Non Coding Rnas In Neurodegeneration is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Non-coding RNAs (ncRNAs) represent a vast class of RNA molecules that are not translated into protein but serve critical regulatory functions in gene expression, chromatin
remodeling, and cellular homeostasis. In the central nervous system, ncRNAs are expressed at particularly high levels and exhibit brain-region-specific patterns, reflecting the
transcriptional complexity required for neuronal function. Dysregulation of ncRNAs—including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and
piwi-interacting RNAs (piRNAs)—has emerged as a central feature of [Alzheimer's disease[/diseases/alzheimers, [Parkinson's disease[/diseases/parkinsons, [amyotrophic lateral sclerosis[/diseases/als, [Huntington's disease[/mechanisms/huntington-pathway,
[frontotemporal dementia[/diseases/ftd, and other [neurodegenerative diseases[/diseases. These molecules regulate critical pathological processes including [amyloid-beta[/entities/amyloid-beta production, tau]
phosphorylation, [neuroinflammation[/mechanisms/neuroinflammation, [oxidative stress[/mechanisms/oxidative-stress, [autophagy[/entities/autophagy, and [synaptic dysfunction[/mechanisms/synaptic-dysfunction, making them promising therapeutic targets and [biomarkers] [1].
MicroRNAs are small (~22 nucleotide) single-stranded RNAs that regulate gene expression post-transcriptionally by binding to complementary
sequences in the 3' untranslated regions (3'UTRs) of target mRNAs. This binding—mediated through the RNA-induced silencing complex (RISC)
and Argonaute proteins—leads to mRNA degradation or translational repression. A single miRNA can regulate hundreds of target mRNAs, and more
than 60% of human protein-coding genes contain conserved miRNA binding sites. In the brain, miRNAs are essential for neuronal
differentiation, synaptic plasticity, and neuroimmune regulation (Bartel, 2018) [2].
miR-132: One of the most consistently downregulated miRNAs in Alzheimer's Disease brain tissue, particularly in the [hippocampus[/brain-regions/hippocampus and prefrontal [cortex[/brain-regions/cortex. miR-132 normally promotes neuronal survival and dendritic morphogenesis. Its loss leads to upregulation of inositol 1,4,5-trisphosphate 3-kinase B (ITPKB), which activates [BACE1[/entities/bace1 and enhances tau] phosphorylation via [GSK-3β[/entities/gsk3-beta, thereby intensifying both [amyloid plaque] burden and [neurofibrillary tangle] formation (Hernandez-Rapp et al., 2016; Salta et al., 2016). Circulating miR-132 levels correlate with [Braak staging[/mechanisms/braak-staging and cognitive decline, supporting its utility as a fluid biomarker.
miR-146a: A key regulator of the innate immune response in the brain. miR-146a is upregulated in [microglia[/astrocytes in AD brain, where it targets complement factor H (CFH) and interleukin-1 receptor-associated kinase 1 (IRAK1), modulating [NLRP3 inflammasome[/mechanisms/nlrp3-inflammasome and [NF-κB[/entities/nf-kb signaling. While initially neuroprotective by dampening [toll-like receptor] responses, chronic miR-146a elevation may paradoxically drive neuroinflammatory pathology by suppressing CFH and impairing complement regulation (Lukiw et al., 2008).
miR-155: A pro-inflammatory miRNA elevated in AD brain, cerebrospinal fluid, and plasma. miR-155 directly represses SOCS1 (suppressor of cytokine signaling 1) and CFH, amplifying [neuroinflammation[/mechanisms/neuroinflammation. Genetic deletion of miR-155 in AD mouse models reduces microglial activation and amyloid burden (Guedes et al., 2014). miR-155 is also elevated in [Parkinson's disease[/diseases/parkinsons and [ALS[/diseases/als, suggesting a shared neuroinflammatory mechanism.
miR-125b: Upregulated in AD brain and cerebrospinal fluid. Promotes tau] phosphorylation by targeting the phosphatases DUSP6 and PPP1CA, and enhances [neuroinflammation[/mechanisms/neuroinflammation by activating [NF-κB[/entities/nf-kb signaling in [astrocytes[/cell-types/astrocytes (Banzhaf-Strathmann et al., 2014).
miR-29a/b/c cluster: Downregulated in sporadic AD brain. miR-29a and miR-29b-1 directly target [BACE1/Aβ production. The miR-29 family also regulates DNA methyltransferases (DNMTs), linking ncRNA dysfunction to [epigenetic] alterations in AD (Hébert et al., 2008).
miR-7: Highly enriched in [dopaminergic neurons[/cell-types/dopaminergic-neurons-snpc of the [substantia nigra[/brain-regions/substantia-nigra. miR-7 directly suppresses [α-synuclein[/proteins/alpha-synuclein expression and protects against [oxidative stress[/mechanisms/oxidative-stress and [mitochondrial dysfunction[/mechanisms/mitochondrial-dysfunction. Loss of miR-7, often mediated by decreased ciRS-7/CDR1as (its circular RNA sponge), contributes to α-synuclein accumulation and dopaminergic neuron vulnerability (Junn et al., 2009).
miR-34b/c: Downregulated early in PD, even in premotor stages. miR-34b/c targets DJ-1 and [Parkin[/genes/prkn, proteins essential for [mitophagy[/mechanisms/mitophagy and mitochondrial quality control. Their deficiency impairs Complex I activity and increases [reactive oxygen species[/mechanisms/oxidative-stress (Miñones-Moyano et al., 2011).
miR-133b: Specifically enriched in midbrain dopaminergic [neurons[/entities/neurons, miR-133b regulates dopaminergic neuron maturation and function via the transcription factor Pitx3. [miR-133b is deficient in PD midbrain, contributing to impaired dopamine neurotransmission (Kim et al., 2007).
In [ALS[/diseases/als, miR-206 is upregulated at the neuromuscular junction and promotes reinnervation, while miR-9 and miR-105 are downregulated, leading to aberrant neurofilament expression and axonal degeneration. In [Huntington's disease[/mechanisms/huntington-pathway, REST/NRSF—normally sequestered by wild-type [huntingtin[/proteins/huntingtin—is released by mutant [huntingtin[/proteins/huntingtin and represses neural miRNAs including miR-9, miR-9*, miR-29b, and miR-124a, driving [transcriptional dysregulation[/mechanisms/transcriptional-dysregulation (Packer et al., 2008) [3].
Long non-coding RNAs are transcripts exceeding 200 nucleotides that do not encode proteins but exert diverse regulatory functions: acting as molecular scaffolds for chromatin-modifying complexes, guides for transcription factors, decoys that sequester proteins or miRNAs, and enhancers of gene expression. The human brain expresses more lncRNAs than any other organ, with many showing exquisite cell-type and brain-region specificity [4].
[BACE1[/entities/bace1 is a conserved lncRNA transcribed from the opposite strand of the [BACE1[/entities/bace1 gene locus. [BACE1[/entities/bace1-AS forms an RNA duplex with BACE1 mRNA,
stabilizing it and increasing both BACE1 mRNA and protein levels. This elevates β-secretase activity and [amyloid-beta[/entities/amyloid-beta production. BACE1-AS
is markedly upregulated in AD brain, particularly in the [hippocampus[/brain-regions/hippocampus and entorhinal [cortex[/brain-regions/cortex, and its levels correlate with Aβ42
concentrations. BACE1-AS also sponges miR-214-3p, further derepressing BACE1 expression. Knockdown of BACE1-AS reduces Aβ40 and Aβ42 levels
in vitro, establishing it as a potential therapeutic target ([Faghihi et al., 2008)(https://doi.org/10.1038/nm1784)) [5].
Nuclear Enriched Abundant Transcript 1 (NEAT1) is essential for the formation and maintenance of nuclear paraspeckles, subnuclear bodies
involved in RNA processing and gene expression regulation. NEAT1 is significantly upregulated in AD brain and in [Aβ[/entities/amyloid-beta-treated neuronal
cultures. It modulates [Aβ[/entities/amyloid-beta metabolism through the miR-124/BACE1 axis and interferes with [PINK1[/genes/pink1-dependent [mitophagy[/mechanisms/mitophagy, promoting
mitochondrial dysfunction and amyloid accumulation. Paradoxically, NEAT1 knockdown also increases p-tau] levels via the FZD3/GSK3β pathway,
suggesting it serves as a fine-tuner of multiple AD pathways (Zhao et al., 2019; Ke et al.,
2019) [6].
Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) is a highly conserved lncRNA enriched in [neurons[/entities/neurons. In neurodegenerative
contexts, MALAT1 is neuroprotective: it reduces neuronal apoptosis, inhibits [neuroinflammation[/mechanisms/neuroinflammation, and promotes neurite outgrowth. MALAT1 is
decreased in Aβ1-42-treated [neurons[/entities/neurons and in AD brain. It modulates miR-125b expression, suppressing neuronal apoptosis and inflammatory
signaling. In [Parkinson's disease[/diseases/parkinsons, MALAT1 regulates α-synuclein expression and microglial activation (Zhang et al.,
2017) [7].
HOX Transcript Antisense Intergenic RNA (HOTAIR) recruits the Polycomb Repressive Complex 2 (PRC2) to specific genomic loci, catalyzing histone H3K27 trimethylation and gene silencing. HOTAIR is elevated in AD brain, where it promotes neuronal apoptosis by repressing neuroprotective gene networks. It may also contribute to [epigenetic] dysregulation of genes involved in synaptic function and neuronal survival [8].
Cerebellar degeneration-related protein 1 antisense (CDR1as), also called circular RNA sponge for miR-7 (ciRS-7), is the most extensively studied circRNA in neurodegeneration. CDR1as contains over 70 conserved binding sites for miR-7 and acts as a potent miRNA sponge. By sequestering miR-7, CDR1as indirectly derepresses miR-7 targets including α-synuclein, BACE1, and ubiquitin-conjugating enzyme UBE2A [10].
CDR1as is significantly reduced in sporadic AD brain, particularly in the hippocampal CA1 region. This reduction releases miR-7 from its
sponge, paradoxically allowing miR-7 to suppress UBE2A, impairing ubiquitin-mediated clearance of [amyloid-beta[/entities/amyloid-beta and contributing to senile
plaque deposition (Lukiw, 2013). In mouse models, genetic deletion of the CDR1as locus causes
miR-7 and miR-671 deregulation, leading to synaptic and neuronal dysfunction (Piwecka et al.,
2017) [11].
Piwi-interacting RNAs are small RNAs (26-31 nucleotides) that silence transposable elements and regulate [epigenetic] modifications through
the PIWI-piRNA pathway. Although initially characterized in germline cells, piRNAs are also expressed in post-mitotic [neurons[/entities/neurons. Dysregulation
of piRNAs in AD brain correlates with [retrotransposon activation], suggesting that loss of transposon silencing may contribute to genomic
instability and neuronal death (Qiu et al., 2017). piR-61648 and piR-34393 are altered in AD
brain and may serve as fluid biomarkers [12].
Non-coding RNAs are attractive biomarkers due to their stability in biofluids (protected within [extracellular vesicles[/mechanisms/extracellular-vesicles or bound to proteins), disease-specific expression patterns, and detectability by sensitive PCR-based assays [13].
| miRNA | Disease | Direction | Clinical Utility |
|---|---|---|---|
| miR-132 | AD | ↓ | Correlates with cognitive decline, Braak staging |
| miR-146a | AD | ↑ | Reflects neuroinflammatory activity |
| miR-155 | AD, PD, ALS | ↑ | Pan-neurodegenerative inflammation marker |
| miR-29a/b | AD | ↓ | Associated with BACE1 elevation and Aβ burden |
| miR-34b/c | PD | ↓ | Early PD marker (premotor stage) |
| miR-7 | PD | ↓ | Reflects dopaminergic vulnerability |
| miR-206 | ALS | ↑ | Correlates with denervation and disease progression |
| miR-9 | HD | ↓ | Reflects REST derepression |
Cerebrospinal fluid ncRNA profiles offer closer proximity to CNS pathology. Exosome-encapsulated miRNAs are of particular interest as they
cross the Blood-Brain Barrier and reflect their cell of origin. Neural-derived exosomal miR-132 and miR-212 are reduced in preclinical AD,
potentially years before symptom onset. lncRNAs such as BACE1-AS and circRNAs like CDR1as are also detectable in CSF and may improve
diagnostic accuracy in combination panels (Leidinger et al., 2013) [14].
ASOs can specifically degrade pathogenic ncRNAs (e.g., BACE1-AS) or modulate [RNA splicing]. The success of nusinersen (Spinraza) for [spinal muscular atrophy[/diseases/spinal-muscular-atrophy demonstrates the clinical viability of ASO therapeutics for neurodegenerative disease [15].
Restoring depleted miRNAs (miR-132 mimics for AD) or inhibiting overexpressed miRNAs (anti-miR-155 for neuroinflammation) are active preclinical strategies. Locked nucleic acid (LNA)-modified anti-miRs improve stability and CNS penetration. Challenges include off-target effects, delivery across the Blood-Brain Barrier, and the promiscuity of miRNA-target interactions [16].
While most ncRNA-targeted therapeutics for neurodegeneration remain preclinical, several platforms are advancing: lipid nanoparticle-encapsulated miRNA mimics, adeno-associated virus (AAV)-delivered ncRNA regulators, and conjugate-based delivery (e.g., GalNAc for liver, transferrin receptor antibody-conjugates for brain). The growing repertoire of [clinical trials[/clinical-trials targeting RNA metabolism underscores the translational potential of this field [17].
Several ncRNAs are dysregulated across multiple neurodegenerative diseases, suggesting convergent regulatory mechanisms:
These shared signatures support the concept of a common ncRNA-mediated [transcriptional dysregulation[/mechanisms/transcriptional-dysregulation axis in neurodegeneration <a href="#references" class="ref-link" data-ref-number="1" data-ref-text="Non-coding RNAs in neurodegenerative diseases: mechanisms and therapeutic potential. Neurobiology of Disease. 2024.
The study of Non Coding Rnas In Neurodegeneration has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
🟡 Moderate Confidence
| Dimension | Score |
|---|---|
| Supporting Studies | 17 references |
| Replication | 0% |
| Effect Sizes | 25% |
| Contradicting Evidence | 33% |
| Mechanistic Completeness | 50% |
Overall Confidence: 45%