Secretory Granule Biogenesis and Neuropeptide Sorting to the Regulated Secretory Pathway in Neuroendocrine Cells

2004 ◽  
Vol 22 (1-2) ◽  
pp. 63-72 ◽  
Author(s):  
Y. Peng Loh ◽  
Taeyoon Kim ◽  
Yazmin M. Rodriguez ◽  
Niamh X. Cawley
Keyword(s):  
Secretory Granule ◽  
Secretory Pathway ◽  
Neuroendocrine Cells ◽  
Regulated Secretory Pathway

The Golgi-associated long coiled-coil protein NECC1 participates in the control of the regulated secretory pathway in PC12 cells

2012 ◽  
Vol 443 (2) ◽  
pp. 387-396 ◽  
Author(s):  
David Cruz-García ◽  
Alberto Díaz-Ruiz ◽  
Yoana Rabanal-Ruiz ◽  
Juan R. Peinado ◽  
Francisco Gracia-Navarro ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Pc12 Cells ◽  
Secretory Pathway ◽  
Hormone Secretion ◽  
Coiled Coil ◽  
Neuroendocrine Cells ◽  
Peripheral Membrane Protein ◽  
Regulated Secretory Pathway ◽  
Regulated Trafficking ◽  
Golgi Matrix

Golgi-associated long coiled-coil proteins, often referred to as golgins, are involved in the maintenance of the structural organization of the Golgi apparatus and the regulation of membrane traffic events occurring in this organelle. Little information is available on the contribution of golgins to Golgi function in cells specialized in secretion such as endocrine cells or neurons. In the present study, we characterize the intracellular distribution as well as the biochemical and functional properties of a novel long coiled-coil protein present in neuroendocrine tissues, NECC1 (neuroendocrine long coiled-coil protein 1). The present study shows that NECC1 is a peripheral membrane protein displaying high stability to detergent extraction, which distributes across the Golgi apparatus in neuroendocrine cells. In addition, NECC1 partially localizes to post-Golgi carriers containing secretory cargo in PC12 cells. Overexpression of NECC1 resulted in the formation of juxtanuclear aggregates together with a slight fragmentation of the Golgi and a decrease in K+-stimulated hormone release. In contrast, NECC1 silencing did not alter Golgi architecture, but enhanced K+-stimulated hormone secretion in PC12 cells. In all, the results of the present study identify NECC1 as a novel component of the Golgi matrix and support a role for this protein as a negative modulator of the regulated trafficking of secretory cargo in neuroendocrine cells.

Corticotropin-releasing factor binding protein enters the regulated secretory pathway in neuroendocrine cells and cortical neurons

Neuropeptides ◽  
2011 ◽  
Vol 45 (4) ◽  
pp. 273-279 ◽  
Author(s):  
Elías H. Blanco ◽  
Juan Pablo Zúñiga ◽  
María Estela Andrés ◽  
Alejandra R. Alvarez ◽  
Katia Gysling
Keyword(s):  
Cortical Neurons ◽  
Secretory Pathway ◽  
Binding Protein ◽  
Corticotropin Releasing Factor ◽  
Neuroendocrine Cells ◽  
Factor Binding ◽  
Regulated Secretory Pathway

Basic mechanisms of secretion: sorting into the regulated secretory pathway

2000 ◽  
Vol 78 (3) ◽  
pp. 181-191 ◽  
Author(s):  
Mercedes Blázquez ◽  
Kathleen I Shennan
Keyword(s):  
Secretory Pathway ◽  
Biological Function ◽  
Neuroendocrine Cells ◽  
Secretory Pathways ◽  
Lipid Interactions ◽  
Trans Golgi Network ◽  
Sorting Signals ◽  
Sorting Process ◽  
Regulated Secretory Pathway ◽  
Golgi Network

Targeting proteins to their correct cellular location is crucial for their biological function. In neuroendocrine cells, proteins can be secreted by either the constitutive or the regulated secretory pathways but the mechanism(s) whereby proteins are sorted into either pathway is unclear. In this review we discuss the possibility that sorting is either an active process occurring at the level of the trans-Golgi network, or that sorting occurs passively in the immature granules. The possible involvement of protein-lipid interactions in the sorting process is also raised. Key words: lipid rafts, regulated secretory pathway, secretion, sorting receptors, sorting signals, trans-Golgi network.

scholarly journals Small molecules that inhibit the late stage of Munc13-4–dependent secretory granule exocytosis in mast cells

2018 ◽  
Vol 293 (21) ◽  
pp. 8217-8229 ◽  
Author(s):  
Stephen Bruinsma ◽  
Declan J. James ◽  
Melanie Quintana Serrano ◽  
Joseph Esquibel ◽  
Sang Su Woo ◽  
...  
Keyword(s):  
Mast Cells ◽  
Secretory Granule ◽  
Small Molecule ◽  
Secretory Pathway ◽  
Small Molecule Inhibitors ◽  
Protein Isoforms ◽  
Secretory Cells ◽  
Granule Exocytosis ◽  
Regulated Secretory Pathway ◽  
Liposome Fusion

Ca2+-dependent secretory granule fusion with the plasma membrane is the final step for the exocytic release of inflammatory mediators, neuropeptides, and peptide hormones. Secretory cells use a similar protein machinery at late steps in the regulated secretory pathway, employing protein isoforms from the Rab, Sec1/Munc18, Munc13/CAPS, SNARE, and synaptotagmin protein families. However, no small-molecule inhibitors of secretory granule exocytosis that target these proteins are currently available but could have clinical utility. Here we utilized a high-throughput screen of a 25,000-compound library that identified 129 small-molecule inhibitors of Ca2+-triggered secretory granule exocytosis in RBL-2H3 mast cells. These inhibitors broadly fell into six different chemical classes, and follow-up permeable cell and liposome fusion assays identified the target for one class of these inhibitors. A family of 2-aminobenzothiazoles (termed benzothiazole exocytosis inhibitors or bexins) was found to inhibit mast cell secretory granule fusion by acting on a Ca2+-dependent, C2 domain–containing priming factor, Munc13-4. Our findings further indicated that bexins interfere with Munc13-4–membrane interactions and thereby inhibit Munc13-4–dependent membrane fusion. We conclude that bexins represent a class of specific secretory pathway inhibitors with potential as therapeutic agents.

scholarly journals Differential trafficking of soluble and integral membrane secretory granule-associated proteins

1994 ◽  
Vol 124 (1) ◽  
pp. 33-41 ◽  
Author(s):  
SL Milgram ◽  
BA Eipper ◽  
RE Mains
Keyword(s):  
Cell Surface ◽  
Secretory Granule ◽  
Secretory Pathway ◽  
Secretory Granules ◽  
Posttranslational Processing ◽  
Endoproteolytic Cleavage ◽  
Associated Proteins ◽  
Storage Granules ◽  
Regulated Secretory Pathway ◽  
And Storage

The posttranslational processing enzyme peptidylglycine alpha-amidating monooxygenase (PAM) occurs naturally in integral membrane and soluble forms. With the goal of understanding the targeting of these proteins to secretory granules, we have compared the maturation, processing, secretion, and storage of PAM proteins in stably transfected AtT-20 cells. Integral membrane and soluble PAM proteins exit the ER and reach the Golgi apparatus with similar kinetics. Biosynthetic labeling experiments demonstrated that soluble PAM proteins were endoproteolytically processed to a greater extent than integral membrane PAM; this processing occurred in the regulated secretory pathway and was blocked by incubation of cells at 20 degrees C. 16 h after a biosynthetic pulse, a larger proportion of soluble PAM proteins remained cell-associated compared with integral membrane PAM, suggesting that soluble PAM proteins were more efficiently targeted to storage granules. The nonstimulated secretion of soluble PAM proteins peaked 1-2 h after a biosynthetic pulse, suggesting that release was from vesicles which bud from immature granules during the maturation process. In contrast, soluble PAM proteins derived through endoproteolytic cleavage of integral membrane PAM were secreted in highest amount during later times of chase. Furthermore, immunoprecipitation of cell surface-associated integral membrane PAM demonstrated that very little integral membrane PAM reached the cell surface during early times of chase. However, when a truncated PAM protein lacking the cytoplasmic tail was expressed in AtT-20 cells, > 50% of the truncated PAM-1 protein reached the cell surface within 3 h. We conclude that the trafficking of integral membrane and soluble secretory granule-associated enzymes differs, and that integral membrane PAM proteins are less efficiently retained in maturing secretory granules.

scholarly journals COOH-terminal signals mediate the trafficking of a peptide processing enzyme in endocrine cells.

1993 ◽  
Vol 121 (1) ◽  
pp. 23-36 ◽  
Author(s):  
S L Milgram ◽  
R E Mains ◽  
B A Eipper
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Endocrine Cells ◽  
Secretory Pathway ◽  
Bioactive Peptides ◽  
Full Length ◽  
Neuroendocrine Cells ◽  
Subcellular Compartment ◽  
Peptide Processing ◽  
Regulated Secretory Pathway

Peptidylglycine alpha-amidating monooxygenase (PAM) catalyzes the COOH-terminal amidation of bioactive peptides through a two step reaction catalyzed by separate enzymes contained within the PAM precursor. To characterize the trafficking of integral membrane PAM proteins in neuroendocrine cells, we have generated stable AtT-20 cell lines expressing full length and COOH-terminally truncated integral membrane PAM proteins. Full length integral membrane PAM was present on the cell surface in low but detectable amounts and PAM proteins which reached the cell surface were rapidly internalized but not immediately degraded in lysosomes. Internalized PAM complexed with PAM antibody was found in a subcellular compartment which overlapped with internalized transferrin and with structures binding WGA. Thus the punctate juxtanuclear staining of full length PAM represents PAM in endosomes. Endoproteolytic processing of full length PAM-1 and PAM-2 resulted in the secretion of soluble PAM proteins; the secretion of these soluble PAM proteins was stimulus dependent. Although some of the truncated PAM protein was also processed and stored in AtT-20 cells, much of the expressed protein was redistributed to the plasma membrane. Soluble proteins not observed in large amounts in cells expressing full length PAM were released from the surface of cells expressing truncated PAM and little internalization of truncated integral membrane PAM was observed. Thus, the COOH-terminal domain of PAM contains information important for its trafficking within the regulated secretory pathway as well as information necessary for its retrieval from the cell surface.

Prohormone transport through the secretory pathway of neuroendocrine cells

2000 ◽  
Vol 78 (3) ◽  
pp. 289-298 ◽  
Author(s):  
Roland P Kuiper ◽  
Gerard JM Martens
Keyword(s):  
Secretory Pathway ◽  
Potential Role ◽  
Protein Transport ◽  
Secretory Granules ◽  
Secretory Protein ◽  
Neuroendocrine Cells ◽  
Secretory Proteins ◽  
Regulated Secretory Pathway ◽  
Made In

En route through the secretory pathway of neuroendocrine cells, prohormones pass a series of membrane-bounded compartments. During this transport, the prohormones are sorted to secretory granules and proteolytically cleaved to bioactive peptides. Recently, progress has been made in a number of aspects concerning secretory protein transport and sorting, particularly with respect to transport events in the early regions of the secretory pathway. In this review we will deal with some of these aspects, including: i) selective exit from the endoplasmic reticulum via COPII-coated vesicles and the potential role of p24 putative cargo receptors in this process, ii) cisternal maturation as an alternative model for protein transport through the Golgi complex, and iii) the mechanisms that may be involved in the sorting of regulated secretory proteins to secretory granules. Although much remains to be learned, interesting new insights into the functioning of the secretory pathway have been obtained.Key words: regulated secretory pathway, p24 family, vesicular transport, POMC, protein sorting, secretory granule, Xenopus laevis.

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