposure to MB/PQ resulted in significant reduction of neuronal precursors and proliferating cells in non-transgenic animals, and this effect was increased in transgenic mice, in particular for Line 61, suggesting that α-synuclein accumulation and environmental toxins have a synergistic effect. We further investigated the transcription of 84 genes with direct function on neurogenesis. Overexpresion of α-synuclein resulted in the downregulation of 12% of target genes, most of which were functionally related to cell differentiation, while LRRK2 mutation had a minor impact on gene expression. MB/PQ also affected transcription in non-transgenic backgrounds, but when transgenic mice were exposed to the pesticides, profound alterations in gene expression affecting 27% of the studied targets were observed in both transgenic lines. Gene enrichment analysis showed that 1:3 of those genes were under the regulation of FoxF2 and FoxO3A, suggesting a primary role of these proteins in the response to genetic and environmental cues.

Conclusions

We report that adult neurogenesis is highly susceptible to multiple “risk factors” for PD, including α-synuclein accumulation, LRRK2 G2019 mutation and exposure to environmental toxins. We identified specific groups of genes that are responsive to each stressor, while uncovering a novel function for Fox transcription factors in PD.

Foxo3a: an integrator of immune dysfunction during HIV infection

Chronic HIV infection, which is primarily characterized by the progressive depletion of total CD4(+) T cells, also causes persistent inflammation and immune activation. This is followed by profound changes in cellular and tissue microenvironments that often lead to prolonged immune dysfunction. The global nature of this immune dysfunction suggests that factors that are involved in immune cell survival, proliferation, differentiation and maturation are all affected. Of particular interest is the transcriptional factor Foxo3a that regulates a number of genes that are critical in the development and the maintenance of T and B cells, dendritic cells (DCs) and macrophages. Alterations in the microenvironment mediated by HIV infection cause significant increase in the transcriptional activity of Foxo3a; this has major impact on T cell and B cell immunity. In fact, recent findings from HIV infected individuals highlight three important points: (1) the alteration of Foxo3a signaling during HIV infection deregulates innate and adaptive immune responses; (2) Foxo3a-mediated effects are reversible and could be restored by interfering with the Foxo3a pathway; and (3) down-regulation of Foxo3a transcriptional activity in elite controllers (ECs) represents a molecular signature, or a correlate of immunity, associated with natural protection and lack of disease progression. In this review, we will discuss how HIV-infection altered microenvironments could result in impaired immune responses via the Foxo3a signaling pathway. Defining precisely the molecular mechanisms of how persistent inflammation and immune activation are able to influence the Foxo3a pathway could ultimately help in the development of novel approaches to improve immune responses in HIV infected subjects.

Gene expression profiles in Parkinson disease prefrontal cortex implicate FOXO1 and genes under its transcriptional regulation

Parkinson disease (PD) is a complex neurodegenerative disorder with largely unknown genetic mechanisms. While the degeneration of dopaminergic neurons in PD mainly takes place in the substantia nigra pars compacta (SN) region, other brain areas, including the prefrontal cortex, develop Lewy bodies, the neuropathological hallmark of PD. We generated and analyzed expression data from the prefrontal cortex Brodmann Area 9 (BA9) of 27 PD and 26 control samples using the 44K One-Color Agilent 60-mer Whole Human Genome Microarray. All samples were male, without significant Alzheimer disease pathology and with extensive pathological annotation available. 507 of the 39,122 analyzed expression probes were different between PD and control samples at false discovery rate (FDR) of 5%. One of the genes with significantly increased expression in PD was the forkhead box O1 (FOXO1) transcription factor. Notably, genes carrying the FoxO1 binding site were significantly enriched in the FDR-significant group of genes (177 genes covered by 189 probes), suggesting a role for FoxO1 upstream of the observed expression changes. Single-nucleotide polymorphisms (SNPs) selected from a recent meta-analysis of PD genome-wide association studies (GWAS) were successfully genotyped in 50 out of the 53 microarray brains, allowing a targeted expression-SNP (eSNP) analysis for 52 SNPs associated with PD affection at genome-wide significance and the 189 probes from FoxO1 regulated genes. A significant association was observed between a SNP in the cyclin G associated kinase (GAK) gene and a probe in the spermine oxidase (SMOX) gene. Further examination of the FOXO1 region in a meta-analysis of six available GWAS showed two SNPs significantly associated with age at onset of PD. These results implicate FOXO1 as a PD-relevant gene and warrant further functional analyses of its transcriptional regulatory mechanisms.

The Lewy body in Parkinson's disease and related neurodegenerative disorders

The histopathological hallmark of Parkinson's disease (PD) is the presence of fibrillar aggregates referred to as Lewy bodies (LBs), in which α-synuclein is a major constituent. Pale bodies, the precursors of LBs, may serve the material for that LBs continue to expand. LBs consist of a heterogeneous mixture of more than 90 molecules, including PD-linked gene products (α-synuclein, DJ-1, LRRK2, parkin, and PINK-1), mitochondria-related proteins, and molecules implicated in the ubiquitin-proteasome system, autophagy, and aggresome formation. LB formation has been considered to be a marker for neuronal degeneration because neuronal loss is found in the predilection sites for LBs. However, recent studies have indicated that nonfibrillar α-synuclein is cytotoxic and that fibrillar aggregates of α-synuclein (LBs and pale bodies) may represent a cytoprotective mechanism in PD.

14-3-3 proteins in neurological disorders

14-3-3 proteins were originally discovered as a family of proteins that are highly expressed in the brain. Through interactions with a multitude of binding partners, 14-3-3 proteins impact many aspects of brain function including neural signaling, neuronal development and neuroprotection. Although much remains to be learned and understood, 14-3-3 proteins have been implicated in a variety of neurological disorders based on evidence from both clinical and laboratory studies. Here we will review previous and more recent research that has helped us understand the roles of 14-3-3 proteins in both neurodegenerative and neuropsychiatric diseases.

Restriction of trophic factors and nutrients induces PARKIN expression

Parkinson’s disease (PD) is the most frequent neurodegenerative movement disorder and manifests at old age. While many details of its pathogenesis remain to be elucidated, in particular the protein and mitochondrial quality control during stress responses have been implicated in monogenic PD variants. Especially the mitochondrial kinase PINK1 and the ubiquitin ligase PARKIN are known to cooperate in autophagy after mitochondrial damage. As autophagy is also induced by loss of trophic signaling and PINK1 gene expression is modulated after deprivation of cytokines, we analyzed to what extent trophic signals and starvation stress regulate PINK1 and PARKIN expression. Time course experiments with serum deprivation and nutrient starvation of human SH-SY5Y neuroblastoma cells and primary mouse neurons demonstrated phasic induction of PINK1 transcript up to twofold and PARKIN transcript levels up to sixfold. The corresponding threefold starvation induction of PARKIN protein was limited by its translocation to lysosomes. Analysis of primary mouse cells from PINK1-knockout mice indicated that PARKIN induction and lysosomal translocation occurred independent of PINK1. Suppression of the PI3K-Akt-mTOR signaling by pharmacological agents modulated PARKIN expression accordingly. In conclusion, this expression survey demonstrates that PARKIN and PINK1 are coregulated during starvation and suggest a role of both PD genes in response to trophic signals and starvation stress.

Nitrosative stress-induced Parkinsonian Lewy-like aggregates prevented through polyphenolic phytochemical analog intervention

Nitrosative stress has recently been demonstrated as a causal in a select sporadic variant of Parkinson's (PD) and Alzheimer's (AD) diseases. Specifically, elevated levels of NO disrupt the redox activity of protein-disulfide isomerase, a key endoplasmic reticulum-resident chaperone by S-nitroso modification of its redox-active cysteines. This leads to accumulation of misfolded AD- and PD-specific protein debris. We have recently demonstrated in vitro that polyphenolic phytochemicals, curcumin and masoprocol, can rescue S-nitroso-PDI formation by scavenging NOx. In this study, using dopaminergic SHSY-5Y cells, we have monitored the aggregation of green-fluorescent protein (GFP)-tagged synphilin-1 (a known constituent of PD Lewy neurites) as a function of rotenone-induced nitrosative stress. Importantly, we demonstrate a marked decrease in synphilin-1 aggregation when the cell line is previously incubated with 3,5-bis(2-flurobenzylidene) piperidin-4-one (EF-24), a curcumin analogue, prior to rotenone insult. Furthermore, our data also reveal that rotenone attenuates PDI expression in the same cell line, a phenomenon that can be mitigated through EF-24 intervention. Together, these results suggest that EF-24 can exert neuroprotective effects by ameliorating nitrosative stress-linked damage to PDI and the associated onset of PD and AD. Essentially, EF-24 can serve as a scaffold for the design and development of PD and AD specific prophylactics.

Expression and localisation of FoxO3 and FoxO4 in human placenta and fetal membranes

Forkhead box O (FoxO) proteins regulate inflammation, extracellular matrix (ECM) remodelling and apoptosis. We have previously identified FoxO1 proteins in human gestational tissues, and demonstrated a link between FoxO1 and rupture of fetal membranes. There is, however, no data available on the expression and localisation of FoxO3 and FoxO4 in human intrauterine tissues. Thus the aim of this study was to characterise the localisation and expression of FoxO3 and FoxO4 in (i) human placenta and fetal membranes before term spontaneous labour onset, and (ii) supracervical site (SCS) and distal site (DS) fetal membranes from non-labouring women. Immunohistochemistry, Western blotting and quantitative RT-PCR (qRT-PCR) was used to localise and quantitate FoxO3 and FoxO4 protein and mRNA expressions. Cytoplasmic and nuclear FoxO3 was localised in the syncytiotrophoblast layer, chorionic trophoblasts, amnion epithelium and decidua. Cytoplasmic FoxO4 was localised in the syncytiotrophoblasts and chorionic trophoblasts. No or very little FoxO4 protein and mRNA was present in amnion epithelium. The intensity and extent of staining of FoxO3 and FoxO4 was greater in fetal membranes obtained from the SCS compared to DS. Presence of FoxO3 and FoxO4 are expected to contribute to apoptosis and/or cell cycle regulation associated with fetal membrane rupture.