From: Current understanding of the role of microRNAs in spinocerebellar ataxias
Observed changes | miRNA prediction | Experimental methods | Experimental models | Refs. |
---|---|---|---|---|
SCA1 | Â | Â | Â | Â |
miR-19, −101 and −130 downregulate the ATXN1 gene | Candidate miRNAs were identified using the PicTar algorithm. | Transfection with miRNA duplexes and their specific 2′-O-methyl inhibitors followed by western blot and RT-PCR analyses. miRNAs transfected to cells either individually or collectively. | MCF7 (highly express endogenous ATXN1), HEK293T, HeLa and NIH3T3 cell lines | [48] |
Eight miRNAs were chosen for further examination based on the number of target sites in the ATXN1 transcript and their neuronal expression. | ||||
Luciferase reporter assays (Promega) with vectors carrying fragments or full length human ATXN1 3′-UTRs. | HeLa cell line |  | ||
miRNA levels and their expression patterns in mouse cerebella were assessed by northern blot analysis and in situ hybridization with LNA probes (Exiqon). | C57/B6 WT mouse | Â | ||
Cell death assays with mutant ATXN1deprived of target sites. | HEK293T cell line | |||
miRNA expression upregulated in SCA1 patients; the increase more prominent in the cortex samples | Regulatory RNA network and TargetScan prediction algorithms. | miRCURY LNA human microRNA Array (Exiqon). | Human cerebellum and cortex, SCA1 patients and healthy controls | [50] |
miR-144 slightly downregulated in SCA1 cerebellum but strongly induced in the cortex | Â | qRT-PCR, TaqMan miRNA assays (Applied Biosystems) for miR-144 and miR-101. | Â | |
Upregulated miRNAs predicted to target ATXN1, e.g., miR-101, -130a, -19a, -302 | Â | ATXN1 mRNA and protein levels analyzed with RT-PCR and western blot. | Â | |
miR-144 and −101 downregulate ATXN1 expression, miR-25 does not affect ATXN1 levels |  | Overexpression of miRNA duplexes and miRNA inhibitors followed by western blotting. | HEK293T cell line | |
 | Luciferase assays (Promega) with full-length ATXN1-3′-UTR-hLuc reporters and miRNA duplexes or 2′-O-methyl modified masking oligos. miRs 144 and 101 tested separately and in combination. | |||
No evidence for a statistically significant difference in miRNA expression. A trend to overexpression of miR-33-5p, −34-5p and -92a-5p | - | Illumina Hi-Seq 2000, small RNAs from fly heads | Drosophila models: UAS-Atxn1-82Q and UAS-Atxn1-30Q | [56] |
34 miRNAs upregulated; 14 at both time points, 15 at the 4-week time point only and 5 at the 12-week time point | Â | miRCURY LNA all species microRNA arrays (Exiqon) | Cerebellar RNA from SCA1 BO5 transgenic mice [82Q] analyzed at two time points (at 4 and 12 weeks of age) | [53] |
Individual miRNAs analyzed by qRT-PCR with TaqMan assays (miRs 150, 335, 23a, 24 and 143) | ||||
12 miRNAs downregulated; 1 miRNA at both time points, 4 and 7, respectively at the 4- and 12-week time points only | ||||
miR-150 levels increased in cerebellar Purkinje neurons and slightly decreased in granule cells | In situ hybridization using dig-labeled DNA-LNA probes (Exiqon) | SCA1 BO5 transgenic mice - Purkinje neurons, granule cells | ||
A concomitant increase in miR-150 and decrease in Rgs8 and Vegfa levels | TargetScan; Rgs8 and Vegfa identified as targets of miR-150 | Quantitative PCR and immunohistochemical analyses | SCA1 cerebella, Purkinje neurons | |
A dose-dependent decrease in Vegfa expression induced by the increased miR-150 activity | Transient transfection with MirVana miR-150 miRNA mimics followed by qPCR and WB. Luciferase assays (Promega) with wild-type Vegfa-3′UTR and miR-150 mimic. | Mouse Neuro2A |  | |
SCA2 | Â | Â | Â | Â |
Upregulation of bantam and miR-12 | - | Confocal microscopy | Drosophila, transgenic recombinant flies, wing imaginal discs cells | [60] |
SCA3 | Â | Â | Â | Â |
bantam miRNA is a downstream modulator/suppressor of polyQ toxicity | - | Phenotype mutants comparison analysis, TUNEL assays, immunostaining and western blots | Drosophila dcr-1 mutants, fly eyes, HeLa cells with normal and pathogenic Ataxin-3 treated with siRNA targeting dicer mRNA | [57] |
No evidence for a statistically significant difference in miRNA expression. A trend to a decrease in miR-1-3p and an increase in miR-100-5p, −33-5p and 92a-5p levels. | - | Illumina Hi-Seq 2000, small RNAs from fly heads | Drosophila models: UAS-Atxn3-70Q and UAS-Atxn3-19Q | [56] |
miR-34b is upregulated, and miR-25, −125b, −29a are downregulated in SCA3 patients. Expression of miR-25 and -125b was associated with the course of disease. | miRbase, TargetScan and micro.org were used to search for miRNA binding sites in the human ATXN3 3′-UTR | miRCURY LNA human miRNA Array (Exiqon) (v.14.0), validation miRNA expression by qRT-PCR (Applied Biosystems) | Blood samples obtained from SCA3 patients (35) and control individuals (25) | [61] |
SCA7 | Â | Â | Â | Â |
No evidence for a statistically significant difference in miRNA expression. A trend to an increase in miR-33-5p and -92a-5p levels and a decrease in miR-375-3p | - | Illumina Hi-Seq 2000, small RNAs from fly heads | Drosophila models: UAS-Atxn7-102Q and UAS-Atxn7-10Q | [56] |