Rab11FIP1 maintains Rab35 at the intercellular bridge to promote actin removal and abscission

Cytokinesis requires precise coordination of actin removal at the intercellular bridge. Prior research has shown that Rab35 vesicles transport MICAL1 and OCRL to the midbody. However, the mechanism of Rab35 recruitment remains unclear. No prior work had resolved how Rab35 is stabilized at the bridge. This gap motivated investigation into Rab11FIP1's role. Studies have established Rab35's role in actin oxidation. Yet, the scaffold for Rab35 localization was unknown. This uncertainty drove the need to identify Rab11FIP1's function. The absence of this scaffold leads to actin overaccumulation.

This study aimed to determine how Rab35 is recruited to the intercellular bridge during cytokinesis. The specific problem is understanding the mechanism that stabilizes Rab35 at the midbody. The motivation stems from the need to clarify how actin is removed before abscission. The researchers propose Rab11FIP1 as a potential scaffold. The study tests whether Rab11FIP1 maintains Rab35 localization. The absence of Rab11FIP1 is hypothesized to disrupt this process. The goal is to show how Rab11FIP1 supports Rab35 function. The findings could clarify how cytokinesis is regulated.

The researchers used fluorescence microscopy to track Rab11FIP1 and Rab35 localization. They performed RNA interference to deplete Rab11FIP1 in cells. Time-lapse imaging captured cytokinesis progression. Actin accumulation was quantified using fluorescent markers. Latrunculin A treatment tested actin overaccumulation. The midbody was analyzed for Rab35 presence. Rab11FIP1 recruitment timing was compared to Rab35. The study focused on spatiotemporal dynamics at the bridge.

Rab11FIP1 recruitment occurs after Rab35 at the intercellular bridge. Depletion of Rab11FIP1 caused Rab35 levels to drop significantly. Cells showed delayed cytokinesis and increased binucleation. Actin overaccumulation was observed in the absence of Rab11FIP1. Latrunculin A treatment rescued these defects. Rab35's function in actin removal was impaired without Rab11FIP1. The midbody lacked Rab35 in Rab11FIP1-depleted cells. These findings suggest Rab11FIP1 is critical for Rab35 stability.

The authors state that Rab11FIP1 is critical for Rab35 function in actin removal. Rab11FIP1 scaffolds Rab35 at the bridge to maintain its localization. Without Rab11FIP1, Rab35 drops from the midbody. This leads to actin overaccumulation and cytokinetic delays. The study proposes that Rab11FIP1 supports Rab35 recruitment. The findings suggest Rab11FIP1 is essential for abscission. The researchers conclude that Rab11FIP1 maintains Rab35 at the bridge. These results highlight the importance of Rab11FIP1 in cytokinesis.