Intracellular organelles in the saga of Ca 2+ homeostasis: Different molecules for different purposes?

Department of Biomedical Sciences, University of Padova, Italy.
Cellular and Molecular Life Sciences CMLS (Impact Factor: 5.81). 10/2011; 69(7):1077-104. DOI: 10.1007/s00018-011-0845-9
Source: PubMed


An increase in the concentration of cytosolic free Ca(2+) is a key component regulating different cellular processes ranging from egg fertilization, active secretion and movement, to cell differentiation and death. The multitude of phenomena modulated by Ca(2+), however, do not simply rely on increases/decreases in its concentration, but also on specific timing, shape and sub-cellular localization of its signals that, combined together, provide a huge versatility in Ca(2+) signaling. Intracellular organelles and their Ca(2+) handling machineries exert key roles in this complex and precise mechanism, and this review will try to depict a map of Ca(2+) routes inside cells, highlighting the uniqueness of the different Ca(2+) toolkit components and the complexity of the interactions between them.

Download full-text


Available from: Paola Pizzo, Oct 01, 2015
1 Follower
46 Reads
  • Source
    • "What is the membrane potential ( , defined as V lumen − V cytosol for comparison) for each organelle? Resting is around 0 mV for the ER and nucleus, very negative (−150 to −180 mV) for mitochondria, and slightly positive (+20 to 30 mV) for the Golgi apparatus, phagosomes, and lysosomes [1] [2] [28]. For plant vacuoles, a membrane potential around +30 mV is assumed, however, it remains unknown whether it can fluctuate in response to changes in environmental conditions [29]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Decades of intensive research have led to the discovery of most plasma membrane ion channels and transporters and the characterization of their physiological functions. In contrast, although over 80% of transport processes occur inside the cells, the ion flux mechanisms across intracellular membranes (the endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes, mitochondria, chloroplasts, and vacuoles) are difficult to investigate and remain poorly understood. Recent technical advances in super-resolution microscopy, organellar electrophysiology, organelle-targeted fluorescence imaging, and organelle proteomics have pushed a large step forward in the research of intracellular ion transport. Many new organellar channels are molecularly identified and electrophysiologically characterized. Additionally, molecular identification of many of these ion channels/transporters has made it possible to study their physiological functions by genetic and pharmacological means. For example, organellar channels have been shown to regulate important cellular processes such as programmed cell death and photosynthesis, and are involved in many different pathologies. This special issue (SI) on organellar channels and transporters aims to provide a forum to discuss the recent advances and to define the standard and open questions in this exciting and rapidly developing field. Along this line, a new Gordon Research Conference dedicated to the multidisciplinary study of intracellular membrane transport proteins will be launched this coming summer. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Cell calcium 03/2015; 63(1). DOI:10.1016/j.ceca.2015.02.006 · 3.51 Impact Factor
  • Source
    • "Cells respond to various stimuli by transient changes in intracellular free Ca 2+ concentration ([Ca 2+ ] i ). However, the diverse physiological processes regulated by Ca 2+ do not merely occur due to increases and decreases in cytosolic Ca 2+ concentration , but also depend on the specific speed, magnitude, frequency and spatio-temporal patterns of the signal [7]. The combination of changes characterizing the Ca 2+ signal, including final Ca 2+ resting levels and the source of the signal induced by a specific stimulus , is called the " Calcium Signature " [3] [8]. Calcium signatures are sensed and decoded by Ca 2+ binding proteins (CaBP) that act as Ca 2+ sensors, transmitting the information via phosphorylation events, protein–protein-interactions and gene expression [8]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca2+) binding motifs including the canonical and pseudo EF-hand motifs, Ca2+-binding ß-roll, Greek key motif and a novel putative Ca2+-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling, and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca2+ in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca2+ in prokaryotes.
    Cell Calcium 12/2014; 57(3). DOI:10.1016/j.ceca.2014.12.006 · 3.51 Impact Factor
  • Source
    • "However, given that SPCA1 is expressed also in post-Golgi vesicles (Mitchell et al., 2001, 2004), the conclusion that these defects depend solely, or primarily, on altered medial/trans-Golgi Ca 2+ homeostasis is presently unwarranted. Similarly, at present, we have no genetic or pharmacological tool that allows to interfere specifically with cis-and medial-Golgi Ca 2+ homeostasis, as the pump and the Ca 2+ release channels of these Golgi regions appear to be indistinguishable from those of the ER (Zampese and Pizzo, 2012) and any attempt to modulate these Ca 2+ mechanisms would inevitably affect both organelles. Thus, the functional significance of the complexity of Ca 2+ handling in the Golgi still remains a fascinating mystery and novel tools should be invented to solve this puzzle. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The Golgi apparatus (GA) is a dynamic intracellular Ca(2+) store endowed with complex Ca(2+) homeostatic mechanisms in part distinct from those of the endoplasmic reticulum (ER). We describe the generation of a novel fluorescent Ca(2+) probe selectively targeted to the medial-Golgi. We demonstrate that in the medial-Golgi: (i) Ca(2+) accumulation takes advantage of two distinct pumps, the sarco/endoplasmic reticulum Ca(2+) ATPase and the secretory pathway Ca(2+) ATPase1; (ii) activation of IP3 or ryanodine receptors causes Ca(2+) release, while no functional two-pore channel was found; (iii) luminal Ca(2+) concentration appears higher than that of the trans-Golgi, but lower than that of the ER, suggesting the existence of a cis- to trans-Golgi Ca(2+) concentration gradient. Thus, the GA represents a Ca(2+) store of high complexity where, despite the continuous flow of membranes and luminal contents, each sub-compartment maintains its Ca(2+) identity with specific Ca(2+) homeostatic characteristics. The functional role of such micro-heterogeneity in GA Ca(2+) handling is discussed.
    Journal of Molecular Cell Biology 08/2013; 5(4):266-76. DOI:10.1093/jmcb/mjt024 · 6.77 Impact Factor
Show more