Tiny non-coding RNAs in Parkinson's disease: implications, expectations and hypes

Comprehensive review for non-coding RNAs: From mechanisms to therapeutic applications

Non-coding RNAs (ncRNAs) are an assorted collection of transcripts that are not translated into proteins. Since their discovery, ncRNAs have gained prominence as crucial regulators of various biological functions across diverse cell types and tissues, and their abnormal functioning has been implicated in disease. Notably, extensive research has focused on the relationship between microRNAs (miRNAs) and human cancers, although other types of ncRNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are also emerging as significant contributors to human disease. In this review, we provide a comprehensive summary of our current knowledge regarding the roles of miRNAs, lncRNAs, and circRNAs in cancer and other major human diseases, particularly cancer, cardiovascular, neurological, and infectious diseases. Moreover, we discuss the potential utilization of ncRNAs as disease biomarkers and as targets for therapeutic interventions.

miRNA and antisense oligonucleotide-based α-synuclein targeting as disease-modifying therapeutics in Parkinson's disease

α-synuclein is the synaptic protein majorly involved in neuronal dysfunction and death and it is well known for the last two decades as a hallmark of Parkinson's disease. Alpha-synuclein is involved in neurodegeneration mediated through various neurotoxic pathways, majorly including autophagy or lysosomal dysregulation, mitochondrial disruption, synaptic dysfunction, and oxidative stress. Moreover, the alpha-synuclein aggregation has been associated with the development of several neurodegenerative conditions such as various forms of Parkinson's disease. The recent discovery in oligonucleotide chemistry has developed potential alpha-synuclein targeting molecules for the treatment of neurodegenerative diseases. The present review article focuses on recent advances in the applications of oligonucleotides acting via alpha-synuclein targeting mechanisms and their implication in combating Parkinson's disease. Moreover, the article emphasizes the potential of miRNAs, and antisense oligonucleotides and the challenges associated with their use in the therapeutical management of Parkinson's disease.

High-resolution arrays reveal burden of copy number variations on Parkinson disease genes associated with increased disease risk in random cohorts

BACKGROUND

Parkinson disease (PD) is a neurological disease responsible for a considerable rate of mortality and morbidity in the society. Since the symptoms of the disease appear much later than the actual onset of neuron degeneration, a majority of cases remain undiagnosed until the manifestation of the symptoms.

OBJECTIVES

In order to investigate the existence of such susceptibility in the population, we analyzed Copy Number Variation (CNV) influences on PD genes in 1715 individuals from 12 different populations.

RESULTS

Overall, 16 CNV-PD genes, 3 known to be causal and 13 associated, were found to be significantly enriched. PARK2, was under heavy burden with ~1% of the population containing CNV in the exonic region. The impact of these genes on the genome and disease pathway was analyzed using several genome analysis tools. Protein interaction network of CNV-PD genes revealed a complex interaction of molecules forming a major hub by the α-Synuclein, whose direct interactors, LRRK2, PARK2 and ATP13A2 are under CNV influence.

CONCLUSIONS

We hypothesize that CNVs may not be the initiating event in the pathogenesis of PD and remain latent until additional secondary hits are acquired and also propose novel genes that may fall under the PD pathway which contribute in pathogenesis.

Investigation of Long Non-coding RNA Expression Profiles in the Substantia Nigra of Parkinson's Disease

Genetics is considered as an important risk factor in the pathological changes of Parkinson's disease (PD). Substantia nigra (SN) is thought to be the most vulnerable area in this process. In recent decades, however, few related long non-coding RNAs (lncRNAs) in the SN of PD patients had been identified and the functions of those lncRNAs had been studied even less. In this study, we sought to investigate the lncRNA expression profiles and their potential functions in the SN of PD patients. We screened lncRNA expression profiles in the SN of PD patients using the lncRNA mining approach from the ArrayExpress database, which included GSE20295. The samples were from 11 of PD and 14 of normal tissue samples. We identified 87 lncRNAs that were altered significantly in the SN during the occurrence of PD. Among these lncRNAs, lncRNA AL049437 and lncRNA AK021630 varied most dramatically. AL049437 was up-regulated in the PD samples, while AK021630 was down-regulated. Based on the results, we focused on the potential roles of the two lncRNAs in the pathogenesis of PD by the knockdown of the expression of AL049437 or AK021630 in human neuroblastoma SH-SY5Y cell line. Results indicated that the reduction in AL049437 level increased cell viability, mitochondrial transmembrane potential (Δψm), mitochondrial mass, and tyrosine hydroxylase (TyrH) secretion. By contrast, the knockdown of AK021630 resulted in the opposite effect. Based on these results, we speculated that lncRNA AL049437 likely contributed to the risk of PD, while lncRNA AK021630 likely inhibited the occurrence of PD.

Rodent models and contemporary molecular techniques: notable feats yet incomplete explanations of Parkinson's disease pathogenesis

Rodent models and molecular tools, mainly omics and RNA interference, have been rigorously used to decode the intangible etiology and pathogenesis of Parkinson's disease (PD). Although convention of contemporary molecular techniques and multiple rodent models paved imperative leads in deciphering the role of putative causative factors and sequential events leading to PD, complete and clear-cut mechanisms of pathogenesis are still hard to pin down. The current article reviews the implications and pros and cons of rodent models and molecular tools in understanding the molecular and cellular bases of PD pathogenesis based on the existing literature. Probable rationales for short of comprehensive leads and future possibilities in spite of the extensive applications of molecular tools and rodent models have also been discussed.

Resveratrol potentiates cytochrome P450 2 d22-mediated neuroprotection in maneb- and paraquat-induced parkinsonism in the mouse

A strong association between polymorphisms of the cytochrome P450 (CYP/Cyp) 2D6 gene and risk to Parkinson's disease (PD) is well established. The present study investigated the neuroprotective potential of Cyp2d22, a mouse ortholog of human CYP2D6, in maneb- and paraquat-induced parkinsonism and the mechanisms involved therein along with the effects of resveratrol on various parameters associated with Cyp2d22-mediated neuroprotection. The animals were treated intraperitoneally with resveratrol (10mg/kg, daily) and paraquat (10mg/kg) alone or in combination with maneb (30 mg/kg), twice a week, for 9 weeks, along with their respective controls. The subsets of animals were also treated intraperitoneally with a Cyp2d22 inhibitor, ketoconazole (100mg/kg, daily). Maneb and paraquat reduced Cyp2d22 and vesicular monoamine transporter type 2 (VMAT-2) expressions, the number of tyrosine hydroxylase-positive cells, and dopamine content and increased paraquat accumulation in the nigrostriatal tissues, oxidative stress, microglial activation, neuroinflammation, and apoptosis. Cyp2d22 inhibitor significantly exacerbated all these neurodegenerative indexes. Resveratrol cotreatment, partially but significantly, ameliorated the neurodegenerative changes by altering Cyp2d22 expression and paraquat accumulation. The results obtained in the study demonstrate that Cyp2d22 offers neuroprotection in maneb- and paraquat-induced dopaminergic neurodegeneration and resveratrol enhances its neuroprotective credentials by influencing Cyp2d22 expression and paraquat accumulation.

High-resolution melting (HRM) analysis for the detection of single nucleotide polymorphisms in microRNA target sites

BACKGROUND

The function of microRNAs (miRNAs) depends on the binding of miRNAs to their target sequences in the 3'UTR of messenger RNAs (mRNAs), which enhances the degradation of mRNAs and consequently, represses their expression. Single nucleotide polymorphisms (SNPs) in the miRNA target sequences may affect or impair the binding of miRNAs. Studies have shown that SNPs in miRNA target sites (miR-TS-SNPs) have a great influence on diverse biological functions, including pharmacogenomics and disease susceptibilities in human.

METHODS

High-resolution melting (HRM) analysis was applied for investigating the allele frequencies of 3 miR-TS-SNPs (PLA2G2A, IL-16, and NOD2) in acute leukemia. We also compared the genotypes of acute lymphoblastic leukemia patients at initial diagnosis and complete remission.

RESULTS

HRM analysis revealed 3 genotypes (both homozygous and heterozygous) in the 3 miR-TS-SNPs. The allele frequencies of all 3 miR-TS-SNPs were similar in normal individuals and patients with acute myelogenous leukemia. Most patients with acute lymphoblastic leukemia had the same genotypes at initial diagnosis and complete remission.

CONCLUSIONS

Large scale scanning of case-control studies for miR-TS-SNPs may contribute to the investigation of their roles and pathogenesis mechanisms in human diseases. Our study showed that HRM analysis can be an efficient tool for studies of miR-TS-SNPs.