scholarly journals LYST Controls the Biogenesis of the Endosomal Compartment Required for Secretory Lysosome Function

Traffic ◽  
2015 ◽  
Vol 16 (2) ◽  
pp. 191-203 ◽  
Author(s):  
Fernando E. Sepulveda ◽  
Agathe Burgess ◽  
Xavier Heiligenstein ◽  
Nicolas Goudin ◽  
Mickaël M. Ménager ◽  
...  
Keyword(s):  
Endosomal Compartment ◽  
Secretory Lysosome

scholarly journals Transport of phagosomal components to an endosomal compartment.

1992 ◽  
Vol 267 (1) ◽  
pp. 126-132
Author(s):  
A Pitt ◽  
L S Mayorga ◽  
A L Schwartz ◽  
P D Stahl
Keyword(s):  
Endosomal Compartment

scholarly journals Endocytic pathways in polarized Caco-2 cells: identification of an endosomal compartment accessible from both apical and basolateral surfaces.

1990 ◽  
Vol 110 (2) ◽  
pp. 337-348 ◽  
Author(s):  
E J Hughson ◽  
C R Hopkins
Keyword(s):  
Cell Line ◽  
Concanavalin A ◽  
Transferrin Receptor ◽  
Apical Surface ◽  
Double Labeling ◽  
Endocytic Compartment ◽  
Endosomal Compartment ◽  
Apical Cytoplasm ◽  
Peroxidase Conjugate ◽  
Endocytic Pathways

The enterocyte-like cell line Caco-2 forms a polarized epithelium when grown on filters. We have investigated the interaction of endocytic pathways from the apical and basolateral surfaces. The transferrin receptor was an appropriate marker for the basolateral route; uptake of radiolabeled transferrin was highly polarized, and recycling of this ligand back to the basolateral surface occurred with an efficiency of 95%, even after prolonged incubations with transferrin. Using a transferrin-peroxidase conjugate to delineate the morphological pathway, we have identified an early endocytic compartment in the basolateral cytoplasm of the cells. Longer incubations revealed a deeper endocytic compartment in the apical cytoplasm. Concanavalin A complexed to gold was used to simultaneously label the apical endocytic route. After 60 min, extensive mixing of the two labels was seen in endocytic elements throughout the apical cytoplasm, including in the Golgi area, but never in the basal cytoplasm. Using a second double labeling procedure in which antitransferrin receptor antibody complexed to gold was applied to the basolateral surface for up to 2 h and free peroxidase applied to the apical surface for shorter periods, we demonstrated that this apical marker rapidly (within 5 min) reached endosomes containing antibody-gold. Our results indicate that, in Caco-2 cells, the endocytic pathways from the apical and basolateral surfaces meet in an endosomal compartment from which transferrin can still be recycled.

The munc13-4–rab27 complex is specifically required for tethering secretory lysosomes at the plasma membrane

Blood ◽  
2011 ◽  
Vol 118 (6) ◽  
pp. 1570-1578 ◽  
Author(s):  
Edo D. Elstak ◽  
Maaike Neeft ◽  
Nadine T. Nehme ◽  
Jarno Voortman ◽  
Marc Cheung ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Immune Cells ◽  
Total Internal Reflection ◽  
Target Cells ◽  
Binding Motif ◽  
Microscopy Imaging ◽  
Secretory Lysosome ◽  
Mast Cell Line ◽  
Type 3 ◽  
Secretory Lysosomes

Abstract Cytotoxic T lymphocytes (CTLs) kill target cells through the polarized release of lytic molecules from secretory lysosomes. Loss of munc13-4 function inhibits this process and causes familial hemophagocytic lymphohistiocytosis type 3 (FHL3). munc13-4 binds rab27a, but the necessity of the complex remains enigmatic, because studies in knockout models suggest separate functions. In the present study, we describe a noncanonical rab27a-binding motif in the N-terminus of munc13-4. Point mutants in this sequence have severely impaired rab27a binding, allowing dissection of rab27a requirements in munc13-4 function. The munc13-4–rab27a complex is not needed for secretory lysosome maturation, as shown by complementation in CTLs from FHL3 patients and in a mast cell line silenced for munc13-4. In contrast, fusion of secretory lysosomes with, and content release at the plasma membrane during degranulation, strictly required the munc13-4–rab27a complex. Total internal reflection fluorescence microscopy imaging revealed that the complex corrals motile secretory lysosomes beneath the plasma membrane during degranulation and controls their docking. The propensity to stall motility of secretory lysosomes is lost in cells expressing munc13-4 point mutants that do not bind rab27. In summary, these results uncovered a mechanism for tethering secretory lysosomes to the plasma membrane that is essential for degranulation in immune cells.

scholarly journals Munc13-4 Is an Effector of Rab27a and Controls Secretion of Lysosomes in Hematopoietic Cells

2005 ◽  
Vol 16 (2) ◽  
pp. 731-741 ◽  
Author(s):  
Maaike Neeft ◽  
Marnix Wieffer ◽  
Arjan S. de Jong ◽  
Gabriela Negroiu ◽  
Corina H.G. Metz ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Mast Cells ◽  
Genetic Disorder ◽  
Hematopoietic Cells ◽  
Lytic Granules ◽  
Secretory Lysosome ◽  
Griscelli Syndrome ◽  
Life Threatening ◽  
Lytic Granule ◽  
Secretory Lysosomes

Griscelli syndrome type 2 (GS2) is a genetic disorder in which patients exhibit life-threatening defects of cytotoxic T lymphocytes (CTLs) whose lytic granules fail to dock on the plasma membrane and therefore do not release their contents. The disease is caused by the absence of functional rab27a, but how rab27a controls secretion of lytic granule contents remains elusive. Mutations in Munc13-4 cause familial hemophagocytic lymphohistiocytosis subtype 3 (FHL3), a disease phenotypically related to GS2. We show that Munc13-4 is a direct partner of rab27a. The two proteins are highly expressed in CTLs and mast cells where they colocalize on secretory lysosomes. The region comprising the Munc13 homology domains is essential for the localization of Munc13-4 to secretory lysosomes. The GS2 mutant rab27aW73G strongly reduced binding to Munc13-4, whereas the FHL3 mutant Munc13-4Δ608-611 failed to bind rab27a. Overexpression of Munc13-4 enhanced degranulation of secretory lysosomes in mast cells, showing that it has a positive regulatory role in secretory lysosome fusion. We suggest that the secretion defects seen in GS2 and FHL3 have a common origin, and we propose that the rab27a/Munc13-4 complex is an essential regulator of secretory granule fusion with the plasma membrane in hematopoietic cells. Mutations in either of the two genes prevent formation of this complex and abolish secretion.

The endosomal compartment of rat hepatocytes

1985 ◽  
Vol 159 (1) ◽  
pp. 113-126 ◽  
Author(s):  
Alec Robert ◽  
Jean-Louis Carpentier ◽  
Emmanuel Van Obberghen ◽  
Bertrand Canivet ◽  
Phillip Gorden ◽  
...  
Keyword(s):  
Rat Hepatocytes ◽  
Endosomal Compartment
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