Hypermethylation of TRIM59 and KLF14 Influences Cell Death Signaling in Familial Alzheimer's Disease

DNA methylation clocks for estimating biological age in Chinese cohorts

Epigenetic clocks are accurate predictors of human chronological age based on the analysis of DNA methylation (DNAm) at specific CpG sites. However, a systematic comparison between DNA methylation data and other omics datasets has not yet been performed. Moreover, available DNAm age predictors are based on datasets with limited ethnic representation. To address these knowledge gaps, we generated and analyzed DNA methylation datasets from two independent Chinese cohorts, revealing age-related DNAm changes. Additionally, a DNA methylation aging clock (iCAS-DNAmAge) and a group of DNAm-based multi-modal clocks for Chinese individuals were developed, with most of them demonstrating strong predictive capabilities for chronological age. The clocks were further employed to predict factors influencing aging rates. The DNAm aging clock, derived from multi-modal aging features (compositeAge-DNAmAge), exhibited a close association with multi-omics changes, lifestyles, and disease status, underscoring its robust potential for precise biological age assessment. Our findings offer novel insights into the regulatory mechanism of age-related DNAm changes and extend the application of the DNAm clock for measuring biological age and aging pace, providing the basis for evaluating aging intervention strategies.

Epigenetics in Alzheimer's Disease: A Critical Overview

Epigenetic modifications have been implicated in a number of complex diseases as well as being a hallmark of organismal aging. Several reports have indicated an involvement of these changes in Alzheimer's disease (AD) risk and progression, most likely contributing to the dysregulation of AD-related gene expression measured by DNA methylation studies. Given that DNA methylation is tissue-specific and that AD is a brain disorder, the limitation of these studies is the ability to identify clinically useful biomarkers in a proxy tissue, reflective of the tissue of interest, that would be less invasive, more cost-effective, and easily obtainable. The age-related DNA methylation changes have also been used to develop different generations of epigenetic clocks devoted to measuring the aging in different tissues that sometimes suggests an age acceleration in AD patients. This review critically discusses epigenetic changes and aging measures as potential biomarkers for AD detection, prognosis, and progression. Given that epigenetic alterations are chemically reversible, treatments aiming at reversing these modifications will be also discussed as promising therapeutic strategies for AD.

Role of Epigenetic Modulation in Neurodegenerative Diseases: Implications of Phytochemical Interventions

Epigenetics defines changes in cell function without involving alterations in DNA sequence. Neuroepigenetics bridges neuroscience and epigenetics by regulating gene expression in the nervous system and its impact on brain function. With the increase in research in recent years, it was observed that alterations in the gene expression did not always originate from changes in the genetic sequence, which has led to understanding the role of epigenetics in neurodegenerative diseases (NDDs) including Alzheimer's disease (AD) and Parkinson's disease (PD). Epigenetic alterations contribute to the aberrant expression of genes involved in neuroinflammation, protein aggregation, and neuronal death. Natural phytochemicals have shown promise as potential therapeutic agents against NDDs because of their antioxidant, anti-inflammatory, and neuroprotective effects in cellular and animal models. For instance, resveratrol (grapes), curcumin (turmeric), and epigallocatechin gallate (EGCG; green tea) exhibit neuroprotective effects through their influence on DNA methylation patterns, histone acetylation, and non-coding RNA expression profiles. Phytochemicals also aid in slowing disease progression, preserving neuronal function, and enhancing cognitive and motor abilities. The present review focuses on various epigenetic modifications involved in the pathology of NDDs, including AD and PD, gene expression regulation related to epigenetic alterations, and the role of specific polyphenols in influencing epigenetic modifications in AD and PD.

Downregulation of Krüppel-like factor 14 accelerated cellular senescence and aging

Aging has been considered as a risk factor in many diseases, thus, comprehensively understanding the cellular and molecular mechanisms of delayed aging is important. Here we investigated whether Krüppel-like factor 14 (KLF14) is a suppressor of cellular senescence and aging. In our research, KLF14 levels significantly decreased not only in the lymphocytes of healthy people but also in the cells and tissues of mice with aging. We performed in vitro and in vivo experiments on cells and mice to reveal the function of KLF14 in aging. KLF14 deficiency facilitates cellular senescence and aging-related pathologies in C57BL/6J mice, whereas KLF14 overexpression attenuates cellular senescence. Mechanistically, KLF14 delays aging by binding to the POLD1 promoter to positively regulate POLD1 expression. Remarkably, cellular senescence mediated by KLF14 downregulation could be alleviated by POLD1 expression. In addition, perhexiline, an agonist of KLF14, could delay cellular senescence and aging-related pathologies in senescence-accelerated P8 mice by inducing POLD1 expression, as perhexiline could enhance the effect of KLF14's transcription activation to POLD1 by elevating the binding level of KLF14 to the POLD1 promoter. Our data indicate that KLF14 might be a critical element in aging by upregulating POLD1 expression, indicating that the activation of KLF14 may delay aging and aging-associated diseases.

Tripartite Motif Protein Family in Central Nervous System Diseases

Tripartite motif (TRIM) protein superfamily is a group of E3 ubiquitin ligases characterized by the conserved RING domain, the B-box domain, and the coiled-coil domain (RBCC). It is widely involved in various physiological and pathological processes, such as intracellular signal transduction, cell cycle regulation, oncogenesis, and innate immune response. Central nervous system (CNS) diseases are composed of encephalopathy and spinal cord diseases, which have a high disability and mortality rate. Patients are often unable to take care of themselves and their life quality can be seriously declined. Initially, the function research of TRIM proteins mainly focused on cancer. However, in recent years, accumulating attention is paid to the roles they play in CNS diseases. In this review, we integrate the reported roles of TRIM proteins in the pathological process of CNS diseases and related signaling pathways, hoping to provide theoretical bases for further research in treating CNS diseases targeting TRIM proteins. TRIM proteins participated in CNS diseases. TRIM protein family is characterized by a highly conserved RBCC domain, referring to the RING domain, the B-box domain, and the coiled-coil domain. Recent research has discovered the relations between TRIM proteins and various CNS diseases, especially Alzheimer's disease, Parkinson's disease, and ischemic stroke.

TRIM family proteins: roles in proteostasis and neurodegenerative diseases

Neurodegenerative diseases (NDs) are a diverse group of disorders characterized by the progressive degeneration of the structure and function of the central or peripheral nervous systems. One of the major features of NDs, such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD), is the aggregation of specific misfolded proteins, which induces cellular dysfunction, neuronal death, loss of synaptic connections and eventually brain damage. By far, a great amount of evidence has suggested that TRIM family proteins play crucial roles in the turnover of normal regulatory and misfolded proteins. To maintain cellular protein quality control, cells rely on two major classes of proteostasis: molecular chaperones and the degradative systems, the latter includes the ubiquitin-proteasome system (UPS) and autophagy; and their dysfunction has been established to result in various physiological disorders including NDs. Emerging evidence has shown that TRIM proteins are key players in facilitating the clearance of misfolded protein aggregates associated with neurodegenerative disorders. Understanding the different pathways these TRIM proteins employ during episodes of neurodegenerative disorder represents a promising therapeutic target. In this review, we elucidated and summarized the diverse roles with underlying mechanisms of members of the TRIM family proteins in NDs.

Determining KLF14 tertiary structure and diagnostic significance in brain cancer progression

Expression analysis of new protein targets may play a crucial role in the early detection and diagnosis of brain tumor progression. The study aimed to investigate the possible relation of KLF14, TPD52, miR-124, and PKCε in the development and progression of brain cancer and space occupying lesion (SOL) of the brain. One hundred human blood samples comprising varying diagnostic groups (SOL brain, grade I, II, III, IV) were analyzed by real-time quantitative PCR to determine the expression level of KLF14, TPD52, miR-124, and PKCε. TPD52 and PKCε were upregulated in brain cancer by 2.5- and 1.6-fold, respectively, whereas, KLF14 and miR-124 were downregulated in brain cancer. In metastatic and high-grade brain cancer, TPD52 and PKCε expression were up-regulated and KLF14 and miR-124 expression were down-regulated. Further, these genes were found to be differentially expressed in the blood of patients with SOL. Upregulation of TPD52 and PKCε, however, reduced expression of KLF14 and miR-124 in SOL of the brain as compared to healthy controls. Expression analysis of TPD52, KLF14, miR-124, and PKCε provided useful information on the differences existing between the normal brain and SOL, in addition to gliomas; thus, might prove to be useful having diagnostic or prognostic value.

Genotoxic Damage During Brain Development Presages Prototypical Neurodegenerative Disease

Western Pacific Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS/PDC) is a disappearing prototypical neurodegenerative disorder (tau-dominated polyproteinopathy) linked with prior exposure to phytogenotoxins in cycad seed used for medicine and/or food. The principal cycad genotoxin, methylazoxymethanol (MAM), forms reactive carbon-centered ions that alkylate nucleic acids in fetal rodent brain and, depending on the timing of systemic administration, induces persistent developmental abnormalities of the cortex, hippocampus, cerebellum, and retina. Whereas administration of MAM prenatally or postnatally can produce animal models of epilepsy, schizophrenia or ataxia, administration to adult animals produces little effect on brain structure or function. The neurotoxic effects of MAM administered to rats during cortical brain development (specifically, gestation day 17) are used to model the histological, neurophysiological and behavioral deficits of human schizophrenia, a condition that may precede or follow clinical onset of motor neuron disease in subjects with sporadic ALS and ALS/PDC. While studies of migrants to and from communities impacted by ALS/PDC indicate the degenerative brain disorder may be acquired in juvenile and adult life, a proportion of indigenous cases shows neurodevelopmental aberrations in the cerebellum and retina consistent with MAM exposure in utero. MAM induces specific patterns of DNA damage and repair that associate with increased tau expression in primary rat neuronal cultures and with brain transcriptional changes that parallel those associated with human ALS and Alzheimer’s disease. We examine MAM in relation to neurodevelopment, epigenetic modification, DNA damage/replicative stress, genomic instability, somatic mutation, cell-cycle reentry and cellular senescence. Since the majority of neurodegenerative disease lacks a solely inherited genetic basis, research is needed to explore the hypothesis that early-life exposure to genotoxic agents may trigger or promote molecular events that culminate in neurodegeneration.

Regulatory mechanism of cyclins and cyclin-dependent kinases in post-mitotic neuronal cell division

Neurodegenerative diseases (NDDs) are the most common life-threatening disease of the central nervous system and it cause the progressive loss of neuronal cells. The exact mechanism of the disease's progression is not clear and thus line of treatment for NDDs is a baffling issue. During the progression of NDDs, oxidative stress and DNA damage play an important regulatory function, and ultimately induces neurodegeneration. Recently, aberrant cell cycle events have been demonstrated in the progression of different NDDs. However, the pertinent role of signaling mechanism, for instance, post-translational modifications, oxidative stress, DNA damage response pathway, JNK/p38 MAPK, MEK/ERK cascade, actively participated in the aberrant cell cycle reentry induced neuronal cell death. Mounting evidence has demonstrated that aberrant cell cycle re-entry is a major contributing factor in the pathogenesis of NDDs rather than a secondary phenomenon. In the brain of AD patients with mild cognitive impairment, post miotic cell division can be seen in the early stage of the disease. However, in the brain of PD patients, response to various neurotoxic signals, the cell cycle re-entry has been observed that causes neuronal apoptosis. On contrary, the contributing factors that leads to the induction of cell cycle events in mature neurons in HD and ALS brain pathology is remain unclear. Various pharmacological drugs have been developed to reduce the pathogenesis of NDDs, but they are still not helpful in eliminating the cause of these NDDs.

TRIM59 promotes osteosarcoma progression via activation of STAT3

Osteosarcoma (OS) is a common, highly malignant bone tumor. Tripartite motif-containing protein 59 (TRIM59) has been identified as a potential oncogenic protein involved in the initiation and progression of various human carcinomas. Nonetheless, the possible roles and molecular mechanisms of action of TRIM59 in OS remain unclear. In this study, we found that TRIM59 expression levels were frequently upregulated in OS tissues and cell lines. TRIM59 knockdown significantly suppressed the proliferation, migration, and invasion of OS cells and promoted OS cell apoptosis, whereas TRIM59 overexpression had the opposite effects. In vivo experiments demonstrated that TRIM59 knockdown suppressed OS tumor growth and metastasis in vivo. Furthermore, we found that TRIM59 directly interacted with phospho-STAT3 in OS cells. The downregulation of STAT3 levels attenuated TRIM59-induced cell proliferation and invasion. Taken together, our results indicate that TRIM59 promoted OS progression via STAT3 activation. Therefore, our study may provide a novel therapeutic target for OS.

EZH2-mediated inhibition of KLF14 expression promotes HSCs activation and liver fibrosis by downregulating PPARγ

OBJECTIVES

Induction of deactivation and apoptosis of hepatic stellate cells (HSCs) are principal therapeutic strategies for liver fibrosis. Krüppel-like factor 14 (KLF14) regulates various biological processes, however, roles, mechanisms and implications of KLF14 in liver fibrosis are unknown.

MATERIALS AND METHODS

KLF14 expression was detected in human, rat and mouse fibrotic models, and its effects on HSCs were assessed. Chromatin immunoprecipitation assays were utilized to investigate the binding of KLF14 to peroxisome proliferator-activated receptor γ (PPARγ) promoter, and the binding of enhancer of zeste homolog 2 (EZH2) to KLF14 promoter. In vivo, KLF14-overexpressing adenovirus was injected via tail vein to thioacetamide (TAA)-treated rats to investigate the role of KLF14 in liver fibrosis progression. EZH2 inhibitor EPZ-6438 was utilized to treat TAA-induced rat liver fibrosis.

RESULTS

KLF14 expression was remarkably decreased in human, rat and mouse fibrotic liver tissues. Overexpression of KLF14 increased LD accumulation, inhibited HSCs activation, proliferation, migration and induced G2/M arrest and apoptosis. Mechanistically, KLF14 transactivated PPARγ promoter activity. Inhibition of PPARγ blocked the suppressive role of KLF14 overexpression in HSCs. Downregulation of KLF14 in activated HSCs was mediated by EZH2-regulated histone H3 lysine 27 trimethylation. Adenovirus-mediated KLF14 overexpression ameliorated TAA-induced rat liver fibrosis in PPARγ-dependent manner. Furthermore, EPZ-6438 dramatically alleviated TAA-induced rat liver fibrosis. Importantly, KLF14 expression was decreased in human with liver fibrosis, which was significantly correlated with EZH2 upregulation and PPARγ downregulation.

CONCLUSIONS

KLF14 exerts a critical anti-fibrotic role in liver fibrosis, and targeting the EZH2/KLF14/PPARγ axis might be a novel therapeutic strategy for liver fibrosis.

A Meta-Analysis of Brain DNA Methylation Across Sex, Age, and Alzheimer's Disease Points for Accelerated Epigenetic Aging in Neurodegeneration

Alzheimer's disease (AD) is characterized by specific alterations of brain DNA methylation (DNAm) patterns. Age and sex, two major risk factors for AD, are also known to largely affect the epigenetic profiles in brain, but their contribution to AD-associated DNAm changes has been poorly investigated. In this study we considered publicly available DNAm datasets of four brain regions (temporal, frontal, entorhinal cortex, and cerebellum) from healthy adult subjects and AD patients, and performed a meta-analysis to identify sex-, age-, and AD-associated epigenetic profiles. In one of these datasets it was also possible to distinguish 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) profiles. We showed that DNAm differences between males and females tend to be shared between the four brain regions, while aging differently affects cortical regions compared to cerebellum. We found that the proportion of sex-dependent probes whose methylation is modified also during aging is higher than expected, but that differences between males and females tend to be maintained, with only a few probes showing age-by-sex interaction. We did not find significant overlaps between AD- and sex-associated probes, nor disease-by-sex interaction effects. On the contrary, we found that AD-related epigenetic modifications are significantly enriched in probes whose DNAm varies with age and that there is a high concordance between the direction of changes (hyper or hypo-methylation) in aging and AD, supporting accelerated epigenetic aging in the disease. In summary, our results suggest that age-associated DNAm patterns concur to the epigenetic deregulation observed in AD, providing new insights on how advanced age enables neurodegeneration.

DNA methylation of AHCY may increase the risk of ischemic stroke

Genetic factors play an important role in the pathogenesis of ischemic stroke. Of these, epigenetic modifications provide a new direction for the study of ischemic stroke pathogenesis. This study aimed to determine the correlation between DNA methylation of the gene encoding S-adenosylhomocysteine hydrolase (AHCY) and the risk of ischemic stroke in 64 ischemic stroke patients and 138 patients with traumatic brain injury (control group). The methylation level of AHCY was analyzed using quantitative methylation-specific polymerase chain reaction. Statistically significant differences in AHCY methylation levels were observed between the case group [medians (interquartile range): 0.13% (0.09%, 0.27%)] and the control group [0.06% (0.00%, 0.17%), p < 0.0001], and these associations remained significant in both male (p = 0.003) and female (p = 0.0005) subjects. A subgroup analysis by age revealed a considerably higher percentage of methylated AHCY in the case group than the control group in all age groups (age < 60 years, p = 0.007; age ≥ 60 years, p < 0.0001). A receiver operating characteristic (ROC) curve analysis revealed a trend toward a role for AHCY methylation as an indicator of risk in all ischemic patients [area under the curve (AUC) = 0.70, p = 0.0001], male patients (AUC = 0.67, p = 0.004), and female patients (AUC = 0.75, p = 0.0002). Our study confirmed a significant association between the AHCY DNA methylation level and the risk of ischemic stroke, suggesting that this gene methylation pattern may be a potential diagnostic marker of ischemic stroke.

Genome Wide Analysis Points towards Subtype-Specific Diseases in Different Genetic Forms of Amyotrophic Lateral Sclerosis

Amyotropic lateral sclerosis (ALS) is a lethally progressive and irreversible neurodegenerative disease marked by apparent death of motor neurons present in the spinal cord, brain stem and motor cortex. While more and more gene mutants being established for genetic ALS, the vast majority suffer from sporadic ALS (>90%). It has been challenging, thus, to model sporadic ALS which is one reason why the underlying pathophysiology remains elusive and has stalled the development of therapeutic strategies of this progressive motor neuron disease. To further unravel these pathological signaling pathways, human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs) from FUS- and SOD1 ALS patients and healthy controls were systematically compared to independent published datasets. Here through this study we created a gene profile of ALS by analyzing the DEGs, the Kyoto encyclopedia of Genes and Genomes (KEGG) pathways, the interactome and the transcription factor profiles (TF) that would identify altered molecular/functional signatures and their interactions at both transcriptional (mRNAs) and translational levels (hub proteins and TFs). Our findings suggest that FUS and SOD1 may develop from dysregulation in several unique pathways and herpes simplex virus (HSV) infection was among the topmost predominant cellular pathways connected to FUS and not to SOD1. In contrast, SOD1 is mainly characterized by alterations in the metabolic pathways and alterations in the neuroactive-ligand-receptor interactions. This suggests that different genetic ALS forms are singular diseases rather than part of a common spectrum. This is important for patient stratification clearly pointing towards the need for individualized medicine approaches in ALS.

DNA Methylation Clocks and Their Predictive Capacity for Aging Phenotypes and Healthspan

The number of age predictors based on DNA methylation (DNAm) profile is rising due to their potential in predicting healthspan and application in age-related illnesses, such as neurodegenerative diseases. The cumulative assessment of DNAm levels at age-related CpGs (DNAm clock) may reflect biological aging. Such DNAm clocks have been developed using various training models and could mirror different aspects of disease/aging mechanisms. Hence, evaluating several DNAm clocks together may be the most effective strategy in capturing the complexity of the aging process. However, various confounders may influence the outcome of these age predictors, including genetic and environmental factors, as well as technical differences in the selected DNAm arrays. These factors should be taken into consideration when interpreting DNAm clock predictions. In the current review, we discuss 15 reported DNAm clocks with consideration for their utility in investigating neurodegenerative diseases and suggest research directions towards developing a more optimal measure for biological aging.

Epigenetic clock analysis of human fibroblasts in vitro: effects of hypoxia, donor age, and expression of hTERT and SV40 largeT

Aging is associated with a genome-wide change of DNA methylation (DNAm). "DNAm age" is defined as the predicted chronological age by the age estimator based on DNAm. The estimator is called the epigenetic clock. The molecular mechanism underlining the epigenetic clock is still unknown. Here, we evaluated the effects of hypoxia and two immortalization factors, hTERT and SV40-LargeT (LT), on the DNAm age of human fibroblasts in vitro. We detected the cell division-associated progression of DNAm age after >10 population doublings. Moreover, the progression of DNAm age was slower under hypoxia (1% oxygen) compared to normoxia (21% oxygen), suggesting that oxygen levels determine the speed of the epigenetic aging. We show that the speed of cell division-associated DNAm age progression depends on the chronological age of the cell donor. hTERT expression did not arrest cell division-associated progression of DNAm age in most cells. SV40LT expression produced inconsistent effects, including rejuvenation of DNAm age. Our results show that a) oxygen and the targets of SV40LT (e.g. p53) modulate epigenetic aging rates and b) the chronological age of donor cells determines the speed of mitosis-associated DNAm age progression in daughter cells.

A New Robust Epigenetic Model for Forensic Age Prediction

Forensic DNA phenotyping refers to an emerging field of forensic sciences aimed at the prediction of externally visible characteristics of unknown sample donors directly from biological materials. The aging process significantly affects most of the above characteristics making the development of a reliable method of age prediction very important. Today, the so-called "epigenetic clocks" represent the most accurate models for age prediction. Since they are technically not achievable in a typical forensic laboratory, forensic DNA technology has triggered efforts toward the simplification of these models. The present study aimed to build an epigenetic clock using a set of methylation markers of five different genes in a sample of the Italian population of different ages covering the whole span of adult life. In a sample of 330 subjects, 42 selected markers were analyzed with a machine learning approach for building a prediction model for age prediction. A ridge linear regression model including eight of the proposed markers was identified as the best performing model across a plethora of candidates. This model was tested on an independent sample of 83 subjects providing a median error of 4.5 years. In the present study, an epigenetic model for age prediction was validated in a sample of the Italian population. However, its applicability to advanced ages still represents the main limitation in forensic caseworks.

Transcriptomic and Network Analysis Identifies Shared and Unique Pathways across Dementia Spectrum Disorders

Background: Dementia is a growing public health concern with an estimated prevalence of 50 million people worldwide. Alzheimer’s disease (AD) and vascular and frontotemporal dementias (VaD, FTD), share many clinical, genetical, and pathological features making the diagnosis difficult. Methods: In this study, we compared the transcriptome from the frontal cortex of patients with AD, VaD, and FTD to identify dysregulated pathways. Results: Upregulated genes in AD were enriched in adherens and tight junctions, mitogen-activated protein kinase, and phosphatidylinositol 3-kinase and protein kinase B/Akt signaling pathways, whereas downregulated genes associated with calcium signaling. Upregulated genes in VaD were centered on infectious diseases and nuclear factor kappa beta signaling, whereas downregulated genes are involved in biosynthesis of amino acids and the pentose phosphate pathway. Upregulated genes in FTD were associated with ECM receptor interactions and the lysosome, whereas downregulated genes were involved in glutamatergic synapse and MAPK signaling. The transcription factor KFL4 was shared among the 3 types of dementia. Conclusions: Collectively, we identified similarities and differences in dysregulated pathways and transcription factors among the dementias. The shared pathways and transcription factors may indicate a potential common etiology, whereas the differences may be useful for distinguishing dementias.

The role of KLF14 in multiple disease processes

Kruppel-like factor 14 (KLF14) is a newly identified member of the KLF family. Expression of KLF14 is induced by TGF-β in intrauterine and ectodermal tissue. Initial researches on KLF14 focused on its role in lipid and glucose metabolism. In recent years, however, the role of KLF14 in regulating cell signaling pathways, cell proliferation and differentiation has been explored. Moreover, the research has gradually extended into the field of tumorigenesis and immune regulation. This paper aims to briefly review the functions of KLF14 in physiologyical and pathological process.

Many Faces of TRIM Proteins on the Road from Pluripotency to Neurogenesis

Tripartite motif (TRIM) proteins participate in numerous biological processes. They are the key players in immune system and are involved in the oncogenesis. Moreover, TRIMs are the highly conserved regulators of developmental pathways in both vertebrates and invertebrates. In particular, numerous data point to the participation of TRIMs in the determination of stem cell fate, as well as in the neurogenesis. TRIMs apply various mechanisms to perform their functions. Their common feature is the ability to ubiquitinate proteins mediated by the Really Interesting New Gene (RING) domain. Different C-terminal domains of TRIMs are involved in DNA and RNA binding, protein/protein interactions, and chromatin-mediated transcriptional regulation. Mutations and alterations of TRIM expression cause significant disturbances in the stem cells' self-renewal and neurogenesis, which result in the various pathologies of the nervous system (neurodegeneration, neuroinflammation, and malignant transformation). This review discusses the diverse molecular mechanisms of participation of TRIMs in stem cell maintenance and self-renewal as well as in neural differentiation processes and neuropathology.

The current status of blood epigenetic biomarkers for dementia

Dementia is an overarching term which describes a group of symptoms that result in long-term decline in cognitive functioning that is significant enough to affect daily function. It is caused by a number of different diseases, the most common of which is Alzheimer's disease. Currently, there are no definitive biomarkers for preclinical or diagnostic use, or which differentiate between underlying disease types. The purpose of this review is to highlight several important areas of research on blood-based biomarkers of dementia, with a specific focus on epigenetic biomarkers. A systematic search of the literature identified 77 studies that compared blood DNA methylation between individuals with dementia and controls and 45 studies that measured microRNA. Very few studies were identified that focused on histone modifications. There were many promising findings from studies in the field of blood-based epigenetic biomarkers of dementia, however, a lack of consistency in study design, technologies, and platforms used for the biomarker measurement, as well as statistical analysis methods, have hampered progress. To date, there are very few findings that have been independently replicated across more than one study, indicating a preponderance of false-positive findings and the field has likely been plagued by positive publication bias. Here, we highlight and discuss several of the limitations of existing studies and provide recommendations for how these could be overcome in future research. A robust framework should be followed to enable development of the most valid and reproducible biomarkers with the strongest clinical utility. Defining a series of biomarkers that may be complimentary to each other could permit a stronger multifactorial biomarker to be developed that would allow for not only accurate dementia diagnosis but preclinical detection.

TRIM59 promotes gefitinib resistance in EGFR mutant lung adenocarcinoma cells

AIMS

The relationship between TRIM59 and drug resistance is elusive despite of its multiple uncovered roles in human cancers. Here we aimed to characterize the expression status of TRIM59 in gefitinib-resistant EGFR mutant lung adenocarcinoma cells and elucidate its mechanism underlying the drug resistance.

MAIN METHODS

Gefitinib-resistant cell lines were established by progressive dosage. Relative expression of TRIM59 was determined by both real-time PCR and Western blot. Target gene knockdown was achieved by specific shRNAs. Cell viability was measured by MTT assay. Cell apoptosis was analyzed by flow cytometry with Annexin V/7-AAD double staining. Cell proliferation was determined by clonogenic formation assay. Migration and invasion capacities were detected using transwell chamber assay. Direct interaction between TRIM59 and STAT3 was analyzed by co-immunoprecipitation assay.

KEY FINDINGS

We first observed overexpression of TRIM59 in gefitinib-resistant EGFR mutant lung adenocarcinoma cells. ShRNA-mediated knockdown of TRIM59 significantly inhibited cell viability and stimulated apoptosis. Meanwhile, TRIM59-deficiency suppressed cell migration and invasion. We further identified the interaction between TRIM59 and STAT3. TRIM59-deficiency remarkably impaired the activation of STAT3 signaling. STAT3-specific shRNAs significantly re-sensitized TRIM59-proficient EGFR mutant lung adenocarcinoma cells to gefitinib.

SIGNIFICANCE

Our data characterized aberrant TRIM59 overexpression in gefitinib-resistance EGFR mutant lung adenocarcinoma cells, and indicated the potential involvement of TRIM59-STAT3 signaling in the occurrence of gefitinib-resistance.

Neuronal Apolipoprotein E4 Expression Results in Proteome-Wide Alterations and Compromises Bioenergetic Capacity by Disrupting Mitochondrial Function

Apolipoprotein (apo) E4, the major genetic risk factor for Alzheimer's disease (AD), alters mitochondrial function and metabolism early in AD pathogenesis. When injured or stressed, neurons increase apoE synthesis. Because of its structural difference from apoE3, apoE4 undergoes neuron-specific proteolysis, generating fragments that enter the cytosol, interact with mitochondria, and cause neurotoxicity. However, apoE4's effect on mitochondrial respiration and metabolism is not understood in detail. Here we used biochemical assays and proteomic profiling to more completely characterize the effects of apoE4 on mitochondrial function and cellular metabolism in Neuro-2a neuronal cells stably expressing apoE4 or apoE3. Under basal conditions, apoE4 impaired respiration and increased glycolysis, but when challenged or stressed, apoE4-expressing neurons had 50% less reserve capacity to generate ATP to meet energy requirements than apoE3-expressing neurons. ApoE4 expression also decreased the NAD+/NADH ratio and increased the levels of reactive oxygen species and mitochondrial calcium. Global proteomic profiling revealed widespread changes in mitochondrial processes in apoE4 cells, including reduced levels of numerous respiratory complex subunits and major disruptions to all detected subunits in complex V (ATP synthase). Also altered in apoE4 cells were levels of proteins related to mitochondrial endoplasmic reticulum-associated membranes, mitochondrial fusion/fission, mitochondrial protein translocation, proteases, and mitochondrial ribosomal proteins. ApoE4-induced bioenergetic deficits led to extensive metabolic rewiring, but despite numerous cellular adaptations, apoE4-expressing neurons remained vulnerable to metabolic stress. Our results provide insights into potential molecular targets of therapies to correct apoE4-associated mitochondrial dysfunction and altered cellular metabolism.