Non-coding RNA Neat1 and Abhd11os expressions are dysregulated in medium spiny neurons of Huntington disease model mice

Huntingtin is an RNA binding protein and participates in NEAT1-mediated paraspeckles

Huntingtin protein, mutated in Huntington's disease, is implicated in nucleic acid-mediated processes, yet the evidence for direct huntingtin-nucleic acid interaction is limited. Here, we show wild-type and mutant huntingtin copurify with nucleic acids, primarily RNA, and interact directly with G-rich RNAs in in vitro assays. Huntingtin RNA-immunoprecipitation sequencing from patient-derived fibroblasts and neuronal progenitor cells expressing wild-type and mutant huntingtin revealed long noncoding RNA NEAT1 as a significantly enriched transcript. Altered NEAT1 levels were evident in Huntington's disease cells and postmortem brain tissues, and huntingtin knockdown decreased NEAT1 levels. Huntingtin colocalized with NEAT1 in paraspeckles, and we identified a high-affinity RNA motif preferred by huntingtin. This study highlights NEAT1 as a huntingtin interactor, demonstrating huntingtin's involvement in RNA-mediated functions and paraspeckle regulation.

Unraveling astrocyte behavior in the space brain: Radiation response of primary astrocytes

Introduction

Exposure to space conditions during crewed long-term exploration missions can cause several health risks for astronauts. Space radiation, isolation and microgravity are major limiting factors. The role of astrocytes in cognitive disturbances by space radiation is unknown. Astrocytes' response toward low linear energy transfer (LET) X-rays and high-LET carbon (12C) and iron (56Fe) ions was compared to reveal possible effects of space-relevant high-LET radiation. Since astronauts are exposed to ionizing radiation and microgravity during space missions, the effect of simulated microgravity on DNA damage induction and repair was investigated.

Methods

Primary murine cortical astrocytes were irradiated with different doses of X-rays, 12C and 56Fe ions at the heavy ion accelerator GSI. DNA damage and repair (γH2AX, 53BP1), cell proliferation (Ki-67), astrocytes' reactivity (GFAP) and NF-κB pathway activation (p65) were analyzed by immunofluorescence microscopy. Cell cycle progression was investigated by flow cytometry of DNA content. Gene expression changes after exposure to X- rays were investigated by mRNA-sequencing. RT-qPCR for several genes of interest was performed with RNA from X-rays- and heavy-ion-irradiated astrocytes: Cdkn1a, Cdkn2a, Gfap, Tnf, Il1β, Il6, and Tgfβ1. Levels of the pro inflammatory cytokine IL-6 were determined using ELISA. DNA damage response was investigated after exposure to X-rays followed by incubation on a 2D clinostat to simulate the conditions of microgravity.

Results

Astrocytes showed distinct responses toward the three different radiation qualities. Induction of radiation-induced DNA double strand breaks (DSBs) and the respective repair was dose-, LET- and time-dependent. Simulated microgravity had no significant influence on DNA DSB repair. Proliferation and cell cycle progression was not affected by radiation qualities examined in this study. Astrocytes expressed IL-6 and GFAP with constitutive NF-κB activity independent of radiation exposure. mRNA sequencing of X-irradiated astrocytes revealed downregulation of 66 genes involved in DNA damage response and repair, mitosis, proliferation and cell cycle regulation.

Discussion

In conclusion, primary murine astrocytes are DNA repair proficient irrespective of radiation quality. Only minor gene expression changes were observed after X-ray exposure and reactivity was not induced. Co-culture of astrocytes with microglial cells, brain organoids or organotypic brain slice culture experiments might reveal whether astrocytes show a more pronounced radiation response in more complex network architectures in the presence of other neuronal cell types.

Placenta-specific lncRNA 1600012P17Rik is expressed in spongiotrophoblast and glycogen trophoblast cells of mouse placenta

A few long noncoding RNAs (long ncRNAs, lncRNAs) exhibit trophoblast cell type-specific expression patterns and functional roles in mouse placenta. However, the cell- and stage-specific expression patterns and functions of most placenta-derived lncRNAs remain unclear. In this study, we explored mouse placenta-associated lncRNAs using a combined bioinformatic and experimental approach. We used the FANTOM5 database to survey lncRNA expression in mouse placenta and found that 1600012P17Rik (MGI: 1919275, designated P17Rik), a long intergenic ncRNA, was the most highly expressed lncRNA at gestational day 17. Polymerase chain reaction analysis confirmed that P17Rik was exclusively expressed in placenta and not in any of the adult organs examined in this study. In situ hybridization analysis revealed that it was highly expressed in spongiotrophoblast cells and to a lesser extent in glycogen trophoblast cells, including migratory glycogen trophoblast cells invading the decidua. Moreover, we found that it is a polyadenylated lncRNA localized mainly to the cytoplasm of these trophoblast cells. As these trophoblast cells also expressed the neighboring protein-coding gene, pappalysin 2 (Pappa2), we investigated the effects of P17Rik on Pappa2 expression using Pappa2-expressing MC3T3-E1 cells and found that P17Rik transfection increased the messenger RNA (mRNA) and protein levels of Pappa2. These results indicate that mouse placenta-specific lncRNA P17Rik modulates the expression of the neighboring protein-coding gene Pappa2 in spongiotrophoblast and glycogen trophoblast cells of mouse placenta during late gestation.

Dysregulation of long non-coding RNAs and their mechanisms in Huntington's disease

Extensive alterations in gene regulatory networks are a typical characteristic of Huntington's disease (HD); these include alterations in protein-coding genes and poorly understood non-coding RNAs (ncRNAs), which are associated with pathology caused by mutant huntingtin. Long non-coding RNAs (lncRNAs) are an important class of ncRNAs involved in a variety of biological functions, including transcriptional regulation and post-transcriptional modification of many targets, and likely contributed to the pathogenesis of HD. While a number of changes in lncRNAs expression have been observed in HD, little is currently known about their functions. Here, we discuss their possible mechanisms and molecular functions, with a particular focus on their roles in transcriptional regulation. These findings give us a better insight into HD pathogenesis and may provide new targets for the treatment of this neurodegenerative disease.

Molecular landscape of long noncoding RNAs in brain disorders

According to current paradigms, various risk factors, such as genetic mutations, oxidative stress, neural network dysfunction, and abnormal protein degradation, contribute to the progression of brain disorders. Through the cooperation of gene transcripts in biological processes, the study of noncoding RNAs can lead to insights into the cause and treatment of brain disorders. Recently, long noncoding RNAs (lncRNAs) which are longer than 200 nucleotides in length have been suggested as key factors in various brain disorders. Accumulating evidence suggests the potential of lncRNAs as diagnostic or prognostic biomarkers and therapeutic targets. High-throughput screening-based sequencing has been instrumental in identification of lncRNAs that demand new approaches to understanding the progression of brain disorders. In this review, we discuss the recent progress in the study of lncRNAs, and addresses the pathogenesis of brain disorders that involve lncRNAs and describes the associations of lncRNAs with neurodegenerative disorders such as Alzheimer disease (AD), Parkinson disease (PD), and neurodevelopmental disorders. We also discuss potential targets of lncRNAs and their promise as novel therapeutics and biomarkers in brain disorders.

LncRNA OIP5-AS1 reduces α-synuclein aggregation and toxicity by targeting miR-126 to activate PLK2 in human neuroblastoma SH-SY5Y cells

It has been reported that many long noncoding RNAs (lncRNA) are abnormally expressed in Parkinson's disease (PD). However, the knowledge about the role of dysregulated lncRNA in the pathological process of PD and the potential molecular regulation mechanism is still limited. Our immunofluorescence data show that miR-126 enhances the aggregation and toxicity of synuclein, while lncRNA OIP5-AS1 reduces the aggregation and toxicity of MPP + induced α-synuclein by targeting miR-126. Luciferase experiments have found that miR-126 regulates α-synuclein by targeting PLK2. Western blot and IP experimental analysis showed that this process is achieved by regulating PLK2/α-synuclein autophagy. In conclusion, our data indicate that OIP5-AS1 promotes the autophagy of PLK2-α-synuclein by targeting the miR-126 axis with pathogenic factors, thus reducing the aggregation toxicity of α-synuclein, which It will help better to understand the mechanism of dopaminergic neuron loss in PD and provide novel treatment options.

Epigenetic mechanisms of neurodegenerative diseases and acute brain injury

Epigenetic modifications are emerging as major players in the pathogenesis of neurodegenerative disorders and susceptibility to acute brain injury. DNA and histone modifications act together with non-coding RNAs to form a complex gene expression machinery that adapts the brain to environmental stressors and injury response. These modifications influence cell-level operations like neurogenesis and DNA repair to large, intricate processes such as brain patterning, memory formation, motor function and cognition. Thus, epigenetic imbalance has been shown to influence the progression of many neurological disorders independent of aberrations in the genetic code. This review aims to highlight ways in which epigenetics applies to several commonly researched neurodegenerative diseases and forms of acute brain injury as well as shed light on the benefits of epigenetics-based treatments.