Continuous network of endoplasmic reticulum in cerebellar Purkinje neurons.

Abstract

Purkiqje neurons in rat cerebellar slices injected with an oil drop saturated with 1,1'4dhexadecyl-3,3,3',3'-tetrmethylndrbocyanlne perchlorate [DIIC,6(3) or DIIC to label the endoplasmic reticulum were observed by confocal microscopy. DII spread throughout the ceil body and dendrites and into the axon. DUI printed by using a Lasertechnics DIR continuous tone printer (Sandia Imaging, Carrollton, TX). In some instances, living Purkinje neurons were injected, and then the slices were immersed for 2 min in fixative (0.25% glutaraldehyde/0.5% paraformaldehyde/100 mM sodium cacodylate/100 mM sucrose, pH 7.3) within 2 min of the injection. Fixed slices were mounted in buffered medium (100 mM sodium cacodylate/ 100 mM sucrose, pH 7.3) under coverslips with glass spacers inserted to prevent mechanical distortion of the slice. Plasma membranes of Purkinje neurons were labeled with DiI either by the extracellular placement of a Dil-containing oil droplet or by micropressure ejection of a Dil-containing solution in ethanol. DIl ejected in ethanol readily precipitates from aqueous solution, and the crystalline precipitates settle onto and stain the cell surface.In some experiments, cerebellar slices were perfused on the stage of the confocal microscope with saline of the following composition: 118 mM NaCl/3 mM KCI/1.5 mM CaCl2/1 mM MgCl2/10 mM Hepes NaOH/11 mM D-glucose (gassed with 100%6 02; pH 7.4). The perfusate was changed to an anoxic (N2-gassed) solution containing increased MgC12 (10 mM), and CaCl2 was omitted. Electron microscopy was performed on anoxic or recovered slices by treating with concentrated aldehyde followed by fixing in 1% osmium tetroxide and embedding in Araldite.Cultured rat hippocampal neurons were prepared by the method of Goslin and Banker (10). Micropipettes of borosilicate glass with an internal fiber (tip diameter of :1 pam) were Abbreviations: DiI, 1,1'-dihexadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate [DiIC,6(3)]; ER, endoplasmic reticulum. 7510The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Light and Electron Microscopic Localization of Presenilin-1 in Primate Brain

“…It is possible that PS1 may be present on a very small subpopulation of synaptic vesicles. Alternatively, the labeled membranes may represent nonsynaptic vesicle components of the presynaptic terminal, such as elements of the SER network, which is known to extend into distal axons and terminals (Takei et al, 1992;Terasaki et al, 1994;Krijnse-Locker et al, 1995). Taken as a whole, these ultrastructural observations in monkey brain suggest a localization of PS1 to a subcompartment of the SER in both cell bodies and processes.…”

“…The morphological appearance of these organelles and their characteristic localization in dendritic spines suggests that they are components of the SER network (Satoh et al, 1990;Takei et al, 1992). The SER in neurons has been characterized as an intricate communicating network that extends from the cell body into the terminal segments of dendritic and axonal processes (Broadwell and Cataldo, 1984;Terasaki et al, 1994). Furthermore, a significant body of evidence suggests that these membranes are heterogeneous and contain biochemically and functionally distinct domains, including molecular specializations involved in calcium regulation (Satoh et al, 1990;Takei et al, 1992).…”

Activity-Dependent Calcium Sequestration in Dendrites of Hippocampal Neurons in Brain Slices

“…Synapses ( S) directly on the dendritic shaft are evident ( B). The typical pleomorphic appearance of smooth-membrane cisterns and tubules was consistent with the organization of dendritic ER as a physically interconnected network (Martone et al, 1993;Terasaki et al, 1994). All such cisterns and tubules were defined as ER, because there was no structural basis for making finer distinctions, even though it was recognized that the ER compartment so defined would be f unctionally heterogeneous (Henzi and MacDermott, 1992;Pozzan et al, 1994).…”

“…This store, because it is engaged in cycles of Ca 2ϩ uptake and release, plays an important role in neuronal Ca 2ϩ buffering (Andrews et al, 1988;Markram et al, 1995). It is also now recognized, on the basis of the heterogeneous distribution of luminal Ca-binding proteins, membrane Ca 2ϩ -ATPase pumps, and Ca 2ϩ -permeable membrane channels, that the various functional aspects of the ER, and particularly the dendritic ER, are spatially compartmentalized (Henzi and MacDermott, 1992;Pozzan et al, 1994), even though the ER forms a structurally continuous network of membranes (Martone et al, 1993;Terasaki et al, 1994).…”

Targeting Axonal Protein Synthesis in Neuroregeneration and Degeneration

“…Depending on the cell type and the subcellular localization ER morphology is very different but 3 main classes can be defined: the nuclear envelope, the sheet-like polyribosome-bound rough ER predominant in cell bodies, and the smooth ER. The ER in axons is formed by a network of longitudinally running, narrow tubules of smooth ER (tubular ER) [71,72], which is likely continuous with the somatodendritic ER [73]. A variety of insults and perturbations of normal cellular function, such as the accumulation of un-or misfolded proteins result in ER stress.…”