Ataxin-1 and Brother of ataxin-1 are components of the Notch signalling pathway

The role of miR-92b-3p in notch signaling and monitoring of oral squamous cell carcinoma

Dysregulation of microRNAs (miRNAs) influences diverse hallmarks of cancer, including proliferative signaling, metastasis, and resistance to cell death. We explored the contribution of miR-92b-3p in oral squamous cell carcinoma (OSCC) and its potential as a monitoring biomarker. Analysis of TCGA, GEO, and our own cohort revealed dysregulation of miR-92b-3p in OSCC, which correlated with aggressive tumor characteristics. miR-92b-3p overexpression augmented proliferation and the epithelial-mesenchymal transition in both YD8 and SCC25 cell lines and xenograft models. Mechanically, augmented miR-92b-3p expression suppressed ATXN1 and CPEB3, activating the Notch signaling pathway and thereby promoting metastasis and cisplatin resistance. In our cohort, serum miR-92b-3p expression reflected the disease status, including relapse. Our results suggest that miR-92b-3p might be an onco-miR involved in OSCC through regulating the ATXN1/CPEB3/Notch pathway. These findings provide novel insights for treating and monitoring OSCC.

CIC/ATXN1-rearranged tumors in the central nervous system are mainly represented by sarcomas: A comprehensive clinicopathological and epigenetic series

CIC fusions have been described in two different central nervous system (CNS) tumor entities. On one hand, fusions of CIC or ATXN1 genes belonging to the same complex of transcriptional repressors, were reported in the CIC-rearranged, sarcoma (SARC-CIC). The diagnosis of this tumor type, which was recently added to the World Health Organization (WHO) Classification of CNS tumors, is difficult mainly because the data concerning its histopathology (as compared to its soft tissue counterpart), immunoprofile, and clinical as well as radiological characteristics are scarce in the literature. On the other hand, a recent study, based on DNA-methylation profiling, has identified a novel high-grade neuroepithelial tumor characterized by recurrent CIC fusions (HGNET-CIC). The aim of this multicentric study was to characterize a cohort of 15 primary CNS tumors harboring a CIC or ATXN1 fusion in terms of clinical, radiological, histopathological, immunophenotypical, and epigenetic characteristics. According to the integrated diagnoses, 14/15 tumors corresponded to SARC-CIC, and only one to HGNET-CIC. The tumors showed similar clinical (mainly pediatric), radiological (mostly supratentorial, cystic, and contrast enhancing), immunophenotypical (common expression of glioneuronal markers), and genetic (similar spectrum of fusions) profiles but their histopathological appearance was clearly distinct. Moreover, we found a novel fusion transcript (CIC::EWSR1) in a SARC-CIC. Most DNA methylation profiles using the Heidelberg Brain Tumor Classifier (v12.8) annotated the samples to the methylation class "SARC-CIC" (9/14 tumors with available data). By using uniform manifold approximation and projection analysis, four other samples were classified as SARC-CIC and another clustered within the methylation class of HGNET-CIC. Our findings confirm that CNS CIC-fused tumors do not represent a single molecular tumor entity. Further analyses are needed to characterize HGNET-CIC in more detail. These results may help to refine the essential diagnostic criteria for SARC-CIC and their terminology (with a suggested consensual name of sarcoma, CIC/ATXN1-complex rearranged).

The capicua-ataxin-1-like complex regulates Notch-driven marginal zone B cell development and sepsis progression

Follicular B (FOB) and marginal zone B (MZB) cells are pivotal in humoral immune responses against pathogenic infections. MZB cells can exacerbate endotoxic shock via interleukin-6 secretion. Here we show that the transcriptional repressor capicua (CIC) and its binding partner, ataxin-1-like (ATXN1L), play important roles in FOB and MZB cell development. CIC deficiency reduces the size of both FOB and MZB cell populations, whereas ATXN1L deficiency specifically affects MZB cells. B cell receptor signaling is impaired only in Cic-deficient FOB cells, whereas Notch signaling is disrupted in both Cic-deficient and Atxn1l-deficient MZB cells. Mechanistically, ETV4 de-repression leads to inhibition of Notch1 and Notch2 transcription, thereby inhibiting MZB cell development in B cell-specific Cic-deficient (Cicf/f;Cd19-Cre) and Atxn1l-deficient (Atxn1lf/f;Cd19-Cre) mice. In Cicf/f;Cd19-Cre and Atxn1lf/f; Cd19-Cre mice, humoral immune responses and lipopolysaccharide-induced sepsis progression are attenuated but are restored upon Etv4-deletion. These findings highlight the importance of the CIC-ATXN1L complex in MZB cell development and may provide proof of principle for therapeutic targeting in sepsis.

MicroRNA-382 as a tumor suppressor during tumor progression

Despite the recent progresses in therapeutic and diagnostic methods, there is still a significantly high rate of mortality among cancer patients. One of the main reasons for the high mortality rate in cancer patients is late diagnosis, which leads to the failure of therapeutic strategies. Therefore, investigation of cancer biology can lead to the introduction of early diagnostic markers in these patients. MicroRNAs (miRNAs) play an important role in regulation of cellular processes associated with tumor progression. Due to the high stability of miRNAs in body fluids, these factors can be considered as the non-invasive tumor markers. Deregulation of miR-382 has been widely reported in different cancers. Therefore, in this review, we investigated the role of miR-382 during tumor development. It has shown that miR-382 has mainly a tumor suppressive, which inhibits the growth of tumor cells through the regulation of signaling pathways, RNA-binding proteins, and transcription factors. Therefore, miR-382 can be suggested as a diagnostic and therapeutic marker in cancer patients.

Genetic and epigenetic landscape of early-onset oral squamous cell carcinoma: Insights of genomic underserved and underrepresented populations

Oral squamous cell carcinoma (OSCC) has a poor prognosis and the treatment employed generates significant physical deformity in patients. In recent years, an increase in the incidence of cases of OSCC has been observed in adult patients up to 45 years old in several genetic underrepresented and underserved countries. The increase in OSCC cases in young people is very relevant because it shows that OSCC does not make exceptions and hereditarily must play an important role. This fact has not been associated with an evident biological basis, and a large majority of these patients do not present the classic principal risk factors association. OSCC is the result of accumulation of genetic and epigenetic alterations and this information is still fragmented in the literature, mainly in the young group. Conducting studies with a comprehensive analysis of genetic and epigenetic data is crucial, to provide greater understanding of the underlying biology of OSCC, because this information can be decisive to determine targets for therapeutic treatment. We review the main germline and somatic aspects of genetic and genomic variation in OSCC considering the absence of genomic data from developing countries such as Chile and the rest of Hispano-America.

Evaluating the expression pattern of ATXN1 and CDC42EP1 genes and related long noncoding RNAs in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a significant health issue worldwide, and the expression of long non-coding RNAs (lncRNAs) are altered in these malignancies. The present study evaluated the expression level of ATXN1 CDC42EP1 genes and the lncRNAs related to these genes (lnc-ATXN1L, lnc-ATXN1, lnc-ATXN10, and lnc-CDC42EP1) in paraffin blocks of oral and pharyngeal squamous cell carcinoma (SCC) samples from patients referred to Amir Alam Hospital in Tehran, Iran.

METHODS AND RESULTS

This cross-sectional study was conducted on 76 paraffin blocks of oral and pharyngeal squamous cell carcinoma (SCC) samples from patients referred to Amir Alam Hospital in Tehran. The expression levels of ATXN1, CDC42EP1, lnc-ATXN1L, lnc-ATXN1, lnc-ATXN10, and lnc-CDC42EP1 were measured in all samples using a qPCR Master Mix kit. Real-time PCR was used to perform the reactions, and GAPDH was considered the housekeeping gene. Statistical analyses were conducted utilizing the Statistical Package for the Social Sciences (SPSS) version 22.0. The expression of lnc-ATXN1, lnc-ATXN10, and lnc-CDC42EP1 significantly differed between the two groups. All of them were downregulated (p < 0.05), and no significant difference was observed between the SCC samples and the adjacent tissue in other genes (p > 0.05). The expression of genes was not related to age, sex, size, and tumor location (p > 0.05).

CONCLUSIONS

Dysexpression of lnc-ATXN1, lnc-ATXN10, and lnc-CDC42EP1 can be used for diagnosing OSCC.

Viral-based animal models in polyglutamine disorders

Polyglutamine disorders are a complex group of incurable neurodegenerative disorders caused by an abnormal expansion in the trinucleotide cytosine-adenine-guanine tract of the affected gene. To better understand these disorders, our dependence on animal models persists, primarily relying on transgenic models. In an effort to complement and deepen our knowledge, researchers have also developed animal models of polyglutamine disorders employing viral vectors. Viral vectors have been extensively used to deliver genes to the brain, not only for therapeutic purposes but also for the development of animal models, given their remarkable flexibility. In a time- and cost-effective manner, it is possible to use different transgenes, at varying doses, in diverse targeted tissues, at different ages, and in different species, to recreate polyglutamine pathology. This paper aims to showcase the utility of viral vectors in disease modelling, share essential considerations for developing animal models with viral vectors, and provide a comprehensive review of existing viral-based animal models for polyglutamine disorders.

Sleeping Beauty transposon mutagenesis in mouse intestinal organoids identifies genes involved in tumor progression and metastasis

To identify genes important for colorectal cancer (CRC) development and metastasis, we established a new metastatic mouse organoid model using Sleeping Beauty (SB) transposon mutagenesis. Intestinal organoids derived from mice carrying actively mobilizing SB transposons, an activating KrasG12D, and an inactivating ApcΔ716 allele, were transplanted to immunodeficient mice. While 66.7% of mice developed primary tumors, 7.6% also developed metastatic tumors. Analysis of SB insertion sites in tumors identified numerous candidate cancer genes (CCGs) identified previously in intestinal SB screens performed in vivo, in addition to new CCGs, such as Slit2 and Atxn1. Metastatic tumors from the same mouse were clonally related to each other and to primary tumors, as evidenced by the transposon insertion site. To provide functional validation, we knocked out Slit2, Atxn1, and Cdkn2a in mouse tumor organoids and transplanted to mice. Tumor development was promoted when these gene were knocked out, demonstrating that these are potent tumor suppressors. Cdkn2a knockout cells also metastasized to the liver in 100% of the mice, demonstrating that Cdkn2a loss confers metastatic ability. Our organoid model thus provides a new approach that can be used to understand the evolutionary forces driving CRC metastasis and a rich resource to uncover CCGs promoting CRC.

Comprehensive transcriptional analysis of early dorsal skin development in pigs

Porcine skin is similar to human skin in physiology, anatomy and histology and is often used as a model animal for human skin research. There are few studies on the transcriptome aspects of pig skin during the embryonic period. In this study, RNA sequencing was performed on the dorsal skin of Chenghua sows at embryonic day 56 (E56), embryonic day 76 (E76), embryonic day 105 (E105), and 3 days after birth (D3) to explore RNA changes in pig dorsal skin at four ages. A number of skin-related differential genes were identified by intercomparison between RNAs at four time points, and KEGG functional analysis showed that these differential genes were mainly enriched in metabolic and developmental, immune, and disease pathways, and the pathways enriched in GO analysis were highly overlapping. Collagen is an important part of the skin, with type I collagen making up the largest portion. In this study, collagen type I alpha 1 (COL1A1) and collagen type I alpha 2 (COL1A2) were significantly upregulated at four time points. In addition, lncRNA-miRNA-mRNA and miRNA-circRNA coexpression networks were constructed. The data obtained may help to explain age-related changes in transcriptional patterns during skin development and provide further references for understanding human skin development at the molecular level.

Cell-free DNA methylation profiles enable early detection of colorectal and gastric cancer

Colorectal cancer (CRC) and gastric cancer (GC) rank the top five common and lethal cancers worldwide. Early detection can significantly reduce the mortality of CRC and GC. However, current clinical screening methods including invasive endoscopic techniques and noninvasive fecal occult blood test screening tests/fecal immunochemical test have shown low sensitivity or unsatisfactory patient's compliance. Aberrant DNA methylation occurs frequently in tumorigenesis and cell-free DNA (cfDNA) methylation has shown the potential in multi-cancer detection. Herein, we aimed to explore the value of cfDNA methylation in the gastrointestinal cancer detection and develop a noninvasive method for CRC and GC detection. We applied targeted methylation sequencing on a total of 407 plasma samples from patients diagnosed with CRC, GC, and noncancerous gastrointestinal benign diseases (Non-Ca). By analyzing the methylation profiles of 34 CRC, 62 GC and 107 Non-Ca plasma samples in the training set (n=203), we identified 40,110 gastrointestinal cancer-specific markers and 63 tissue of origin (TOO) prediction markers. A new integrated model composed of gastrointestinal cancer detection and TOO prediction for three types of classification of CRC, GC and Non-Ca patients was further developed through logistic regression algorithm and validated in an independent validation set (n=103). The model achieved overall sensitivities of 83% and 81.3% at specificities of 81.5% and 80% for identifying gastrointestinal cancers in the test set and validation set, respectively. The detection sensitivities for GC and CRC were respectively 81.4% and 83.3% in the cohort of the test and validation sets. Among these true positive cancer samples, further TOO prediction showed accuracies of 95.8% and 95.8% for GC patients and accuracies of 86.7% and 93.3% for CRC patients, in test set and validation set, respectively. Collectively, we have identified novel cfDNA methylation biomarkers for CRC and GC detection and shown the promising potential of cfDNA as a noninvasive gastrointestinal cancer detection tool.

Chronic metabolic stress drives developmental programs and loss of tissue functions in non-transformed liver that mirror tumor states and stratify survival

Under chronic stress, cells must balance competing demands between cellular survival and tissue function. In metabolic dysfunction-associated steatotic liver disease (MASLD, formerly NAFLD/NASH), hepatocytes cooperate with structural and immune cells to perform crucial metabolic, synthetic, and detoxification functions despite nutrient imbalances. While prior work has emphasized stress-induced drivers of cell death, the dynamic adaptations of surviving cells and their functional repercussions remain unclear. Namely, we do not know which pathways and programs define cellular responses, what regulatory factors mediate (mal)adaptations, and how this aberrant activity connects to tissue-scale dysfunction and long-term disease outcomes. Here, by applying longitudinal single-cell multi -omics to a mouse model of chronic metabolic stress and extending to human cohorts, we show that stress drives survival-linked tradeoffs and metabolic rewiring, manifesting as shifts towards development-associated states in non-transformed hepatocytes with accompanying decreases in their professional functionality. Diet-induced adaptations occur significantly prior to tumorigenesis but parallel tumorigenesis-induced phenotypes and predict worsened human cancer survival. Through the development of a multi -omic computational gene regulatory inference framework and human in vitro and mouse in vivo genetic perturbations, we validate transcriptional (RELB, SOX4) and metabolic (HMGCS2) mediators that co-regulate and couple the balance between developmental state and hepatocyte functional identity programming. Our work defines cellular features of liver adaptation to chronic stress as well as their links to long-term disease outcomes and cancer hallmarks, unifying diverse axes of cellular dysfunction around core causal mechanisms.

Functional implications of paralog genes in polyglutamine spinocerebellar ataxias

Polyglutamine (polyQ) spinocerebellar ataxias (SCAs) comprise a group of autosomal dominant neurodegenerative disorders caused by (CAG/CAA)n expansions. The elongated stretches of adjacent glutamines alter the conformation of the native proteins inducing neurotoxicity, and subsequent motor and neurological symptoms. Although the etiology and neuropathology of most polyQ SCAs have been extensively studied, only a limited selection of therapies is available. Previous studies on SCA1 demonstrated that ATXN1L, a human duplicated gene of the disease-associated ATXN1, alleviated neuropathology in mice models. Other SCA-associated genes have paralogs (i.e., copies at different chromosomal locations derived from duplication of the parental gene), but their functional relevance and potential role in disease pathogenesis remain unexplored. Here, we review the protein homology, expression pattern, and molecular functions of paralogs in seven polyQ dominant ataxias-SCA1, SCA2, MJD/SCA3, SCA6, SCA7, SCA17, and DRPLA. Besides ATXN1L, we highlight ATXN2L, ATXN3L, CACNA1B, ATXN7L1, ATXN7L2, TBPL2, and RERE as promising functional candidates to play a role in the neuropathology of the respective SCA, along with the parental gene. Although most of these duplicates lack the (CAG/CAA)n region, if functionally redundant, they may compensate for a partial loss-of-function or dysfunction of the wild-type genes in SCAs. We aim to draw attention to the hypothesis that paralogs of disease-associated genes may underlie the complex neuropathology of dominant ataxias and potentiate new therapeutic strategies.

MAPK Is a Mutual Pathway Targeted by Anxiety-Related miRNAs, and E2F5 Is a Putative Target for Anxiolytic miRNAs

Anxiety-related disorders (ARDs) are chronic neuropsychological diseases and the sixth leading cause of disability in the world. As dysregulation of microRNAs (miRs) are observed in the pathological course of neuropsychiatric disorders, the present study aimed to introduce miRs that underlie anxiety processing in the brain. First, we collected the experimentally confirmed anxiety-related miRNAs (ARmiRs), predicted their target transcripts, and introduced critical cellular pathways with key commune hub genes. As a result, we have found nine anxiolytic and ten anxiogenic ARmiRs. The anxiolytic miRs frequently target the mRNA of Acyl-CoA synthetase long-chain family member 4 (Acsl4), AFF4-AF4/FMR2 family member 4 (Aff4), and Krüppel like transcription factor 4 (Klf4) genes, where miR-34b-5p and miR-34c-5p interact with all of them. Moreover, the anxiogenic miRs frequently target the mRNA of nine genes; among them, only two miR (miR-142-5p and miR-218-5p) have no interaction with the mRNA of trinucleotide repeat-containing adaptor 6B (Tnrc6b), and miR-124-3p interacts with all of them where MAPK is the main signaling pathway affected by both anxiolytic and anxiogenic miR. In addition, the anxiolytic miR commonly target E2F transcription factor 5 (E2F5) in the TGF-β signaling pathway, and the anxiogenic miR commonly target Ataxin 1 (Atxn1), WASP-like actin nucleation promoting factor (Wasl), and Solute Carrier Family 17 Member 6 (Slc17a6) genes in the notch signaling, adherence junction, and synaptic vesicle cycle pathways, respectively. Taken together, we conclude that the most important anxiolytic (miR-34c, Let-7d, and miR-17) and anxiogenic (miR-19b, miR-92a, and 218) miR, as hub epigenetic modulators, potentially influence the pathophysiology of anxiety, primarily via interaction with the MAPK signaling pathway. Moreover, the role of E2F5 as a novel putative target for anxiolytic miRNAs in ARDs disorders deserves further exploration.

Neurogenetic motor disorders

Advances in the field of neurogenetics have practical applications in rapid diagnosis on blood and body fluids to extract DNA, obviating the need for invasive investigations. The ability to obtain a presymptomatic diagnosis through genetic screening and biomarkers can be a guide to life-saving disease-modifying therapy or enzyme replacement therapy to compensate for the deficient disease-causing enzyme. The benefits of a comprehensive neurogenetic evaluation extend to family members in whom identification of the causal gene defect ensures carrier detection and at-risk counseling for future generations. This chapter explores the many facets of the neurogenetic evaluation in adult and pediatric motor disorders as a primer for later chapters in this volume and a roadmap for the future applications of genetics in neurology.

Polyglutamine Ataxias: Our Current Molecular Understanding and What the Future Holds for Antisense Therapies

Polyglutamine (polyQ) ataxias are a heterogenous group of neurological disorders all caused by an expanded CAG trinucleotide repeat located in the coding region of each unique causative gene. To date, polyQ ataxias encompass six disorders: spinocerebellar ataxia types 1, 2, 3, 6, 7, and 17 and account for a larger group of disorders simply known as polyglutamine disorders, which also includes Huntington's disease. These diseases are typically characterised by progressive ataxia, speech and swallowing difficulties, lack of coordination and gait, and are unfortunately fatal in nature, with the exception of SCA6. All the polyQ spinocerebellar ataxias have a hallmark feature of neuronal aggregations and share many common pathogenic mechanisms, such as mitochondrial dysfunction, impaired proteasomal function, and autophagy impairment. Currently, therapeutic options are limited, with no available treatments that slow or halt disease progression. Here, we discuss the common molecular and clinical presentations of polyQ spinocerebellar ataxias. We will also discuss the promising antisense oligonucleotide therapeutics being developed as treatments for these devastating diseases. With recent advancements and therapeutic approvals of various antisense therapies, it is envisioned that some of the studies reviewed may progress into clinical trials and beyond.

The Role of circRNAs in Human Papillomavirus (HPV)-Associated Cancers

Circular RNAs (circRNAs) are a new class of "non-coding RNAs" that originate from non-sequential back-splicing of exons and/or introns of precursor messenger RNAs (pre-mRNAs). These molecules are generally produced at low levels in a cell-type-specific manner in mammalian tissues, but due to their circular conformation they are unaffected by the cell mRNA decay machinery. circRNAs can sponge multiple microRNAs or RNA-binding proteins and play a crucial role in the regulation of gene expression and protein translation. Many circRNAs have been shown to be aberrantly expressed in several cancer types, and to sustain specific oncogenic processes. Particularly, in virus-associated malignancies such as human papillomavirus (HPV)-associated anogenital carcinoma and oropharyngeal and oral cancers, circRNAs have been shown to be involved in tumorigenesis and cancer progression, as well as in drug resistance, and some are useful diagnostic and prognostic markers. HPV-derived circRNAs, encompassing the HPV E7 oncogene, have been shown to be expressed and to serve as transcript for synthesis of the E7 oncoprotein, thus reinforcing the virus oncogenic activity in HPV-associated cancers. In this review, we summarize research advances in the biogenesis of cell and viral circRNAs, their features and functions in the pathophysiology of HPV-associated tumors, and their importance as diagnostic, prognostic, and therapeutic targets in anogenital and oropharyngeal and oral cancers.

The mutational landscape of early- and typical-onset oral tongue squamous cell carcinoma

BACKGROUND

The incidence of oral tongue squamous cell carcinoma (OTSCC) is increasing among younger birth cohorts. The etiology of early-onset OTSCC (diagnosed before the age of 50 years) and cancer driver genes remain largely unknown.

METHODS

The Sequencing Consortium of Oral Tongue Cancer was established through the pooling of somatic mutation data of oral tongue cancer specimens (n = 227 [107 early-onset cases]) from 7 studies and The Cancer Genome Atlas. Somatic mutations at microsatellite loci and Catalog of Somatic Mutations in Cancer mutation signatures were identified. Cancer driver genes were identified with the MutSigCV and WITER algorithms. Mutation comparisons between early- and typical-onset OTSCC were evaluated via linear regression with adjustments for patient-related factors.

RESULTS

Two novel driver genes (ATXN1 and CDC42EP1) and 5 previously reported driver genes (TP53, CDKN2A, CASP8, NOTCH1, and FAT1) were identified. Six recurrent mutations were identified, with 4 occurring in TP53. Early-onset OTSCC had significantly fewer nonsilent mutations even after adjustments for tobacco use. No associations of microsatellite locus mutations and mutation signatures with the age of OTSCC onset were observed.

CONCLUSIONS

This international, multicenter consortium is the largest study to characterize the somatic mutational landscape of OTSCC and the first to suggest differences by age of onset. This study validates multiple previously identified OTSCC driver genes and proposes 2 novel cancer driver genes. In analyses by age, early-onset OTSCC had a significantly smaller somatic mutational burden that was not explained by differences in tobacco use.

LAY SUMMARY

This study identifies 7 specific areas in the human genetic code that could be responsible for promoting the development of tongue cancer. Tongue cancer in young patients (under the age of 50 years) has fewer overall changes to the genetic code in comparison with tongue cancer in older patients, but the authors do not think that this is due to differences in smoking rates between the 2 groups. The cause of increasing cases of tongue cancer in young patients remains unclear.

Therapeutic antisense oligonucleotides for movement disorders

Movement disorders are a group of neurological conditions characterized by abnormalities of movement and posture. They are broadly divided into akinetic and hyperkinetic syndromes. Until now, no effective symptomatic or disease-modifying therapies have been available. However, since many of these disorders are monogenic or have some well-defined genetic component, they represent strong candidates for antisense oligonucleotide (ASO) therapies. ASO therapies are based on the use of short synthetic single-stranded ASOs that bind to disease-related target RNAs via Watson-Crick base-pairing and pleiotropically modulate their function. With information arising from the RNA sequence alone, it is possible to design ASOs that not only alter the expression levels but also the splicing defects of any protein, far exceeding the intervention repertoire of traditional small molecule approaches. Following the regulatory approval of ASO therapies for spinal muscular atrophy and Duchenne muscular dystrophy in 2016, there has been tremendous momentum in testing such therapies for other neurological disorders. This review article initially focuses on the chemical modifications aimed at improving ASO effectiveness, the mechanisms by which ASOs can interfere with RNA function, delivery systems and pharmacokinetics, and the common set of toxicities associated with their application. It, then, describes the pathophysiology and the latest information on preclinical and clinical trials utilizing ASOs for the treatment of Parkinson's disease, Huntington's disease, and ataxias 1, 2, 3, and 7. It concludes with issues that require special attention to realize the full potential of ASO-based therapies.

Post-Developmental Roles of Notch Signaling in the Nervous System

Since its discovery in Drosophila, the Notch signaling pathway has been studied in numerous developmental contexts in diverse multicellular organisms. The role of Notch signaling in nervous system development has been extensively investigated by numerous scientists, partially because many of the core Notch signaling components were initially identified through their dramatic ‘neurogenic’ phenotype of developing fruit fly embryos. Components of the Notch signaling pathway continue to be expressed in mature neurons and glia cells, which is suggestive of a role in the post-developmental nervous system. The Notch pathway has been, so far, implicated in learning and memory, social behavior, addiction, and other complex behaviors using genetic model organisms including Drosophila and mice. Additionally, Notch signaling has been shown to play a modulatory role in several neurodegenerative disease model animals and in mediating neural toxicity of several environmental factors. In this paper, we summarize the knowledge pertaining to the post-developmental roles of Notch signaling in the nervous system with a focus on discoveries made using the fruit fly as a model system as well as relevant studies in C elegans, mouse, rat, and cellular models. Since components of this pathway have been implicated in the pathogenesis of numerous psychiatric and neurodegenerative disorders in human, understanding the role of Notch signaling in the mature brain using model organisms will likely provide novel insights into the mechanisms underlying these diseases.

Nuclear inclusions of pathogenic ataxin-1 induce oxidative stress and perturb the protein synthesis machinery

Spinocerebellar ataxia type-1 (SCA1) is caused by an abnormally expanded polyglutamine (polyQ) tract in ataxin-1. These expansions are responsible for protein misfolding and self-assembly into intranuclear inclusion bodies (IIBs) that are somehow linked to neuronal death. However, owing to lack of a suitable cellular model, the downstream consequences of IIB formation are yet to be resolved. Here, we describe a nuclear protein aggregation model of pathogenic human ataxin-1 and characterize IIB effects. Using an inducible Sleeping Beauty transposon system, we overexpressed the ATXN1(Q82) gene in human mesenchymal stem cells that are resistant to the early cytotoxic effects caused by the expression of the mutant protein. We characterized the structure and the protein composition of insoluble polyQ IIBs which gradually occupy the nuclei and are responsible for the generation of reactive oxygen species. In response to their formation, our transcriptome analysis reveals a cerebellum-specific perturbed protein interaction network, primarily affecting protein synthesis. We propose that insoluble polyQ IIBs cause oxidative and nucleolar stress and affect the assembly of the ribosome by capturing or down-regulating essential components. The inducible cell system can be utilized to decipher the cellular consequences of polyQ protein aggregation. Our strategy provides a broadly applicable methodology for studying polyQ diseases.

Circulating tumor DNA methylation profiles enable early diagnosis, prognosis prediction, and screening for colorectal cancer

Circulating tumor DNA (ctDNA) has emerged as a useful diagnostic and prognostic biomarker in many cancers. Here, we conducted a study to investigate the potential use of ctDNA methylation markers for the diagnosis and prognostication of colorectal cancer (CRC) and used a prospective cohort to validate their effectiveness in screening patients at high risk of CRC. We first identified CRC-specific methylation signatures by comparing CRC tissues to normal blood leukocytes. Then, we applied a machine learning algorithm to develop a predictive diagnostic and a prognostic model using cell-free DNA (cfDNA) samples from a cohort of 801 patients with CRC and 1021 normal controls. The obtained diagnostic prediction model discriminated patients with CRC from normal controls with high accuracy (area under curve = 0.96). The prognostic prediction model also effectively predicted the prognosis and survival of patients with CRC (P < 0.001). In addition, we generated a ctDNA-based molecular classification of CRC using an unsupervised clustering method and obtained two subgroups of patients with CRC with significantly different overall survival (P = 0.011 in validation cohort). Last, we found that a single ctDNA methylation marker, cg10673833, could yield high sensitivity (89.7%) and specificity (86.8%) for detection of CRC and precancerous lesions in a high-risk population of 1493 participants in a prospective cohort study. Together, our findings showed the value of ctDNA methylation markers in the diagnosis, surveillance, and prognosis of CRC.

ATXN1 N-terminal region explains the binding differences of wild-type and expanded forms

Background

Wild-type (wt) polyglutamine (polyQ) regions are implicated in stabilization of protein-protein interactions (PPI). Pathological polyQ expansion, such as that in human Ataxin-1 (ATXN1), that causes spinocerebellar ataxia type 1 (SCA1), results in abnormal PPI. For ATXN1 a larger number of interactors has been reported for the expanded (82Q) than the wt (29Q) protein.

Methods

To understand how the expanded polyQ affects PPI, protein structures were predicted for wt and expanded ATXN1, as well as, for 71 ATXN1 interactors. Then, the binding surfaces of wt and expanded ATXN1 with the reported interactors were inferred.

Results

Our data supports that the polyQ expansion alters the ATXN1 conformation and that it enhances the strength of interaction with ATXN1 partners. For both ATXN1 variants, the number of residues at the predicted binding interface are greater after the polyQ, mainly due to the AXH domain. Moreover, the difference in the interaction strength of the ATXN1 variants was due to an increase in the number of interactions at the N-terminal region, before the polyQ, for the expanded form.

Conclusions

There are three regions at the AXH domain that are essential for ATXN1 PPI. The N-terminal region is responsible for the strength of the PPI with the ATXN1 variants. How the predicted motifs in this region affect PPI is discussed, in the context of ATXN1 post-transcriptional modifications.

Genetics, Mechanisms, and Therapeutic Progress in Polyglutamine Spinocerebellar Ataxias

Autosomal dominant cerebellar ataxias (ADCAs) are a group of neurodegenerative disorders characterized by degeneration of the cerebellum and its connections. All ADCAs have progressive ataxia as their main clinical feature, frequently accompanied by dysarthria and oculomotor deficits. The most common spinocerebellar ataxias (SCAs) are 6 polyglutamine (polyQ) SCAs. These diseases are all caused by a CAG repeat expansion in the coding region of a gene. Currently, no curative treatment is available for any of the polyQ SCAs, but increasing knowledge on the genetics and the pathological mechanisms of these polyQ SCAs has provided promising therapeutic targets to potentially slow disease progression. Potential treatments can be divided into pharmacological and gene therapies that target the toxic downstream effects, gene therapies that target the polyQ SCA genes, and stem cell replacement therapies. Here, we will provide a review on the genetics, mechanisms, and therapeutic progress in polyglutamine spinocerebellar ataxias.

Circular RNAs and their roles in head and neck cancers

Circular RNAs are abundant endogenous non-coding RNA with no 5′ cap and 3′ polyadenylation tail that modify liner mRNAs and have no terminal structures. Our knowledge of the biogenesis of circular RNAs has been expanded, and circular RNAs were shown to be key regulators of various diseases, especially cancers. Head and neck cancers are the sixth most popular cancers worldwide, and the overall survival rates remain unsatisfactory. Recent studies have indicated that circular RNAs are involved in the tumorigenesis, progression, invasion and chemosensitivity of head and neck cancers and that some circular RNAs could serve as diagnostic and prognostic biomarkers. In this study, we summarize research advances in the regulation of circular RNA biogenesis, their characteristics and functions, the involvement of circular RNAs in the pathophysiology of head and neck cancers and their potential clinical utilization, as well as the likely directions of future studies.

Structural signature in SCA1: clinical correlates, determinants and natural history

Spinocerebellar ataxia type 1 is an autosomal dominant disorder caused by a CAG repeat expansion in ATXN1, characterized by progressive cerebellar and extracerebellar symptoms. MRI-based studies in SCA1 focused in the cerebellum and connections, but there are few data about supratentorial/spinal damage and its clinical relevance. We have thus designed this multimodal MRI study to uncover the structural signature of SCA1. To accomplish that, a group of 33 patients and 33 age-and gender-matched healthy controls underwent MRI on a 3T scanner. All patients underwent a comprehensive neurological and neuropsychological evaluation. We correlated the structural findings with the clinical features of the disease. In addition, we evaluated the disease progression looking at differences in SCA1 subgroups defined by disease duration. Ataxia and pyramidal signs were the main symptoms. Neuropsychological evaluation disclosed cognitive impairment in 53% with predominant frontotemporal dysfunction. Gray matter analysis unfolded cortical thinning of primary and associative motor areas with more restricted impairment of deep structures. Deep gray matter atrophy was associated with motor handicap and poor cognition skills. White matter integrity loss was diffuse in the brainstem but restricted in supratentorial structures. Cerebellar cortical thinning was found in multiple areas and correlated not only with motor disability but also with verbal fluency. Spinal cord atrophy correlated with motor handicap. Comparison of MRI findings in disease duration-defined subgroups identified a peculiar pattern of progressive degeneration.

Hsa_circ_0008309 May Be a Potential Biomarker for Oral Squamous Cell Carcinoma

Objective

Oral squamous cell carcinoma (OSCC) is the most common cancer of the head and neck region. The circular RNA (circRNA) is known to serve an important role in the carcinogenesis of different types of cancer. However, the circRNA role of OSCC remains unclear.

Methods

8 pairs of OSCC tissues and adjacent normal tissues were obtained to detect circRNAs expression by high-throughput sequencing, and 45 pairs of OSCC tissues were selected to verify the differentially significant circRNAs by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). To further investigate the role of hsa_circ_0008309, the circRNA-microRNA (miR)-mRNA network was predicted using bioinformatics databases. The expression levels of hsa_circ_0008309, miR-1290, miR-136-5P, and miR-382-5P in SCC-15 and CAL27 cell lines were detected by RT-qPCR. Western blotting was performed to detect the protein level of Ataxin 1 (ATXN1).

Results

The high-throughput sequencing results demonstrated that circRNAs were abundantly expressed in OSCC, and 16 circRNAs were significantly differentially expressed. Hsa_circ_0008309 was significantly downregulated in 45 pairs of OSCC tissue samples and was statistically correlated with pathological differentiation. The bioinformatics databases suggested that hsa_circ_0008309 could combine with miR-1290, miR-136-5P, and miR-382-5P, respectively, to regulate the expression of ATXN1. It was subsequently identified that hsa_circ_0008309 may inhibit miR-136-5P and miR-382-5P expression and increase ATXN1 expression in the OSCC cell lines.

Conclusion

In summary, the results of the present study revealed that OSCC tissues have abundant circRNAs and, to the best of our knowledge, we firstly explore the regulatory role of the hsa_circ_0008309-miR-136-5P/hsa-miR-382-5P-ATXN1 network in OSCC. The results indicated that hsa_circ_0008309 may be a potential biomarker for OSCC.

Transcriptomic analysis of CIC and ATXN1L reveal a functional relationship exploited by cancer

Aberrations in Capicua (CIC) have recently been implicated as a negative prognostic factor in a multitude of cancer types through activation of the MAPK signalling cascade and derepression of oncogenic ETS transcription factors. The Ataxin-family protein ATXN1L has previously been reported to interact with CIC in developmental and disease contexts to facilitate the repression of CIC target genes. To further investigate this relationship, we performed functional in vitro studies utilizing ATXN1L^KO and CIC^KO human cell lines and characterized a reciprocal functional relationship between CIC and ATXN1L. Transcriptomic interrogation of the CIC-ATXN1-ATXN1L axis in low-grade glioma, prostate adenocarcinoma and stomach adenocarcinoma TCGA cohorts revealed context-dependent convergence of gene sets and pathways related to mitotic cell cycle and division. This study highlights the CIC-ATXN1-ATXN1L axis as a more potent regulator of the cell cycle than previously appreciated.

The genetic component of preeclampsia: A whole-exome sequencing study

Preeclampsia is a major cause of maternal and perinatal deaths. The aetiology of preeclampsia is largely unknown but a polygenetic component is assumed. To explore this hypothesis, we performed an in-depth whole-exome sequencing study in women with (cases, N = 50) and without (controls, N = 50) preeclampsia. The women were identified in an unselected cohort of 2,545 pregnant women based on data from the Danish National Patient Registry and the Medical Birth Registry. Matching DNA was obtained from a biobank containing excess blood from routine antenatal care visits. Novogene performed the whole-exome sequencing blinded to preeclampsia status. Variants for comparison between cases and controls were filtered in the Ingenuity Variant Analysis software. We applied two different strategies; a disease association panel approach, which included variants in single genes associated with established clinical risk factors for preeclampsia, and a gene panel approach, which included biological pathways harbouring genes previously reported to be associated with preeclampsia. Variant variability was compared in cases and controls at the level of biological processes, signalling pathways, and in single genes. Regardless of the applied strategy and the level of variability examined, we consistently found positive correlations between variant numbers in cases and controls (all R²s>0.88). Contrary to what was expected, cases carried fewer variants in biological processes and signalling pathways than controls (all p-values ≤0.02). In conclusion, our findings challenge the hypothesis of a polygenetic aetiology for preeclampsia with a common network of susceptibility genes. The greater genetic diversity among controls may suggest a protective role of genetic diversity against the development of preeclampsia.

Key genes and regulatory networks involved in the initiation, progression and invasion of colorectal cancer

Aim

Until now, identification of drug targets for treatment of patients with specific stages of colorectal cancer (CRC) has remained a challenging field of research. Herein, we aimed to identify the key genes and regulatory networks involved in each stage of CRC.

Results

The results of gene expression profiles were integrated with protein-protein interaction networks, and topologically analyzed. The most important regulatory genes (e.g., CDK1, UBC, ESR1 and ATXN1) and signaling pathways (e.g., Wnt, MAPK and JAK-STAT) in CRC initiation, progression and metastasis were identified. In vitro analysis confirmed some in silico findings.

Conclusion

Our study introduces functional hub genes, subnetworks, prioritizes signaling pathways and novel biomarkers in CRC that may guide further development of targeted therapy programs.

ATXN1L, CIC, and ETS Transcription Factors Modulate Sensitivity to MAPK Pathway Inhibition

Intrinsic resistance and RTK-RAS-MAPK pathway reactivation has limited the effectiveness of MEK and RAF inhibitors (MAPKi) in RAS- and RAF-mutant cancers. To identify genes that modulate sensitivity to MAPKi, we performed genome-scale CRISPR-Cas9 loss-of-function screens in two KRAS mutant pancreatic cancer cell lines treated with the MEK1/2 inhibitor trametinib. Loss of CIC, a transcriptional repressor of ETV1, ETV4, and ETV5, promoted survival in the setting of MAPKi in cancer cells derived from several lineages. ATXN1L deletion, which reduces CIC protein, or ectopic expression of ETV1, ETV4, or ETV5 also modulated sensitivity to trametinib. ATXN1L expression inversely correlates with response to MAPKi inhibition in clinical studies. These observations identify the ATXN1L-CIC-ETS transcription factor axis as a mediator of resistance to MAPKi.

Intrinsic Disorder in Proteins with Pathogenic Repeat Expansions

Intrinsically disordered proteins and proteins with intrinsically disordered regions have been shown to be highly prevalent in disease. Furthermore, disease-causing expansions of the regions containing tandem amino acid repeats often push repetitive proteins towards formation of irreversible aggregates. In fact, in disease-relevant proteins, the increased repeat length often positively correlates with the increased aggregation efficiency and the increased disease severity and penetrance, being negatively correlated with the age of disease onset. The major categories of repeat extensions involved in disease include poly-glutamine and poly-alanine homorepeats, which are often times located in the intrinsically disordered regions, as well as repeats in non-coding regions of genes typically encoding proteins with ordered structures. Repeats in such non-coding regions of genes can be expressed at the mRNA level. Although they can affect the expression levels of encoded proteins, they are not translated as parts of an affected protein and have no effect on its structure. However, in some cases, the repetitive mRNAs can be translated in a non-canonical manner, generating highly repetitive peptides of different length and amino acid composition. The repeat extension-caused aggregation of a repetitive protein may represent a pivotal step for its transformation into a proteotoxic entity that can lead to pathology. The goals of this article are to systematically analyze molecular mechanisms of the proteinopathies caused by the poly-glutamine and poly-alanine homorepeat expansion, as well as by the polypeptides generated as a result of the microsatellite expansions in non-coding gene regions and to examine the related proteins. We also present results of the analysis of the prevalence and functional roles of intrinsic disorder in proteins associated with pathological repeat expansions.

Ataxin-1 is involved in tumorigenesis of cervical cancer cells via the EGFR-RAS-MAPK signaling pathway

Ataxin-1 (ATXN1) is a coregulator protein within which expansion of the polyglutamine tract causes spinocerebellar ataxia type 1, an autosomal dominant neurodegenerative disorder. Previously, we reported that ATXN1 regulates the epithelial–mesenchymal transition of cervical cancer cells. In the present study, we demonstrate that ATXN1 is involved in cervical cancer tumorigenesis by promoting the proliferation of human cervical cancer cells. Chromatin immunoprecipitation assays showed that ATXN1 bound to the promoter region within cyclin D1 and activated cyclin D1 transcription, resulting in cell proliferation. ATXN1 promoted cyclin D1 expression through the EGFR–RAS–MAPK signaling pathway. Mouse xenograft tumorigenicity assays showed that ATXN1 downregulation inhibited tumorigenesis in cervical cancer cell lines in nude mice. Human cervical cancer tissue microarrays and immunohistochemical techniques showed that ATXN1 was significantly upregulated in many such tissues. Our results suggest that ATXN1 plays an important role in cervical cancer tumorigenesis and is a prognostic marker for cervical cancer.

Ataxin-1 regulates epithelial-mesenchymal transition of cervical cancer cells

The mutant form of the protein ataxin-1 (ATXN1) causes the neurodegenerative disease spinocerebellar ataxia type-1. Recently, ATXN1 was reported to enhance E-cadherin expression in the breast cancer cell line MCF-7, suggesting a potential association between ATXN1 and cancer development. In the present study, we discovered a novel mechanism through which ATXN1 regulates the epithelial–mesenchymal transition (EMT) of cancer cells. Hypoxia-induced upregulation of the Notch intracellular domain expression decreased ATXN1 expression via MDM2-associated ubiquitination and degradation. In cervical cancer cells, ATXN1 knockdown induced EMT by directly regulating Snail expression, leading to matrix metalloproteinase activation and the promotion of cell migration and invasion. These findings provide insights into a novel mechanism of tumorigenesis and will facilitate the development of new and more effective therapies for cancer.

Atrophin protein RERE positively regulates Notch targets in the developing vertebrate spinal cord

The Notch signaling pathway controls cell fate decision, proliferation, and other biological functions in both vertebrates and invertebrates. Precise regulation of the canonical Notch pathway ensures robustness of the signal throughout development and adult tissue homeostasis. Aberrant Notch signaling results in profound developmental defects and is linked to many human diseases. In this study, we identified the Atrophin family protein RERE (also called Atro2) as a positive regulator of Notch target Hes genes in the developing vertebrate spinal cord. Prior studies have shown that during early embryogenesis in mouse and zebrafish, deficit of RERE causes various patterning defects in multiple organs including the neural tube. Here, we detected the expression of RERE in the developing chick spinal cord, and found that normal RERE activity is needed for proper neural progenitor proliferation and neuronal differentiation possibly by affecting Notch-mediated Hes expression. In mammalian cells, RERE co-immunoprecipitates with CBF1 and Notch intracellular domain (NICD), and is recruited to nuclear foci formed by over-expressed NICD1. RERE is also necessary for NICD to activate the expression of Notch target genes. Our findings suggest that RERE stimulates Notch target gene expression by preventing degradation of NICD protein, thereby facilitating the assembly of a transcriptional activating complex containing NICD, CBF1/RBPjκ in vertebrate, Su(H) in Drosophila melanogaster, Lag1 in C. elegans, and other coactivators.

Ataxin 2-binding protein 1 is a context-specific positive regulator of Notch signaling during neurogenesis in Drosophila melanogaster

The role of the Notch pathway during the lateral inhibition that underlies binary cell fate choice is extensively studied, but the context specificity that generates diverse outcomes is less well understood. In the peripheral nervous system of Drosophila melanogaster, differential Notch signaling between cells of the proneural cluster orchestrates sensory organ specification. Here we report functional analysis of Drosophila Ataxin 2-binding protein 1 (A2BP1) during this process. Its human ortholog is linked to type 2 spinocerebellar ataxia and other complex neuronal disorders. Downregulation of Drosophila A2BP1 in the proneural cluster increases adult sensory bristle number, whereas its overexpression results in loss of bristles. We show that A2BP1 regulates sensory organ specification by potentiating Notch signaling. Supporting its direct involvement, biochemical analysis shows that A2BP1 is part of the Suppressor of Hairless [Su(H)] complex in the presence and absence of Notch. However, in the absence of Notch signaling, the A2BP1 interacting fraction of Su(H) does not associate with the repressor proteins Groucho and CtBP. We propose a model explaining the requirement of A2BP1 as a positive regulator of context-specific Notch activity.

Molecular Programming of Tumor-Infiltrating CD8+ T Cells and IL15 Resistance

Despite clinical potential and recent advances, durable immunotherapeutic ablation of solid tumors is not routinely achieved. IL15 expands natural killer cell (NK), natural killer T cell (NKT) and CD8(+) T-cell numbers and engages the cytotoxic program, and thus is under evaluation for potentiation of cancer immunotherapy. We found that short-term therapy with IL15 bound to soluble IL15 receptor α-Fc (IL15cx; a form of IL15 with increased half-life and activity) was ineffective in the treatment of autochthonous PyMT murine mammary tumors, despite abundant CD8(+) T-cell infiltration. Probing of this poor responsiveness revealed that IL15cx only weakly activated intratumoral CD8(+) T cells, even though cells in the lung and spleen were activated and dramatically expanded. Tumor-infiltrating CD8(+) T cells exhibited cell-extrinsic and cell-intrinsic resistance to IL15. Our data showed that in the case of persistent viral or tumor antigen, single-agent systemic IL15cx treatment primarily expanded antigen-irrelevant or extratumoral CD8(+) T cells. We identified exhaustion, tissue-resident memory, and tumor-specific molecules expressed in tumor-infiltrating CD8(+) T cells, which may allow therapeutic targeting or programming of specific subsets to evade loss of function and cytokine resistance, and, in turn, increase the efficacy of IL2/15 adjuvant cytokine therapy. Cancer Immunol Res; 4(9); 799-811. ©2016 AACR.

Ataxin-1 regulates the cerebellar bioenergetics proteome through the GSK3β-mTOR pathway which is altered in Spinocerebellar ataxia type 1 (SCA1)

A polyglutamine expansion within the ataxin-1 protein (ATXN1) underlies spinocerebellar ataxia type-1 (SCA1), a neurological disorder mainly characterized by ataxia and cerebellar deficits. In SCA1, both loss and gain of ATXN1 biological functions contribute to cerebellar pathogenesis. However, the critical ATXN1 functions and pathways involved remain unclear. To further investigate the early signalling pathways regulated by ATXN1, we performed an unbiased proteomic study of the Atxn1-KO 5-week-old mice cerebellum. Here, we show that lack of ATXN1 expression induces early alterations in proteins involved in glycolysis [pyruvate kinase, muscle, isoform 1 protein (PKM-i1), citrate synthase (CS), glycerol-3-phosphate dehydrogenase 2 (GPD2), glucose-6-phosphate isomerase (GPI), alpha -: enolase (ENO1)], ATP synthesis [CS, Succinate dehydrogenase complex,subunit A (SDHA), ATP synthase subunit d, mitochondrial (ATP5H)] and oxidative stress [peroxiredoxin-6 (PRDX6), aldehyde dehydrogenase family 1, subfamily A1, 10-formyltetrahydrofolate dehydrogenase]. In the SCA1 mice, several of these proteins (PKM-i1, ATP5H, PRDX6, proteome subunit A6) were down-regulated and ATP levels decreased. The underlying mechanism does not involve modulation of mitochondrial biogenesis, but dysregulation of the activity of the metabolic regulators glycogen synthase kinase 3B (GSK3β), decreased in Atxn1-KO and increased in SCA1 mice, and mechanistic target of rapamycin (serine/threonine kinase) (mTOR), unchanged in the Atxn1-KO and decreased in SCA1 mice cerebellum before the onset of ataxic symptoms. Pharmacological inhibition of GSK3β and activation of mTOR in a SCA1 cell model ameliorated identified ATXN1-regulated metabolic proteome and ATP alterations. Taken together, these results point to an early role of ATXN1 in the regulation of bioenergetics homeostasis in the mouse cerebellum. Moreover, data suggest GSK3β and mTOR pathways modulate this ATXN1 function in SCA1 pathogenesis that could be targeted therapeutically prior to the onset of disease symptoms in SCA1 and other pathologies involving dysregulation of ATXN1 functions.

Large-Scale Functional RNAi Screen in C. elegans Identifies TGF-β and Notch Signaling Pathways as Modifiers of CACNA1A

Variants in CACNA1A that encodes the pore-forming α₁-subunit of human voltage-gated Cav2.1 (P/Q-type) Ca²⁺ channels cause several autosomal-dominant neurologic disorders, including familial hemiplegic migraine type 1, episodic ataxia type 2, and spinocerebellar ataxia type 6. To identify modifiers of incoordination in movement disorders, we performed a large-scale functional RNAi screen, using the Caenorhabditis elegans strain CB55, which carries a truncating mutation in the unc-2 gene, the worm ortholog for the human CACNA1A. The screen was carried out by the feeding method in 96-well liquid culture format, using the ORFeome v1.1 feeding library, and time-lapse imaging of worms in liquid culture was used to assess changes in thrashing behavior. We looked for genes that, when silenced, either ameliorated the slow and uncoordinated phenotype of unc-2, or interacted to produce a more severe phenotype. Of the 350 putative hits from the primary screen, 37 genes consistently showed reproducible results. At least 75% of these are specifically expressed in the C. elegans neurons. Functional network analysis and gene ontology revealed overrepresentation of genes involved in development, growth, locomotion, signal transduction, and vesicle-mediated transport. We have expanded the functional network of genes involved in neurodegeneration leading to cerebellar ataxia related to unc-2/CACNA1A, further confirming the involvement of the transforming growth factor β pathway and adding a novel signaling cascade, the Notch pathway.

Ataxin-1 regulates proliferation of hippocampal neural precursors

Polyglutamine expansion in the protein ATAXIN-1 (ATXN1) causes spinocerebellar ataxia type 1 (SCA1), an inherited neurodegenerative disease characterized by motor deficits, cognitive impairment and depression. Although ubiquitously expressed, mutant ATXN1 causes neurodegeneration primarily in the cerebellum, which is responsible for the observed motor deficits. The role of ATXN1 outside of the cerebellum and the causes of cognitive deficits and depression in SCA1 are less understood. In this study, we demonstrate a novel role of ATXN1 in the hippocampus as a regulator of adult neurogenesis. Adult hippocampal neurogenesis is the process of generating new hippocampal neurons and is linked to cognition and mood. We found that loss of ATXN1 causes a decrease in hippocampal neurogenesis in ATXN1 null (Atxn1(-/-)) mice. This decrease was caused by reduced proliferation of neural precursors in the hippocampus of Atxn1(-/-) mice, and persisted even when Atxn1(-/-) hippocampal neural precursors were removed from their natural environment and grown in vitro, suggesting that ATXN1 affects proliferation in a cell-autonomous manner. Moreover, expression of ATXN1 with a pathological polyglutamine (polyQ) expansion in wild-type neural precursor cells inhibited their proliferation. Our data establish a novel role for ATXN1 in the hippocampus as an intrinsic regulator of precursor cell proliferation, and suggest a mechanism by which polyQ expansion and loss of ATXN1 affect hippocampal function, potentially contributing to cognitive deficits and depression. These results indicate that while depletion of ATXN1 is a promising therapeutic approach to treat the cerebellar aspects of SCA1, this approach should be employed with caution given the potential for side effects on hippocampal function with loss of wild-type ATXN1.

Bone morphogenetic protein 7 sensitizes O6-methylguanine methyltransferase expressing-glioblastoma stem cells to clinically relevant dose of temozolomide

Background

Temozolomide (TMZ) is an oral DNA-alkylating agent used for treating patients with glioblastoma. However, therapeutic benefits of TMZ can be compromised by the expression of O6-methylguanine methyltransferase (MGMT) in tumor tissue. Here we used MGMT-expressing glioblastoma stem cells (GSC) lines as a model for investigating the molecular mechanism underlying TMZ resistance, while aiming to explore a new treatment strategy designed to possibly overcome resistance to the clinically relevant dose of TMZ (35 μM).

Methods

MGMT-expressing GSC cultures are resistant to TMZ, and IC50 (half maximal inhibitory concentration) is estimated at around 500 μM. Clonogenic GSC surviving 500 μM TMZ (GSC-500 μM TMZ), were isolated. Molecular signatures were identified via comparative analysis of expression microarray against parental GSC (GSC-parental). The recombinant protein of top downregulated signature was used as a single agent or in combination with TMZ, for evaluating therapeutic effects of treatment of GSC.

Results

The molecular signatures characterized an activation of protective stress responses in GSC-500 μM TMZ, mainly including biotransformation/detoxification of xenobiotics, blocked endoplasmic reticulum stress-mediated apoptosis, epithelial-to-mesenchymal transition (EMT), and inhibited growth/differentiation. Bone morphogenetic protein 7 (BMP7) was identified as the top down-regulated gene in GSC-500 μM TMZ. Although augmenting BMP7 signaling in GSC by exogenous BMP7 treatment did not effectively stop GSC growth, it markedly sensitized both GSC-500 μM TMZ and GSC-parental to 35 μM TMZ treatment, leading to loss of self-renewal and migration capacity. BMP7 treatment induced senescence of GSC cultures and suppressed mRNA expression of CD133, MGMT, and ATP-binding cassette drug efflux transporters (ABCB1, ABCG2), as well as reconfigured transcriptional profiles in GSC by downregulating genes associated with EMT/migration/invasion, stemness, inflammation/immune response, and cell proliferation/tumorigenesis. BMP7 treatment significantly prolonged survival time of animals intracranially inoculated with GSC when compared to those untreated or treated with TMZ alone (p = 0.0017), whereas combination of two agents further extended animal survival compared to BMP7 alone (p = 0.0489).

Conclusions

These data support the view that reduced endogenous BMP7 expression/signaling in GSC may contribute to maintained stemness, EMT, and chemoresistant phenotype, suggesting that BMP7 treatment may provide a novel strategy in combination with TMZ for an effective treatment of glioblastoma exhibiting unmethylated MGMT.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0459-1) contains supplementary material, which is available to authorized users.

Integrated molecular analysis of adult T cell leukemia/lymphoma

Adult T cell leukemia/lymphoma (ATL) is a peripheral T cell neoplasm of largely unknown genetic basis, associated with human T cell leukemia virus type-1 (HTLV-1) infection. Here we describe an integrated molecular study in which we performed whole-genome, exome, transcriptome and targeted resequencing, as well as array-based copy number and methylation analyses, in a total of 426 ATL cases. The identified alterations overlap significantly with the HTLV-1 Tax interactome and are highly enriched for T cell receptor-NF-κB signaling, T cell trafficking and other T cell-related pathways as well as immunosurveillance. Other notable features include a predominance of activating mutations (in PLCG1, PRKCB, CARD11, VAV1, IRF4, FYN, CCR4 and CCR7) and gene fusions (CTLA4-CD28 and ICOS-CD28). We also discovered frequent intragenic deletions involving IKZF2, CARD11 and TP73 and mutations in GATA3, HNRNPA2B1, GPR183, CSNK2A1, CSNK2B and CSNK1A1. Our findings not only provide unique insights into key molecules in T cell signaling but will also guide the development of new diagnostics and therapeutics in this intractable tumor.

Drosophila as an In Vivo Model for Human Neurodegenerative Disease

With the increase in the ageing population, neurodegenerative disease is devastating to families and poses a huge burden on society. The brain and spinal cord are extraordinarily complex: they consist of a highly organized network of neuronal and support cells that communicate in a highly specialized manner. One approach to tackling problems of such complexity is to address the scientific questions in simpler, yet analogous, systems. The fruit fly, Drosophila melanogaster, has been proven tremendously valuable as a model organism, enabling many major discoveries in neuroscientific disease research. The plethora of genetic tools available in Drosophila allows for exquisite targeted manipulation of the genome. Due to its relatively short lifespan, complex questions of brain function can be addressed more rapidly than in other model organisms, such as the mouse. Here we discuss features of the fly as a model for human neurodegenerative disease. There are many distinct fly models for a range of neurodegenerative diseases; we focus on select studies from models of polyglutamine disease and amyotrophic lateral sclerosis that illustrate the type and range of insights that can be gleaned. In discussion of these models, we underscore strengths of the fly in providing understanding into mechanisms and pathways, as a foundation for translational and therapeutic research.

Phosphoproteomic analysis reveals compensatory effects in the piriform cortex of VX nerve agent exposed rats

To gain insights into the toxicity induced by the nerve agent VX, an MS-based phosphoproteomic analysis was carried out on the piriform cortex region of brains from VX-treated rats. Using isobaric tag based TMT labeling followed by titanium dioxide enrichment strategy, we identified 9975 unique phosphosites derived from 3287 phosphoproteins. Temporal changes in the phosphorylation status of peptides were observed over a time period of 24 h in rats exposed to a 1× LD50, intravenous (i.v.) dose with the most notable changes occurring at the 1 h postexposure time point. Five major functional classes of proteins exhibited changes in their phosphorylation status: (i) ion channels/transporters, including ATPases, (ii) kinases/phosphatases, (iii) GTPases, (iv) structural proteins, and (v) transcriptional regulatory proteins. This study is the first quantitative phosphoproteomic analysis of VX toxicity in the brain. Understanding the toxicity and compensatory signaling mechanisms will improve the understanding of the complex toxicity of VX in the brain and aid in the elucidation of novel molecular targets that would be important for development of improved countermeasures. All MS data have been deposited in the ProteomeXchange with identifier PXD001184 (http://proteomecentral.proteomexchange.org/dataset/PXD001184).

The autosomal dominant spinocerebellar ataxias: emerging mechanistic themes suggest pervasive Purkinje cell vulnerability

The spinocerebellar ataxias are a genetically heterogeneous group of disorders with clinically overlapping phenotypes arising from Purkinje cell degeneration, cerebellar atrophy and varying degrees of degeneration of other grey matter regions. For 22 of the 32 subtypes, a genetic cause has been identified. While recurring themes are emerging, there is no clear correlation between the clinical phenotype or penetrance, the type of genetic defect or the category of the disease mechanism, or the neuronal types involved beyond Purkinje cells. These phenomena suggest that cerebellar Purkinje cells may be a uniquely vulnerable neuronal cell type, more susceptible to a wider variety of genetic/cellular insults than most other neuron types.

Analysis of hippocampal gene expression profile of Alzheimer's disease model rats using genome chip bioinformatics

In this study, an Alzheimer's disease model was established in rats through stereotactic injection of condensed amyloid beta 1–40 into the bilateral hippocampus, and the changes of gene expression profile in the hippocampus of rat models and sham-operated rats were compared by genome expression profiling analysis. Results showed that the expression of 50 genes was significantly up-regulated (fold change ≥ 2), while 21 genes were significantly down-regulated in the hippocampus of Alzheimer's disease model rats (fold change ≤ 0.5) compared with the sham-operation group. The differentially expressed genes are involved in many functions, such as brain nerve system development, neuronal differentiation and functional regulation, cellular growth, differentiation and apoptosis, synaptogenesis and plasticity, inflammatory and immune responses, ion channels/transporters, signal transduction, cell material/energy metabolism. Our findings indicate that several genes were abnormally expressed in the metabolic and signal transduction pathways in the hippocampus of amyloid beta 1–40-induced rat model of Alzheimer's disease, thereby affecting the hippocampal and brain functions.

The expanding role for chromatin and transcription in polyglutamine disease

Nine genetic diseases arise from expansion of CAG repeats in seemingly unrelated genes. They are referred to as polyglutamine (polyQ) diseases due to the presence of elongated glutamine tracts in the corresponding proteins. The pathologic consequences of polyQ expansion include progressive spinal, cerebellar, and neural degeneration. These pathologies are not identical, however, suggesting that disruption of protein-specific functions is crucial to establish and maintain each disease. A closer examination of protein function reveals that several act as regulators of gene expression. Here we examine the roles these proteins play in regulating gene expression, discuss how polyQ expansion may disrupt these functions to cause disease, and speculate on the neural specificity of perturbing ubiquitous gene regulators.

Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias

Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.