scholarly journals Phagosome resolution regenerates lysosomes and maintains the degradative capacity in phagocytes

2021 ◽  
Vol 220 (9) ◽  
Author(s):  
Charlene E. Lancaster ◽  
Aaron Fountain ◽  
Roaya M. Dayam ◽  
Elliott Somerville ◽  
Javal Sheth ◽  
...  
Keyword(s):  
Phagosome Maturation ◽  
Vesicle Budding ◽  
Membrane Fission

Phagocytes engulf unwanted particles into phagosomes that then fuse with lysosomes to degrade the enclosed particles. Ultimately, phagosomes must be recycled to help recover membrane resources that were consumed during phagocytosis and phagosome maturation, a process referred to as “phagosome resolution.” Little is known about phagosome resolution, which may proceed through exocytosis or membrane fission. Here, we show that bacteria-containing phagolysosomes in macrophages undergo fragmentation through vesicle budding, tubulation, and constriction. Phagosome fragmentation requires cargo degradation, the actin and microtubule cytoskeletons, and clathrin. We provide evidence that lysosome reformation occurs during phagosome resolution since the majority of phagosome-derived vesicles displayed lysosomal properties. Importantly, we show that clathrin-dependent phagosome resolution is important to maintain the degradative capacity of macrophages challenged with two waves of phagocytosis. Overall, our work suggests that phagosome resolution contributes to lysosome recovery and to maintaining the degradative power of macrophages to handle multiple waves of phagocytosis.

scholarly journals VPS4 triggers constriction and cleavage of ESCRT-III helical filaments

2019 ◽  
Vol 5 (4) ◽  
pp. eaau7198 ◽  
Author(s):  
Sourav Maity ◽  
Christophe Caillat ◽  
Nolwenn Miguet ◽  
Guidenn Sulbaran ◽  
Gregory Effantin ◽  
...  
Keyword(s):  
High Speed ◽  
Membrane Structures ◽  
Vesicle Budding ◽  
Endosomal Sorting ◽  
Force Microscopy ◽  
Cellular Processes ◽  
Membrane Fission ◽  
End Caps

Many cellular processes such as endosomal vesicle budding, virus budding, and cytokinesis require extensive membrane remodeling by the endosomal sorting complex required for transport III (ESCRT-III). ESCRT-III protein family members form spirals with variable diameters in vitro and in vivo inside tubular membrane structures, which need to be constricted to proceed to membrane fission. Here, we show, using high-speed atomic force microscopy and electron microscopy, that the AAA-type adenosine triphosphatase VPS4 constricts and cleaves ESCRT-III CHMP2A-CHMP3 helical filaments in vitro. Constriction starts asymmetrically and progressively decreases the diameter of CHMP2A-CHMP3 tubular structure, thereby coiling up the CHMP2A-CHMP3 filaments into dome-like end caps. Our results demonstrate that VPS4 actively constricts ESCRT-III filaments and cleaves them before their complete disassembly. We propose that the formation of ESCRT-III dome-like end caps by VPS4 within a membrane neck structure constricts the membrane to set the stage for membrane fission.

scholarly journals Phagosome resolution regenerates lysosomes and maintains the degradative capacity in phagocytes

2020 ◽  
Author(s):  
Charlene Lancaster ◽  
Aaron Fountain ◽  
Elliott Somerville ◽  
Javal Sheth ◽  
Roaya M. Dayam ◽  
...  
Keyword(s):  
Dependent Manner ◽  
Vesicle Budding ◽  
Membrane Fission ◽  
Ultimate Fate

AbstractDuring phagocytosis, phagocytes like macrophages engulf and sequester unwanted particles like bacteria into phagosomes. Phagosomes then fuse with lysosomes to mature into phagolysosomes, resulting in the degradation of the enclosed particle. Ultimately, phagosomes must be recycled to help recover membrane resources like lysosomes consumed during phagocytosis, a process referred to as phagosome resolution. Little is known about phagosome resolution, which may proceed through exocytosis or membrane fission. Here, we show that bacteria-containing phagolysosomes in macrophages undergo fragmentation through vesicle budding, tubulation, and constriction. Phagosome fragmentation required cargo degradation, the actin and microtubule cytoskeletons, and clathrin. We provide evidence that lysosome reformation occurs during phagosome resolution since the majority of phagosome-derived vesicles displayed lysosomal properties. Importantly, we showed that the clathrin-dependent phagosome resolution is important to maintain the degradative capacity of macrophages challenged with two waves of phagocytosis. Overall, our work suggests that phagosome resolution contributes to lysosome recovery and to maintain the degradative power of macrophages to handle multiple waves of phagocytosis.SummaryPhagocytes engulf particles into phagolysosomes for degradation. However, the ultimate fate of phagolysosomes is undefined. Lancaster, Fountain et al. show that phagosomes undergo fragmentation to reform lysosomes in a clathrin-dependent manner. This process is necessary to maintain the degradative capacity of phagocytes during subsequent phagocytosis.

scholarly journals Cytosol- and clathrin-dependent stimulation of endocytosis in vitro by purified adaptors.

1992 ◽  
Vol 119 (5) ◽  
pp. 1163-1171 ◽  
Author(s):  
E Smythe ◽  
L L Carter ◽  
S L Schmid
Keyword(s):  
Plasma Membrane ◽  
Coated Vesicle ◽  
A431 Cells ◽  
Coated Pits ◽  
Vesicle Budding ◽  
Membrane Fission ◽  
Cytosolic Factors ◽  
Insight Into ◽  
Stimulation Of

Using stage-specific assays for receptor-mediated endocytosis of transferrin (Tfn) into perforated A431 cells we show that purified adaptors stimulate coated pit assembly and ligand sequestration into deeply invaginated coated pits. Late events in endocytosis involving membrane fission and coated vesicle budding which lead to the internalization of Tfn are unaffected. AP2, plasma membrane adaptors, are active at physiological concentrations, whereas AP1, Golgi adaptors, are inactive. Adaptor-dependent stimulation of Tfn sequestration requires cytosolic clathrin, but is unaffected by clathrin purified from coated vesicles suggesting that soluble and assembled clathrin pools are functionally distinct. In addition to adaptors and cytosolic clathrin other, as yet unidentified, cytosolic factors are also required for efficient coated pit invagination. These results provide new insight into the mechanisms and regulation of coated pit assembly and invagination.

Sign in / Sign up

Export Citation Format

Share Document