Accessory ESCRT‐III proteins are conserved and selective regulators of Rab11a‐exosome formation

Abstract

Exosomes are secreted nanovesicles with potent signalling activity that are initially formed as intraluminal vesicles (ILVs) in late Rab7‐positive multivesicular endosomes, and also in recycling Rab11a‐positive endosomes, particularly under some forms of nutrient stress. The core proteins of the Endosomal Sorting Complex Required for Transport (ESCRT) participate in exosome biogenesis and ILV‐mediated destruction of ubiquitinylated cargos. Accessory ESCRT‐III components have reported roles in ESCRT‐III‐mediated vesicle scission, but their precise functions are poorly defined. They frequently only appear essential under stress. Comparative proteomics analysis of human small extracellular vesicles revealed that accessory ESCRT‐III proteins, CHMP1A, CHMP1B, CHMP5 and IST1, are increased in Rab11a‐enriched exosome preparations. We show that these proteins are required to form ILVs in Drosophila secondary cell recycling endosomes, but unlike core ESCRTs, they are not involved in degradation of ubiquitinylated proteins in late endosomes. Furthermore, CHMP5 knockdown in human HCT116 colorectal cancer cells selectively inhibits Rab11a‐exosome production. Accessory ESCRT‐III knockdown suppresses seminal fluid‐mediated reproductive signalling by secondary cells and the growth‐promoting activity of Rab11a‐exosome‐containing EVs from HCT116 cells. We conclude that accessory ESCRT‐III components have a specific, ubiquitin‐independent role in Rab11a‐exosome generation, a mechanism that might be targeted to selectively block pro‐tumorigenic activities of these vesicles in cancer.

Three‐dimensional printed biomimetic multilayer scaffolds coordinated with sleep‐related small extracellular vesicles: A strategy for extracellular matrix homeostasis and macrophage polarization to enhance osteochondral regeneration

“…NTA of the particle size‐distribution showed that the particle size of sEV was in the range of 30–200 nm, similar to the findings of a previous study (Figure S5). 37 The results of TEM showed that sEV exhibited a characteristic globular morphology similar to reports in previous literature (Figure S6). 38 …”

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

“…Larval haemocytes (Tassetto et al, 2017) Adaptive immune system Adult male secondary cells (Corrigan et al, 2014;Fan et al, 2020;Marie et al, 2023) Large MVBs: exosome subtype biogenesis; reproductive functions Adult muscle cells (Jewett et al, 2021) Neurodegeneration…”

APP and β-amyloid modulate protein aggregation and dissociation from recycling endosomal and exosomal membranes

“…Our analysis of APPL function has provided an explanation for the link between membranes and protein aggregation in SCs (Marie et al, 2023; Wells et al, 2023; Figure 8). APPL is the only APP-like homologue in flies; it is expressed at high levels in the nervous system, but is also transcribed in other tissues (Leader et al, 2018).…”

“…Rab11-exosomes are a novel subtype of exosomes formed in compartments labelled by the recycling endosomal marker Rab11 (Fan et al, 2020), rather than by late endosomes, which were previously thought to be the key source of these secreted vesicles. Even though Rab11-exosomes may make up only a small proportion of cellular EV output, when their biogenesis is selectively inhibited, specific defects in physiological and pathological cell communication are observed (Marie et al, 2023). In SCs, Rab11-exosomes form in regulated secretory compartments, where they have an additional role, as evidenced by GAPDH2 knockdown, co-ordinately controlling with endosomal membranes the normal protein aggregation events required for large DCG biogenesis.…”

“…SC DCG compartments are marked by Rab11 and also generate intraluminal vesicles (ILVs), which are secreted as exosomes (Corrigan et al, 2014; Fan et al, 2020). Since these exosomes are not generated in late endosomes, the previously identified source of exosomes, and they carry distinct cargos, they are termed Rab11-exosomes (Fan et al, 2020; Marie et al, 2023).…”