Deficiency in Parvalbumin, but Not in Calbindin D-28k Upregulates Mitochondrial Volume and Decreases Smooth Endoplasmic Reticulum Surface Selectively in a Peripheral, Subplasmalemmal Region in the Soma of Purkinje Cells.
From: University of Fribourg, Division of Histology, Department of Medicine, University of Fribourg, 14, chemin du Musée, CH-1705 Fribourg, Switzerland.
Neuroscience
- Publish Date: Sep 2006
- ISSN: 0306-4522
- Volume: 142
- Issue: 1
- Pages: 97-105
- Medium: Print
- Language: English
- Citation (JAMA): Chen G, Racay P, Bichet S, et al. Deficiency in Parvalbumin, but Not in Calbindin D-28k Upregulates Mitochondrial Volume and Decreases Smooth Endoplasmic Reticulum Surface Selectively in a Peripheral, Subplasmalemmal Region in the Soma of Purkinje Cells.. Neuroscience Sep 2006;142:97-105
Abstract
The Ca(2+)-binding proteins parvalbumin (PV) and calbindin D-28k (CB) are key players in the intracellular Ca(2+)-buffering in specific cells including neurons and have profound effects on spatiotemporal aspects of Ca(2+) transients. The previously observed increase in mitochondrial volume density in fast-twitch muscle of PV-/- mice is viewed as a specific compensation mechanism to maintain Ca(2+) homeostasis. Since cerebellar Purkinje cells (PC) are characterized by high expression levels of the Ca(2+) buffers PV and CB, the question was raised, whether homeostatic mechanisms are induced in PC lacking these buffers. Mitochondrial volume density, i.e. relative mitochondrial mass was increased by 40% in the soma of PV-/- PC. Upregulation of mitochondrial volume density was not homogenous throughout the soma, but was selectively restricted to a peripheral region of 1.5 microm width underneath the plasma membrane. Accompanied was a decreased surface of subplasmalemmal smooth endoplasmic reticulum (sPL-sER) in a shell of 0.5 microm thickness underneath the plasma membrane. These alterations were specific for the absence of the “slow-onset” buffer PV, since in CB-/- mice neither changes in peripheral mitochondria nor in sPL-sER were observed. This implicates that the morphological alterations are aimed to specifically substitute the function of the slow buffer PV. We propose a novel concept that homeostatic mechanisms of components involved in Ca(2+) homeostasis do not always occur at the level of similar or closely related molecules. Rather the cell attempts to restore spatiotemporal aspects of Ca(2+) signals prevailing in the undisturbed (wildtype) situation by subtly fine tuning existing components involved in the regulation of Ca(2+) fluxes.
Mesh Headings (Keywords): Animals, Blotting, Western, Calcium, Calcium-Binding Protein, Vitamin D-Dependent, Cerebellar Cortex, Electrophoresis, Gel, Two-Dimensional, Endoplasmic Reticulum, Fluorescent Antibody Technique, Mice, Mice, Inbred C57BL, Mice, Knockout, Microscopy, Electron, Transmission, Mitochondria, Parvalbumins, Plasma Membrane Calcium-Transporting ATPases, Purkinje Cells, Statistics, Nonparametric
Check for Full Text / PubMed Unique Identifier (PMID): 16860487
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