Arf6, JIP3, and dynein shape and mediate macropinocytosis.

Molecular biology of the cell (2019-04-11)
Chad D Williamson, Julie G Donaldson
ABSTRACT

Macropinocytosis is an actin-driven form of clathrin-independent endocytosis that generates an enlarged structure, the macropinosome. Although many studies focus on signaling molecules and phosphoinositides involved in initiating macropinocytosis, the commitment to forming a macropinosome and the handling of that membrane have not been studied in detail. Here we show in HT1080 cells, a human fibrosarcoma cell line, a requirement for microtubules, dynein, the JIP3 microtubule motor scaffold protein, and Arf6, a JIP3 interacting protein, for the formation and inward movement of the macropinosome. While actin and myosin II also play critical roles in the formation of ruffling membrane, microtubules provide an important tract for initiation, sealing, and transport of the macropinosome through the actin- and myosin-rich lamellar region.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Nocodazole, ≥99% (TLC), powder
Sigma-Aldrich
Anti-Myosin IIA, non muscle antibody produced in rabbit, affinity isolated antibody, buffered aqueous solution
Sigma-Aldrich
Anti-Dynein Antibody, 74 kDa Intermediate chains, cytoplasmic, clone 74.1, clone 74.1, Chemicon®, from mouse