title: The position of mitochondria and ER in relation to that of the secretory sites in chromaffin cells.
abstract: Knowledge of the distribution of mitochondria and endoplasmic reticulum (ER) in relation to the position of exocytotic sites is relevant to understanding the influence of these organelles in tuning Ca(2+) signals and secretion. Confocal images of probes tagged to mitochondria and the F-actin cytoskeleton revealed the existence of two populations of mitochondria, one that was cortical and one that was perinuclear. This mitochondrial distribution was also confirmed by using electron microscopy. In contrast, ER was sparse in the cortex and more abundant in deep cytoplasmic regions. The mitochondrial distribution might be due to organellar transport, which experiences increasing restrictions in the cell cortex. Further study of organelle distribution in relation to the position of SNARE microdomains and the granule fusion sites revealed that a third of the cortical mitochondria colocalized with exocytotic sites and another third located at a distance closer than two vesicle diameters. ER structures were also present in the vicinity of secretory sites but at a lower density. Therefore, mitochondria and ER have a spatial distribution that suggests a specialized role in modulation of exocytosis that fits with the role of cytosolic Ca(2+) microdomains described previously.
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Villanueva
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Viniegra
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Gimenez-Molina
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: García-Martinez
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Expósito-Romero
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: del Mar Frances
authors.affiliation: Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and CSIC, c/Sanz y Forés, 3, 47003 Valladolid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: García-Sancho
authors.affiliation: Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Cra de Valencia S/N, Sant Joan d'Alacant, 03550 Alicante, Spain luisguti@umh.es.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Gutiérrez
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000378:metabolism* / Q000648:ultrastructure*; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure*; D004734:Energy Metabolism; D005089:Exocytosis; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure*; D013997:Time Factors; D014162:Transfection
keywords: Chromaffin cell; Confocal microscopy; Endoplasmic reticulum; Exocytosis; Mitochondria