MicroRNAs are post-transcriptional regulators of gene expression, crucial for neuronal differentiation, survival, and activity. Age-related dysregulation of microRNA biogenesis increases neuronal vulnerability to cellular stress and may contribute to the development and progression of neurodegenerative diseases. All major neurodegenerative disorders are also associated with oxidative stress, which is widely recognized as a potential target for protective therapies. Albeit often considered separately, microRNA networks and oxidative stress are inextricably entwined in neurodegenerative processes. Oxidative stress affects expression levels of multiple microRNAs and, conversely, microRNAs regulate many genes involved in an oxidative stress response. Both oxidative stress and microRNA regulatory networks also influence other processes linked to neurodegeneration, such as mitochondrial dysfunction, deregulation of proteostasis, and increased neuroinflammation, which ultimately lead to neuronal death. Modulating the levels of a relatively small number of microRNAs may therefore alleviate pathological oxidative damage and have neuroprotective activity. Here, we review the role of individual microRNAs in oxidative stress and related pathways in four neurodegenerative conditions: Alzheimer’s (AD), Parkinson’s (PD), Huntington’s (HD) disease, and amyotrophic lateral sclerosis (ALS). We also discuss the problems associated with the use of oversimplified cellular models and highlight perspectives of studying microRNA regulation and oxidative stress in human stem cell-derived neurons.

Intersectin 1 (ITSN1) is an evolutionarily conserved adaptor protein that functions in clathrin-mediated endocytosis, cell signalling and cytoskeleton rearrangements. The ITSN1 gene encodes two main isoforms: a short form (ITSN1-s), which is ubiquitously expressed and consists of two Eps15 homology (EH) domains and five Src homology 3 (SH3) domains, and a long form (ITSN1-l), which is predominantly expressed in the brain and contains three additional domains, a Dbl homology (DH) domain, a Pleckstrin homology (PH) domain and a C2 domain. Using computational analysis of the EST database and 3' RACE we determined the length of the 3' untranslated region of ITSN1-l and demonstrated that the polyadenylation site is located 11,559 nt downstream of the stop codon of the ITSN1-l mRNA. Recently, additional splicing events affecting ITSN1 transcripts were reported, but full-length transcriptional isoforms with different combinations of alternatively spliced exons remained unknown. Here we report the identification of fifteen novel transcriptional isoforms of the human ITSN1 gene with full-length coding sequences that are the result of different combinations of the alternatively spliced exons 5, 6/6', 20, 23, 25, 26, 26a and 35. The isoforms identified differ in domain organization and expression level in different tissues and more likely contribute to the modulation of many complex protein interactions in which ITSN1 participates.

Mesencephalic astrocyte derived neurotrophic factor (MANF) and cerebral dopamine neurotrophic factor (CDNF) are novel evolutionary conserved trophic factors, which exhibit cytoprotective activity via negative regulation of unfolded protein response (UPR) and inflammation. Despite multiple reports demonstrating detrimental effect of MANF/CDNF downregulation, little is known about the control of their expression. miRNAs—small non-coding RNAs—are important regulators of gene expression. Their dysregulation was demonstrated in multiple pathological processes and their ability to modulate levels of other neurotrophic factors, glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF), was previously reported. Here, for the first time we demonstrated direct regulation of MANF and CDNF by miRNAs. Using bioinformatic tools, reporter assay and analysis of endogenous MANF and CDNF, we identified that miR-144 controls MANF expression, and miR-134 and miR-141 downregulate CDNF levels. We also demonstrated that this effect is human-specific and is executed via predicted binding sites of corresponding miRNAs. Finally, we found that miR-382 suppressed hCDNF expression indirectly. In conclusion, we demonstrate for the first time direct regulation of MANF and CDNF expression by specific miRNAs, despite the fact their binding sites are not strongly evolutionary conserved. Furthermore, we demonstrate a functional effect of miR-144 mediated regulation of MANF on ER stress response markers. These findings emphasize that (1) prediction of miRNA targets based on evolutionary conservation may miss biologically meaningful regulatory pairs; and (2) interpretation of miRNA regulatory effects in animal models should be cautiously validated.

No abstract

Aim. Despite scientific and clinical success, glioblastoma remains the most aggressive tumor of the brain with extremely low prognostic potential for the patient. Biomarkers determining prognosis, and hence a treatment strategy, remains an actual problem at the moment. miRNAs can be considered as markers of glioblastoma. World’s long-term study confirm the legitimacy of miRNAs usage as reliable markers for the tumors diagnosis and prognosis, in particular brain tumors. The purpose of our study was miRNAs targeting, the change in expression of which in gliomas can be reliably associated with malignancy degree and tumor progression. Methods. To achieve the purpose of the investigation there were used such methods as bioinformatics search of the miRNAs for 3’-UTR genes associated with gliomas development, RNA isolation and miRNA-specific synthesis of cDNAs. The expression levels of miRNAs were determined by the real-time quantitative PCR (qPCR). The relative expression levels of targeted miRNAs were evaluated by comparing their content in tumor and adjacent tissues, conditionally healthy brain tissues of the same patients. Results. The analysis of qPCR results showed a decreased concentration of miR-30a-5p and miR-200c-3p in brain tumors relative to adjacent normal tissue in average of the 5 and 5.8 times, respectively (p <0.0001). Area under the ROC curve analysis of miR-30a-5p was AUC = 0.88528, for miR-200c-3p - AUC = 0.808. Conclusions. As an additional diagnostic and prognostic marker of glibalastoma signature determination, the expression level of hsa-miR-30a-3p and hsa-miR-200c-3p showed a good diagnostic potential (AUC = 7-9). Keywords: glioblastoma, microRNA, hsa-miR-30a-5p, hsa-miR-200c-3p.

ITSN1 adaptor/scaffold protein takes part in a variety of physiological and pathological cellular processes. It has a complex expression regulation and many protein partners. Aim. Characterization of the ITSN1 functio ning and expression control is important for understanding its role in cell. Methods. Bioinformatic analysis, semiquantitative expression analysis by RTPCR, immunoprecipitation. Results. We have described and ana lyzed the ITSN1 promoter regions, detected ITSN1 alternatively spliced isoforms at mRNA and protein levels in different cancer specimens. Using different bioinformatic servers, we have identified the sites for miRNA binding and analyzed the sites for serine, threonine and tyrosine phosphorylation of the ITSN1 protein. Conclusions.We have obtained new data on the ITSN1 expression in pathology. We have also shown the pos sibility of ITSN1 expression regulation by miRNA and phosphorylation of serine, threonine and tyrosine. K e y w o r d s: ITSN1, bidirectional promoter, alternative splicing, miRs, phosphorylation.