Regulation of exosome secretion by Rab35 and its GTPase-activating proteins TBC1D10A–C

Abstract

Oligodendrocytes secrete vesicles into the extracellular space, where they might play a role in neuron–glia communication. These exosomes are small vesicles with a diameter of 50–100 nm that are formed within multivesicular bodies and are released after fusion with the plasma membrane. The intracellular pathways that generate exosomes are poorly defined. Because Rab family guanosine triphosphatases (GTPases) together with their regulators are important membrane trafficking organizers, we investigated which Rab GTPase-activating proteins interfere with exosome release. We find that TBC1D10A–C regulate exosome secretion in a catalytic activity–dependent manner. We show that Rab35 is the target of TBC1D10A–C and that the inhibition of Rab35 function leads to intracellular accumulation of endosomal vesicles and impairs exosome secretion. Rab35 localizes to the surface of oligodendroglia in a GTP-dependent manner, where it increases the density of vesicles, suggesting a function in docking or tethering. These findings provide a basis for understanding the biogenesis and function of exosomes in the central nervous system.

Engineering mesenchymal stem cells to improve their exosome efficacy and yield for cell‐free therapy

“…A study found that the overexpression of PLD2 led to twice the number of exosomes released from the cells while the knockdown of PLD2 led to twice the amount lower than exosomes released [65]. Another component of the EV biogenesis that could be of interest is the multivesicular body fusion with the plasma membrane and its regulatory molecules such as the Rab protein family along with their GTPases [66]. The Rab GTPases are known for their roles in membrane trafficking activity, which are part of the endosomal system.…”

Adaptor Protein CD2AP and L-type Lectin LMAN2 Regulate Exosome Cargo Protein Trafficking through the Golgi Complex

“…Proteins mediating exosome biogenesis can themselves be released on exosomes as reported for Rab35, Syntenin, and Flotillin-1 (23,26,36). We thus focused on exosome components found in human urine (15) and tested their requirements for GPRC5B-HA exosomal release by knocking down their expression using small interfering RNA (siRNA).…”

“…To address this issue, we investigated intracellular vesicle trafficking of the orphan G-protein-coupled receptor GPRC5B as a model exosome cargo protein (18). Although GPRC5B proteins are released in exosomes via a pathway relying on the GTPase activity of the exosome release regulator Rab35 (18,26), a substantial fraction of GPRC5B proteins are also released in microvesicles along with other known exosome cargo proteins (18), complicating the mechanistic understanding of GPRC5B exosome loading. To circumvent this promiscuity, we focused our investigation on the early intracellular trafficking events of newly synthesized GPRC5B proteins.…”

Exosomes in cancer theranostic: Diamonds in the rough

“…ESCRT is involved in the process of membrane invagination to the formation of ILVs and in the selection of proteins integrating these vesicles. 34 Concerning ESCRT-independent signals that regulate exosomes secretion we can name the ceramide pathway, 35 intracellular Ca 2C levels, 36 p53 status, 37 Rab protein family, 38,39 Syndecan-Syntenin-ALIX proteins, 40 high level of heparanase 41 and pH. 42 How the exosome penetrates into the recipient cell is still a debated issue.…”