Astrocytes are no longer considered subservient to neurons, and are, instead, now understood to play an active role in brain signaling. The intercellular communication of astrocytes with neurons and other non-neuronal cells involves the exchange of molecules by exocytotic and endocytotic processes. This type of communication is being the subject of intensive research. In this presentation I will first elucidate our study of the anatomy of single vesicles in astrocytes using super-resolution stimulated emission depletion (STED) microscopy and structured illumination microscopy (SIM). Then, I will focus on the interaction of these vesicles with the plasma membrane, measured by a high-resolution membrane capacitance approach. Last, I will show results, which indicate that certain disorders, like X-linked non-syndromic intellectual disability (XLID), that have traditionally been linked to neurons, exhibit strong vesicle related phenotypes also in astrocytes. These findings will contribute to the debate on gliotransmission.
B.04 Guest lecture
COBISS.SI-ID: 32774617The invention relates to a method of screening for a compound useful in the treatment of a disease selected from neurodegenerative diseases and neuro-inflammatory diseases, said method comprising providing a test cell; staining at least one organelle of said test cell; contacting said test cell with a test compound; and recording the path of said stained organelle in said test cell. Suitable compounds are identified from a comparison of the recorded path with a suitable reference.
F.32 International patent
COBISS.SI-ID: 33601753Astrocytes are neuroglial cells in the nervous system that participate in cellular communication via vesicle exo-/endocytosis. To better understand single vesicle interactions with the plasmalemma, we employed electrophysiological cell-attached capacitance measurements and super-resolution structured illumination microscopy, and examined the effects of different pharmacological agents on exo-/endocytosis and the fusion pore in cultured rat astrocytes. Ketamine, a lipophilic anesthetic with antidepressant action, inhibited evoked exocytotic BDNF secretion as well as full and transient vesicle fusions with the plasmalemma. Ketamine also inhibited endocytosis by evoking fusion pore flickering of vesicles that remained attached to the plasmalemma and were unable to undergo endocytotic fission. Similar to ketamine, the dynamin inhibitors Dynole-34-2 and Dyngo-4a caused flickering of fusion pores with decreased conductances. Using fluorescent dextrans and the lipophilic dye DiD, we demonstrated that dynamin inhibition prevents internalization of vesicles that instead likely remained attached to the plasmalemma via a flickering fusion pore. On the other hand, the dynamin activator Ryngo-1-23 decreased fusion pore flickering, favored a closed fusion pore configuration, and increased vesicle internalization. Dynamin is also involved in fusion of exocytotic VAMP2- and Syt4-positive vesicles. In contrast, the secondary messenger cAMP increased fusion pore conductance, favored an open fusion pore configuration, and caused larger vesicles to transit to full fusion. Whereas ketamine decreased secretion, cAMP increased the probability of gliotransmitter secretion. These newly discovered pharmacological effects on the fusion pore and exo-/endocytosis at the single vesicle level contribute to a better understanding of gliotransmission in neurophysiology.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 921463Noradrenergic Signaling and Astroglia integrates what is known about the active role of astroglia in the locus coeruleus-noradrenergic system and outlines the most recent advances in the field. It discusses the molecular mechanisms underlying norepinephrine-induced receptor activation in astroglia, cellular metabolism and CNS energy provision, in vitro, ex vivo, and in vivo models, gliosignalling and neuronal activity, and astroglial networks, gap junctions, and morphological plasticity. The book also addresses the role of astroglial adrenergic receptor activation in memory formation, cognition, regulation of sleep homeostasis, and lastly in neurological disorders, including trauma (cellular edema), neurodegeneration (Alzheimer’s disease), and neuroinflammation (multiple sclerosis). Noradrenergic Signaling and Astroglia is a valuable source of new knowledge for a wide audience, including graduate students, post-doctoral fellows, and researchers in neuroscience, life sciences, and the biological and biomedical sciences.
C.01 Editorial board of a foreign/international collection of papers/book
COBISS.SI-ID: 42375469Fluorescence microscopy is one of the most powerful tools in the biological investigation of subcellular structures and dynamic processes, since it allows us measurements in live samples in real time. In the past decades far field fluorescence microscopy techniques have undergone extraordinary developments. The invention of super-resolution techniques has enabled fluorescence nanoscopy to achieve resolution well below the diffraction limit (~200 nm in the focal plane and ~600 nm along the optic axis). The first of the three general types of fluorescence-based super-resolution microscopies invented was stimulated emission depletion (STED) microscopy (the other two types are structured illumination microscopy (SIM) and single-molecule switching (SMS)). In the first part of my presentation I will explain the basic concept of STED microscopy and present a two-color STED microscope, developed in the collaboration with colleagues from Laser Laboratorium Goettingen (Germany). In the second part of my talk I will illustrate the potential of STED microscopy on biological samples. Astrocytes are a sub-type of glial cells in the central nervous system that are now understood to play an active role in brain signaling. The intercellular communication of astrocytes with neurons and other non-neuronal cells involves the exchange of molecules by exocytotic and endocytotic processes. Studying the synaptic-like vesicles with diffraction-limited microscopies has proved to be challenging, since the diameters of these organelles are in the range of 30–50 nm. Here, I will compare astrocytic vesicle diameters, as measured by a diffraction-limited confocal microscopy and super-resolution microscopies STED and SIM.
B.04 Guest lecture
COBISS.SI-ID: 33442777