G1/S Cell Cycle Checkpoint Dysfunction in Lymphoblasts from Sporadic Parkinson's Disease Patients

Exploring the therapeutic potential of Potentilla fragarioides var. major (Rosaceae) extract in Alzheimer's disease using in vitro and in vivo models: A multi-faceted approach

Alzheimer's disease (AD) is the most common cause of dementia and is caused by various factors including amyloid-beta (Aβ) aggregation. We investigated the pharmacological effects of the ethanol extract of Potentilla fragarioides var. major (Rosaceae) (EEPF) on AD-related pathogenesis, which remain elusive. We observed the effects of EEPF on Aβ disaggregation and free-radical scavenging activities for 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) using in vitro assays, evaluated the effects of EEPF on memory loss in two animal models, and examined the molecular regulatory mechanisms of EEPF using an antibody-protein microarray in EEPF-treated neuronal cell lines. EEPF inhibited Aβ aggregation in a concentration-dependent manner and enhanced free-radical scavenging activities for ABTS and DPPH. EEPF significantly inhibited memory impairment in the passive avoidance task, Y-maze test, and Morris water maze test in scopolamine-induced short-term memory loss mice and Aβ-injected AD-like mice. Nissl staining and immunohistochemistry for NeuN and Iba-1 confirmed the neuroprotective and anti-inflammatory effects of EEPF in both animal models. In H2O2-treated HT22 hippocampal cells, EEPF significantly prevented cell damage, enhanced CaMK2, and reduced ferric reductase. In lipopolysaccharide (LPS)-stimulated BV-2 microglia, EEPF significantly inhibited LPS-induced production of inflammatory factors, such as nitric oxide, prostaglandin E2, tumor necrosis factor-α, and interleukin-6, and decreased the phosphorylation of Smad3 and cyclin D3. High-performance liquid chromatography confirmed that EEPF has five major components: neochlorogenic acid, chlorogenic acid, polydatin, isochlorogenic acid A, and buddleoside, with amounts ranging across 1.91-9.41 mg/g. EEPF may be a promising drug for treatment of AD and AD-related brain disorders.

Role of RB1 in neurodegenerative diseases: inhibition of post-mitotic neuronal apoptosis via Kmt5b

During the development of the vertebrate nervous system, 50% of the nerve cells undergo apoptosis shortly after formation. This process is important for sculpting tissue during morphogenesis and removing transiently functional cells that are no longer needed, ensuring the appropriate number of neurons in each region. Dysregulation of neuronal apoptosis can lead to neurodegenerative diseases. However, the molecular events involved in activating and regulating the neuronal apoptosis program are not fully understood. In this study, we identified several RB1 mutations in patients with neurodegenerative diseases. Then, we used a zebrafish model to investigate the role of Rb1 in neuronal apoptosis. We showed that Rb1-deficient mutants exhibit a significant hindbrain neuronal apoptosis, resulting in increased microglia infiltration. We further revealed that the apoptotic neurons in Rb1-deficient zebrafish were post-mitotic neurons, and Rb1 inhibits the apoptosis of these neurons by regulating bcl2/caspase through binding to Kmt5b. Moreover, using this zebrafish mutant, we verified the pathogenicity of the R621S and L819V mutations of human RB1 in neuronal apoptosis. Collectively, our data indicate that the Rb1-Kmt5b-caspase/bcl2 axis is crucial for protecting post-mitotic neurons from apoptosis and provides an explanation for the pathogenesis of clinically relevant mutations.

α-synuclein regulates Cyclin D1 to promote abnormal initiation of the cell cycle and induce apoptosis in dopamine neurons

The etiology of Parkinson's disease (PD) is characterized by the death of dopamine neurons in the substantia nigra pars compacta, while misfolding and abnormal aggregation of α-synuclein (α-syn) are core pathological features. Previous studies have suggested that damage to dopamine neurons may be related to cell cycle dysregulation, but the specific mechanisms remain unclear. In this study, a PD mouse model was induced by stereotactic injection of α-syn into the nucleus, and treated with the cell cycle inhibitor, roscovitine (Rosc). The results demonstrated that Rosc improved behavioral disorders caused by α-syn, increased TH protein expression, inhibited α-syn and p-α-syn protein expression, and reduced the expression levels of G1/S phase cell cycle genes Cyclin D1, Cyclin E, CDK2, CDK4, E2F and pRB. Additionally, Rosc decreased Bax and Caspase-3 expression caused by α-syn, while increasing Bcl-2 protein expression. Meanwhile, we observed that α-syn can influence neuronal cell autophagy by decreasing the expression level of Beclin 1 and increasing the expression level of P62. However, Rosc can improve this phenomenon. In a cell model induced by α-syn in dopamine neuron injury cells, knockdown of Cyclin D1 led to similar results as those observed in animal experiments: Knocking down Cyclin D1 improved the abnormal initiation of the cell cycle caused by α-syn and regulated cellular autophagy, resulting in a reduction of apoptosis in dopamine neurons. In summary, exogenous α-syn can lead to the accumulation of α-syn and phosphorylated α-syn in dopamine neurons, increase key factors of the G1/S phase cell cycle such as Cyclin D1, and regulate downstream related indicators, causing the cell cycle to restart and leading to apoptosis of dopamine neurons. This exacerbates PD symptoms. However, knockdown of Cyclin D1 inhibits the progression of the cell cycle and can reverse this situation. These findings suggest that a Cyclin D inhibitor may be a novel therapeutic target for treating PD.

Cell cycle deregulation in neurodegenerative diseases

Background: Cell cycle is critical for a wide range of cellular processes such as proliferation, differentiation and apoptosis in dividing cells. Neurons are postmitotic cells which have withdrawn from the cell division cycle. Recent data show us that inappropriate activation of cell cycle regulators including cyclins, cyclin dependent kinases (CDKs) and endogenous cyclin dependent kinase inhibitors (CDKIs) may take part in the aetiology of neurodegenerative diseases. However, the mechanisms for cell cycle reentry in neurodegenerative disease remain unclear.Methods: Electronic databases such as Pubmed, Science Direct, Directory of Open Access Journals, PLOS were searched for relevant articles.Conclusion: The present work reviews basic aspects of cell cycle mechanism, as well as the evidence showing the expression of cell cycle proteins in neurodegenerative disease. We provide a brief summary of these findings and hope to highlight the interaction between the cell cycle reentry and neurodegenerative diseases. Moreover, we outline the possible signaling pathways. However more understanding of the mechanism of cell cycle is of great importance. Because these represents an alternative target for therapeutic interventions, leading to novel treatments of neurodegenerative diseases.

FDA-Approved Kinase Inhibitors in Preclinical and Clinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases. We previously developed a new concept termed "Aberrant Cell Cycle Diseases" (ACCD), revealing that these two diseases share a common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncogene activation and tumor suppressor inactivation, which are hallmarks of both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase inhibition, tumor suppressor elevation) can be leveraged for neurological treatments. The United States Food and Drug Administration (US FDA) has so far approved 74 kinase inhibitors, with numerous other kinase inhibitors in clinical trials, mostly for the treatment of cancers. In contrast, there are dire unmet needs of FDA-approved drugs for neurological treatments, such as Alzheimer's disease (AD), intracerebral hemorrhage (ICH), ischemic stroke (IS), traumatic brain injury (TBI), and others. In this review, we list these 74 FDA-approved kinase-targeted drugs and identify those that have been reported in preclinical and/or clinical trials for neurological disorders, with a purpose of discussing the feasibility and applicability of leveraging these cancer drugs (FDA-approved kinase inhibitors) for neurological treatments.

Effect of pH on the structure and function of cyclin-dependent kinase 6

Cyclin-dependent kinase 6 (CDK6) is an important protein kinase that regulates cell growth, development, cell metabolism, inflammation, and apoptosis. Its overexpression is associated with reprogramming glucose metabolism through alternative pathways and apoptosis, which ultimately plays a significant role in cancer development. In the present study, we have investigated the structural and conformational changes in CDK6 at varying pH employing a multi-spectroscopic approach. Circular dichroism (CD) spectroscopy revealed at extremely acidic conditions (pH 2.0–4.0), the secondary structure of CDK6 got significantly disrupted, leading to aggregates formation. These aggregates were further characterized by employing Thioflavin T (ThT) fluorescence. No significant secondary structural changes were observed over the alkaline pH range (pH 7.0–11.0). Further, fluorescence and UV spectroscopy revealed that the tertiary structure of CDK6 was disrupted under extremely acidic conditions, with slight alteration occurring in mild acidic conditions. The tertiary structure remains intact over the entire alkaline range. Additionally, enzyme assay provided an insight into the functional aspect of CDK at varying pH; CDK6 activity was optimal in the pH range of 7.0–8.0. This study will provide a platform that provides newer insights into the pH-dependent dynamics and functional behavior of CDK6 in different CDK6 directed diseased conditions, viz. different types of cancers where changes in pH contribute to cancer development.

MiRNA-494-3p Regulates Bupivacaine-Induced Neurotoxicity by the CDK6-PI3K/AKT Signaling

Bupivacaine (BUP) is a long-acting amide local anesthetic that may induce strong neurotoxicity and neurological complications. In this study, we elucidate the influence of microRNA-494-3p (miR-494-3p) in BUP-induced neurotoxicity in primary mouse hippocampal neuronal cells. In this study, primary hippocampal neurons were isolated from neonatal C57BL/6 mice. The isolated neurons were treated with various doses of BUP. MTT assay was conducted to analyze neuronal viability. Gene expression measurement was done by RT-qPCR. The impact of miR-494-3p in BUP-mediated neural injury was examined using TUNEL, flow cytometry, western blotting, and ROS activity detection. The regulatory relationship between miR-494-3p and cyclin-dependent kinases 4 and 6 (CDK6) was identified using a luciferase reporter assay. BUP treatment led to neurotoxicity and miR-494-3p upregulation in primary cultured hippocampal neurons. Functionally, miR-494-3p depletion alleviated neuronal apoptosis and oxidative damage induced by BUP. We verified that miR-494-3p targeted and negatively modulated CDK6. MiR-494-3p depletion also activated PI3K/AKT signaling by elevating CDK6 expression in BUP-treated neurons. Furthermore, CDK6 knockdown or PI3K/AKT inactivation attenuated the neuroprotective role of miR-494-3p depletion. Silencing miR-494-3p exerts neuroprotective function in hippocampal neuronal cells against BUP-induced injury by the CDK6-PI3K/AKT pathway.

Transcriptomic and Genetic Associations between Alzheimer's Disease, Parkinson's Disease, and Cancer

Simple Summary

Epidemiological studies have identified a link between neurodegenerative disorders and a reduced risk of overall cancer. Increases and decreases in the risk of site-specific cancers have also been reported. However, it is still unknown whether these associations arise due to shared genetic and molecular factors or are explained by other phenomena (e.g., biases in epidemiological studies or the use of medication). In this study, we aimed to investigate the potential molecular, genetic, and pharmacological links between Alzheimer’s and Parkinson’s diseases and a large panel of 22 cancer types. To examine the overlapping involvement of genes and pathways, we obtained differential gene expression profiles through meta-analyses of post-mortem brain tissues from Alzheimer’s and Parkinson’s disease patients, primary tumors, and tissue-matched controls, and compared them. Genetic similarities were assessed through network-based methods and the computation of genetic correlations. Finally, the potential impact of drugs indicated for each disorder in the identified associations was evaluated using transcriptomic methods. Our research extends previous work in the field by identifying new significant patterns of transcriptomic associations (direct and inverse) between Alzheimer’s disease, Parkinson’s disease, and different site-specific cancers. The results reveal significant genetic correlations between Parkinson’s disease, prostate cancer, and melanoma. In addition, to our knowledge, this is the first time that the role of drugs indicated for the treatment of both sets of disorders has been investigated in the context of their comorbid associations using transcriptomic methods.

Abstract

Alzheimer’s (AD) and Parkinson’s diseases (PD) are the two most prevalent neurodegenerative disorders in human populations. Epidemiological studies have shown that patients suffering from either condition present a reduced overall risk of cancer than controls (i.e., inverse comorbidity), suggesting that neurodegeneration provides a protective effect against cancer. Reduced risks of several site-specific tumors, including colorectal, lung, and prostate cancers, have also been observed in AD and PD. By contrast, an increased risk of melanoma has been described in PD patients (i.e., direct comorbidity). Therefore, a fundamental question to address is whether these associations are due to shared genetic and molecular factors or are explained by other phenomena, such as flaws in epidemiological studies, exposure to shared risk factors, or the effect of medications. To this end, we first evaluated the transcriptomes of AD and PD post-mortem brain tissues derived from the hippocampus and the substantia nigra and analyzed their similarities to those of a large panel of 22 site-specific cancers, which were obtained through differential gene expression meta-analyses of array-based studies available in public repositories. Genes and pathways that were deregulated in both disorders in each analyzed pair were examined. Second, we assessed potential genetic links between AD, PD, and the selected cancers by establishing interactome-based overlaps of genes previously linked to each disorder. Then, their genetic correlations were computed using cross-trait LD score regression and GWAS summary statistics data. Finally, the potential role of medications in the reported comorbidities was assessed by comparing disease-specific differential gene expression profiles to an extensive collection of differential gene expression signatures generated by exposing cell lines to drugs indicated for AD, PD, and cancer treatment (LINCS L1000). We identified significant inverse associations of transcriptomic deregulation between AD hippocampal tissues and breast, lung, liver, and prostate cancers, and between PD substantia nigra tissues and breast, lung, and prostate cancers. Moreover, significant direct (same direction) associations of deregulation were observed between AD and PD and brain and thyroid cancers, as well as between PD and kidney cancer. Several biological processes, including the immune system, oxidative phosphorylation, PI3K/AKT/mTOR signaling, and the cell cycle, were found to be deregulated in both cancer and neurodegenerative disorders. Significant genetic correlations were found between PD and melanoma and prostate cancers. Several drugs indicated for the treatment of neurodegenerative disorders and cancer, such as galantamine, selegiline, exemestane, and estradiol, were identified as potential modulators of the comorbidities observed between neurodegeneration and cancer.

Neuroprotective effects of allocryptopine-rich alkaloid extracts against oxidative stress-induced neuronal damage

BACKGROUND

Oxidative stress is a significant feature in the pathomechanism of neurodegenerative diseases. Thus, the search for an effective and safe novel antioxidant agent with neuroprotective properties has increased the interest in medicinal plant products as a bioactive phytochemical source. However, little is known about the potential effects of the medically important Glaucium corniculatum as a natural antioxidant.

OBJECTIVE

In the present study, it was aimed to investigate the anti-oxidative, anti-apoptotic, and cell cycle regulatory mechanisms underlying the neuroprotective effects of alkaloid extracts (chloroform, methanol, and water) from G. corniculatum, which was profiled for major alkaloid/alkaloids, against H₂O₂-induced neuronal damage in differentiated PC12 cells.

MATERIALS AND METHODS

The profiles of the alkaloid extracts were analyzed by GC-MS. The effects of the alkaloid extracts on intracellular ROS production, level of apoptotic cells, and cell cycle dysregulation were analyzed by flow cytometry; the effects on mRNA expression of apoptosis-related genes were also analyzed by qRT-PCR.

RESULTS

The same alkaloid components, allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide were obtained in all three solvents, but the ratios of the components differed according to the solvents. Allocryptopine was determined to be the major alkaloid ingredient in the alkaloid extracts, with the highest amount of allocryptopine (497 μg/mg) being found in the chloroform alkaloid extract (CAE) (*p < 0.05). The best results were obtained from CAE, which has the highest amount of allocryptopine among alkaloid extracts in all studies. CAE suppressed intracellular ROS production (5.7-fold), percentage of apoptotic cells (3.0-fold), and cells in the sub G1 phase (6.8-fold); additionally, it increased cells in the G1 phase (1.5-fold) (**p < 0.01). CAE remarkably reduced the expressions of Bax, Caspase-9/-3 mRNA (2.4-3.5-fold) while increasing the expression of Bcl-2 mRNA (3.0-fold) (*p < 0.05).

CONCLUSIONS

Our results demonstrated that alkaloid extracts from G. corniculatum, which contain allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide suppressed oxidative stress-induced neuronal apoptosis, possibly by suppressing the mitochondrial apoptotic pathway and regulating the cell cycle. These results are the first report that related alkaloids have played a neuroprotective role by regulating multiple mechanisms. Thus, our study indicated that these alkaloids especially allocryptopine could offer an efficient and novel strategy to explore novel drugs for neuroprotection and cognitive improvement.

Dexmedetomidine protects SH-SY5Y cells against MPP+ -induced declining of mitochondrial membrane potential and cell cycle deficits

Dexmedetomidine (Dex), an adrenergic α2 receptor agonist, is commonly used in deep-brain stimulation surgery for Parkinson's disease (PD). However, there is evidence that the use of anaesthetics may accelerate the progression of neurodegenerative diseases. The effect of Dex on PD remains unclear. Here, we cultured the all-trans-retinoicacid (ATRA) differentiated SH-SY5Y cells in vitro and then treated with MPP+ (1.5mM) with or without Dex (10nM) or Dex combined with Atipamezole (Ati,100nM, adrenergic α2 receptor inhibitor). The ratio of apoptotic cells, mitochondrial membrane potential (Δψm), reactive oxygen species (ROS), cell cycle and apoptotic markers (Cleaved caspase-3, 9) were analysed by flow cytometry and immunofluorescence. We found that the levels of apoptotic ratio and cleaved caspase-3, 9 increased, ROS accumulated, and mitochondrial membrane potential decreased after MPP+treatment, while these changes were partially reversed by Dex. Dex also prevented MPP+ induced cell arrest by increasing G1 phase cells, decreasing S phase cells, and decreasing the expression of cyclinD1 and Cdk4. Moreover the effects of Dex were partially reversed by Ati. These findings reveal that Dex attenuated MPP+ -induced apoptosis of SH-SY5Y cells by preventing the loss of Δψm, reducing ROS, and regulating the cell cycle. Our findings indicated that Dex is more likely to be a potential drug for the treatment of PD.

Evaluation of the neuroprotective potential of caffeic acid phenethyl ester in a cellular model of Parkinson's disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease, and oxidative stress and mitochondrial dysfunction play a major role in the pathogenesis of PD. Since conventional therapeutics are not sufficient for the treatment of PD, the development of new agents with anti-oxidant potential is crucial. Caffeic Acid Phenethyl Ester (CAPE), a biologically active flavonoid of propolis, possesses several biological properties such as immunomodulatory, anti-inflammatory and anti-oxidative. In the present study, we investigated the neuroprotective effects of CAPE against 6-hydroxydopamine (6-OHDA)-induced SH-SY5Y cells. The neuroprotective effects were detected by using cell viability, Annexin V, Hoechst staining, total caspase activity, cell cycle, as well as western blotting. Besides, the anti-oxidative activity was measured by the production of reactive oxygen species and mitochondrial function was determined by measurement of mitochondrial membrane potential (ΔΨm). We found that CAPE significantly increased cell viability and decreased apoptotic cell death (~20%) after 150 μM 6-OHDA exposure following 24 h. 1.25 μM CAPE also prevented 6-OHDA-induced changes in condensed nuclear morphology. Furthermore, treatment with 1.25 μM CAPE increased mitochondrial membrane potential in 6-OHDA-exposed cells. CAPE inhibited 6-OHDA-induced caspase activity (~2 fold) and production of reactive oxygen species. In addition, 150 μM 6-OHDA-induced down-regulation of Bcl-2 and Akt levels and up-regulation of Bax and cleaved caspase-9/caspase-9 levels were partially restored by 1.25 μM CAPE treatment. These results revealed a neuroprotective potential of CAPE against 6-OHDA-induced apoptosis in an in vitro PD model and may be a potential therapeutic candidate for the prevention of neurodegeneration in Parkinson's Disease.

Targeting Cannabinoid Receptor Activation and BACE-1 Activity Counteracts TgAPP Mice Memory Impairment and Alzheimer's Disease Lymphoblast Alterations

Alzheimer's disease (AD), the leading cause of dementia in the elderly, is a neurodegenerative disorder marked by progressive impairment of cognitive ability. Patients with AD display neuropathological lesions including senile plaques, neurofibrillary tangles, and neuronal loss. There are no disease-modifying drugs currently available. With the number of affected individuals increasing dramatically throughout the world, there is obvious urgent need for effective treatment strategy for AD. The multifactorial nature of AD encouraged the development of multifunctional compounds, able to interact with several putative targets. Here, we have evaluated the effects of two in-house designed cannabinoid receptors (CB) agonists showing inhibitory actions on β-secretase-1 (BACE-1) (NP137) and BACE-1/butyrylcholinesterase (BuChE) (NP148), on cellular models of AD, including immortalized lymphocytes from late-onset AD patients. Furthermore, the performance of TgAPP mice in a spatial navigation task was investigated following chronic administration of NP137 and NP148. We report here that NP137 and NP148 showed neuroprotective effects in amyloid-β-treated primary cortical neurons, and NP137 in particular rescued the cognitive deficit of TgAPP mice. The latter compound was able to blunt the abnormal cell response to serum addition or withdrawal of lymphoblasts derived from AD patients. It is suggested that NP137 could be a good drug candidate for future treatment of AD.

Lymphoproliferation Impairment and Oxidative Stress in Blood Cells from Early Parkinson's Disease Patients

In Parkinson’s Disease (PD), the peripheral changes in the functional capacity and redox state of immune cells has been scarcely investigated, especially in the early PD stages. Aging is a risk factor for PD, and the age-related impairment of the immune system, based on a chronic-oxidative stress situation, is involved in the rate of aging. We analyzed several functions in isolated peripheral blood neutrophils and mononuclear cells from PD stage 2 patients, and compared the results to those in healthy elderly and adult controls. Several oxidative stress and damage parameters were studied in whole blood cells. The results showed an impairment of the lymphoproliferative response in stimulated conditions in the PD patients compared with age-matched controls, who also showed typical immunosenescence in comparison with adult individuals. Higher oxidative stress and damage were observed in whole blood cells from PD patients (lower glutathione peroxidase activity, and higher oxidized glutathione and malondialdehyde contents). Our results suggest an accelerated immunosenescence in PD stage 2, and that several of the parameters studied could be appropriate peripheral biomarkers in the early stages of PD.

Recapitulation of Pathological TDP-43 Features in Immortalized Lymphocytes from Sporadic ALS Patients

Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurodegenerative disorder of still unknown etiology that results in loss of motoneurons, paralysis, and death, usually between 2 and 4 years from onset. There are no currently available ALS biomarkers to support early diagnosis and to facilitate the assessment of the efficacy of new treatments. Since ALS is considered a multisystemic disease, here we have investigated the usefulness of immortalized lymphocytes from sporadic ALS patients to study TDP-43 homeostasis as well as to provide a convenient platform to evaluate TDP-43 phosphorylation as a novel therapeutic approach for ALS. We report here that lymphoblasts from ALS patients recapitulate the hallmarks of TDP-43 processing in affected motoneurons, such as increased phosphorylation, truncation, and mislocalization of TDP-43. Moreover, modulation of TDP-43 by an in-house designed protein casein kinase-1δ (CK-1δ) inhibitor, IGS3.27, reduced phosphorylation of TDP-43, and normalized the nucleo-cytosol translocation of TDP-43 in ALS lymphoblasts. Therefore, we conclude that lymphoblasts, easily accessible cells, from ALS patients could be a useful model to study pathological features of ALS disease and a suitable platform to test the effects of potential disease-modifying drugs even in a personalized manner.

Targeted proteomic analysis of cognitive dysfunction in remitted major depressive disorder: Opportunities of multi-omics approaches towards predictive, preventive, and personalized psychiatry

In order to accelerate the understanding of pathophysiological mechanisms and clinical biomarker discovery and in psychiatry, approaches that integrate multiple -omics platforms are needed. We introduce a workflow that investigates a narrowly defined psychiatric phenotype, makes use of the potent and cost-effective discovery technology of gene expression microarrays, applies Weighted Gene Co-Expression Network Analysis (WGCNA) to better capture complex and polygenic traits, and finally explores gene expression findings on the proteomic level using targeted mass-spectrometry (MS) technologies. To illustrate the effectiveness of the workflow, we present a proteomic analysis of peripheral blood plasma from patient's remitted major depressive disorder (MDD) who experience ongoing cognitive deficits. We show that co-expression patterns previous detected on the transcript level could be replicated for plasma proteins, as could the module eigengene correlation with cognitive performance. Further, we demonstrate that functional analysis of multi-omics data has the potential to point to cellular mechanisms and candidate biomarkers for cognitive dysfunction in MDD, implicating cell cycle regulation by cyclin D3 (CCND3), regulation of protein processing in the endoplasmatic reticulum by Thioredoxin domain-containing protein 5 (TXND5), and modulation of inflammatory cytokines by Tripartite Motif Containing 26 (TRI26).

SIGNIFICANCE

This paper discusses how data from multiple -omics platforms can be integrated to accelerate biomarker discovery in psychiatry. Using the phenotype of cognitive impairment in remitted major depressive disorder (MDD) as an example, we show that the application of a systems biology approach - weighted gene co-expression network analysis (WGCNA) - in the discovery phase, and targeted proteomic follow-up of results, provides a structured avenue towards uncovering novel candidate markers and pathways for personalized clinical psychiatry.

Immortalized Parkinson's disease lymphocytes have enhanced mitochondrial respiratory activity

In combination with studies of post-mortem Parkinson's disease (PD) brains, pharmacological and genetic models of PD have suggested that two fundamental interacting cellular processes are impaired - proteostasis and mitochondrial respiration. We have re-examined the role of mitochondrial dysfunction in lymphoblasts isolated from individuals with idiopathic PD and an age-matched control group. As previously reported for various PD cell types, the production of reactive oxygen species (ROS) by PD lymphoblasts was significantly elevated. However, this was not due to an impairment of mitochondrial respiration, as is often assumed. Instead, basal mitochondrial respiration and ATP synthesis are dramatically elevated in PD lymphoblasts. The mitochondrial mass, genome copy number and membrane potential were unaltered, but the expression of indicative respiratory complex proteins was also elevated. This explains the increased oxygen consumption rates by each of the respiratory complexes in experimentally uncoupled mitochondria of iPD cells. However, it was not attributable to increased activity of the stress- and energy-sensing protein kinase AMPK, a regulator of mitochondrial biogenesis and activity. The respiratory differences between iPD and control cells were sufficiently dramatic as to provide a potentially sensitive and reliable biomarker of the disease state, unaffected by disease duration (time since diagnosis) or clinical severity. Lymphoblasts from control and PD individuals thus occupy two distinct, quasi-stable steady states; a 'normal' and a 'hyperactive' state characterized by two different metabolic rates. The apparent stability of the 'hyperactive' state in patient-derived lymphoblasts in the face of patient ageing, ongoing disease and mounting disease severity suggests an early, permanent switch to an alternative metabolic steady state. With its associated, elevated ROS production, the 'hyperactive' state might not cause pathology to cells that are rapidly turned over, but brain cells might accumulate long-term damage leading ultimately to neurodegeneration and the loss of mitochondrial function observed post-mortem. Whether the 'hyperactive' state in lymphoblasts is a biomarker specifically of PD or more generally of neurodegenerative disease remains to be determined.

Progranulin deficiency induces overactivation of WNT5A expression via TNF-α/NF-κB pathway in peripheral cells from frontotemporal dementia-linked granulin mutation carriers

BACKGROUND

Loss-of-function progranulin gene (GRN) mutations have been identified as the major cause of frontotemporal lobar degeneration with transactive response (TAR) DNA-binding protein 43 (TDP-43) pathology (frontotemporal lobar degeneration [FTLD]-TDP); however, little is known about the association between progranulin (PGRN) deficiency and neuronal loss in individuals with FTLD-TDP. Previously we reported enhanced proliferative activity associated with the activation of WNT5A/CDK6/pRb signalling in PGRN-deficient cells. The objective of this work was to elucidate the association between PGRN deficiency, WNT5A signalling and cell proliferation in immortalized lymphoblasts from carriers of the c.709-1G > A GRN mutation (asymptomatic and FTLD-TDP).

METHODS

We assessed cell proliferation in carriers of the c.709-1G > A GRN gene mutation and controls without GRN mutation and without sign of neurologic degeneration by cell counting or using an MTT assay. We used a luciferase assay to measure the nuclear factor-κ (NF-κ) activity. We evaluated messenger RNA levels using quantitative real-time polymerase chain reaction and protein levels by immunoblotting. Co-immunoprecipitation was used to analyze the interaction between PGRN and its receptors.

RESULTS

We enrolled 19 carriers of the GRN gene mutation and 10 controls in this study. The PGRN-deficient cells showed increased expression of WNT5A due to NF-κB signalling overactivation. We observed a competition between PGRN and tumour necrosis factor-α (TNF-α) for binding both TNF receptors (TNFR) I and II. Blocking NF-κB signalling using wedelolactone or specific antibodies against TNFRs inhibited WNT5A overexpression and proliferation of PGRN-deficient cells. Conversely, the activation of NF-κB signalling by TNF-α increased WNT5A-dependent proliferation of control cells.

LIMITATIONS

All cell lines were derived from individuals harboring the same splicing GRN mutation. Nevertheless, most of the known GRN mutations lead to haploinsufficiency of the protein.

CONCLUSION

Our results revealed an important role of NF-κB signalling in PGRN-associated FTLD-TDP and confirm that PGRN can bind to TNF-α receptors regulating the expression of WNT5A, suggesting novel targets for treatment of FTLD-TDP linked to GRN mutations.

Targeting TDP-43 phosphorylation by Casein Kinase-1δ inhibitors: a novel strategy for the treatment of frontotemporal dementia

Background

Mutations in the progranulin gene (GRN) are the most common cause of frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP). TDP-43 pathology is characterized by the hyperphosphorylation of the protein at Serine 409/410 residues. Casein kinase-1δ (CK-1δ) was reported to phosphorylate TDP-43 directly. Previous works from our laboratory described the presence of CDK6/pRb-dependent cell cycle alterations, and cytosolic accumulation of TDP-43 protein in lymphoblast from FTLD-TDP patients carriers of a loss-of function mutation in GRN gene (c.709-1G > A). In this work, we have investigated the effects of two brain penetrant CK-1δ inhibitors (IGS-2.7 and IGS-3.27) designed and synthetized in our laboratory on cell proliferation, TDP-43 phosphorylation and subcellular localization, as well as their effects on the known nuclear TDP-43 function repressing the expression of CDK6.

Results

We report here that both CK-1δ inhibitors (IGS-2.7 and IGS-3.27) normalized the proliferative activity of PGRN-deficient lymphoblasts by preventing the phosphorylation of TDP-43 fragments, its nucleo-cytosol translocation and the overactivation of the CDK6/pRb cascade. Moreover, ours results show neuroprotective effects of CK-1δ inhibitors in a neuronal cell model of induced TDP-43 phosphorylation.

Conclusions

Our results suggest that modulating CK-1δ activity could be considered a novel therapeutic approach for the treatment of FTLD-TDP and other TDP-43 proteinopathies.

Targeting cyclin D3/CDK6 activity for treatment of Parkinson's disease

At present, treatment for Parkinson's disease (PD) is only symptomatic; therefore, it is important to identify new targets tackling the molecular causes of the disease. We previously found that lymphoblasts from sporadic PD patients display increased activity of the cyclin D3/CDK6/pRb pathway and higher proliferation than control cells. These features were considered systemic manifestations of the disease, as aberrant activation of the cell cycle is involved in neuronal apoptosis. The main goal of this work was to elucidate whether the inhibition of cyclin D3/CDK6-associated kinase activity could be useful in PD treatment. For this purpose, we investigated the effects of two histone deacetylase (HDAC) inhibitors, suberoylanilide hydroxamic (SAHA) acid and sodium butyrate (NaB), and the m-TOR inhibitor rapamycin on cell viability and cyclin D3/CDK6 activity. Moreover, the potential neuroprotective action of these drugs was evaluated in 6-hydroxy-dopamine (6-OHDA) treated dopaminergic SH-SY5Y cells and primary rat mesencephalic cultures. Here, we report that both compounds normalized the proliferative activity of PD lymphoblasts and reduced the 6-OHDA-induced cell death in neuronal cells by preventing the over-activation of the cyclin D3/CDK6/pRb cascade. Considering that these drugs are already used in clinic for treatment of other diseases with good tolerance, it is plausible that they may serve as novel therapeutic drugs for PD. We report here that peripheral cells from Parkinson's disease (PD) patients show an enhanced proliferative activity due to the activation of cyclin D3/CDK6-mediated phosphorylation of retinoblastoma protein (pRb). Treatment of PD lymphoblasts with inhibitors of histone deacetylases like suberoylanilide hydroxamic acid (SAHA) and sodium butyrate (NaB), or with rapamycin, inhibitor of mechanistic target of rapamycin (mTOR) normalized the proliferation of PD lymphoblasts by preventing the over-activation of the cyclin D3/CDK6/pRb cascade. These drugs were shown to have neuroprotective effects in both human neuroblastoma SH-SY5Y cells and primary rat mid-brain dopaminergic neuronal cultures toxicity induced by 6-hidroxydopamine. Considering that these drugs are already used in clinic for treatment of other diseases with good tolerance, it seems reasonable to believe that the repositioning of these drugs toward PD holds promise as a novel therapeutic strategy.