Branched actin constrains endosomal cargo to control sorting and fission
This article has been Reviewed by the following groups
Discuss this preprint
Start a discussion What are Sciety discussions?Listed in
- Evaluated articles (Arcadia Science)
Abstract
At the early endosome, cargos are sorted into subdomains; receptors destined for recycling to the plasma membrane are sorted into tubulovesicular structures that undergo fission and release cargo-laden vesicles that traffic along microtubules. Although branched actin has been implicated in the establishment/maintenance of endosomal membrane subdomains, its role in cargo segregation, fission, and recycling has not been extensively studied. Using inhibitors of formin-and ARP2/3-mediated actin assembly, we show that branched actin, but not linear actin, is required for endosome fission and receptor recycling. To examine the spatial relationship between actin and cargo, we transfected cells with constitutively active RAB5 Q79L to generate enlarged endosomes and demonstrated that internalized transferrin localized to discrete endosomal regions adjacent to branched actin. ARP2/3 inhibition disrupted this organization, resulting in broader cargo distribution on the endosomal membrane and coalescence of degradative and retrieval subdomains. Consistent with impaired endosomal sorting and fission, branched actin inhibition led to cargo accumulation. Our findings identify ARP2/3-mediated branched actin as a key regulator of cargo segregation, subdomain maintenance, and fission at the early endosome.
Article activity feed
-
he formin inhibitor SMIFH2
SMIFH2 has been reported to inhibit myosin family members in addition to formins, were any controls considered to rule out myosin-dependent effects on the observed phenotypes? https://pmc.ncbi.nlm.nih.gov/articles/PMC8121067/
-
Figure
Using endosome size as a fission surrogate is reasonable and well-supported by the Figure 3 data. One question, could larger endosomes alternatively reflect increased fusion or altered EEA1 recruitment rather than impaired fission? Also, in the representative images the endosomes are often very closely clustered, and it's not clear how Imaris is distinguishing individual endosomes from clumps. How were individual endosomes distinguished from multi-endosome clumps during segmentation? It could be helpful to include a representative segmentation output image in the supplemental to let the reader evaluate this.
And was endosome count per cell considered as a complementary readout?
-
t.
probably good to link (Figure 1K) here
-
Cels
minor typo
-
