A Primary Role for the Tsix lncRNA in Maintaining Random X-Chromosome Inactivation

Transcriptional stochasticity reveals multiple mechanisms of long non-coding RNA regulation at the Xist-Tsix locus

Long noncoding RNAs (LncRNAs) are increasingly recognized as being involved in human physiology and diseases, but there is a lack of mechanistic understanding for the majority of lncRNAs. We comparatively test proposed mechanisms of antisense lncRNA regulation at the X-chromosome Inactivation (XCI) locus. We find that due to stochasticity in transcription, different mechanisms based on the act of transcription regulate Xist and Tsix at different levels of nascent transcription. At medium levels, RNA polymerases transcribe Xist and Tsix on each strand at the same transcription site and deposit significant amounts of the histone mark H3K36me3, which inhibits Xist. At high levels of nascent transcription, many RNA polymerases transcribe Xist or Tsix resulting in transcriptional interference. Therefore, lncRNA expression variability is not just a quirk of transcription but an important aspect of regulation that allows multiple mechanisms to be employed by the same gene locus within the same cell population.

Long non coding RNA function in epigenetic memory with a particular emphasis on genomic imprinting and X chromosome inactivation

Cells preserve and convey certain gene expression patterns to their progeny through the mechanism called epigenetic memory. Epigenetic memory, encoded by epigenetic markers and components, determines germline inheritance, genomic imprinting, and X chromosome inactivation. First discovered long non coding RNAs were implicated in genomic imprinting and X-inactivation and these two phenomena clearly demonstrate the role of lncRNAs in epigenetic memory regulation. Undoubtedly, lncRNAs are well-suited for regulating genes in close proximity at imprinted loci. Due to prolonged association with the transcription site, lncRNAs are able to guide chromatin modifiers to certain locations, thereby enabling accurate temporal and spatial regulation. Nevertheless, the current state of knowledge regarding lncRNA biology and imprinting processes is still in its nascent phase. Herein, we provide a synopsis of recent scientific advancements to enhance our comprehension of lncRNAs and their functions in epigenetic memory, with a particular emphasis on genomic imprinting and X chromosome inactivation, thus gaining a deeper understanding of the role of lncRNAs in epigenetic regulatory networks.

The X chromosome's influences on the human brain

Genes on the X chromosome are extensively expressed in the human brain. However, little is known for the X chromosome's impact on the brain anatomy, microstructure, and functional networks. We examined 1045 complex brain imaging traits from 38,529 participants in the UK Biobank. We unveiled potential autosome-X chromosome interactions while proposing an atlas outlining dosage compensation for brain imaging traits. Through extensive association studies, we identified 72 genome-wide significant trait-locus pairs (including 29 new associations) that share genetic architectures with brain-related disorders, notably schizophrenia. Furthermore, we found unique sex-specific associations and assessed variations in genetic effects between sexes. Our research offers critical insights into the X chromosome's role in the human brain, underscoring its contribution to the differences observed in brain structure and functionality between sexes.

Multifaceted role of CTCF in X-chromosome inactivation

Therian female mammals compensate for the dosage of X-linked gene expression by inactivating one of the X-chromosomes. X-inactivation is facilitated by the master regulator Xist long non-coding RNA, which coats the inactive-X and facilitates heterochromatinization through recruiting different chromatin modifiers and changing the X-chromosome 3D conformation. However, many mechanistic aspects behind the X-inactivation process remain poorly understood. Among the many contributing players, CTCF has emerged as one of the key players in orchestrating various aspects related to X-chromosome inactivation by interacting with several other protein and RNA partners. In general, CTCF is a well-known architectural protein, which plays an important role in chromatin organization and transcriptional regulation. Here, we provide significant insight into the role of CTCF in orchestrating X-chromosome inactivation and highlight future perspectives.

Long noncoding nuclear enriched abundant transcript 1_2 is a promising biomarker for childhood-onset systemic lupus erythematosus

Importance

Systemic lupus erythematosus (SLE) is a diffuse connective tissue disease with complex clinical manifestations and prolonged course. The early diagnosis and condition monitoring of SLE are crucial to disease prognosis.

Objective

To assess the diagnostic value of long noncoding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) in childhood-onset SLE (cSLE).

Methods

Fifty-seven children diagnosed with SLE, 40 children diagnosed with juvenile idiopathic arthritis (JIA), and 40 healthy children were included. Peripheral blood samples from each patient were collected. A quantitative polymerase chain reaction was used to confirm the expression of lncNEAT1_1 and lncNEAT1_2 in peripheral blood. Associations among parameters were analyzed using the Mann-Whitney U test or independent sample t-test.

Results

The expression of both lncNEAT1_1 and lncNEAT1_2 in patients with cSLE were significantly higher than that of healthy control and patients with JIA. Receiver operating characteristic curves revealed an area under the curve (AUC) of 0.633 (95% confidence interval [CI], 0.524-0.742; P = 0.024) for lncNEAT1_1. The AUC of lncNEAT1_2 was 0.812 (95% CI, 0.727-0.897; P < 0.0001) to discriminate individuals with cSLE from health control and children with JIA with a sensitivity of 0.622 and a specificity of 0.925. Moreover, lncNEAT1_2 expression was higher in patients with cSLE presenting with fever, lupus nephritis, elevated erythrocyte sedimentation rate, active disease activity, and decreased C3 level, compared with those without these conditions. However, no similar correlation was observed for lncNEAT1_1.

Interpretation

The expression of lncNEAT1_2 was significantly elevated in children with SLE, especially those with fever, renal involvement, and low C3 levels. These findings suggest that lncNEAT1_2 may represent a potential biomarker for cSLE.

The pivotal role of the X-chromosome in the genetic architecture of the human brain

Genes on the X-chromosome are extensively expressed in the human brain. However, little is known for the X-chromosome's impact on the brain anatomy, microstructure, and functional network. We examined 1,045 complex brain imaging traits from 38,529 participants in the UK Biobank. We unveiled potential autosome-X-chromosome interactions, while proposing an atlas outlining dosage compensation (DC) for brain imaging traits. Through extensive association studies, we identified 72 genome-wide significant trait-locus pairs (including 29 new associations) that share genetic architectures with brain-related disorders, notably schizophrenia. Furthermore, we discovered unique sex-specific associations and assessed variations in genetic effects between sexes. Our research offers critical insights into the X-chromosome's role in the human brain, underscoring its contribution to the differences observed in brain structure and functionality between sexes.

Epigenomic states contribute to coordinated allelic transcriptional bursting in iPSC reprogramming

Two alleles of a gene can be transcribed independently or coordinatedly, which can lead to temporal expression heterogeneity with potentially distinct impacts on cell fate. Here, we profiled genome-wide allelic transcriptional burst kinetics during the reprogramming of MEF to induced pluripotent stem cells. We show that the degree of coordination of allelic bursting differs among genes, and alleles of many reprogramming-related genes burst in a highly coordinated fashion. Notably, we show that the chromatin accessibility of the two alleles of highly coordinated genes is similar, unlike the semi-coordinated or independent genes, suggesting the degree of coordination of allelic bursting is linked to allelic chromatin accessibility. Consistently, we show that many transcription factors have differential binding affinity between alleles of semi-coordinated or independent genes. We show that highly coordinated genes are enriched with chromatin accessibility regulators such as H3K4me3, H3K4me1, H3K36me3, H3K27ac, histone variant H3.3, and BRD4. Finally, we demonstrate that enhancer elements are highly enriched in highly coordinated genes. Our study demonstrates that epigenomic states contribute to coordinated allelic bursting to fine-tune gene expression during induced pluripotent stem cell reprogramming.

A Comparative Analysis of Mouse Imprinted and Random X-Chromosome Inactivation

The mammalian sexes are distinguished by the X and Y chromosomes. Whereas males harbor one X and one Y chromosome, females harbor two X chromosomes. To equalize X-linked gene expression between the sexes, therian mammals have evolved X-chromosome inactivation as a dosage compensation mechanism. During X-inactivation, most genes on one of the two X chromosomes in females are transcriptionally silenced, thus equalizing X-linked gene expression between the sexes. Two forms of X-inactivation characterize eutherian mammals, imprinted and random. Imprinted X-inactivation is defined by the exclusive inactivation of the paternal X chromosome in all cells, whereas random X-inactivation results in the silencing of genes on either the paternal or maternal X chromosome in individual cells. Both forms of X-inactivation have been studied intensively in the mouse model system, which undergoes both imprinted and random X-inactivation early in embryonic development. Stable imprinted and random X-inactivation requires the induction of the Xist long non-coding RNA. Following its induction, Xist RNA recruits proteins and complexes that silence genes on the inactive-X. In this review, we present a current understanding of the mechanisms of Xist RNA induction, and, separately, the establishment and maintenance of gene silencing on the inactive-X by Xist RNA during imprinted and random X-inactivation.

Single-cell analysis reveals X upregulation is not global in pre-gastrulation embryos

In mammals, transcriptional inactivation of one X chromosome in female compensates for the dosage of X-linked gene expression between the sexes. Additionally, it is believed that the upregulation of active X chromosome in male and female balances the dosage of X-linked gene expression relative to autosomal genes, as proposed by Ohno. However, the existence of X chromosome upregulation (XCU) remains controversial. Here, we have profiled gene-wise dynamics of XCU in pre-gastrulation mouse embryos at single-cell level and found that XCU is dynamically linked with X chromosome inactivation (XCI); however, XCU is not global like XCI. Moreover, we show that upregulated genes are enriched with activating marks and have enhanced burst frequency. Finally, our In-silico model predicts that recruitment probabilities of activating factors and a surge of these factors upon X-inactivation trigger XCU. Altogether, our study provides significant insight into the gene-wise dynamics and mechanistic basis of XCU during early development and extends support for Ohno’s hypothesis.

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X-upregulation coincides with X chromosome inactivation in pre-gastrulation embryos

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X-upregulation is not chromosome-wide like X-inactivation

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Upregulated genes have enhanced burst frequency and are enriched with activating marks

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A surge of activating factors on X-inactivation triggers X-upregulation

Activation of Xist by an evolutionarily conserved function of KDM5C demethylase

XX female and XY male therian mammals equalize X-linked gene expression through the mitotically-stable transcriptional inactivation of one of the two X chromosomes in female somatic cells. Here, we describe an essential function of the X-linked homolog of an ancestral X-Y gene pair, Kdm5c-Kdm5d, in the expression of Xist lncRNA, which is required for stable X-inactivation. Ablation of Kdm5c function in females results in a significant reduction in Xist RNA expression. Kdm5c encodes a demethylase that enhances Xist expression by converting histone H3K4me2/3 modifications into H3K4me1. Ectopic expression of mouse and human KDM5C, but not the Y-linked homolog KDM5D, induces Xist in male mouse embryonic stem cells (mESCs). Similarly, marsupial (opossum) Kdm5c but not Kdm5d also upregulates Xist in male mESCs, despite marsupials lacking Xist, suggesting that the KDM5C function that activates Xist in eutherians is strongly conserved and predates the divergence of eutherian and metatherian mammals. In support, prototherian (platypus) Kdm5c also induces Xist in male mESCs. Together, our data suggest that eutherian mammals co-opted the ancestral demethylase KDM5C during sex chromosome evolution to upregulate Xist for the female-specific induction of X-inactivation.

Preventing erosion of X-chromosome inactivation in human embryonic stem cells

X-chromosome inactivation is a paradigm of epigenetic transcriptional regulation. Female human embryonic stem cells (hESCs) often undergo erosion of X-inactivation upon prolonged culture. Here, we investigate the sources of X-inactivation instability by deriving new primed pluripotent hESC lines. We find that culture media composition dramatically influenced the expression of XIST lncRNA, a key regulator of X-inactivation. hESCs cultured in a defined xenofree medium stably maintained XIST RNA expression and coating, whereas hESCs cultured in the widely used mTeSR1 medium lost XIST RNA expression. We pinpointed lithium chloride in mTeSR1 as a cause of XIST RNA loss. The addition of lithium chloride or inhibitors of GSK-3 proteins that are targeted by lithium to the defined hESC culture medium impeded XIST RNA expression. GSK-3 inhibition in differentiating female mouse embryonic stem cells and epiblast stem cells also resulted in a loss of XIST RNA expression. Together, these data may reconcile observed variations in X-inactivation in hESCs and inform the faithful culture of pluripotent stem cells.

BAF complex-mediated chromatin relaxation is required for establishment of X chromosome inactivation

The process of epigenetic silencing, while fundamentally important, is not yet completely understood. Here we report a replenishable female mouse embryonic stem cell (mESC) system, Xmas, that allows rapid assessment of X chromosome inactivation (XCI), the epigenetic silencing mechanism of one of the two X chromosomes that enables dosage compensation in female mammals. Through a targeted genetic screen in differentiating Xmas mESCs, we reveal that the BAF complex is required to create nucleosome-depleted regions at promoters on the inactive X chromosome during the earliest stages of establishment of XCI. Without this action gene silencing fails. Xmas mESCs provide a tractable model for screen-based approaches that enable the discovery of unknown facets of the female-specific process of XCI and epigenetic silencing more broadly.

Female embryonic stem cells (ESCs) are the ideal model to study X chromosome inactivation (XCI) establishment; however, these cells are challenging to keep in culture. Here the authors create fluorescent ‘Xmas’ reporter mice as a renewable source of ESCs and show nucleosome remodelers Smarcc1 and Smarca4 create a nucleosome-free promoter region prior to the establishment of silencing.

Loss of MAGEC3 Expression Is Associated with Prognosis in Advanced Ovarian Cancers

Simple Summary

Familial studies connect variants in the X-linked gene MAGEC3 to early-onset ovarian cancers. In this retrospective cohort study, we determined that, unlike other MAGE family members, the MAGEC3 protein is normally expressed in ovarian tissue but is lost in half of the ovarian cancers. Similar to other predisposition genes like BRCA2, survival modeling suggests that expression loss is associated with favorable progression-free survival, and continued expression is associated with response to platinum therapy. Because of the assumed antigenicity of MAGE genes, we tested and observed associations with lymphocyte infiltration, NY-ESO-1 seropositivity, and the co-expression of tumor antigens at Xq28. Using transcriptomic modeling, we predicted that MAGEC3 expression is associated with stress-related cell cycle stalling and DNA repair pathway expression.

Abstract

Rare variants in MAGEC3 are associated with BRCA negative, early-onset ovarian cancers. Given this association, we evaluated the impact of MAGEC3 protein expression on prognosis and transcription. We quantified normal and tumor protein expression of MAGEC3 via immunohistochemistry in n = 394 advanced ovarian cancers, assessed the correlation of these values with clinicopathologic and immunological features and modeled survival using univariate and multivariate models. To extend these results, we quantified MAGEC3 protein expression in n = 180 cancers and used matching RNA sequencing data to determine MAGEC3-associated differentially expressed genes and to build an RNA-based model of MAGEC3 protein levels. This model was tested in a third independent cohort of patients from TCGA’s OV dataset (n = 282). MAGEC3 protein was sporadically lost in ovarian cancers, with half of the cases falling below the 9.5th percentile of normal tissue expression. Cases with MAGEC3 loss demonstrated better progression-free survival [HR = 0.71, p = 0.004], and analyses performed on predicted protein scores were consistent [HR = 0.57 p = 0.002]. MAGEC3 protein was correlated with CD8 protein expression [Pearson’s r = 0.176, p = 0.011], NY-ESO-1 seropositivity, and mRNA expression of tumor antigens at Xq28. Results of gene set enrichment analysis showed that genes associated with MAGEC3 protein expression cluster around G2/M checkpoint (NES = 3.20, FDR < 0.001) and DNA repair (NES = 2.28, FDR < 0.001) hallmark pathways. These results show that MAGEC3 is a prognostic biomarker in ovarian cancer.

The Role of Long Non-Coding RNAs (lncRNAs) in Female Oriented Cancers

Recent advances in molecular biology have discovered the mysterious role of long non-coding RNAs (lncRNAs) as potential biomarkers for cancer diagnosis and targets for advanced cancer therapy. Studies have shown that lncRNAs take part in the incidence and development of cancers in humans. However, previously they were considered as mere RNA noise or transcription byproducts lacking any biological function. In this article, we present a summary of the progress on ascertaining the biological functions of five lncRNAs (HOTAIR, NEAT1, H19, MALAT1, and MEG3) in female-oriented cancers, including breast and gynecological cancers, with the perspective of carcinogenesis, cancer proliferation, and metastasis. We provide the current state of knowledge from the past five years of the literature to discuss the clinical importance of such lncRNAs as therapeutic targets or early diagnostic biomarkers. We reviewed the consequences, either oncogenic or tumor-suppressing features, of their aberrant expression in female-oriented cancers. We tried to explain the established mechanism by which they regulate cancer proliferation and metastasis by competing with miRNAs and other mechanisms involved via regulating genes and signaling pathways. In addition, we revealed the association between stated lncRNAs and chemo-resistance or radio-resistance and their potential clinical applications and future perspectives.

SPEN is required for Xist upregulation during initiation of X chromosome inactivation

At initiation of X chromosome inactivation (XCI), Xist is monoallelically upregulated from the future inactive X (Xi) chromosome, overcoming repression by its antisense transcript Tsix. Xist recruits various chromatin remodelers, amongst them SPEN, which are involved in silencing of X-linked genes in cis and establishment of the Xi. Here, we show that SPEN plays an important role in initiation of XCI. Spen null female mouse embryonic stem cells (ESCs) are defective in Xist upregulation upon differentiation. We find that Xist-mediated SPEN recruitment to the Xi chromosome happens very early in XCI, and that SPEN-mediated silencing of the Tsix promoter is required for Xist upregulation. Accordingly, failed Xist upregulation in Spen-/- ESCs can be rescued by concomitant removal of Tsix. These findings indicate that SPEN is not only required for the establishment of the Xi, but is also crucial in initiation of the XCI process.

Developmental Acquisition of p53 Functions

Remarkably, the p53 transcription factor, referred to as “the guardian of the genome”, is not essential for mammalian development. Moreover, efforts to identify p53-dependent developmental events have produced contradictory conclusions. Given the importance of pluripotent stem cells as models of mammalian development, and their applications in regenerative medicine and disease, resolving these conflicts is essential. Here we attempt to reconcile disparate data into justifiable conclusions predicated on reports that p53-dependent transcription is first detected in late mouse blastocysts, that p53 activity first becomes potentially lethal during gastrulation, and that apoptosis does not depend on p53. Furthermore, p53 does not regulate expression of genes required for pluripotency in embryonic stem cells (ESCs); it contributes to ESC genomic stability and differentiation. Depending on conditions, p53 accelerates initiation of apoptosis in ESCs in response to DNA damage, but cell cycle arrest as well as the rate and extent of apoptosis in ESCs are p53-independent. In embryonic fibroblasts, p53 induces cell cycle arrest to allow repair of DNA damage, and cell senescence to prevent proliferation of cells with extensive damage.

Systematic Analysis and Identification of Dysregulated Panel lncRNAs Contributing to Poor Prognosis in Head-Neck Cancer

Head and neck cancer (HNC) is one of the most prevalent cancers worldwide, accounting for approximately 5% of all cancers. While the underlying molecules and their pathogenetic mechanisms in HNC have yet to be well elucidated, recent studies have shown that dysregulation of lncRNAs may disrupt the homeostasis of various biological pathways. However, the understanding of lncRNAs in HNC is still limited by the lack of expression profiling. In the present study, we employed a systematic strategy to identify a panel of lncRNA associated with HNC. A cancer-related lncRNA profile PCR array was screened to explore potential molecules specific for HNC. A total of 55 lncRNAs were found to be dysregulated in HNC cells when compared to normal keratinocytes. Further analysis of the prognostic significance using The Cancer Genome Atlas (TCGA) database revealed 15 lncRNAs highly correlated with overall survival in HNC patients. Additionally, clinical sample expression analysis of the TCGA-HNSC cohort revealed 16 highly dysregulated lncRNAs in HNC, resulting in a combined 31-lncRNA signature panel that could predict prognosis. Validation of these molecules confirmed the considerable level of altered expressions in HNC cells, with XIST, HOXA11-AS, TSIX, MALAT1, WT1-AS, and IPW being the most prominently dysregulated. We further selected a molecule from our panel (XIST) to confirm the validity of these lncRNAs in the regulation of cancer aggressiveness. Gene ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analyses demonstrated that XIST participated in various cancer-related functions, including cell proliferation and metastasis. XIST silencing with the RNAi technique substantially reduced invasion and migration in several HNC cell lines. Thus, our study defined a 31-lncRNA panel as prognostic signatures in HNC. These perspective results provide a knowledge foundation for further application of these molecules in precision medicine.

The role of nuclear organization in trans-splicing based expression of heat shock protein 90 in Giardia lamblia

Hsp90 gene of G. lamblia has a split nature comprising two ORFs separated by 777 kb on chromosome 5. The ORFs of the split gene on chromosome 5 undergo transcription to generate independent pre-mRNAs that join by a unique trans-splicing reaction that remains partially understood. The canonical cis-acting nucleotide elements such as 5'SS-GU, 3'SS-AG, polypyrimidine tract and branch point adenine are present in the independent pre-mRNAs and therefore trans-splicing of Hsp90 must be assisted by spliceosomes in vivo. Using an approach of RNA-protein pull down, we show that an RNA helicase selectively interacts with HspN pre-mRNA. Our experiments involving high resolution chromosome conformation capture technology as well as DNA FISH show that the trans-spliced genes of Giardia are in three-dimensional spatial proximity in the nucleus. Altogether our study provides a glimpse into the in vivo mechanisms involving protein factors as well as chromatin structure to facilitate the unique inter-molecular post-transcriptional stitching of split genes in G. lamblia.

Semicoordinated allelic-bursting shape dynamic random monoallelic expression in pregastrulation embryos

Recently, allele-specific single-cell RNA-seq analysis has demonstrated widespread dynamic random monoallelic expression of autosomal genes (aRME) in different cell types. However, the prevalence of dynamic aRME during pregastrulation remains unknown. Here, we show that dynamic aRME is widespread in different lineages of pregastrulation embryos. Additionally, the origin of dynamic aRME remains elusive. It is believed that independent transcriptional bursting from each allele leads to dynamic aRME. Here, we show that allelic burst is not perfectly independent; instead it happens in a semicoordinated fashion. Importantly, we show that semicoordinated allelic bursting of genes, particularly with low burst frequency, leads to frequent asynchronous allelic bursting, thereby contributing to dynamic aRME. Furthermore, we found that coordination of allelic bursting is lineage specific and genes regulating the development have a higher degree of coordination. Altogether, our study provides significant insights into the prevalence and origin of dynamic aRME and their developmental relevance during early development.

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Dynamic aRME is widespread in different lineages of pregastrulation embryos

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Semicoordinated bursting of genes with low burst frequency leads to dynamic aRME

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Degree of coordination of allelic bursting is lineage specific

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Developmental genes have higher degree of coordination of allelic bursting

LncRNA-H19 regulates chemoresistance to carboplatin in epithelial ovarian cancer through microRNA-29b-3p and STAT3

Background: Platinum-based chemotherapy is part of current standard treatment for epithelial ovarian cancer (EOC). However, chemoresistance often rapidly developed, leading to chemotherapy failure and unfavored prognosis. Increasing evidence has demonstrated the important role of oncogenic long noncoding RNA H19 in various cancers, including EOC. No current study is available in exploring the role of lncRNA-H19 in carboplatin resistance of EOC and its underlying mechanism.

Methods: Levels of lncRNA-H19, miR-29b-3p, and STAT3 mRNA were measured by qRT-PCR. The 50% inhibitory concentration value was detected with Cell Counting Kit-8 (CCK8). Colony-formation and CCK8 assays were employed to measure cell viability. Cell migration and invasion ability was evaluated with transwells. Western blot assay was utilized to measure P-gp, MRP1, LRP, and STAT3 protein levels. The targeting between lncRNA-H19 and miR-29b-3p, as well as miR-29b-3p and STAT3, was verified by dual-luciferase, RNA immunoprecipitation, and RNA pull-down experiments.

Results: lncRNA-H19 and STAT3 were sharply increased, while miR-29b-3p was decreased in carboplatin-resistant EOC. Carboplatin efficacy was enhanced by lncRNA-H19 silencing in chemo-resistant EOC cells. lncRNA-H19 served as a competing endogenous RNA of miR-29b-3p, causing the derepression of miR-29b-3p downstream target STAT3, leading to chemoresistance in carboplatin-tolerated EOC.

Conclusions: The lncRNA-H19/miR-29b-3p axis improved carboplatin resistance of EOC by targeting STAT3, indicating a possible approach to improving chemotherapy for EOC.

Long non-coding RNAs XIST and MALAT1 hijack the PD-L1 regulatory signaling pathway in breast cancer subtypes

Long non-coding RNAs (lncRNAs) have attracted widespread attention as potential biological and pathological regulators. lncRNAs are involved in several biological processes in cancer. Triple negative breast cancer (TNBC) is characterized by strong heterogeneity and aggressiveness. At present, the implication of microRNAs (miRs) and lncRNAs in immunotherapy has been poorly studied. Nevertheless, the blockade of immune checkpoints, particularly that of the programmed cell-death protein-1/programmed cell-death ligand-1 (PD-L1) axis, is considered as a principle approach in breast cancer (BC) therapy. The present study aimed to investigate the interaction between immune-modulatory upstream signaling pathways of the PD-L1 transcript that could enhance personalized targeted therapy. MDA-MB-231 cells were transfected with miR-182-5p mimics followed by RNA extraction and cDNA synthesis using a reverse transcription kit, and the expression levels of the target genes were assessed by reverse transcription-quantitative PCR. Furthermore, the expression levels of target genes were measured in tissues derived from 41 patients with BC, including patients with luminal BC and TNBC, as well as their adjacent lymph nodes. The results revealed that the expression levels of miR-182-5p, PD-L1 and metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) were upregulated in MDA-MB-231 cells and BC tissues. However, X-inactive specific transcript (XIST) expression was downregulated in cancer tissues and TNBC cells. Following co-transfection of cells with small interfering RNAs specific for each target gene and miR-182-5p antagomirs, the effect of miR-182-5p was abolished in the presence of lncRNAs. Therefore, the results of the present study indicated that although miR-182-5p exhibited an oncogenic effect, XIST exerted a dominant effect on the regulation of the PD-L1 signaling pathway via the inhibition of the oncogenic function of MALAT1.

Long Intergenic Non-Coding RNAs in HNSCC: From "Junk DNA" to Important Prognostic Factor

Head and neck squamous cell carcinoma is one of the most common and fatal cancers worldwide. Even a multimodal approach consisting of standard chemo- and radiotherapy along with surgical resection is only effective in approximately 50% of the cases. The rest of the patients develop a relapse of the disease and acquire resistance to treatment. Especially this group of individuals needs novel, personalized, targeted therapy. The first step to discovering such solutions is to investigate the tumor microenvironment, thus understanding the role and mechanism of the function of coding and non-coding sequences of the human genome. In recent years, RNA molecules gained great interest when the complex character of their impact on our biology allowed them to come out of the shadows of the "junk DNA" label. Furthermore, long non-coding RNAs (lncRNA), specifically the intergenic subgroup (lincRNA), are one of the most aberrantly expressed in several malignancies, which makes them particularly promising future diagnostic biomarkers and therapeutic targets. This review contains characteristics of known and validated lincRNAs in HNSCC, such as XIST, MALAT, HOTAIR, HOTTIP, lincRNA-p21, LINC02487, LINC02195, LINC00668, LINC00519, LINC00511, LINC00460, LINC00312, and LINC00052, with a description of their prognostic abilities. Even though much work remains to be done, lincRNAs are important factors in cancer biology that will become valuable biomarkers of tumor stage, outcome prognosis, and contribution to personalized medicine.

Biological Function of Long Non-coding RNA (LncRNA) Xist

Long non-coding RNAs (lncRNAs) regulate gene expression in a variety of ways at epigenetic, chromatin remodeling, transcriptional, and translational levels. Accumulating evidence suggests that lncRNA X-inactive specific transcript (lncRNA Xist) serves as an important regulator of cell growth and development. Despites its original roles in X-chromosome dosage compensation, lncRNA Xist also participates in the development of tumor and other human diseases by functioning as a competing endogenous RNA (ceRNA). In this review, we comprehensively summarized recent progress in understanding the cellular functions of lncRNA Xist in mammalian cells and discussed current knowledge regarding the ceRNA network of lncRNA Xist in various diseases. Long non-coding RNAs (lncRNAs) are transcripts that are more than 200 nt in length and without an apparent protein-coding capacity (Furlan and Rougeulle, 2016; Maduro et al., 2016). These RNAs are believed to be transcribed by the approximately 98-99% non-coding regions of the human genome (Derrien et al., 2012; Fu, 2014; Montalbano et al., 2017; Slack and Chinnaiyan, 2019), as well as a large variety of genomic regions, such as exonic, tronic, and intergenic regions. Hence, lncRNAs are also divided into eight categories: Intergenic lncRNAs, Intronic lncRNAs, Enhancer lncRNAs, Promoter lncRNAs, Natural antisense/sense lncRNAs, Small nucleolar RNA-ended lncRNAs (sno-lncRNAs), Bidirectional lncRNAs, and non-poly(A) lncRNAs (Ma et al., 2013; Devaux et al., 2015; St Laurent et al., 2015; Chen, 2016; Quinn and Chang, 2016; Richard and Eichhorn, 2018; Connerty et al., 2020). A range of evidence has suggested that lncRNAs function as key regulators in crucial cellular functions, including proliferation, differentiation, apoptosis, migration, and invasion, by regulating the expression level of target genes via epigenomic, transcriptional, or post-transcriptional approaches (Cao et al., 2018). Moreover, lncRNAs detected in body fluids were also believed to serve as potential biomarkers for the diagnosis, prognosis, and monitoring of disease progression, and act as novel and potential drug targets for therapeutic exploitation in human disease (Jiang W. et al., 2018; Zhou et al., 2019a). Long non-coding RNA X-inactive specific transcript (lncRNA Xist) are a set of 15,000-20,000 nt sequences localized in the X chromosome inactivation center (XIC) of chromosome Xq13.2 (Brown et al., 1992; Debrand et al., 1998; Kay, 1998; Lee et al., 2013; da Rocha and Heard, 2017; Yang Z. et al., 2018; Brockdorff, 2019). Previous studies have indicated that lncRNA Xist regulate X chromosome inactivation (XCI), resulting in the inheritable silencing of one of the X-chromosomes during female cell development. Also, it serves a vital regulatory function in the whole spectrum of human disease (notably cancer) and can be used as a novel diagnostic and prognostic biomarker and as a potential therapeutic target for human disease in the clinic (Liu et al., 2018b; Deng et al., 2019; Dinescu et al., 2019; Mutzel and Schulz, 2020; Patrat et al., 2020; Wang et al., 2020a). In particular, lncRNA Xist have been demonstrated to be involved in the development of multiple types of tumors including brain tumor, Leukemia, lung cancer, breast cancer, and liver cancer, with the prominent examples outlined in Table 1. It was also believed that lncRNA Xist (Chaligne and Heard, 2014; Yang Z. et al., 2018) contributed to other diseases, such as pulmonary fibrosis, inflammation, neuropathic pain, cardiomyocyte hypertrophy, and osteoarthritis chondrocytes, and more specific details can be found in Table 2. This review summarizes the current knowledge on the regulatory mechanisms of lncRNA Xist on both chromosome dosage compensation and pathogenesis (especially cancer) processes, with a focus on the regulatory network of lncRNA Xist in human disease.

Serum RNA Profiling in the 10-Years Period Prior to Diagnosis of Testicular Germ Cell Tumor

Although testicular germ cell tumor (TGCT) overall is highly curable, patients may experience late effects after treatment. An increased understanding of the mechanisms behind the development of TGCT may pave the way for better outcome for patients. To elucidate molecular changes prior to TGCT diagnosis we sequenced small RNAs in serum from 69 patients who were later diagnosed with TGCT and 111 matched controls. The deep RNA profiles, with on average 18 million sequences per sample, comprised of nine classes of RNA, including microRNA. We found that circulating RNA signals differed significantly between cases and controls regardless of time to diagnosis. Different levels of TSIX related to X-chromosome inactivation and TEX101 involved in spermatozoa production are among the interesting findings. The RNA signals differed between seminoma and non-seminoma TGCT subtypes, with seminoma cases showing lower levels of RNAs and non-seminoma cases showing higher levels of RNAs, compared with controls. The differentially expressed RNAs were typically associated with cancer related pathways. Our results indicate that circulating RNA profiles change during TGCT development according to histology and may be useful for early detection of this tumor type.

Decapping enzyme 1A breaks X-chromosome symmetry by controlling Tsix elongation and RNA turnover

How allelic asymmetry is generated remains a major unsolved problem in epigenetics. Here we model the problem using X-chromosome inactivation by developing "BioRBP", an enzymatic RNA-proteomic method that enables probing of low-abundance interactions and an allelic RNA-depletion and -tagging system. We identify messenger RNA-decapping enzyme 1A (DCP1A) as a key regulator of Tsix, a noncoding RNA implicated in allelic choice through X-chromosome pairing. DCP1A controls Tsix half-life and transcription elongation. Depleting DCP1A causes accumulation of X-X pairs and perturbs the transition to monoallelic Tsix expression required for Xist upregulation. While ablating DCP1A causes hyperpairing, forcing Tsix degradation resolves pairing and enables Xist upregulation. We link pairing to allelic partitioning of CCCTC-binding factor (CTCF) and show that tethering DCP1A to one Tsix allele is sufficient to drive monoallelic Xist expression. Thus, DCP1A flips a bistable switch for the mutually exclusive determination of active and inactive Xs.

Dysregulation in the expression of (lncRNA-TSIX, TP53INP2 mRNA, miRNA-1283) in spinal cord injury

AIM

The objective of this study is to examine the alterations in the levels of expression of serum lncRNA-TSIX, TP53INP2 mRNA, miRNA-1283 in spinal cord injured (SCI) patients versus healthy control.

METHOD

The expression of the selected RNAs in the sera was determined in 23 patients suffering from acute spinal cord injury, 41 individuals with chronic spinal cord injury, and 36 healthy control using real-time reverse-transcription polymerase chain reaction method.

RESULTS

The results showed that lncRNA-TSIX and the TP53INP2 mRNA expression levels in SCI patients was overexpressed in comparison to the control group alongside with a significant downregulation of miR-1283. Statistically,there was a highly significant positive correlation between lnc-RNA-TRIX and TP53INP2 mRNA with inverse correlation between miRNA-1283 and lnc-RNA-TRIX based on fold changes.

CONCLUSION

Up-regulation of lncRNA-TSIX, TP53INP2 mRNA with downregulation of miRNA-1283 might be closely associated with progression of SCI.

Generating primed pluripotent epiblast stem cells: A methodology chapter

At least two distinct pluripotent states, referred to as naïve and primed, define the early mammalian embryo. In the mouse, the pluripotent epiblast cells in the pre/peri-implantation embryo are the source of naïve embryonic stem cells (ESCs). After the embryo implants, the epiblast lineage generates a restricted or primed population of stem cells, referred to as epiblast stem cells (EpiSCs). ESCs can be cultured in EpiSC media to generate epiblast-like cells (EpiLCs). The differentiation of naive ESCs into primed EpiLCs permits insights into the development and differentiation of the pluripotent epiblast lineage. This chapter describes the generation and characterization of EpiSCs as well as EpiLCs.

XIST and TSIX: Novel Cancer Immune Biomarkers in PD-L1-Overexpressing Breast Cancer Patients

Escaping antitumor immunity is a hallmark in cancer progression. Programmed cell death protein 1 (PD-1) is an immune checkpoint receptor responsible for the maintenance of immune tolerance; PD-1 ligand (PD-L1) is overexpressed in tumor cells, simplifying their escape from the immune system through T-cell function suppression. Notwithstanding that cancer antigen (CA)125, carcinoembryonic antigen (CEA), CA15-3, and alpha-fetoprotein (AFP) are among conventional breast cancer diagnostic biomarkers, their lack of sensitivity and specificity resides among their major limitations. Furthermore, human epidermal growth factor receptor (HER)2 and interleukin (IL)-6-demonstrated as breast cancer immune biomarkers-still possess limitations, for instance, technical detection problems and stability problems, which necessitate the discovery of novel, stable non-invasive cancer immune biomarkers. XIST and TSIX are two long non-coding (lnc)RNAs possessing a role in X chromosome inactivation (XCI) as well as in breast cancer (BC). In the present study, they were investigated as stable non-invasive breast cancer immune biomarkers. The study demonstrated that PD-L1 was overexpressed in the different molecular subtypes of breast cancer patients as well as in MDA-MB-231 cells. Furthermore, lncRNAs XIST and TSIX were markedly increased in the tissues, lymph nodes, and different body fluids of breast cancer patients compared to controls. In addition, XIST and TSIX were differentially expressed in subtypes of BC patients, and their levels were correlated to PD-L1 expression level. In conclusion, this correlative study has shed light on the role of both lncRNAs XIST and TSIX as potential non-invasive BC immune biomarkers reflecting the evaded immune system of the patient and overcoming the instability problem of common BC biomarkers.

Ligand dependent gene regulation by transient ERα clustered enhancers

Unliganded Estrogen receptor alpha (ERα) has been implicated in ligand-dependent gene regulation. Upon ligand exposure, ERα binds to several EREs relatively proximal to the pre-marked, unliganded ERα-bound sites and affects transient but robust gene expression. However, the underlying mechanisms are not fully understood. Here we demonstrate that upon ligand stimulation, persistent sites interact extensively, via chromatin looping, with the proximal transiently ERα-bound sites, forming Ligand Dependent ERα Enhancer Cluster in 3D (LDEC). The E2-target genes are regulated by these clustered enhancers but not by the H3K27Ac super-enhancers. Further, CRISPR-based deletion of TFF1 persistent site disrupts the formation of its LDEC resulting in the loss of E2-dependent expression of TFF1 and its neighboring genes within the same TAD. The LDEC overlap with nuclear ERα condensates that coalesce in a ligand and persistent site dependent manner. Furthermore, formation of clustered enhancers, as well as condensates, coincide with the active phase of signaling and their later disappearance results in the loss of gene expression even though persistent sites remain bound by ERα. Our results establish, at TFF1 and NRIP1 locus, a direct link between ERα condensates, ERα enhancer clusters, and transient, but robust, gene expression in a ligand-dependent fashion.

LncRNA RHPN1-AS1 Targeting miR-625/REG3A Promotes Cell Proliferation And Invasion Of Glioma Cells

Introduction

Glioma arises from the proliferation of neuroglial cells differentiated from the ectoderm. Evidence has confirmed that differentially expressed long non-coding RNAs (lncRNAs) may be involved in the development and progression of various tumors. The present study aimed to explore the biological function of lncRNA RHPN1-AS1 in glioma.

Materials and methods

The expressions of RHPN1-AS1 in glioma tissues and cells were examined using RT-PCR. Colony formation assay, MTT assay, wound healing assay and transwell assay were performed to detect cell cloning efficiency, proliferation, migration and invasion of glioma cells, respectively. Western blot was applied to assess the expression levels of migration-related and invasion-related proteins. Online bioinformatic tools and luciferase reporter assay were, respectively, employed to predict and verify the downstream target microRNA/gene of RHPN1-AS1.

Results

RHPN1-AS1 was up-regulated in glioma tissues and cells. The cell proliferation, migration and invasion of glioma were inhibited when the expression of RHPN1-AS1 was down-regulated in glioma cells. The expressions of migration-related and invasion-related proteins were also suppressed in siRHPN1-AS1 groups. Furthermore, we predicted and verified that RHPN1-AS1 was directly targeted to miR-625-5p/REG3A. Our study demonstrated that the knockdown of RHPN1-AS1 inhibited the proliferation, migration and invasion activity of glioma cells via regulating miR-625-5p/REG3A expression.

Conclusion

The results revealed that the lncRNA RHPN1-AS1 may be a molecular target in glioma therapy.

Potential role of lncRNA-TSIX, miR-548-a-3p, and SOGA1 mRNA in the diagnosis of hepatocellular carcinoma

Recent trends are moving towards the use of the circulating transcriptome as a potential diagnostic and therapeutic tool for hepatocellular carcinoma (HCC). The aim of this study is to identify circulatory RNA based biomarker panel, in addition to their relationship to the outcome in HCC. First, utilizing bioinformatics tools, we selected an HCC-specific RNA-based biomarker panel that depended on the integration of suppressor of glucose autophagy-associated (SOGA1) gene expression with the chosen panel of epigenetic regulators of this gene [long non-coding RNA antisense for X-inactive-specific transcript (lncRNA-TSIX) and microRNA-548-a-3p (miR-548-a-3p)]. Second, we attempted to validate these biomarkers using the sera of 65 patients with HCC, 34 patients with chronic hepatitis C virus (CHC) infection and 32 healthy volunteers. Finally, the expression levels of the chosen RNA-based biomarker panel were assessed in the serum samples using qRT-PCR assays. The panel of 3 RNA-based biomarkers (lncRNA-TSIX, miR-548-a-3p, and SOGA1) exhibited high sensitivity and specificity in differentiating HCC patients from CHC patients and healthy controls. Among these 3 RNAs, serum lncRNA-TSIX and SOGA1 were independent prognostic factor. The chosen circulatory RNA-based biomarker panel may serve as a diagnostic and prognostic biomarker for HCC.

Long non‑coding RNA CASC2 enhances berberine‑induced cytotoxicity in colorectal cancer cells by silencing BCL2

Berberine, a natural isoquinoline alkaloid derived from Berberis species, has been reported to have anticancer effects. However, the mechanisms of action in human colorectal cancer (CRC) are not well established to date. In the present study, the cell cytotoxicity effect of berberine on human CRC cells, as well as the possible mechanisms involved, was investigated. The results of the cell viability and apoptosis assay revealed that treatment of CRC cells with berberine resulted in inhibition of cell viability and activation of cell apoptosis in a concentration-dependent manner. To reveal the underlying mechanism of berberine-induced anti-tumor activity and cell apoptosis, RNA-sequencing followed by reverse-transcription quantitative PCR were performed. In addition, RNA immunoprecipitation, chromatin immunoprecipitation and western blot analysis were used to identify the functional regulation of CASC2/EZH2/BCL2 axis in berberine-induced CRC cell apoptosis. The data revealed that lncRNA CASC2 was upregulated by berberine treatment. Gain- or loss-of-function assays suggested that lncRNA CASC2 was required for the berberine-induced inhibition of cell viability and activation of cell apoptosis. Subsequently, the downstream antiapoptotic gene BCL2 was identified as a functional target of the berberine/CASC2 mechanism, as BCL2 reversed the berberine/CASC2-induced cell cytotoxicity. lncRNA CASC2 silenced BCL2 expression by binding to the promoter region of BCL2 in an EZH2-dependent manner. In summary, berberine may be a novel therapeutic agent for CRC and lncRNA CASC2 may serve as an important therapeutic target to improve the anticancer effect of berberine.

Sex-Biased lncRNAs Inversely Correlate With Sex-Opposite Gene Coexpression Networks in Diversity Outbred Mouse Liver

Sex differences in liver gene expression are determined by pituitary growth hormone secretion patterns, which regulate sex-dependent liver transcription factors and establish sex-specific chromatin states. Hypophysectomy (hypox) identifies two major classes of liver sex-biased genes, defined by their sex-dependent positive or negative responses to pituitary hormone ablation. However, the mechanisms that underlie each hypox-response class are unknown. We sought to discover candidate, regulatory, long noncoding RNAs (lncRNAs) controlling responsiveness to hypox. We characterized gene structures and expression patterns for 15,558 mouse liver-expressed lncRNAs, including many sex-specific lncRNAs regulated during postnatal development or subject to circadian regulation. Using the high natural allelic variance of Diversity Outbred (DO) mice, we discovered tightly coexpressed clusters of sex-specific protein-coding genes (gene modules) in male and female DO liver. Remarkably, many gene modules were strongly enriched for sex-specific genes within a single hypox-response class, indicating that the genetic heterogeneity of DO mice encompasses responsiveness to hypox. Moreover, several distant gene modules were enriched for gene subsets of the same hypox-response class, highlighting the complex regulation of hypox-responsiveness. Finally, we identified eight sex-specific lncRNAs with strong negative regulatory potential, as indicated by their strong negative correlation of expression across DO mouse livers with that of protein-coding gene modules enriched for genes of the opposite sex bias and inverse hypox-response class. These findings reveal an important role for genetic factors in regulating responsiveness to hypox, and present testable hypotheses for the roles of sex-biased liver lncRNAs in controlling the sex-bias of liver gene expression.

P-TEFb Regulates Transcriptional Activation in Non-coding RNA Genes

Many non-coding RNAs (ncRNAs) serve as regulatory molecules in various physiological pathways, including gene expression in mammalian cells. Distinct from protein-coding RNA expression, ncRNA expression is regulated solely by transcription and RNA processing/stability. It is thus important to understand transcriptional regulation in ncRNA genes but is yet to be known completely. Previously, we identified that a subset of mammalian ncRNA genes is transcriptionally regulated by RNA polymerase II (Pol II) promoter-proximal pausing and in a tissue-specific manner. In this study, human ncRNA genes that are expressed in the early G₁ phase, termed immediate early ncRNA genes, were monitored to assess the function of positive transcription elongation factor b (P-TEFb), a master Pol II pausing regulator for protein-coding genes, in ncRNA transcription. Our findings indicate that the expression of many ncRNA genes is induced in the G₀–G₁ transition and regulated by P-TEFb. Interestingly, a biphasic characteristic of P-TEFb-dependent transcription of serum responsive ncRNA genes was observed: Pol II carboxyl-terminal domain phosphorylated at serine 2 (S2) was largely increased in the transcription start site (TSS, -300 to +300) whereas overall, it was decreased in the gene body (GB, > +350) upon chemical inhibition of P-TEFb. In addition, the three representative, immediate early ncRNAs, whose expression is dependent on P-TEFb, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), nuclear enriched abundant transcript 1 (NEAT1), and X-inactive specific transcript (XIST), were further analyzed for determining P-TEFb association. Taken together, our data suggest that transcriptional activation of many human ncRNAs utilizes the pausing and releasing of Pol II, and that the regulatory mechanism of transcriptional elongation in these genes requires the function of P-TEFb. Furthermore, we propose that ncRNA and mRNA transcription are regulated by similar mechanisms while P-TEFb inhibition unexpectedly increases S2 Pol II phosphorylation in the TSSs in many ncRNA genes.

One Sentence Summary: P-TEFb regulates Pol II phosphorylation for transcriptional activation in many stimulus-inducible ncRNA genes.

Being in a loop: how long non-coding RNAs organise genome architecture

Chromatin architecture has a significant impact on gene expression. Evidence in the last two decades support RNA as an important component of chromatin structure [Genes Dev. (2005) 19, 1635–1655; PLoS ONE (2007) 2, e1182; Nat. Genet. (2002) 30, 329–334]. Long non-coding RNAs (lncRNAs) are able to control chromatin structure through nucleosome positioning, interaction with chromatin re-modellers and chromosome looping. These functions are carried out in cis at the site of lncRNAs transcription or in trans at distant loci. While the evidence for a role in lncRNAs in regulating gene expression through chromatin interactions is increasing, there is still very little conclusive evidence for a potential role in looping organisation. Here, we review models for the involvement of lncRNAs in genome architecture and the experimental evidence to support them.

Conversion of random X-inactivation to imprinted X-inactivation by maternal PRC2

Imprinted X-inactivation silences genes exclusively on the paternally-inherited X-chromosome and is a paradigm of transgenerational epigenetic inheritance in mammals. Here, we test the role of maternal vs. zygotic Polycomb repressive complex 2 (PRC2) protein EED in orchestrating imprinted X-inactivation in mouse embryos. In maternal-null (Eedm-/-) but not zygotic-null (Eed-/-) early embryos, the maternal X-chromosome ectopically induced Xist and underwent inactivation. Eedm-/- females subsequently stochastically silenced Xist from one of the two X-chromosomes and displayed random X-inactivation. This effect was exacerbated in embryos lacking both maternal and zygotic EED (Eedmz-/-), suggesting that zygotic EED can also contribute to the onset of imprinted X-inactivation. Xist expression dynamics in Eedm-/- embryos resemble that of early human embryos, which lack oocyte-derived maternal PRC2 and only undergo random X-inactivation. Thus, expression of PRC2 in the oocyte and transmission of the gene products to the embryo may dictate the occurrence of imprinted X-inactivation in mammals.

Full high-throughput sequencing analysis of differences in expression profiles of long noncoding RNAs and their mechanisms of action in systemic lupus erythematosus

Background

The specific function of long noncoding RNAs (lncRNAs) in systemic lupus erythematosus (SLE) and the mechanism of their involvement in related pathological changes remain to be elucidated, so, in this study, we analyzed the differences in the expression profiles of lncRNAs and their mechanisms of action in SLE using full high-throughput sequencing, bioinformatics, etc. methods.

Methods

We used high-throughput sequencing to detect differences in the expression profiles of lncRNAs, miRNAs, and mRNAs in PBMCs from patients with SLE at the genome-wide level. Next, we predicted target genes of 30 lincRNAs (long intergenic noncoding RNAs) by constructing a coexpression network of differential lincRNAs and mRNAs and identified the role of lincRNAs. Then, we analyzed the coexpression network of 23 optimized lincRNAs and their corresponding 353 miRNAs, evaluated the cis- and trans-effects of these lincRNAs, and performed GO and KEGG analyses of target genes. We also selected 8 lincRNAs and 2 newly discovered lncRNAs for q-PCR validation and lncRNA–miRNA–mRNA analysis. Finally, we also analyzed respectively the relation between lncRNAs and gender bias in SLE patients using RT-qPCR, the relation between Systemic Lupus Erythematosus Disease Activity Index score and the “IFN signature” using ELISA, and the relation between the differential expression of lncRNAs and a change in the number of a cell type of PBMCs in SLE patients using RT-qPCR.

Results

The profiles of 1087 lncRNAs, 102 miRNAs, and 4101 mRNAs in PBMCs significantly differed between patients with SLE and healthy controls. The coexpression network analysis showed that the network contained 23 lincRNAs and 353 mRNAs. The evaluation of the cis- and trans-effects showed that the 23 lincRNAs acted on 704 target genes. GO and KEGG analyses of the target genes predicted the biological functions of the 23 lincRNAs. q-PCR validation showed 7 lincRNAs and 2 novel lncRNAs were identical to the sequencing results. The ceRNA network contained 7 validated lincRNAs, 15 miRNAs, and 155 mRNAs. In addition, the differential expression of lncRNAs may be gender dependent in SLE patients, SLE patients also exhibit a robust “IFN signature,” and PBMCs exhibiting differential expression of lncRNAs may be due to a change in the number of a cell type.

Conclusion

This work determined specific lncRNAs that play important biological functions in the pathogenesis of lupus and provided a new direction for diagnosis and treatment of disease.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1853-7) contains supplementary material, which is available to authorized users.

Exosomal FMR1-AS1 facilitates maintaining cancer stem-like cell dynamic equilibrium via TLR7/NFκB/c-Myc signaling in female esophageal carcinoma

Background

Though esophageal cancer is three to four times more common among males than females worldwide, this type of cancer still ranks in the top incidence among women, even more than the female specific cancer types. The occurrence is currently attributed to extrinsic factors, including tobacco use and alcohol consumption. However, limited attention has been given to gender-specific intrinsic genetic factors, especially in female.

Methods

We re-annotated a large cohort of microarrays on 179 ESCC patients and identified female-specific differently expressed lncRNAs. The associations between FMR1-AS1 and the risk and prognosis of ESCC were examined in 206 diagnosed patients from eastern China and validated in 188 additional patients from southern China. The effects of FMR1-AS1 on the malignant phenotypes on female ESCC cells were detected in vitro and in vivo. ChIRP-MS, reporter gene assays and EMSA were conducted to identify the interaction and regulation among FMR1-AS1, TLR7 and NFκB.

Results

We found FMR1-AS1 expression is exclusively altered and closely associated with the level of sXCI in female ESCC patients, and its overexpression may correlate to poor clinical outcome. ChIRP-MS data indicate that FMR1-AS1 could be packaged into exosomes and released into tumor microenvironment. Functional studies demonstrated that FMR1-AS1 could bind to endosomal toll-like receptor 7 (TLR7) and activate downstream TLR7-NFκB signaling, promoting the c-Myc expression, thus inducing ESCC cell proliferation, anti-apoptosis and invasion ability. Exosome incubation and co-xenograft assay indicate that FMR1-AS1 exosomes may secreted from ESCC CSCs, transferring stemness phenotypes to recipient non-CSCs in tumor microenvironment. Furthermore, we also found a correlation between the serum levels of FMR1-AS1 and the overall survival (OS) of the female ESCC patients.

Conclusions

Our results highlighted exosomal FMR1-AS1 in maintaining CSC dynamic interconversion state through the mechanism of activating TLR7-NFκB signaling, upregulating c-Myc level in recipient cells, which may be taken as an attractive target approach for advancing current precision cancer therapeutics in female patients.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-0949-7) contains supplementary material, which is available to authorized users.

lncRNA H19 promotes viability and epithelial-mesenchymal transition of lung adenocarcinoma cells by targeting miR-29b-3p and modifying STAT3

Considering the joint contribution of long non‑coding RNAs (lncRNAs) and microRNAs (miRNAs/miRs) to tumorigenesis, the aim of the present study was to investigate whether and how lncRNA H19 targets miR‑29b‑3p to affect the progression of lung adenocarcinoma by the modulation of signal transducer and activator of transcription 3 (STAT3). A total of 305 lung adenocarcinoma tissues and four human lung adenocarcinoma cell lines (i.e. Calu‑3, NCI‑H1975, A549 and NCI‑H23) were used. pcDNA3.1‑H19, short interfering RNA (si‑)H19, miR‑29b‑3p mimic, miR‑29b‑3p inhibitor and negative control (NC) were transfected into the cells, and the proliferation, viability and apoptosis of the cells were determined using a Cell Counting Kit‑8 assay, colony formation assay and flow cytometry, respectively. The results indicated that highly expressed H19 and poorly expressed miR‑29b‑3p could serve as predictors for the poor prognosis of lung adenocarcinoma patients. Additionally, si‑H19 and miR‑29b‑3p mimic significantly increased the apoptosis of lung adenocarcinoma cells, and decreased the survival rate and viability of cells. Simultaneously, expression of epithelial‑mesenchymal transition (EMT)‑specific proteins was significantly altered, i.e. increased epithelial cadherin expression, as well as decreased vimentin, Snail and Slug expression. Furthermore, miR‑29b‑3p was verified to be targeted and regulated by H19, and STAT3 was targeted and modified by miR‑29b‑3p. Ultimately, STAT3 was identified to decrease lung adenocarcinoma cell viability, survival, apoptosis and EMT imposed by miR‑29b‑3p. In conclusion, the results of the present study indicated that lncRNA H19/miR‑29b‑3p/STAT3 signaling was involved in the development of lung adenocarcinoma, which may be critical for developing effective diagnostic and treatment strategies for lung adenocarcinoma.

LncRNA XIST facilitates proliferation and epithelial-mesenchymal transition of colorectal cancer cells through targeting miR-486-5p and promoting neuropilin-2

This study was designed to acertain whether the long noncoding RNA (lncRNA) X-inactive specific transcript (XIST)/miR-486-5p/neuropilin-2 (NRP-2) pathway might promote the viability and epithelial-mesenchymal transition (EMT) of colorectal cancer (CRC) cells. In this investigation, we included 317 pathologically confirmed CRC patients and purchased several human CRC cells (i.e. HCT116, HT29, SW620, and SW480). Moreover, pcDNA3.1-XIST, si-XIST, miR-486-5p mimic, miR-486-5p inhibitor, and pcDNA3.1-NRP-2 were transfected into the CRC cells. And the dual-luciferase reporter gene assay managed to verify the targeted relationships among XIST, miR-486-5p, and NRP-2. Ultimately, the MTT assay, flow cytometry, colony formation assay, and transwell assay were carried out to assess the influence of XIST, miR-486-5p, and NRP-2 on the proliferation, apoptosis, migration, and invasion of CRC cells. Our study results demonstrated that CRC tissues and cells were detected with significantly elevated XIST and NRP-2 expressions as well as markedly reduced miR-486-5p expression when compared with normal tissues and cells (all p < 0.05). Besides this, the highly expressed XIST and NRP-2, as well as the lowly expressed miR-486-5p all could substantially encourage proliferation and EMT of CRC cells and simultaneously restrict apoptosis of the cells ( p < 0.05). Moreover, XIST was found to directly target miR-486-5p, and NRP-2 was directly targeted and modulated by miR-486-5p. Finally, CRC cells of the miR-NC + pcDNA3.1-NRP-2 groups showed stronger proliferation, viability, and EMT than those of miR-NC and miR-486-5p mimic groups ( p < 0.05). In conclusion, the XIST/miR-486 -5p/NRP-2 axis appeared to participate in the progression of CRC, which could assist in developing efficacious therapies for CRC.

Multiple Linear Regression Analysis of lncRNA-Disease Association Prediction Based on Clinical Prognosis Data

Long noncoding RNAs (lncRNAs) have an important role in various life processes of the body, especially cancer. The analysis of disease prognosis is ignored in current prediction on lncRNA-disease associations. In this study, a multiple linear regression model was constructed for lncRNA-disease association prediction based on clinical prognosis data (MlrLDAcp), which integrated the cancer data of clinical prognosis and the expression quantity of lncRNA transcript. MlrLDAcp could realize not only cancer survival prediction but also lncRNA-disease association prediction. Ultimately, 60 lncRNAs most closely related to prostate cancer survival were selected from 481 alternative lncRNAs. Then, the multiple linear regression relationship between the prognosis survival of 176 patients with prostate cancer and 60 lncRNAs was also given. Compared with previous studies, MlrLDAcp had a predominant survival predictive ability and could effectively predict lncRNA-disease associations. MlrLDAcp had an area under the curve (AUC) value of 0.875 for survival prediction and an AUC value of 0.872 for lncRNA-disease association prediction. It could be an effective biological method for biomedical research.

Megadomains and superloops form dynamically but are dispensable for X-chromosome inactivation and gene escape

The mammalian inactive X-chromosome (Xi) is structurally distinct from all other chromosomes and serves as a model for how the 3D genome is organized. The Xi shows weakened topologically associated domains and is instead organized into megadomains and superloops directed by the noncoding loci, Dxz4 and Firre. Their functional significance is presently unclear, though one study suggests that they permit Xi genes to escape silencing. Here, we find that megadomains do not precede Xist expression or Xi gene silencing. Deleting Dxz4 disrupts the sharp megadomain border, whereas deleting Firre weakens intra-megadomain interactions. However, deleting Dxz4 and/or Firre has no impact on Xi silencing and gene escape. Nor does it affect Xi nuclear localization, stability, or H3K27 methylation. Additionally, ectopic integration of Dxz4 and Xist is not sufficient to form megadomains on autosomes. We conclude that Dxz4 and megadomains are dispensable for Xi silencing and escape from X-inactivation.

The mammalian inactive X-chromosome (Xi) is organized into megadomains and superloops directed by the noncoding loci, Dxz4 and Firre. Here the authors provide evidence that megadomains do not precede Xist expression or Xi gene silencing, and suggest that Dxz4, Firre, and megadomains are dispensable for Xi silencing and escape from X-inactivation.

Long noncoding RNAs in autoimmune diseases

With the completion of the human genome project and further development of high-throughput genomic technologies, interest in long noncoding RNAs (lncRNAs), which are defined as non-protein-coding RNAs at least 200 nucleotides in length, has strongly increased, and lncRNAs have become a major research direction. Increasing evidence demonstrates that lncRNAs are closely related to human growth and development and to disease occurrence via various mechanisms. lncRNAs also play crucial roles in the differentiation and activation of immune cells, and their relationships with human autoimmune diseases have received increasing attention. The development of biotechnology has led to the gradual discovery of many potential lncRNA functions. In this review, we discuss various lncRNAs that have been implicated in different human autoimmune diseases, focusing on their clinical applications as potential biomarkers and therapeutic targets in the pathologies of diverse human autoimmune diseases. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 468-475, 2019.

Long noncoding RNA expression profile and association with SLEDAI score in monocyte-derived dendritic cells from patients with systematic lupus erythematosus

BACKGROUND

Monocyte-derived dendritic cells (moDCs) play important roles in the pathogenesis of systemic lupus erythematosus (SLE). Aberrant expression of long noncoding RNAs (lncRNAs) could affect the function of moDCs. The aim of this study was to explore the lncRNA expression profile in moDCs of SLE patients to provide new insights into SLE.

METHODS

LncRNA and mRNA microarrays were performed to identify differentially expressed lncRNAs and mRNAs in moDCs of SLE patients compared with normal controls. Bioinformatics analysis was also performed. Quantitative polymerase chain reaction (qPCR) was used to validate the results, and correlation analysis was used to analyze the relationship between these aberrantly expressed lncRNAs and SLE disease activity index (SLEDAI) scores.

RESULTS

According to the gene expression profiles, 163 lncRNAs were differentially expressed between SLE and normal controls, including 118 that were upregulated and 45 that were downregulated. A total of 137 mRNAs were differentially expressed in moDCs of patients with SLE, including 83 that were upregulated and 54 that were downregulated. Furthermore, qPCR data showed that lncRNA ENST00000604411.1 (18.23-fold, P < 0.001) and ENST00000501122.2 (1.96-fold, P < 0.001) were upregulated and the other two lncRNAs, lnc-HSFY2-3:3 (0.42-fold, P < 0.001) and lnc-SERPINB9-1:2 (0.50-fold, P = 0.040), were downregulated in moDCs of SLE patients. The expression levels of ENST00000604411.1 (r = 0.593, P = 0.020) and ENST00000501122.2 (r = 0.539, P = 0.038) were positively correlated with the SLEDAI score, respectively.

CONCLUSIONS

The results indicate that the abnormal expression of lncRNAs in moDCs may be involved in the pathological processes of SLE. The expression level of ENST00000604411.1 and ENST00000501122.2 may have potential value for the assessment of disease activity in SLE.

Increased expression of antisense lncRNA SPINT1-AS1 predicts a poor prognosis in colorectal cancer and is negatively correlated with its sense transcript

Purpose

Colorectal cancer (CRC) is a leading cause of cancer-associated mortality worldwide. Natural antisense transcripts (NATs) are pervasively expressed in human genome and have been confirmed to contribute to cancer progression. In our study, we aimed to investigate the expression and clinical pertinence of serine peptidase inhibitor, Kunitz type 1 antisense RNA1 (SPINT1-AS1) in CRC.

Materials and methods

The expression levels of SPINT1-AS1 and the corresponding sense transcript SPINT1 mRNA were analyzed in 150 pairs of CRC tissues and adjacent normal (AN) tissues, along with 45 pairs of preoperative and postoperative serum exosome samples by the strand-specific real-time quantitative polymerase chain reaction.

Results

Compared with AN tissues, the expression of SPINT1-AS1 was increased (P<0.001, 3.771 vs 0.980) in CRC tissues, while SPINT1 mRNA expression was decreased in CRC (P<0.001, 0.927 vs 1.165), and there was an obviously negative correlation between SPINT1-AS1 expression and its sense transcript (r=-0.701, P<0.001). SPINT1-AS1 yielded an area under the receiver operating characteristic curve value of 0.865 (95% confidence interval, 0.821-0.902) for discriminating CRC tissues from AN tissues. Moreover, high SPINT1-AS1 expression was correlated with regional lymph node metastasis (P<0.001), distant metastasis (P<0.001), and shorter relapse-free survival (RFS) time (P<0.001), and Cox regression analysis indicated that SPINT1-AS1 was an independent prognostic factor for RFS. Meanwhile, significant reduction of SPINT1-AS1 expression level (P=0.001) was observed in CRC serum exosomes after surgical resection.

Conclusion

SPINT1-AS1 is upregulated in CRC tissues and plays an essential role in CRC progression and prognosis. Thereby, SPINT1-AS1 may serve as a candidate prognostic biomarker and molecular therapy target for CRC.

The Role of Xist in X-Chromosome Dosage Compensation

In each somatic cell of a female mammal one X chromosome is transcriptionally silenced via X-chromosome inactivation (XCI), initiating early in development. Although XCI events are conserved in mouse and human postimplantation development, regulation of X-chromosome dosage in preimplantation development occurs differently. In preimplantation development, mouse embryos undergo imprinted form of XCI, yet humans lack imprinted XCI and instead regulate gene expression of both X chromosomes by dampening transcription. The long non-coding RNA Xist/XIST is expressed in mouse and human preimplantation and postimplantation development to orchestrate XCI, but its role in dampening is unclear. In this review, we discuss recent advances in our understanding of the role of Xist in X chromosome dosage compensation in mouse and human.

Regulation of X-chromosome dosage compensation in human: mechanisms and model systems

The human blastocyst forms 5 days after one of the smallest human cells (the sperm) fertilizes one of the largest human cells (the egg). Depending on the sex-chromosome contribution from the sperm, the resulting embryo will either be female, with two X chromosomes (XX), or male, with an X and a Y chromosome (XY). In early development, one of the major differences between XX female and XY male embryos is the conserved process of X-chromosome inactivation (XCI), which compensates gene expression of the two female X chromosomes to match the dosage of the single X chromosome of males. Most of our understanding of the pre-XCI state and XCI establishment is based on mouse studies, but recent evidence from human pre-implantation embryo research suggests that many of the molecular steps defined in the mouse are not conserved in human. Here, we will discuss recent advances in understanding the control of X-chromosome dosage compensation in early human embryonic development and compare it to that of the mouse.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.

Long noncoding RNA TUG1 facilitates osteogenic differentiation of periodontal ligament stem cells via interacting with Lin28A

Periodontal ligament stem cells (PDLSCs) are mesenchymal stem cells derived from dental tissues with multidirectional differentiation potential and excellent self-renewing ability. Recently, long noncoding RNAs (lncRNAs) have been shown to play important roles in MSC osteogenic differentiation. In this study, we found that taurine upregulated gene 1 (TUG1), an evolutionarily conserved and widely present lncRNA was significantly upregulated in osteogenically induced PDLSCs compared to their undifferentiated counterparts. Further investigation demonstrated that the expression of TUG1 was positively correlated with the osteogenic differentiation of PDLSCs following the induction, as evidenced by the increase in cellular alkaline phosphatase (ALP) level, formation of calcium nodules, and the upregulation of several osteogenic-related gene markers such as ALP, osteocalcin (OCN), and runt-related transcription factor 2 (Runx2). Conversely, TUG1 knockdown was demonstrated to inhibit the potential of PDLSCs for osteogenic differentiation. Using bioinformatics analysis, we identified lin-28 homolog A (Lin28A) as a potential target of TUG1 during osteogenic differentiation of PDLSCs. Lin28A was found to be significantly downregulated in TUG1-repressed PDLSCs and contained multiple binding sites for lncRNA TUG1. Moreover, suppression of Lin28A was shown to be able to inhibit osteogenic differentiation and decreased the expression of several osteogenic genes. Taken together, these results could help researchers better understand the mechanism that governs the osteogenic differentiation of PDLSCs, and also serve as a stepping stone for the development of novel therapeutic strategies that can be used to regenerate dental tissues.

Besides Pathology: Long Non-Coding RNA in Cell and Tissue Homeostasis

A significant proportion of mammalian genomes corresponds to genes that transcribe long non-coding RNAs (lncRNAs). Throughout the last decade, the number of studies concerning the roles played by lncRNAs in different biological processes has increased considerably. This intense interest in lncRNAs has produced a major shift in our understanding of gene and genome regulation and structure. It became apparent that lncRNAs regulate gene expression through several mechanisms. These RNAs function as transcriptional or post-transcriptional regulators through binding to histone-modifying complexes, to DNA, to transcription factors and other DNA binding proteins, to RNA polymerase II, to mRNA, or through the modulation of microRNA or enzyme function. Often, the lncRNA transcription itself rather than the lncRNA product appears to be regulatory. In this review, we highlight studies identifying lncRNAs in the homeostasis of various cell and tissue types or demonstrating their effects in the expression of protein-coding or other non-coding RNA genes.

Experimental Analysis of Imprinted Mouse X-Chromosome Inactivation

X-chromosome inactivation is a dosage compensation mechanism that equalizes X-linked gene expression between male and female mammals through the transcriptional silencing of most genes on one of the two X-chromosomes in females. With a few key exceptions, once the X-chromosome is inactivated replicated copies of that X-chromosome are maintained as inactive in all descendant cells. X-inactivation is therefore a paradigm of epigenetic inheritance. Imprinted X-inactivation is a specialized form of X-inactivation that results in the silencing of the paternally derived X-chromosome. Due to its parent-of-origin-specific pattern of inactivation, imprinted X-inactivation is a model of mitotic as well as meiotic, i.e., transgenerational, epigenetic inheritance. All cells of the early mouse embryo undergo imprinted X-inactivation, a pattern that is subsequently maintained in extraembryonic cell types in vivo and in vitro. Here, we describe both high- and low-throughput approaches to interrogate imprinted X-inactivation in the mouse embryo as well in cultured extraembryonic stem cells.