Immunohistochemical Analysis of Mitochondrial Dynamics in Different Zones of the Hippocampus during Experimental Modeling of Alzheimer's Disease

We performed a comparative assessment of the immunohistochemical distribution of markers of mitochondrial fission (Drp-1), mitochondrial fusion (Mfn-2), and mitochondrial biogenesis (PGC-1α) in pyramidal neurons of different zones of the hippocampus in mice with intrahippocampal administration of β-amyloid peptide 25-35. The most pronounced changes in the dynamics associated with a decrease in the amount of the fission marker and an increase in the amount of the fusion marker were observed in the CA3 field on day 38 after peptide administration. In the CA1 field, a significant decrease in the marker of mitochondrial biogenesis PGC-1α was found on day 38, which can indicate a decrease in the intensity of mitochondrial biogenesis. Early mitochondrial changes can play an important role in the pathogenesis of all types of memory impairment in Alzheimer's disease.

Current progress and challenges in the development of brain tissue models: How to grow up the changeable brain in vitro?

In vitro modeling of brain tissue is a promising but not yet resolved problem in modern neurobiology and neuropharmacology. Complexity of the brain structure and diversity of cell-to-cell communication in (patho)physiological conditions make this task almost unachievable. However, establishment of novel in vitro brain models would ultimately lead to better understanding of development-associated or experience-driven brain plasticity, designing efficient approaches to restore aberrant brain functioning. The main goal of this review is to summarize the available data on methodological approaches that are currently in use, and to identify the most prospective trends in development of neurovascular unit, blood-brain barrier, blood-cerebrospinal fluid barrier, and neurogenic niche in vitro models. The manuscript focuses on the regulation of adult neurogenesis, cerebral microcirculation and fluids dynamics that should be reproduced in the in vitro 4D models to mimic brain development and its alterations in brain pathology. We discuss approaches that are critical for studying brain plasticity, deciphering the individual person-specific trajectory of brain development and aging, and testing new drug candidates in the in vitro models.

Novel Approaches to the Establishment of Local Microenvironment from Resorbable Biomaterials in the Brain In Vitro Models

The development of brain in vitro models requires the application of novel biocompatible materials and biopolymers as scaffolds for controllable and effective cell growth and functioning. The "ideal" brain in vitro model should demonstrate the principal features of brain plasticity like synaptic transmission and remodeling, neurogenesis and angiogenesis, and changes in the metabolism associated with the establishment of new intercellular connections. Therefore, the extracellular scaffolds that are helpful in the establishment and maintenance of local microenvironments supporting brain plasticity mechanisms are of critical importance. In this review, we will focus on some carbohydrate metabolites-lactate, pyruvate, oxaloacetate, malate-that greatly contribute to the regulation of cell-to-cell communications and metabolic plasticity of brain cells and on some resorbable biopolymers that may reproduce the local microenvironment enriched in particular cell metabolites.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.

The Neurotoxic Effect of β-Amyloid Is Accompanied by Changes in the Mitochondrial Dynamics and Autophagy in Neurons and Brain Endothelial Cells in the Experimental Model of Alzheimer's Disease

A comparative assessment of the expression of the mitochondrial fission marker Drp1 and the autophagy marker LC3 in neurons and endothelial cells in the hippocampus and entorhinal cortex during progression of cognitive deficit was performed in animals with intrahippocampal administration of β-amyloid. In both brain regions, the expression of Drp1 and LC3 in neuronal and endothelial cells was enhanced. The peak of cognitive impairment corresponded to the maximum expression of Drp1 and LC3 in hippocampal neurons and was preceded by an increase in the number of Drp1+ and LC3+ endothelial cells in this brain region. These data attests to a possible role of aberrant mitochondrial dynamics and autophagy of endothelial cells in the impairment of brain plasticity in the Alzheimer's type neurodegeneration.

Physiological and Pathological Remodeling of Cerebral Microvessels

There is growing evidence that the remodeling of cerebral microvessels plays an important role in plastic changes in the brain associated with development, experience, learning, and memory consolidation. At the same time, abnormal neoangiogenesis, and deregulated regulation of microvascular regression, or pruning, could contribute to the pathogenesis of neurodevelopmental diseases, stroke, and neurodegeneration. Aberrant remodeling of microvesselsis associated with blood-brain barrier breakdown, development of neuroinflammation, inadequate microcirculation in active brain regions, and leads to the dysfunction of the neurovascular unit and progressive neurological deficits. In this review, we summarize current data on the mechanisms of blood vessel regression and pruning in brain plasticity and in Alzheimer's-type neurodegeneration. We discuss some novel approaches to modulating cerebral remodeling and preventing degeneration-coupled aberrant microvascular activity in chronic neurodegeneration.

[<i<FOXC1-Mediated Effects of miR-204-5p on Melanoma Cell Proliferation]

MicroRNAs epigenetically regulate physiological and pathological processes. Previously, we found that miR-204-5p is expressed at low levels in melanoma cells, and an increase in its level leads to a change in proliferation, migration, and invasion of these cancer cells. Now, using bioinformatics analysis, it has been shown that the target of miR-204-5p is FOXC1 transcription factor, which is implicated in carcinogenesis. Using the luciferase reporter assay, it was found that miR-204-5p suppresses expression of the FOXC1 gene by binding to its 3' non-coding region. Transfection of small interfering RNA (siRNA) targeting FOXC1 into melanoma cells caused a decrease in miR-204-5p levels, which is consistent with the generally accepted concept of feedback regulation of miRNA expression by target genes. According to the results of the MTT test and fluorescence microscopy, the proliferation level of melanoma cells under the influence of siRNA to FOXC1 decreased 72 h after transfection. Changes in the ratio of cells by cell cycle phase were analyzed using flow cytometry. Regulatory relationships between FOXC1 and miR-204-5p, and an inhibitory effect of FOXC1 knockdown on melanoma cell proliferation were revealed. Based on the results, it can be assumed that miR-204-5p regulates proliferation of melanoma cells by affecting FOXC1 expression.