Cytosolic organelles shape calcium signals and exo–endocytotic responses of chromaffin cells

Abstract

a b s t r a c tfluxes between the different cell compartments support the proposal that the chromaffin cell has developed functional calcium tetrads formed by calcium channels, cytosolic calcium buffers, the endoplasmic reticulum, and mitochondria nearby the exocytotic plasmalemmal sites. These tetrads shape the Ca 2+ transients occurring during cell activation to regulate early and late steps of exocytosis, and the ensuing endocytotic responses. The different patterns of catecholamine secretion in response to stress may thus depend on such local [Ca 2+ ] c transients occurring at different cell compartments, and generated by redistribution and release of Ca 2+ by cytoplasmic organelles. In this manner, the calcium tetrads serve to couple the variable energy demands due to exo-endocytotic activities with energy production and protein synthesis.

Depressed excitability and ion currents linked to slow exocytotic fusion pore in chromaffin cells of the SOD1G93A mouse model of amyotrophic lateral sclerosis

“…In this context, we found that chromaffin cells contain two subpopulations of mitochondria that buffer the [Ca 2ϩ ] c transients with quite different capacities: population M1 takes up high Ca 2ϩ concentrations at subplasmalemmal sites while population M2 located at inner cytosolic sites takes up much lesser amounts of Ca 2ϩ (47). The relative contribution of these two mitochondrial pools and/or an altered mitochondrial Ca 2ϩ cycling through their uniporter and their Na 2ϩ /Ca 2ϩ exchanger (26) could explain the paradox of enhanced K ϩ -stimulated [Ca 2ϩ ] c transients with normal secretion in the mSOD1 with respect WT chromaffin cells.…”

The Differential Organization of F-Actin Alters the Distribution of Organelles in Cultured When Compared to Native Chromaffin Cells

“…The secretory process in these cells involves granule transport, the translocation of the secretory vesicles to the plasma membrane, their docking at secretory sites and finally, the fusion of the vesicle with the plasma membrane that results in the extrusion of their soluble contents (Burgoyne et al, 1993). Distinct cellular structures play fundamental roles in different stages of this secretory cascade, such as the cortical cytoskeleton (Trifaro et al, 2008; Gutierrez, 2012; Meunier and Gutierrez, 2016; Villanueva et al, 2016), while organelles like the mitochondria and endoplasmic reticulum appear to control and shape the elevations in intracellular calcium that govern multiple steps of this cascade (Garcia-Sancho and Verkhratsky, 2008; Garcia et al, 2012; Garcia-Sancho et al, 2012). …”

Faster kinetics of quantal catecholamine release in mouse chromaffin cells stimulated with acetylcholine, compared with other secretagogues

“…Chromaffin cells (CCs) from the adrenal medulla have served as invaluable neurosecretory models for investigating the fine tuning of Ca 2+ signalling and exocytosis at molecular, cellular, physiological and pharmacological levels (Livett ; Neher ; Garcia et al . , ; Mahapatra et al . ).…”

“…Chromaffin cells (CCs) from the adrenal medulla have served as invaluable neurosecretory models for investigating the fine tuning of Ca 2+ signalling and exocytosis at molecular, cellular, physiological and pharmacological levels (Livett 1984;Neher 1998;Garcia et al 2006Garcia et al , 2012Mahapatra et al 2012). These cells offer important advantages as they have compact cell bodies ideally suited for capacitance measurements, are accessible to amperometric electrodes and are readily loaded with Ca 2+ indicator dyes and caged Ca 2+ compounds.…”