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Updated: Apr 19, 2026

Measuring Cell-Edge Protrusion Dynamics during Spreading using Live-Cell Microscopy
Published on: November 1, 2021
Numb controls integrin endocytosis for directional cell migration with aPKC and PAR-3
Takashi Nishimura1, Kozo Kaibuchi
1Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 466-8550, Japan.
Abstract:
Migrating cells extend protrusions to establish new adhesion sites at their leading edges. One of the driving forces for cell migration is the directional trafficking of cell-adhesion molecules such as integrins. Here, we show that the endocytic adaptor protein Numb is an important component of the machinery for directional integrin trafficking in migrating cells. Numb binds to integrin-betas and localizes to clathrin-coated structures (CCSs) at the substratum-facing surface of the leading edge. Numb inhibition by RNAi impairs both integrin endocytosis and cell migration toward integrin substrates. Numb is regulated by phosphorylation since the protein is released from CCSs and no longer binds integrins when phosphorylated by atypical protein kinase C (aPKC). Because Numb interacts with the aPKC binding partner PAR-3, we propose a model in which polarized Numb phosphorylation contributes to cell migration by directing integrin endocytosis to the leading edge.
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