Cerebellar degeneration-related antigen: a highly conserved neuroectodermal marker mapped to chromosomes X in human and mouse

A novel upregulated hsa_circ_0032746 regulates the oncogenesis of esophageal squamous cell carcinoma by regulating miR-4270/MCM3 axis

INTRODUCTION

Circular RNAs (CircRNA) have emerged as an interest of research in recent years due to its regulatory role in various kinds of cancers of human body. Esophageal squamous cell carcinoma (ESCC) is one of the major disease subtype in Asian countries, including China. CircRNAs are formed by back-splicing covalently joined 3'- and 5'- ends rather than canonical splicing and are found to have binding affinity with miRNAs that conjointly contribute to oncogenesis.

MATERIALS AND METHODS

4 pairs of normal, cancer adjacent tissues and cancer tissues were analyzed by high-throughput RNA sequencing and 84 differentially upregulated circRNAs were detected in cancer tissues. hsa_circ_0032746 was silenced by siRNA and lentivirus and then further proliferation, migration and invasion were performed by CCK-8 and transwell assays. Bioinformatic analysis  predicted binding affinity of circRNA/miRNA/mRNA axis.

RESULTS

After qPCR validation, we selected a novel upregulated hsa_circ_0032746 to explore its biogenetic functions which showed high expression in cancer tissues but not in cancer adjacent tissues. The clinicopathological relation of hsa_circ_0032746 showed positive correlation with the tumor location (P = 0.026) and gender (P = 0.05). We also predicted that hsa_circ_0032746 could sponge with microRNA. Bioinformatic analysis predicted 11 microRNA response element (MRE) sequences of hsa_circ_0032746 and dual luciferase reporter assay confirmed binding affinity with miR4270 evidencing further study of circRNA/miRNA role. The knockdown of hsa_circ_0032746 by siRNA and lentivirus demonstrated that proliferation, invasion and migration of ESCC were inhibited in vitro and vivo experiments. Bioinformatic analysis further predicted MCM3 as a target of miR-4270 and was found upregulated in ESCC upon validation. miR4270 mimic decreased the level of hsa_circ_0032746 and MCM3 while further rescue experiments demonstrated that hsa_circ_0032746 was dependent on miR4270/MCM3 axis on the development process of ESCC.

CONCLUSION

We revealed for the first time that circ_0032746/mir4270/MCM3 contributes in proliferation, migration and invasion of ESCC and could have potential prognostic and therapeutic significance.

CircNFIX regulates chondrogenesis and cartilage homeostasis by targeting the miR758 ‐3p/ KDM6A axis

Objectives

Osteoarthritis (OA) is a degenerative disease causing the progressive destruction of articular cartilage; however, the aetiology has not yet been elucidated. Circular RNAs (circRNAs) are reportedly involved in cartilage degeneration and OA development. In the present study, we identified that circNFIX regulates chondrogenesis and cartilage homeostasis.

Materials and Methods

Microarray analysis was performed to explore circRNA expression during the chondrogenic differentiation of human adipose‐drived stem cells (hADSCs). CircNFIX expression was determined using quantitative reverse transcription‐polymerase chain reaction and in situ hybridization. Gain‐ and loss‐of‐function assays were performed to validate the role of circNFIX in cartilage homeostasis. RNA pull‐down, Argonaute2‐RNA immunoprecipitation and luciferase reporter assays were performed to evaluate the interactions among circNFIX, miR758‐3p and KDM6A.

Results

CircNFIX expression was upregulated in the early and middle stages, whereas downregulated in the late stage of hADSC chondrogenesis. CircNFIX inhibition attenuated hADSC chondrogenesis. CircNFIX was remarkably downregulated in OA samples, circNFIX overexpression protected against chondrocyte degradation and alleviated OA progression in the destabilization of the medial meniscus OA model. Mechanistically, circNFIX acted as a sponge of miR758‐3p and played a role in the chondrogenesis and chondrocyte degeneration by targeting the miR‐758‐3p/KDM6A axis.

Conclusions

Our results revealed a key role of circNFIX in chondrogenesis and cartilage homeostasis, which may provide a potential therapeutic strategy for OA treatment.

TGF-β1 regulates chondrocyte proliferation and extracellular matrix synthesis via circPhf21a-Vegfa axis in osteoarthritis

Background

The transforming growth factor-beta (TGF-β) signaling pathway is an important pathway associated with the pathogenesis of osteoarthritis (OA). This study was to investigate the involvement of circRNAs in the TGF-β signaling pathway.

Methods

Cell Counting Kit-8 (CCK-8) assay and 5-ethynyl-2′-deoxyuridine (EdU) assay were used to detect the proliferation of primary mouse chondrocytes (PMCs). RNA-sequencing together with bioinformatics analysis were used to systematically clarify TGF-β1 induced alternations of circRNAs in PMCs. The regulatory and functional role of circPhf21a was examined in PMCs. Downstream targets of circPhf21a were explored by RNA-sequencing after overexpression of circPhf21a and verified by RT-qPCR in PMCs. Finally, the role and mechanism of circPhf21a in OA were explored in mouse models.

Results

We found that TGF-β1 promoted the proliferation of PMCs. Meanwhile, RT-qPCR and western blotting indicated that TGF-β1 promoted extracellular matrix (ECM) anabolism. RNA-sequencing revealed that a total of 36 circRNAs were differentially expressed between PMCs treated with and without TGF-β1. Of these, circPhf21a was significantly decreased by TGF-β1. Furthermore, circPhf21a knockdown promoted the proliferation and ECM synthesis of PMCs, whereas overexpression of circPhf21a showed the opposite effects. Mechanically, the expression profiles of the mRNAs revealed that Vegfa may be the target of circPhf21a. Additionally, we found that circPhf21a was significantly upregulated in the mouse OA model, and inhibition of circPhf21a significantly relieved the progression of OA.

Conclusions

Our results found that TGF-β1 promoted the proliferation and ECM synthesis of PMCs via the circPhf21a-Vegfa axis, which may provide novel therapeutic targets for OA treatment.

Competing Endogenous RNA Networks in Glioma

Gliomas are the most common and malignant primary brain tumors. Various hallmarks of glioma, including sustained proliferation, migration, invasion, heterogeneity, radio- and chemo-resistance, contribute to the dismal prognosis of patients with high-grade glioma. Dysregulation of cancer driver genes is a leading cause for these glioma hallmarks. In recent years, a new mechanism of post-transcriptional gene regulation was proposed, i.e., "competing endogenous RNA (ceRNA)." Long non-coding RNAs, circular RNAs, and transcribed pseudogenes act as ceRNAs to regulate the expression of related genes by sponging the shared microRNAs. Moreover, coding RNA can also exert a regulatory role, independent of its protein coding function, through the ceRNA mechanism. In the latest glioma research, various studies have reported that dysregulation of certain ceRNA regulatory networks (ceRNETs) accounts for the abnormal expression of cancer driver genes and the establishment of glioma hallmarks. These achievements open up new avenues to better understand the hidden aspects of gliomas and provide new biomarkers and potential efficient targets for glioma treatment. In this review, we summarize the existing knowledge about the concept and logic of ceRNET and highlight the emerging roles of some recently found ceRNETs in glioma progression.

A Circle RNA Regulatory Axis Promotes Lung Squamous Metastasis via CDR1-Mediated Regulation of Golgi Trafficking

Lung squamous carcinoma (LUSC) is a highly metastatic disease with a poor prognosis. Using an integrated screening approach, we found that miR-671-5p reduces LUSC metastasis by inhibiting a circular RNA (circRNA), CDR1as. Although the putative function of circRNA is through miRNA sponging, we found that miR-671-5p more potently silenced an axis of CDR1as and its antisense transcript, cerebellar degeneration related protein 1 (CDR1). Silencing of CDR1as or CDR1 significantly inhibited LUSC metastases and CDR1 was sufficient to promote migration and metastases. CDR1, which directly interacted with adaptor protein 1 (AP1) complex subunits and coatomer protein I (COPI) proteins, no longer promoted migration upon blockade of Golgi trafficking. Therapeutic inhibition of the CDR1as/CDR1 axis with miR-671-5p mimics reduced metastasis in vivo. This report demonstrates a novel role for CDR1 in promoting metastasis and Golgi trafficking. These findings reveal an miRNA/circRNA axis that regulates LUSC metastases through a previously unstudied protein, CDR1. SIGNIFICANCE: This study shows that circRNA, CDR1as, promotes lung squamous migration, metastasis, and Golgi trafficking through its complimentary transcript, CDR1.

Biogenesis, Features, Functions, and Disease Relationships of a Specific Circular RNA: CDR1as

In 2011, Hansen discovered the natural antisense transcript (NAT) of the cerebellar degeneration-related protein 1 gene (CDR1), and further described CDR1 NAT as a circular RNA (CircRNA). CDR1 antisense RNA (CDR1as), which is the official name of CDR1 NAT, is conserved and extensively expressed in most eutherian mammal brains and other specialized tissues. Further studies have elucidated its biogenesis, features, functions, and relationships with diseases. CDR1as is involved in many disease processes as a microRNA (miR) sponge. Therefore, it seems that further research on CDR1as could facilitate the diagnosis and treatment of some diseases, such as cancer and diabetes. However, a detailed analysis of the results of studies on CDR1as revealed that they are inconsistent and make unclear conclusions. In this review, we gathered and analyzed the recent studies about CDR1as in detail and aimed to elucidate accurate conclusions from them.

Cerebellar Degeneration-related Antigen 1 Is Ubiquitously Expressed in Human Epidermis and Dermis

Cerebellar degeneration-related antigen 1 (CDR1) was described to be expressed in the nervous system and in different types of cancer tissues. In the present study, we demonstrate that CDR1 is in addition ubiquitously expressed in human epidermis, dermis and isolated skin cells. Both CDR1 mRNA and protein were detected in human skin-derived mast cells, melanocytes, fibroblasts and keratinocytes, suggesting that CDR1 does not have a neuron-specific function.

CircSERPINE2 protects against osteoarthritis by targeting miR-1271 and ETS-related gene

Objectives

Circular RNAs (circRNA) expression aberration has been identified in various human diseases. In this study, we investigated whether circRNAs could act as competing endogenous RNAs to regulate the pathological process of osteoarthritis (OA).

Methods

CircRNA deep sequencing was performed to the expression of circRNAs between OA and control cartilage tissues. The regulatory and functional role of CircSERPINE2 upregulation was examined in OA and was validated in vitro and in vivo, downstream target of CircSERPINE2 was explored. RNA pull down, a luciferase reporter assay, biotin-coupled microRNA capture and fluorescence in situ hybridisation were used to evaluate the interaction between CircSERPINE2 and miR-1271-5 p, as well as the target mRNA, E26 transformation-specific-related gene (ERG). The role and mechanism of CircSERPINE2 in OA was also explored in rabbit models.

Results

The decreased expression of CircSERPINE2 in the OA cartilage tissues was directly associated with excessive apoptosis and imbalance between anabolic and catabolic factors of extracellular matrix (ECM). Mechanistically, CircSERPINE2 acted as a sponge of miR-1271-5 p and functioned in human chondrocytes (HCs) through targeting miR-1271-5 p and ERG. Intra-articular injection of adeno-associated virus-CircSERPINE2-wt alleviated OA in the rabbit model.

Conclusions

Our results reveal an important role for a novel circRNA-CircSERPINE2 in OA progression. CircSERPINE2 overexpression could alleviate HCs apoptosis and promote anabolism of ECM through miR-1271-ERG pathway. It provides a potentially effective therapeutic strategy for OA progression.

Circular RNA and Alzheimer's Disease

Circular RNAs (circRNAs) represent a special group of noncoding single-stranded highly stable ribonucleic acid entities abundant in the eukaryotic transcriptome. These circular forms of RNAs are significantly enriched in human brain and retinal tissues. However, the biological evolution and function of these circRNAs are poorly understood. Recent reports showed circRNA to be an important player in the development of neurodegenerative diseases like Alzheimer's disease. With the progression of age, circRNA level increases in the brain and also in age-associated neurological disorder like Alzheimer's disease (AD), Parkinson's disease, inflammatory neuropathy, nervous system neoplasms, and prion diseases. One highly represented circRNA in the human brain and retina is a ciRS-7 (CDR1as) which acts as an endogenous, anticomplementary miRNA inhibitor or "sponge" to quench the normal functioning of miRNA-7. Low CDR1as level can lead to increase in miR-7 expression which downregulates the activity of ubiquitin protein ligase A (UBE2A), an important AD target, functionally involved in clearing toxic amyloid peptides from AD brain. This chapter focuses on the functional relationship of circRNA with AD and interplay of miRNA-mRNA-mediated genetic regulatory networks. Our conceptual understanding also suggests that circRNA can be considered as a potential biomarker and therapeutic target in AD diagnosis and treatment.

Elevated expression of ciRS-7 in peripheral blood mononuclear cells from rheumatoid arthritis patients

BACKGROUND

Circular RNAs (circRNAs) represent a class of widespread and variety endogenous RNAs that may regulate gene expression. Thousands of mammalian circRNAs harbor miRNA response elements (MREs), suggesting a potential role as competitive endogenous RNAs (ceRNAs). Recent studies have demonstrated that ciRS-7 (circular CDR1 antisense), which acts as a powerful miR-7 sponge, contains more than 70 putative binding sites for miR-7 and may inhibit its target genes. The aim of this preliminary study was to investigate the expression of ciRS-7 in patients with rheumatoid arthritis (RA) as well as the correlation between ciRS-7 and the target genes of miR-7.

METHODS

Eighteen patients with RA and 14 healthy controls were enrolled in the current study. The relative expression of ciRS-7, miR-7, miR-671 and mTOR in peripheral blood mononuclear cells (PBMCs) from these samples were detected by real-time PCR.

RESULTS

We found that ciRS-7 was significantly increased in RA patients and could potentially differentiate the RA patients from healthy controls. Additionally, the expression of mTOR, one of the miR-7 target genes, had positive and negative relationships with ciRS-7 and miR-7 expression, respectively. Notably, the relative expression of miR-671, which mediated the regulation of circular CDR1 antisense homeostasis, was significantly decreased in RA patients.

CONLUSION

Downregulated miR-671 may influence the level of ciRS-7 in RA patients. Enhanced ciRS-7 could inhibit the function of miR-7 and further relieve the inhibitory effect of miR-7 on mTOR.

Circular RNA circ_0001946 acts as a competing endogenous RNA to inhibit glioblastoma progression by modulating miR-671-5p and CDR1

OBJECTIVES

In many malignant tumors, circRNAs play an important role. However, the biological role and clinical significance of circRNAs remain unclear. In this study, we investigated the effects of circ_0001946 on the progression of glioblastoma (GBM) and the molecular mechanism of circ_0001946.

METHODS

Microarrays were applied to test the expression profiles of circRNAs and messenger RNAs (mRNAs). Coexpressed genes were identified by constructing differentially expressed circRNA-mRNA networks. The expression of circ_0001946, miR-671-5p, and cerebellar degeneration-related autoantigen 1 (CDR1) was detected by real-time quantitative PCR, and the protein expression of CDR1 was determined by western blotting. A dual-luciferase reporter assay was used to evaluate potential miR-671-5p target sites on circ_0001946 and CDR1. The proliferation, apoptosis, migration, and invasion of GBM cells were assessed by a colony formation assay, flow cytometry assay, transwell migration assay, and transwell invasion assay. Xenograft mouse models were used to determine the role of circ_0001946 in vivo.

RESULTS

The expression of circ_0001946 and CDR1 was low and that of miR-671-5p was high in GBM cells. Circ_0001946 suppressed the expression of miR-671-5p, thus upregulating the expression of CDR1, the gene downstream of miR-671-5p. Circ_0001946 and CDR1 reduced proliferation, migration, and invasion and increased apoptosis in GBM cells, whereas miR-671-5p had an opposite effect. The xenograft mouse model and immunohistochemistry results indicated that circ_0001946 inhibited GBM growth as well as the expression of Ki67 in GBM cells.

CONCLUSION

Our study confirmed that the circ_0001946/miR-671-5p/ CDR1 pathway modulates the development of GBM, and this pathway might be a promising target for the development of therapeutics for GBM.

Expression of the onconeural protein CDR1 in cerebellum and ovarian cancer

Cerebellar degeneration related protein 1 (CDR1) is expressed in the cerebellum, and CDR1 antibodies have been associated with paraneoplastic cerebellar degeneration (PCD). In this study, we examined CDR1 expression in cerebellum and in ovarian and breast tumors, as well as the intracellular localization of CDR1 in cancer cells in culture. CDR1 was strongly expressed in the cytosol and dendrites of Purkinje cells and in interneurons of the molecular layer in cerebellum. CDR1 was also present in ovarian and breast tumors, as well as in ovarian and breast cancer cell lines, but was not present in normal breast or ovarian tissue. In cells overexpressing CDR1, CDR1 localized close to the plasma membrane in a polarized pattern at one edge. CDR1 was strongly expressed on the outer surface, apparently in filopodias or lamellipodias, in cells endogenously expressing CDR1. Overexpression of CDR1 showed a 37 and a 45 kDa band in western blot. The 37-kDa isoform was present in 16 ovarian cancer lysates, while the 45-kDa isoform was only found in three ovarian cancer patients. The presence of CDR1 in ovarian cancer was not associated with PCD. CDR1 antibodies were only found in serum from one patient with PCD and ovarian tumor with metastases. Therefore, CDR1 is probably not a marker for PCD. However, CDR1 may be associated with cell migration and differentiation.

Circular RNAs and hereditary bone diseases

Circular RNA (circRNA) is a non-linear form of RNA derived from exonic, intronic, and exon-intron gene regions. circRNAs are characterized by covalent closed loops, highly stable nuclease resistance, and specific expression in species and developmental stages. CircRNA molecules have been identified as playing roles in the regulation of cell transcription, transcriptional expression after translation, interactions with microRNAs, and protein coding. A high stability and tissue- and disease-specific expression allow circRNAs to serve as potential biomarkers both for diseases and prognosis. CircRNAs function in bone remodeling by directly participating in bone-related signaling pathways and by forming the circRNA-miRNA-mRNA axis. Studies have seldom reported on the low incidence of circRNAs in genetic bone disorders. The current study reviews the characteristics of circRNAs and recent research on their role in rare hereditary bone diseases.

Screening of up- and downregulation of circRNAs in HBV-related hepatocellular carcinoma by microarray

The present study describes circular RNA (circRNA) profiles in three pairs of hepatocellular carcinoma (HCC) tissues and the corresponding adjacent non-tumorous tissues (NTs) by microarray. circRNA is a type of endogenous RNA that serve a crucial role in disease development and aberrantly express in a number of types of cancer. In the present study, 3 paired HCC tissues and paired adjacent NTs were collected from HCC surgical specimens from 3 hepatitis B virus-infected patients with HCC. With abundant and varied probes accounting for 5,396 circRNAs, a large number of circRNAs are able to be quantitatively determined. Based on the microarray data, 222,567,556 upregulated circRNAs and 125,439,219 downregulated circRNAs were identified respectively. Further analysis revealed 24 upregulated and 23 downregulated significantly circRNAs (fold-change ≥2; P≤0.05) in HCC tissues compared with NTs. By means of computer analysis and database inquiring, the microRNA (miRNA) response elements associated with the abnormally expressed circRNAs were annotated. The present study showed novel evidence determining genome-wide circRNA expression patterns in HCC using microarray analysis. The results demonstrated that clusters of circRNAs were aberrantly expressed in HCC compared with NTs. These circRNAs may be involved in the occurrence and development of HCC. Therefore, the results of the present study may provide a novel approach for improving the understanding of the molecular basis of HCC. Furthermore, the identified circRNAs may be potential biomarkers for the diagnosis of HCC.

Microarray expression profile of circular RNAs in chronic thromboembolic pulmonary hypertension

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but debilitating and life-threatening complication of acute pulmonary embolism. Circular RNAs (circRNAs), presenting as covalently closed continuous loops, are RNA molecules with covalently joined 3'- and 5'-ends formed by back-splicing events. circRNAs may be significant biological molecules to understand disease mechanisms and to identify biomarkers for disease diagnosis and therapy. The aim of this study was to investigate the potential roles of circRNAs in CTEPH.

METHODS

Ten human blood samples (5 each from CTEPH and control groups) were included in the Agilent circRNA chip. The differentially expressed circRNAs were evaluated using t test, with significance set at a P value of < .05. A functional enrichment analysis for differentially expressed circRNAs was performed using DAVID online tools, and a Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis for target genes of miRNAs was performed using the R package clusterProfiler. Furthermore, miRNAs that interacted with differentially expressed circRNAs were predicted using the miRanda package. mRNAs that had clear biological functions and were regulated by miRNAs were predicted using miRWalk2.0 and then combined into a circRNA-miRNA-mRNA network.

RESULTS

In total, 351 differentially expressed circRNAs (122 upregulated and 229 downregulated) between CTEPH and control groups were obtained; among these circRNAs, hsa_circ_0002062 and hsa_circ_0022342 might be important because they can regulate 761 (e.g., hsa-miR-942-5p) and 453 (e.g., hsa-miR-940) miRNAs, respectively. Target genes (e.g., cyclin-dependent kinase 6) of hsa-miR-942-5p were mainly enriched in cancer-related pathways, whereas target genes (e.g., CRK-Like Proto-Oncogene, Adaptor Protein) of hsa-miR-940 were enriched in the ErbB signaling pathway. Therefore, these pathways are potentially important in CTEPH.

CONCLUSIONS

Our findings suggested that hsa_circ_0002062 and hsa_circ_0022342 may be key circRNAs for CTEPH development and that their targeted regulation may be an effective approach for treating CTEPH.

Spectrum construction of differentially expressed circular RNAs in patients with leukoaraiosis and function analysis of differentially expressed genes

Circular RNAs (circRNAs) are class of endogenous RNAs that have a role in the regulation of gene expression. The present study aimed to investigate the diagnostic value and role of circRNA in the pathogenesis of leukoaraiosis (LA). The present study performed Arraystar Human circRNA Array analysis of 6 samples from LA cases and 6 samples from control cases. Differentially expressed (DE) circRNAs between two samples were identified through fold-change (>1.5-fold) screening. Afterwards, based on DE circRNAs, the gene ontology (GO) analysis of upregulated DE genes identified from DE circRNAs demonstrated that DE genes were primarily associated with cellular metabolic processes, membrane-bound organelles and binding. However, none were enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Downregulated DE genes were enriched in cellular localization, cytoplasm and kinase binding. For the KEGG pathways, the downregulated DE genes were primarily associated with the insulin signaling pathway. The results of the present study indicated that the DE genes from differently expressed circRNAs may have an important role in the pathogenesis of LA and may be a novel targfet for further research.

Emerging Roles of circRNA Related to the Mechanical Stress in Human Cartilage Degradation of Osteoarthritis

Circular RNAs (circRNAs) are involved in the development of various diseases; however, knowledge on circRNAs in osteoarthritis (OA) is limited. This study aims to identify circRNA expression in different regions affected by OA and to explore the function of mechanical stress-related circRNAs (circRNAs-MSR) in cartilage. Bioinformatics was employed to predict the interaction of circRNAs and mRNAs in the cartilage. Loss-of-function experiments for circRNAs-MSR were performed in vitro. A total of 104 circRNAs were differentially expressed in damaged versus intact cartilage. Of these circRNAs, 44 and 60 were upregulated and downregulated, respectively, in the damaged tissue. circRNA-MSR expression increased under mechanical stress in chondrocytes. circRNAs-MSR were silenced using small interfering RNA, and knockdown of circRNAs-MSR could suppress tumor necrosis factor alpha (TNF-α) expression and increase extracellular matrix (ECM) formation. Our results demonstrated that circRNAs-MSR regulated TNF-α expression and participated in the chondrocyte ECM degradation process. We propose that the inhibition of circRNAs-MSR could inhibit the degradation of chondrocyte ECM and knockdown of circRNAs-MSR could be a potential therapeutic target for OA.

ZKSCAN1 gene and its related circular RNA (circZKSCAN1) both inhibit hepatocellular carcinoma cell growth, migration, and invasion but through different signaling pathways

There is increasing evidence that circular RNA (circRNA) are involved in cancer development, but the regulation and function of human circRNA remain largely unknown. In this study, we demonstrated that ZKSCAN1, a zinc finger family gene, is expressed in both linear and circular (circZKSCAN1) forms of RNA in human hepatocellular carcinoma (HCC) tissues and cell lines. Here, we analyzed a cohort of 102 patients and found that expression of both ZKSCAN1mRNA and circZKSCAN1 was significantly lower (P < 0.05) in the HCC samples compared with that in matched adjacent nontumorous tissues by reverse transcription PCR (RT-PCR). The low expression level of ZKSCAN1 was only associated with tumor size (P = 0.032), while the cirZKSCAN1 levels varied in patients with different tumor numbers (P < 0.01), cirrhosis (P = 0.031), vascular invasion (P = 0.002), or microscopic vascular invasion (P = 0.002), as well as with the tumor grade (P < 0.001). Silencing both ZKSCAN1mRNA and circZKSCAN1 promoted cell proliferation, migration, and invasion. In contrast, overexpression of both forms of RNA repressed HCC progression in vivo and in vitro. Silencing or overexpression of both forms of RNA did not interfere with each other. RNA-seq revealed a very different molecular basis for the observed effects; ZKSCAN1mRNA mainly regulated cellular metabolism, while circZKSCAN1 mediated several cancer-related signaling pathways, suggesting a nonredundant role for ZKSCAN1mRNA and circRNA. In conclusion, our results revealed two post-translational products (ZKSCAN1mRNA and circZKSCAN1) that cooperated closely with one another to inhibit growth, migration, and invasion of HCC. cirZKSCAN1 might be a useful marker for the diagnosis of HCC.

Circles reshaping the RNA world: from waste to treasure

A new type of RNAs was identified from genes traditionally thought to express messenger or linear ncRNA (noncoding RNA) only. They were subsequently named as circRNAs (circular RNAs) due to the covalently closed structure. Accumulating studies were performed to explore the expression profile of circRNAs in different cell types and diseases, the outcomes totally changed our view of ncRNAs, which was thought to be junk by-products in the process of gene transcription, and enriched our poor understanding of its underlying functions. The expression profile of circRNAs is tissue-specific and alters across various stages of cell differentiation. The biological function of circRNAs is multi-faceted, involving five main features (sponge effect, post-transcriptional regulation, rolling circle translation, circRNA-derived pseudogenes and splicing interference) and varying differently from the locations, binding sites and acting modes of circRNAs. The regulating role of circRNAs is not isolated but through an enormous complicated network involving mRNAs, miRNAs and proteins. Although most of the potential functions still remain unclear, circRNAs have been proved to be ubiquitous and critical in regulating cellular processes and diseases, especially in cancers, from the laboratory to the clinic. Herein, we review circRNAs’ classification, biogenesis and metabolism, their well-studied and anticipated functions, the current understanding of the potential implications of circRNAs in tumorigenesis and cancer targeted therapy.

Dysregulated miR-671-5p / CDR1-AS / CDR1 / VSNL1 axis is involved in glioblastoma multiforme

MiR-671-5p is encoded by a gene localized at 7q36.1, a region amplified in human glioblastoma multiforme (GBM), the most malignant brain cancer. To investigate whether expression of miR-671-5p were altered in GBM, we analyzed biopsies from a cohort of forty-five GBM patients and from five GBM cell lines. Our data show significant overexpression of miR-671-5p in both biopsies and cell lines. By exploiting specific miRNA mimics and inhibitors, we demonstrated that miR-671-5p overexpression significantly increases migration and to a less extent proliferation rates of GBM cells. Through a combined in silico and in vitro approach, we identified CDR1-AS, CDR1, VSNL1 as downstream miR-671-5p targets in GBM. Expression of these genes significantly decreased both in GBM biopsies and cell lines and negatively correlated with that of miR-671-5p. Based on our data, we propose that the axis miR-671-5p / CDR1-AS / CDR1 / VSNL1 is functionally altered in GBM cells and is involved in the modification of their biopathological profile.

hsa_circRNA_103636: potential novel diagnostic and therapeutic biomarker in Major depressive disorder

Aim: This study aimed to determine whether circular RNA (circRNA) molecules in peripheral blood mononuclear cells (PBMCs) could be used as novel non-invasive biomarkers for major depressive disorder (MDD). Materials & methods: Differentially expressed circRNAs were screened using an Arraystar Human CircRNA Array (which includes 13,617 human circRNAs) and qRT-PCR. Thirty MDD patients were randomly selected to retest the circRNA levels after 4-week and 8-week antidepressant regimens. Results: Four differentially expressed circRNAs were identified between MDD patients and controls, and only down-regulated hsa_circRNA_103636 was significantly altered after the 8-week treatment in MDD patients. Conclusion: These results suggest that altered expression of hsa_circRNA_103636 in PBMCs is a potential novel biomarker for the diagnosis and treatment of MDD.

Roles of Circular RNAs in Neurologic Disease

Circular RNAs (circRNAs) are a novel type of endogenous noncoding RNA receiving increasing attention. They have been shown to act as a natural microRNA sponges that repress the activity of corresponding miRNAs by binding with them, thus regulating target genes. Numerous studies have shown that miRNAs are involved in the pathogenesis of neurological diseases. Therefore, circRNAs may act as important regulatory factors in the occurrence and development processes of neurological disease.

Circular RNA Related to the Chondrocyte ECM Regulates MMP13 Expression by Functioning as a MiR-136 'Sponge' in Human Cartilage Degradation

Circular RNAs (circRNAs) are involved in the development of various diseases, but there is little knowledge of circRNAs in osteoarthritis (OA). The aim of study was to identify circRNA expression in articular cartilage and to explore the function of chondrocyte extracellular matrix (ECM)-related circRNAs (circRNA-CER) in cartilage. To identify circRNAs that are specifically expressed in cartilage, we compared the expression of circRNAs in OA cartilage with that in normal cartilage. Bioinformatics was employed to predict the interaction of circRNAs and mRNAs in cartilage. Loss-of-function and rescue experiments for circRNA-CER were performed in vitro. A total of 71 circRNAs were differentially expressed in OA and normal cartilage. CircRNA-CER expression increased with interleukin-1 and tumor necrosis factor levels in chondrocytes. Silencing of circRNA-CER using small interfering RNA suppressed MMP13 expression and increased ECM formation. CircRNA-CER could compete for miR-136 with MMP13. Our results demonstrated that circRNA-CER regulated MMP13 expression by functioning as a competing endogenous RNA (ceRNA) and participated in the process of chondrocyte ECM degradation. We propose that circRNA-CER could be used as a potential target in OA therapy.

Paraneoplastic Cerebellar Degeneration

Paraneoplastic cerebellar degeneration is a rare complication of a number of cancers, particularly small cell lung cancer, gynecologic cancers and Hodgkin’s disease. The disorder is clinically characterized by rapid development of pancerebellar dysfunction, which usually does not improve, and pathologically characterized by loss of Purkinje cells with or without inflammatory infiltrates. In some but not all patients, an autoantibody that reacts with the tumor and Purkinje cells can be found in the serum and spinal fluid of patients with paraneoplastic cerebellar degeneration. The presence of the autoantibody suggests, but does not prove, that the disorder has an autoimmune mechanism for its pathogenesis.

Using circular RNA as a novel type of biomarker in the screening of gastric cancer

BACKGROUND

Circular RNAs (circRNAs), a class of endogenous RNAs, have emerged as an enigmatic class of RNAs. Little is known about their value in the diagnosis of cancers.

METHODS

The targeted circRNA of this study was selected using two circRNA databases: CircBase (http://circbase.org/) and circ2Traits (http://gyanxet-beta.com/circdb/). Divergent primers, rather than commonly used convergent primers, for the circRNA were designed. The circRNA levels in 101 paired gastric cancer tissues and adjacent nontumorous tissues from surgical gastric cancer patients and 36 paired plasma samples from preoperative and postoperative gastric cancer patients were analyzed by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The specificity of the amplified products was measured by melting curve analysis and DNA sequencing. To observe the stability of circRNA, three randomly selected samples of gastric cancer tissues were stored at room temperature, 4°C and -20°C, and then, their circRNA levels were analyzed. To verify the reproducibility of qRT-PCR, circRNA levels were detected in a set of specimens (n=15) in two independent experiments with an interval of one day. Then, the correlation of their Ct values was determined. The relationships between circRNA expression levels and clinicopathological factors of patients with gastric cancer were further analyzed by one-way analysis of variance. A receiver operating characteristic (ROC) curve was established to evaluate the diagnostic value.

RESULTS

Hsa_circ_002059, a typical circular RNA, was first found to be significantly downregulated in gastric cancer tissues compared with paired adjacent nontumorous tissues (p<0.001). Its levels in plasma collected from postoperative gastric cancer patients were found significantly different from those from preoperative gastric cancer patients. The area under the ROC curve was 0.73. Importantly, we further found that lower expression levels were significantly correlated with distal metastasis (P=0.036), TNM stage (P=0.042), gender (P=0.002) and age (P=0.022). The stability of circRNAs and the reproducibility of the qRT-PCR method for detecting circRNA levels were determined.

CONCLUSION

These results suggested that circRNAs are highly stable in mammalian cells and that one specific circRNA, hsa_circ_002059, may be a potential novel and stable biomarker for the diagnosis of gastric carcinoma.

Cerebellar degeneration-related autoantigen 1 (CDR1) gene expression in prostate cancer cell lines

Prostate cancer (PCa) is the most frequent cancer among men in many developing countries, and the second leading cause of cancer-related death in men. A genetic component has been implicated in PCa onset and development. The cerebellar degeneration-related autoantigen 1 (CDR1) gene, mapping in Xq26-q27.2, is expressed in cerebrum, cerebellum, heart, lung, liver, and kidney. In addition, CDR1 expression has been detected in neuroblastoma, renal carcinoma cell lines, and other cancer cell lines. In this study, we investigated the expression of the CDR1 gene in the LNCaP and PC-3 PCa cell lines, and in the PNT1A normal prostate cell line. CDR1 mRNA expression was evaluated by qRT-PCR. We found that the CDR1 gene was overexpressed in the LNCaP and PC-3 PCa cell lines as compared with the PNT1A normal prostate cell line. These data suggest that CDR1 could be a new biomarker for PCa identification.

Circular RNA and miR-7 in cancer

MicroRNAs (miRNA) play important roles in fine-tuning gene expression and are often deregulated in cancer. The identification of competing endogenous RNA and circular RNA (circRNA) as important regulators of miRNA activity underscores the increasing complexity of ncRNA-mediated regulatory networks. Particularly, the recently identified circular RNA, ciRS-7, which acts as a designated miR-7 inhibitor/sponge, has conceptually changed the mechanistic understanding of miRNA networks. As miR-7 modulates the expression of several oncogenes, disclosing the regulation of miR-7 activity will likely advance the understanding of various cancer etiologies. Here, we review the current knowledge about the ciRS-7/miR-7 axis in cancer-related pathways and discuss possible models explaining the relevance of coexpressing miR-7 along with a circRNA inhibitor.

Exclusion of the 750-kb genetically unstable region at Xq27 as a candidate locus for prostate malignancy in HPCX1-linked families

Several linkage studies provided evidence for the presence of the hereditary prostate cancer locus, HPCX1, at Xq27-q28. The strongest linkage peak of prostate cancer overlies a variable region of ~750 kb at Xq27 enriched by segmental duplications (SDs), suggesting that the predisposition to prostate cancer may be a genomic disorder caused by recombinational interaction between SDs. The large size of SDs and their sequence similarity make it difficult to examine this region for possible rearrangements using standard methods. To overcome this problem, direct isolation of a set of genomic segments by in vivo recombination in yeast (a TAR cloning technique) was used to perform a mutational analysis of the 750 kb region in X-linked families. We did not detect disease-specific rearrangements within this region. In addition, transcriptome and computational analyses were performed to search for nonannotated genes within the Xq27 region, which may be associated with genetic predisposition to prostate cancer. Two candidate genes were identified, one of which is a novel gene termed SPANXL that represents a highly diverged member of the SPANX gene family, and the previously described CDR1 gene that is expressed at a high level in both normal and malignant prostate cells, and mapped 210 kb of upstream the SPANX gene cluster. No disease-specific alterations were identified in these genes. Our results exclude the 750-kb genetically unstable region at Xq27 as a candidate locus for prostate malignancy. Adjacent regions appear to be the most likely candidates to identify the elusive HPCX1 locus.

Capture and sequence analysis of RNAs with terminal 2',3'-cyclic phosphates

The combination of ligation-based RNA capture methods and high-throughput sequencing has facilitated the characterization of transcriptomes and the identification of novel noncoding RNAs. However, current ligation-based RNA capture methods require RNA substrates with terminal 3'-hydroxyl groups, limiting their utility for identifying RNAs with modified termini like 2',3'-cyclic phosphates. Cyclic phosphate-terminated RNAs are generated by endonucleolytic cleavages and self-cleaving ribozymes and are found as stable modifications on cellular RNAs such as the U6 spliceosomal RNA. We developed a method that uses the Arabidopsis thaliana tRNA ligase to add an adaptor oligonucleotide to RNAs that terminate in 2',3'-cyclic phosphates. The adaptor allows specific priming by reverse transcriptase, which is followed by additional steps for PCR amplification and high-throughput DNA sequencing. Applying the method to total human RNA, we found 2836 sequencing reads corresponding to the 3' terminus of U6 snRNA, validating the method. In addition to a large background of reads that map throughout abundantly transcribed RNAs, we also found 42,324 reads of specific fragments from several tRNA isoacceptor families, suggesting that this method may identify processing events previously undetected by other RNA cloning techniques.

Antibody to CCDC104 is associated with a paraneoplastic antibody to CDR2 (anti-Yo)

Patients with cancer may develop paraneoplastic neurological syndromes (PNS) in which onconeural antibodies are important diagnostic findings. As the functional role of onconeural antibodies is largely unknown, insight gained by identifying associated antibodies may help to clarify the pathogenesis of the PNS. In this study, we identified patients with Yo antibodies who also had antibodies to an uncharacterized protein called coiled-coil domain-containing protein 104 (CCDC104). We found a significant association between CCDC104 and Yo antibodies (4 of 38, 10.5%), but not other onconeural antibodies (0 of 158) (P = 0.007, Fisher's exact test). The prevalence of CCDC104 antibodies was approximately similar in patients with cancer (8 of 756, 1.1%) and in healthy blood donors (2 of 300, 0.7%). CCDC104 antibodies were not associated with PNS, as this was found in only two of the ten CCDC104-positive patients. The CCDC104 protein, whose function is unknown, is expressed in various human tissues, including the brain, and is localized mainly to the nucleus, but is also found in the cytoplasm. The association between Yo and CCDC104 antibodies may indicate functional similarities.

A high percentage of skin melanoma cells expresses SPANX proteins

The expression of SPANX (sperm protein associated with the nucleus in the X chromosome) gene family has been reported in many tumors, such as melanoma, myeloma, glioblastoma, breast carcinoma, ovarian cancer, testicular germ cell tumors, and hematological malignancies. However, no systematic approach has so far been devised to estimate the percentage of cancer cells expressing SPANX. This study was undertaken to quantify the expression of SPANX proteins in melanomas. The expression of SPANX proteins was evaluated by immunohistochemistry in normal skin (n = 12), melanomas (n = 21), and benign nevi (n = 10), using a polyclonal antibody raised in our laboratory. Seventeen of the 21 melanomas (80.9%) examined expressed SPANX proteins. A high percentage of their cells (49.0% +/- 5.5%) stained positively for SPANX proteins compared with no expression found in normal skin cells. Benign nevi had an intermediate number of cells expressing SPANX proteins (25% +/- 8.5%), which resulted significantly higher than normal skin cells and significantly lower than skin melanoma cells. In melanoma cells, the labeling was mostly nuclear, sometimes incomplete or limited to the perinuclear wall, even if cytoplasmic staining was also seen in SPANX-positive tumor cells. In contrast, the 5 of 10 SPANX-positive nevi had a clear nuclear localization of the signal. These data suggest that the SPANX protein family is expressed in the vast majority of the melanomas tested. The mechanism(s), which brings up SPANX gene expression and the role of these proteins are not known.

SPANX-B and SPANX-C (Xq27 region) gene dosage analysis in Sicilian patients with melanoma

The incidence of melanoma has dramatically increased in many countries (it is 4.5 cases every 100 000 inhabitants in Sicily) and Xq27 region contains genes important in cancer like the SPANX (sperm protein associated with the nucleus in the X chromosome) gene family. These genes, made up of two exons separated by an intron of about 650 base pair, are expressed in sperm cells and in many tumours, including melanoma. These observations suggested that SPANX genes, or some of them, may be involved in melanoma development. The aim of this study was to investigate the genetic variability of SPANX-B and SPANX-C in a sample of Sicilian male population including patients with melanoma of the skin and controls. A total of 99 patients were enrolled in this study. They included: 17 male patients with cutaneous melanoma and 82 normal males. Semiquantitative fluorescent multiplex PCR dosage analysis was carried out to identify the variety of classes of SPANX-B and SPANX-C genes. Sixteen and 13 genetic classes were detected for SPANX-B and SPANX-C genes, respectively. A statistical significant difference for a particular class of SPANX-C gene was found comparing patients with melanoma and controls (P=0.011). Further investigations should be conducted to confirm these observations and to evaluate the possible implication of other genes of the region Xq27-28 in melanoma.

Evidence for a novel x-linked modifier locus for leber hereditary optic neuropathy

Leber Hereditary Optic Neuropathy (LHON) is a maternally inherited blinding disease caused by missense mutations in the mitochondrial DNA (mtDNA). However, incomplete penetrance and a predominance of male patients presenting with vision loss suggest that modifying factors play an important role in the development of the disease. Evidence from several studies suggests that both nuclear modifier genes and environmental factors may be necessary to trigger the optic neuropathy in individuals harboring an LHON-causing mtDNA mutation. Recently, an optic neuropathy susceptibility locus at Xp21-Xq21 has been reported. In this study, we performed X-chromosomal linkage analysis in a large Brazilian family harboring a homoplasmic G11778A mtDNA mutation on a haplogroup J background. We report the identification of a novel LHON susceptibility locus on chromosome Xq25-27.2, with multipoint non-parametric linkage scores of > 5.00 (P = 0.005) and a maximum two-point non-parametric linkage score of 10.12, (P = 0.003) for marker DXS984 (Xq27.1). These results suggest genetic heterogeneity for X-linked modifiers of LHON.

Immunological features of neurological paraneoplastic syndromes

Neurological paraneoplastic syndromes are a rare group of disorders that occur in 1-2% of people with malignancy. They are usually caused by an immune response, triggered by and directed against a tumour, that cross-reacts with protein expressed by the peripheral or central nervous system. Any part of the nervous system can be affected and patients often develop severe and permanent disability. Diagnosis can be difficult as in two-thirds of patients the neurological problems appear up to 5 years before the tumour manifests. However, certain of these syndromes are often associated with specific serum autoantibodies that can be useful both in diagnosis of the neurological syndrome and in focusing the search for a particular tumour. Thus, these antibodies can allow earlier identification and treatment of cancer and, potentially, a reduction in morbidity and mortality. It was only in the 1980s that the first anti-neuronal autoantibodies were characterized and their associations with clinical syndromes and tumours defined. Further antibodies have been isolated over the past 20 years and novel pathogenic mechanisms for several syndromes have been recognized. For example, voltage-gate ion channels seem to be a common target for autoantibodies involved in peripheral nerve diseases such as the Lambert-Eaton myasthenic syndrome and neuromyotonia (Isaacs' syndrome). However, the place of most paraneoplastic antibodies in the pathogenesis of central syndromes is yet to be fully elucidated.

Gene Expression Profile Following Stable Expression of the Cellular Prion Protein

1. The cellular prion protein (PrPC) is expressed widely in neural and nonneural tissues at the highest level in neurons in the central nervous system (CNS). 2. Recent studies indicated that transgenic mice with the cytoplasmic accumulation of PrPC exhibited extensive neurodegeneration in the cerebellum, although the underlying mechanism remains unknown. To identify the genes whose expression is controlled by over-expression of PrPC in human cells, we have established a stable PrPC-expressing HEK293 cell line designated P1 by the site-specific recombination technique. 3. Microarray analysis identified 33 genes expressed differentially between P1 and the parent PrPC-non-expressing cell line among 12,814 genes examined. They included 18 genes involved in neuronal and glial functions, 5 related to production of extracellular matrix proteins, and 2 located in the complement cascade. 4. Northern blot analysis verified marked upregulation in P1 of the brain-specific protein phosphatase 2A beta subunit (PPP2R2B), a causative gene of spinocerebellar ataxia 12, and the cerebellar degeneration-related autoantigen (CDR34) gene associated with development of paraneoplastic cerebellar degeneration. 5. These results indicate that accumulation of PrPC in the cell caused aberrant regulation of a battery of the genes important for specific neuronal function. This represents a possible mechanism underlying PrPC-mediated selective neurodegeneration.

Novel perspective: focusing on the X chromosome in reproductive cancers

In an XX female, one of the two X chromosomes has been inactivated during early embryonic life to achieve a compensation of X-linked gene products between males and females, leaving only one allele of X-linked genes functional. There are some X-linked genes escaping the X-inactivation, i.e., being expressed from both alleles. Escape from X-inactivation varies at different levels; some genes have both alleles active in some women but only one allele active in others, whereas some other genes have both alleles active in neoplastic tissue but only one allele active normally. The X-inactivation may be considered functionally equivalent to a loss of heterozygosity (LOH) for some genes, whereas escape from X-inactivation may be equivalent to functional gene amplification for others. The physiological LOH may make X-linked tumor suppressor genes lose their function more easily, compared with autosomal tumor suppressor genes, thus predisposing women to cancer formation more easily. Moreover, the human X chromosome contains many genes related to cancer or to sex and reproduction. All these properties of the X chromosome suggest that it may play more important roles than any autosomal chromosome in the development and progression of reproductive and urologic cancers.

Paraneoplastic syndromes: an unsolved murder

With neuroimmunology playing an ever greater role in child neurology, paraneoplastic syndromes--uncommon but often devastating complications of cancer--are in the forefront. Abnormalities of both humoral and cellular immunity support the immunological theory of causation. Through co-complicity of host and tumor factors, targets of immunologically mediated injury remote from the tumor may be damaged or destroyed, giving rise to discrete neurological deficits. In the nervous system, the main targets are neuronal nuclei or cell bodies, structural constituents, surface receptors, synapses, and ion channels. The clinical syndromes and response to treatment differ substantially between children and adults. Current pharmacological and biological therapies, which are nonselective, include noncytotoxic and cytotoxic drugs, intravenous immunoglobulins, plasma exchange, and immunoadsorption, some chosen for induction and others for maintenance. Tumor resection and thymectomy are surgical treatments. Combination immunotherapies allow steroid sparing, targeting of more than one immunologic effector pathway, and deploy an advantageous mixture of early- and late-acting drugs. More selective and efficacious immunotherapies are needed.

Serological identification of embryonic neural proteins as highly immunogenic tumor antigens in small cell lung cancer

Serological analysis of expression cDNA libraries (SEREX) derived from two small cell lung cancer (SCLC) cell lines using pooled sera of SCLC patients led to the isolation of 14 genes, including 4 SOX group B genes (SOX1, SOX2, SOX3, and SOX21) and ZIC2. SOX group B genes and ZIC2 encode DNA-binding proteins; SOX group B proteins regulate transcription of target genes in the presence of cofactors, whereas ZIC2 is also suspected to be a transcriptional regulator. These genes are expressed at early developmental stages in the embryonic nervous system, but are down-regulated in the adult. Although SOX2 mRNA can be detected in some adult tissues, ZIC2 is expressed only in brain and testis, and SOX1, SOX3, and SOX21 transcripts are not detectable in normal adult tissues. Of SCLC cell lines tested, 80% expressed ZIC2 mRNA, and SOX1, SOX2, and SOX3 expression was detected in 40%, 50%, and 10%, respectively. SOX group B and ZIC2 antigens elicited serological responses in 30-40% of SCLC patients in this series, at titers up to 1:10(6). In sera from 23 normal adults, no antibody was detected against SOX group B or ZIC2 proteins except for one individual with low-titer anti-SOX2 antibody. Seroreactivity against SOX1 and 2 was consistently higher titered than SOX3 and 21 reactivity, suggesting SOX1 and/or SOX2 as the main antigens eliciting anti-SOX responses. Although paraneoplastic neurological syndromes have been associated with several SCLC antigens, neurological symptoms have not been observed in patients with anti-SOX or anti-ZIC2 antibodies.

Autoimmunity in paraneoplastic neurological syndromes

In patients with Paraneoplastic Neurological Disorders, the researcher detected several autoantibodies reacting with neuronal antigens and tumors; their characteristics supported the hypothesis that autoimmunity plays a part in these diseases and gave impetus to the study of these neurological disorders. The relationship between detection of anti-neuronal antibodies, clinical syndromes, and certain types of tumors suggested the utility of these antibodies as a new tool for clinical diagnosis, although their function in the pathogenesis of the various syndromes is still unclear. This paper intends to review the characteristics of the anti-neuronal antibodies so far identified, their correlation with clinical syndromes, and the function of antigens. In addition, the paper will offer some insights on the immunological mechanisms of neuronal damage and on treatment options.

Congenital motor nystagmus linked to Xq26-q27

Congenital motor nystagmus (CMN) is a hereditary disorder characterized by bilateral ocular oscillations that begin in the first 6 mo of life. It must be distinguished from those genetic disorders-such as ocular albinism (OA), congenital stationary night blindness (CSNB), and blue-cone monochromatism (BCM)-in which nystagmus accompanies a clinically apparent defect in the visual sensory system. Although CMN is presumed to arise from a neurological abnormality of fixation, it is not known whether the molecular defect is located in the eye or in the brain. It may be inherited in an autosomal dominant, autosomal recessive, or X-linked pattern. Three families with CMN inherited in an X-linked, irregularly dominant pattern were investigated with linkage and candidate gene analysis. The penetrance among obligate female carriers was 54%. Evaluation of markers in the region of the genes for X-linked OA, CSNB, and BCM revealed no evidence of linkage, supporting the hypothesis that CMN represents a distinct entity. The gene was mapped to chromosome Xq26-q27 with the following markers: GATA172D05 (LOD score 3.164; recombination fraction [theta] = 0.156), DXS1047 (LOD score 10.296; theta = 0), DXS1192 (LOD score 8.174; theta = 0.027), DXS1232 (LOD score 6.015; theta = 0.036), DXS984 (LOD score 6.695; theta = 0), and GATA31E08 (LOD score 4.940; theta = 0.083). Assessment of haplotypes and multipoint linkage analysis, which gave a maximum LOD score of 10.790 with the 1-LOD-unit support interval spanning approximately 7 cM, place the gene in a region between GATA172D05 and DXS1192. Evaluation of candidate genes CDR1 and SOX3 did not reveal mutations in affected male subjects.

A novel locus (RP24) for X-linked retinitis pigmentosa maps to Xq26-27

Two genetic loci, RP2 and RP3, for X-linked retinitis pigmentosa (XLRP) have been localized to Xp11.3-11.23 and Xp21.1, respectively. RP3 appears to account for 70% of XLRP families; however, mutations in the RPGR gene (isolated from the RP3 region) are identified in only 20% of affected families. Close location of XLRP loci at Xp and a lack of unambiguous clinical criteria do not permit assignment of genetic subtype in a majority of XLRP families; nonetheless, in some pedigrees, both RP2 and RP3 could be excluded as the causative locus. We report the mapping of a novel locus, RP24, by haplotype and linkage analysis of a single XLRP pedigree. The RP24 locus was identified at Xq26-27 by genotyping 52 microsatellite markers spanning the entire X chromosome. A maximum LOD score of 4.21 was obtained with DXS8106. Haplotype analysis assigned RP24 within a 23-cM region between the DXS8094 (proximal) and DXS8043 (distal) markers. Other chromosomal regions and known XLRP loci were excluded by obligate recombination events between markers in those regions and the disease locus. Hemizygotes from the RP24 family have early onset of rod photoreceptor dysfunction; cone receptor function is normal at first, but there is progressive loss. Patients at advanced stages show little or no detectable rod or cone function and have clinical hallmarks of typical RP. Mapping of the RP24 locus expands our understanding of the genetic heterogeneity in XLRP and will assist in development of better tools for diagnosis.

Familial cosegregation of manic-depressive illness and a form of hereditary cerebellar ataxia

We report on a Spanish family with cooccurrence of manic-depression and a form of hereditary cerebellar ataxia. All affected individuals in the second generation showed cerebellar ataxia and manic-depression simultaneously. Since anticipation has been described in both disorders and the pattern of segregation may be autosomal as well as X-linked, we have searched for a possible involvement of two candidate genes which are located either on an autosome (SCA1) or on the X-chromosome (GABRA3). We concluded that expansion of trinucleotide repeats at SCA1 gene cannot be considered as a disease-causing mutation, and this gene should be initially discarded.

Autoimmune central nervous system paraneoplastic disorders: mechanisms, diagnosis, and therapeutic options

The presence of specific antineuronal antibodies in some patients with paraneoplastic central nervous system (CNS) disorders supports the theory that these syndromes have an autoimmune etiology. The anti-Purkinje cell antibodies (APCAs) in some patients with paraneoplastic cerebellar degeneration and ovarian or breast carcinomas stain the cytoplasm of Purkinje cells. APCAs react with several distinct neuronal protein autoantigens, including proteins featuring a "leucine zipper" sequence motif, which suggests that they function in regulating DNA transcription. Type 1 anti-neuronal nuclear antibodies (ANNA-1) associated with paraneoplastic encephalomyelitis and small-cell lung carcinoma stain the nucleus and cytoplasm of all neurons, and react with a group of 35- to 40-kd proteins in neuronal immunoblots. The protein targets of ANNA-1 belong to a family of RNA-binding proteins that probably regulate posttranscriptional processing of RNA. Type 2 anti-neuronal nuclear antibodies (ANNA-2) associated with paraneoplastic opsoclonus-ataxia and breast carcinoma also produce a panneuronal immunocytochemical staining pattern, but react with a group of higher-molecular-mass proteins (53-61 kd and 79-84 kd); these autoantigens probably also function as RNA-binding proteins. Several patients with paraneoplastic stiff-man syndrome have antibodies against a 128-kd synaptic protein. These antineuronal antibodies are highly specific (but not infallible) diagnostic markers for the presence of a neoplasm in patients who present with neurological dysfunction. The actual role of these autoantibodies in the pathogenesis of neuronal damage and clinical disease remains to be determined. Current management options for patients with CNS neurological paraneoplastic syndromes are very limited. Only a small minority of patients with paraneoplastic cerebellar degeneration or encephalomyelitis show significant neurological improvement after successful tumor treatment and/or immunosuppressive treatments, while patients with paraneoplastic opsoclonus or stiff-man syndrome have a somewhat better outlook.

A panel of deleted mouse X chromosome somatic cell hybrids derived from the embryonic stem cell line HD3 shows preferential breakage in the Hprt-DXHX254E region

A panel of 91 somatic cell hybrids containing deleted mouse X chromosomes and falling into seven nested intervals has been isolated and characterized from fusions involving the murine embryonic stem cell HD3. Many of the X chromosome breakpoints present in these hybrids fall within regions in which few or no other hybrids were previously available. The apparent enrichment for breakpoints lying within the Hprt-DXHX254E region is discussed in relation to both the nature of the embryonic stem cell fusions and the presence of the Fmr1 gene associated with FRAXA in man within this span.

Paraneoplastic cerebellar degeneration with a circulating antibody against neurons and non-neuronal cells

We describe a woman with paraneoplastic cerebellar degeneration associated with para-ovarian adenocarcinoma, who had a circulating antibody with a corresponding antigen not only in cerebellar Purkinje cells but also in neurons located in the molecular layer of the human and rat cerebellum. The antigen was also present in neurons in the cerebral cortex, brain stem, anterior horn cells, dorsal root ganglia, intestinal autonomic neurons, retinal ganglion cells, Schwann cells of the peripheral nerve and epithelial cells of the renal glomerulus in rats. Immunoelectron microscopy revealed immunoprecipitates in the smooth and rough endoplasmic reticulum and polyribosomes in human and rat cerebellar Purkinje cells and other neuronal cell bodies as well as Schwann cells of the peripheral nerve. Even though patients with this disorder manifest primarily with cerebellar and some extracerebellar signs, the antigen also exists in many neurons other than cerebellar Purkinje cells and even in non-neuronal cells. The clinicopathologic significance of the observed immunologic reaction in diverse neurons remains to be determined.

Effects of hyperbilirubinaemia on glutathione S-transferase isoenzymes in cerebellar cortex of the Gunn rat

The glutathione S-transferases (GSTs) are a family of isoenzymes involved in the detoxication of a variety of electrophilic xenobiotics. The present investigation demonstrates that GST activity and the concentration of cytosolic GSTs in cerebellar cortex of Gunn rats were increased in hyperbilirubinaemic animals compared with non-jaundiced controls. Age-dependent and region-specific increases in GST isoenzymes were seen in three regions of the cerebellar cortex of jaundiced Gunn rats, whereas GST concentrations were not altered in the brainstem, thalamus/hypothalamus, cortex or liver. Cytosolic GST activity was increased 1.3-fold in the flocculus and lateral hemispheres of 20-day-old and 1.7-fold in the flocculus, lateral hemispheres and vermis of 60-day-old jaundiced (jj; homozygous) Gunn rats compared with non-jaundiced (Jj; heterozygous) Gunn rats. H.p.l.c. was used to determine the GST subunit protein concentrations in cytosolic fractions isolated from liver and brain regions of jaundiced and non-jaundiced animals. In all regions of the cerebellum from 20-day-old animals, the levels of Alpha-class GST subunits 2 (Yc1; 3.0-fold) and 8 (Yk; 2.0-fold) were increased in jaundiced rats. In 60-day-old animals, the concentrations of Alpha-class GST subunits 2 (Yc1; 5.0-fold) and 8 (Yk; 3.0-fold), Mu-class subunit 11 (Yo; 2.5-fold) and Pi-class subunit 7 (Yp; 2.0-fold) were increased in all regions of cerebellar cortex of jaundiced animals. In cerebellum of 10-, 20- and 60-day-old non-jaundiced and jaundiced Gunn rats, the flocculus had the highest concentration of Mu-class GST subunit 4 (Yb2) and vermis the lowest; hyperbilirubinaemia increased the concentration of subunit 4 (Yb2; 3- to 5-fold) in the flocculus and lateral hemispheres, but not the vermis, of 20- and 60-day-old rats. Intraperitoneal injection of sulphadimethoxine, a long-acting sulphonamide which displaces bilirubin from its albumin-binding sites and increases the bilirubin levels in tissues, further increased the already elevated concentrations of GST subunits in the lateral regions of cerebellar cortex of hyperbilirubinaemic rats. For example, the concentration of subunit 4 (Yb2) was increased 2.2-fold (compared with non-jaundiced controls) in Gunn rats injected with saline and 7.4-fold in rats injected with 100 mg of sulphadimethoxine/kg body weight. In contrast, GSTs in the vermis of jaundiced animals were not affected by sulphadimethoxine injection. Sulphadimethoxine had no effect on GST concentrations in lateral regions and vermis of heterozygous (Jj) Gunn rats.(ABSTRACT TRUNCATED AT 400 WORDS)