|
|
|
|
|
||
|
|||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | |||||
First published online 20 January 2004
doi: 10.1242/jcs.00934
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Research Article |
1 Department of Neuroscience, DIBIT, Vita-Salute San Raffaele University, Via Olgettina, 58, 20132 Milan, Italy
2 Immunology of Diabetes Unit, IRCCS San Raffaele, Via Olgettina 60, 20132 Milan, Italy
3 Department of Pharmacology, University of Innsbruck, Peter-Mayr-Strasse 1a, A-6020 Innsbruck, Austria
* Author for correspondence (e-mail: meldolesi.jacopo{at}hsr.it)
Accepted 8 October 2003
Expression of dense-core granules, a typical exocytic organelle, is widely believed to be controlled by coordinate gene expression mechanisms specific to neurones and neurosecretory cells. Recent studies in PC12 cells, however, have suggested the number of granules/cells depends on the levels of only one of their cargo proteins, chromogranin A, regulating the metabolism of the other proteins, and thus the composition of the organelles, by an on/off switch mechanism. In addition, transfection of chromogranin A was reported to induce appearance of dense-core granules in the non-neurosecretory fibroblasts of the CV-1 line. Here the role of chromogranin A has been reinvestigated using not the heterogeneous PC12 line but several clones isolated therefrom. In these clones, investigated as such or after transfection with chromogranin A antisense sequences, the ratio between chromogranin A and its secretory protein mate, chromogranin B, was not constant but highly and apparently randomly variable. Variability of the chromogranin A/chromogranin B ratio was seen by confocal immunofluorescence also among the cells of single clones and subclones and among the granules of single cells. Moreover, stable and transient transfections of chromogranin A in a PC12 clone characterised by a low number of dense-core granules (one fifth of the reference clone) failed to modify significantly the number of the organelles, despite the several-fold increase of the granin. Finally, in three types of non-neurosecretory cells (CV-1, adenocarcinoma TS/A and a clone of PC12 incompetent for secretion) the transfected chromogranin A accumulated mostly in the Golgi/transGolgi area and was released rapidly from resting cells (constitutive secretion) as revealed by both immunofluorescence during cycloheximide treatment and pulse-chase experiments. Only a minor fraction was sorted to discrete organelles that were not dense-core granules, but primarily lysosomes because they contained no chromogranin B, and were largely positive for the late endosomal-lysosomal markers, lamp1 and lamp3. Dense-core granules are therefore true hallmarks of neurones and neurosecretory cells. Their number/cell appears independent of chromogranin A and their composition does not appear to be constant; in particular, they exhibit considerable, and so far unexplained variability in the chromogranin A/chromogranin B ratio.
Key words: Dense-core granules, Neurosecretory cells, Regulated exocytosis, Chromogranin A, Chromogranin B
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  A. Klajn, C. Ferrai, L. Stucchi, I. Prada, P. Podini, T. Baba, M. Rocchi, J. Meldolesi, and R. D'Alessandro The Rest Repression of the Neurosecretory Phenotype Is Negatively Modulated by BHC80, a Protein of the BRAF/HDAC Complex J. Neurosci., May 13, 2009; 29(19): 6296 - 6307. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Han, M. Suda, K. Tsuzuki, R. Wang, Y. Ohe, H. Hirai, T. Watanabe, T. Takeuchi, and M. Hosaka A Large Form of Secretogranin III Functions as a Sorting Receptor for Chromogranin A Aggregates in PC12 Cells Mol. Endocrinol., August 1, 2008; 22(8): 1935 - 1949. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. D. Dikeakos and T. L. Reudelhuber Sending proteins to dense core secretory granules: still a lot to sort out J. Cell Biol., April 23, 2007; 177(2): 191 - 196. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Courel, C. Rodemer, S. T. Nguyen, A. Pance, A. P. Jackson, D. T. O'Connor, and L. Taupenot Secretory Granule Biogenesis in Sympathoadrenal Cells: IDENTIFICATION OF A GRANULOGENIC DETERMINANT IN THE SECRETORY PROHORMONE CHROMOGRANIN A J. Biol. Chem., December 8, 2006; 281(49): 38038 - 38051. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. N. Hendy, T. Li, M. Girard, R. C. Feldstein, S. Mulay, R. Desjardins, R. Day, A. C. Karaplis, M. L. Tremblay, and L. Canaff Targeted Ablation of the Chromogranin A (Chga) Gene: Normal Neuroendocrine Dense-Core Secretory Granules and Increased Expression of Other Granins Mol. Endocrinol., August 1, 2006; 20(8): 1935 - 1947. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Kim, M. C. Gondre-Lewis, I. Arnaoutova, and Y. P. Loh Dense-Core Secretory Granule Biogenesis Physiology, April 1, 2006; 21(2): 124 - 133. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. R. Peinado, R. Vazquez-Martinez, D. Cruz-Garcia, A. Ruiz-Navarro, Y. Anouar, M. C. Tonon, H. Vaudry, F. Gracia-Navarro, J. P. Castano, and M. M. Malagon Differential Expression and Processing of Chromogranin A and Secretogranin II in Relation to the Secretory Status of Endocrine Cells Endocrinology, March 1, 2006; 147(3): 1408 - 1418. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Kim and Y. P. Loh Protease Nexin-1 Promotes Secretory Granule Biogenesis by Preventing Granule Protein Degradation Mol. Biol. Cell, February 1, 2006; 17(2): 789 - 798. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. V. Gerasimenko, M. Sherwood, A. V. Tepikin, O. H. Petersen, and O. V. Gerasimenko NAADP, cADPR and IP3 all release Ca2+ from the endoplasmic reticulum and an acidic store in the secretory granule area J. Cell Sci., January 15, 2006; 119(2): 226 - 238. [Abstract] [Full Text] [PDF]
|
|
