Faculty Opinions recommendation of Capping protein regulates endosomal trafficking by controlling F-actin density around endocytic vesicles and recruiting RAB5 effectors.

Actin filaments (F-actin) have been implicated in various steps of endosomal trafficking, and the length of F-actin is controlled by actin capping proteins, such as CapZ, which is a stable heterodimeric protein complex consisting of a and β subunits. However, the role of these capping proteins in endosomal trafficking remains elusive. Here, we found that CapZ docks to endocytic vesicles via its C-terminal actin-binding motif. CapZ knockout significantly increases the F-actin density around immature early endosomes, and this impedes fusion between these vesicles, manifested by the accumulation of small endocytic vesicles in CapZ-knockout cells. CapZ also recruits several RAB5 effectors, such as Rabaptin-5, to RAB5-positive early endosomes via its N-terminal domain, and this further activates RAB5. Collectively, our results indicate that CapZ regulates endosomal trafficking by controlling actin density around early endosomes and recruiting RAB5 effectors.

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Actin-based Motility during Endocytosis in Budding Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.e05-10-0925 ◽

2006 ◽

Vol 17 (3) ◽

pp. 1354-1363 ◽

Cited By ~ 48

Author(s):

Kyoungtae Kim ◽

Brian J. Galletta ◽

Kevin O. Schmidt ◽

Fanny S. Chang ◽

Kendall J. Blumer ◽

...

Keyword(s):

Plasma Membrane ◽

Force Production ◽

Actin Assembly ◽

Capping Protein ◽

Actin Cables ◽

Endocytic Vesicles ◽

Initial Movement ◽

Fluorescence Markers

Actin assembly nucleated by Arp2/3 complex has been implicated in the formation and movement of endocytic vesicles. The dendritic nucleation model has been proposed to account for Arp2/3-mediated actin assembly and movement. Here, we explored the model by examining the role of capping protein in vivo, with quantitative tracking analysis of fluorescence markers for different stages of endocytosis in yeast. Capping protein was most important for the initial movement of endocytic vesicles away from the plasma membrane, which presumably corresponds to vesicle scission and release. The next phase of endosome movement away from the plasma membrane was also affected, but less so. The results are consistent with the dendritic nucleation model's prediction of capping protein as important for efficient actin assembly and force production. In contrast, the movement of late-stage endocytic vesicles, traveling through the cytoplasm en route to the vacuole, did not depend on capping protein. The movement of these vesicles was found previously to depend on Lsb6, a WASp interactor, whereas Lsb6 was found here to be dispensable for early endosome movement. Thus, the molecular requirements for Arp2/3-based actin assembly differ in early versus later stages of endocytosis. Finally, acute loss of actin cables led to increased patch motility.

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Vacuolin-1 inhibits endosomal trafficking and metastasis via CapZβ

Oncogene ◽

10.1038/s41388-021-01662-3 ◽

2021 ◽

Author(s):

Zuodong Ye ◽

Dawei Wang ◽

Yingying Lu ◽

Yunjiao He ◽

Jingting Yu ◽

...

Keyword(s):

Cancer Cells ◽

Focal Adhesions ◽

Migration And Invasion ◽

Endosomal Trafficking ◽

Capping Protein ◽

Fundamental Cause ◽

Metastatic Activity ◽

Small Chemical

AbstractMetastasis is the fundamental cause of cancer mortality, but there are still very few anti-metastatic drugs available. Endosomal trafficking has been implicated in tumor metastasis, and we have previously found that small chemical vacuolin-1 (V1) potently inhibits autophagosome-lysosome fusion and general endosomal-lysosomal degradation. Here, we assessed the anti-metastatic activity of V1 both in vitro and in vivo. V1 significantly inhibits colony formation, migration, and invasion of various cancer cells in vitro. It also compromises the assembly-disassembly dynamics of focal adhesions (FAs) by inhibiting the recycling and degradation of integrins. In various experimental or transgenic mouse models, V1 significantly suppresses the metastasis and/or tumor growth of breast cancer or melanoma. We further identified capping protein Zβ (CapZβ) as a V1 binding protein and showed that it is required for the V1-mediated inhibition of migration and metastasis of cancer cells. Collectively, our results indicate that V1 targets CapZβ to inhibit endosomal trafficking and metastasis.

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