Publications by authors named "Robert Zorec"

The concept of cognitive reserve was born to account for the disjunction between the objective extent of brain damage in pathology and its clinical and intellectual outcome. The cognitive reserve comprises structural (brain reserve) and functional (brain maintenance, resilience, compensation) aspects of the nervous tissue reflecting exposome-driven life-long plasticity, which defines the ability of the brain to withstand aging and pathology. The mechanistic background of this concept was primarily focused on adaptive changes in neurones and neuronal networks.

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Aim: Astrocytes respond to stressors by acquiring a reactive state characterized by changes in their morphology and function. Molecules underlying reactive astrogliosis, however, remain largely unknown. Given that several studies observed increase in the Amyloid Precursor Protein (APP) in reactive astrocytes, we here test whether APP plays a role in reactive astrogliosis.

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Background: The expression of aquaporin 4 (AQP4) and intermediate filament (IF) proteins is altered in malignant glioblastoma (GBM), yet the expression of the major IF-based cytolinker, plectin (PLEC), and its contribution to GBM migration and invasiveness, are unknown. Here, we assessed the contribution of plectin in affecting the distribution of plasmalemmal AQP4 aggregates, migratory properties, and regulation of cell volume in astrocytes.

Methods: In human GBM, the expression of glial fibrillary acidic protein (GFAP), AQP4 and PLEC transcripts was analyzed using publicly available datasets, and the colocalization of PLEC with AQP4 and with GFAP was determined by immunohistochemistry.

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We present and evidence demonstrating that Amyloid Precursor Protein (APP) acts as an essential instigator of reactive astrogliosis. Cell-specific overexpression of APP in cultured astrocytes led to remodelling of the intermediate filament network, enhancement of cytokine production and activation of cellular programs centred around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion in cultured astrocytes abrogated remodelling of the intermediate filament network and blunted expression of IFN stimulated gene (ISG) products in response to lipopolysaccharide (LPS).

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Although we have learned much about how the brain fuels its functions over the last decades, there remains much still to discover in an organ that is so complex. This article lays out major gaps in our knowledge of interrelationships between brain metabolism and brain function, including biochemical, cellular, and subcellular aspects of functional metabolism and its imaging in adult brain, as well as during development, aging, and disease. The focus is on unknowns in metabolism of major brain substrates and associated transporters, the roles of insulin and of lipid droplets, the emerging role of metabolism in microglia, mysteries about the major brain cofactor and signaling molecule NAD, as well as unsolved problems underlying brain metabolism in pathologies such as traumatic brain injury, epilepsy, and metabolic downregulation during hibernation.

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Astroglia are a broad class of neural parenchymal cells primarily dedicated to homoeostasis and defence of the central nervous system (CNS). Astroglia contribute to the pathophysiology of all neurological and neuropsychiatric disorders in ways that can be either beneficial or detrimental to disorder outcome. Pathophysiological changes in astroglia can be primary or secondary and can result in gain or loss of functions.

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Astrocytes are increasingly recognized as important viral host cells in the central nervous system. These cells can produce relatively high quantities of new virions. In part, this can be attributed to the characteristics of astrocyte metabolism and its abundant and dynamic cytoskeleton network.

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Prostate cancer (PCa) is the most commonly diagnosed cancer and the second most common cause of death due to cancer. About 30% of patients with PCa who have been castrated develop a castration-resistant form of the disease (CRPC), which is incurable. In the last decade, new treatments that control the disease have emerged, slowing progression and spread and prolonging survival while maintaining the quality of life.

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A single sub-anesthetic dose of ketamine evokes rapid and long-lasting beneficial effects in patients with a major depressive disorder. However, the mechanisms underlying this effect are unknown. It has been proposed that astrocyte dysregulation of extracellular K concentration ([K]) alters neuronal excitability, thus contributing to depression.

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Regulated exocytosis, a universal process of eukaryotic cells, involves the merging between the vesicle membrane and the plasma membrane, plays a key role in cell-to-cell communication, particularly in the release of hormones and neurotransmitters. There are a number of barriers a vesicle needs to pass to discharge vesicle content to the extracellular space. At the pre-fusion site vesicles need to be transported to the sites on the plasma membrane where the merger may begin.

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Ageing is a key factor in the development of cognitive decline and dementia, an increasing and challenging problem of the modern world. The most commonly diagnosed cognitive decline is related to Alzheimer's disease (AD), the pathophysiology of which is poorly understood. Several hypotheses have been proposed.

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Key homeostasis providing cells in the central nervous system (CNS) are astrocytes, which belong to the class of cells known as atroglia, a highly heterogeneous type of neuroglia and a prominent element of the brain defence. Diseases evolve due to altered homeostatic state, associated with pathology-induced astroglia remodelling represented by reactive astrocytes, astroglial atrophy and astrodegeneration. These features are hallmarks of most infectious insults, mediated by bacteria, protozoa and viruses; they are also prominent in the systemic infection.

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Regulated exocytosis consists of the fusion between vesicles and the plasma membranes, leading to the formation of a narrow fusion pore through which secretions exit the vesicle lumen into the extracellular space. An increase in the cytosolic concentration of free Ca ([Ca]) is considered the stimulus of this process. However, whether this mechanism can be preserved in a simplified system of membrane lawns with docked secretory vesicles, devoid of cellular components, is poorly understood.

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Astrocytes, an abundant type of glial cells, are the key cells providing homeostasis in the central nervous system. Due to their susceptibility to infection, combined with high resilience to virus-induced cell death, astrocytes are now considered one of the principal types of cells, responsible for virus retention and dissemination within the brain. Autophagy plays an important role in elimination of intracellular components and in maintaining cellular homeostasis and is also intertwined with the life cycle of viruses.

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The aim of this study was to quantify the effectiveness of intradermal application of autologous fibroblasts on lean tissue structures. The histological sections of the skin were analysed and evaluated for the expansion potential of autologous fibroblasts in the control skin patch area and the nearby pre-treated skin patch into which we had injected expanded autologous fibroblasts nine month earlier. The results show that the pre-injection of fibroblasts into the dermis leads to a long-term rejuvenation of the skin, as evaluated from the histological appearance and from the significantly increased density of fibroblasts in the pre-injected skin vs.

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G-protein-coupled receptors (GPCRs) represent a family with over 800 members in humans, and one-third of these are targets for approved drugs. A large number of GPCRs have unknown physiologic roles. Here, we investigated GPR27, an orphan GPCR belonging to the family of super conserved receptor expressed in the brain, with unknown functions.

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Interactive mechanical forces between pairs of individual SNARE proteins synaptobrevin 2 (Sb2) and syntaxin 1A (Sx1A) may be sufficient to mediate vesicle docking. This notion, based on force spectroscopy single molecule measurements probing recombinant Sx1A an Sb2 in silico, questioned a predominant view of docking via the ternary SNARE complex formation, which includes an assembly of the intermediate cis binary complex between Sx1A and SNAP25 on the plasma membrane to engage Sb2 on the vesicle. However, whether a trans binary Sx1A-Sb2 complex alone could mediate vesicle docking in a cellular environment remains unclear.

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In 2009, new EU legislation regulating advanced therapy medicinal products (ATMPs), consisting of gene therapy, tissue engineering and cell-based medicines, was introduced. Although less than 20 ATMPs were authorized since that time, the awarding of the Nobel Prize for Physiology or Medicine in 2018 revived interest in developing new cancer immunotherapies involving significant manipulation of the patient's own immune cells, including lymphocytes and dendritic cells. The lymphocytes are mainly thought to directly affect tumour cells, dendritic cells are involved in indirect mechanisms by antigen presentation to other leukocytes orchestrating the immune response.

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In recent years, increasing evidence regarding the functional importance of lipid droplets (LDs), cytoplasmic storage organelles in the central nervous system (CNS), has emerged. Although not abundantly present in the CNS under normal conditions in adulthood, LDs accumulate in the CNS during development and aging, as well as in some neurologic disorders. LDs are actively involved in cellular lipid turnover and stress response.

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Ketamine, a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, exerts rapid, potent and long-lasting antidepressant effect already after a single administration of a low dose into depressed individuals. Apart from targeting neuronal NMDARs essential for synaptic transmission, ketamine also interacts with astrocytes, the principal homoeostatic cells of the central nervous system. The cellular mechanisms underlying astrocyte-based rapid antidepressant effect are incompletely understood.

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In some lysosomal storage diseases (LSD) cholesterol accumulates in vesicles. Whether increased vesicle cholesterol affects vesicle fusion with the plasmalemma, where the fusion pore, a channel between the vesicle lumen and the extracellular space, is formed, is unknown. Super-resolution microscopy revealed that after stimulation of exocytosis, pituitary lactotroph vesicles discharge cholesterol which transfers to the plasmalemma.

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Astrocytes, heterogeneous neuroglial cells, contribute to metabolic homeostasis in the brain by providing energy substrates to neurons. In contrast to predominantly oxidative neurons, astrocytes are considered primarily as glycolytic cells. They take up glucose from the circulation and in the process of aerobic glycolysis (despite the normal oxygen levels) produce L-lactate, which is then released into the extracellular space lactate transporters and possibly channels.

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