Probing nano-organization of astroglia with multi-color super-resolution microscopy.
Astroglia are essential for brain development, homeostasis, and metabolic support. They also contribute actively to the formation and regulation of synaptic circuits, by successfully handling, integrating, and propagating physiological signals of neural networks. The latter occurs mainly by engaging a versatile mechanism of internal Ca2+fluctuations and regenerative waves prompting targeted release of signaling molecules into the extracellular space. Astroglia also show substantial structural plasticity associated with age- and use-dependent changes in neural circuitry. However, the underlying cellular mechanisms are poorly understood, mainly because of the extraordinary complex morphology of astroglial compartments on the nanoscopic scale. This complexity largely prevents direct experimental access to astroglial processes, most of which are beyond the diffraction limit of optical microscopy. Here we employed super-resolution microscopy (direct stochastic optical reconstruction microscopy; dSTORM), to visualize astroglial organization on the nanoscale, in culture and in thin brain slices, as an initial step to understand the structural basis of astrocytic nano-physiology. We were able to follow nanoscopic morphology of GFAP-enriched astrocytes, which adapt a flattened shape in culture and a sponge-like structure in situ, with GFAP fibers of varied diameters. We also visualized nanoscopic astrocytic processes using the ubiquitous cytosolic astrocyte marker proteins S100β and glutamine synthetase. Finally, we overexpressed and imaged membrane-targeted pHluorin and lymphocyte-specific protein tyrosine kinase (N-terminal domain) -green fluorescent protein (lck-GFP), to better understand the molecular cascades underlying some common astroglia-targeted fluorescence imaging techniques. The results provide novel, albeit initial, insights into the cellular organization of astroglia on the nanoscale, paving the way for function-specific studies. © 2017 Wiley Periodicals, Inc.
UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom.
Janosch P
0000-0002-8825-3787
JP
Heller
UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom.
Piotr
P
Michaluk
UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom.|Molecular Pathophysiology Research, Drug Research Division, Sumitomo Dainippon Pharma Co., Ltd., Tokyo, 104-8356, Japan.
Kohtaroh
K
Sugao
UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom.
Dmitri A
0000-0001-9539-9947
DA
Rusakov
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism* / Q000648:ultrastructure*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008853:Microscopy / Q000379:methods; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D036103:Nanotechnology / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley
C000614142:Gfap protein, rat; D005904:Glial Fibrillary Acidic Protein
Astroglia; GFAP; S100β; dSTORM; glutamine synthetase; lck-GFP; pHluorin; super-resolution microscopy