Arl4d Recruits Cytohesin-2/Arno to Modulate Actin Remodeling
Resource
MOLECULAR BIOLOGY OF THE CELL v.18 n.11 pp.4420-4437
Journal
MOLECULAR BIOLOGY OF THE CELL
Journal Volume
v.18
Journal Issue
n.11
Pages
4420-4437
Date Issued
2007
Date
2007
Author(s)
LI, CHUN-CHUN
WU, TSUNG-SHENG
LEE, FANG-JEN
Abstract
ARL4D is a developmentally regulated member of the ADP- ribosylation factor/ARF-like protein (ARF/ARL) family of Ras -related GTPases. Although the primary structure of ARL4D is very similar to that of other ARF/ARL molecules, its function remains unclear. Cytohesin-2/ARF nucleotide- binding -site opener (ARNO) is a guanine nucleotide-exchange factor( GEF) for ARE, and, at the plasma membrane, it can activate ARF6 to regulate actin reorganization and membrane ruffling. We show here that ARL4D interacts with the C-terminal pleckstrin homology (PH) and polybasic c domains of cytohesin-2/ARNO in a GTP-dependent manner. Localization of ARL 4D at the plasma membrane is GTP- and N-terminal myristoylation-dependent. ARL4D(Q80L), a putative active form of ARL4D, induced accumulation of cytohesin-2/ARNO at the plasma membrane. Consistent with a known action of cytohesin-2/ARNO, ARL4D(Q80L) increased GTP-bound ARF6 and induced disassembly of actin stress fibers. Expression of inactive cytohesin-2/ ARNO(E156K) or small interfering RNA knockdown of cytohesin-2/ARNO blocked ARL4D-mediated disassembly of actin stress fibers. Similar to the results with cytohesin-2/ARNO or ARF6, reduction of ARL4D suppressed cell migration activity. Furthermore, ARL4D-induced translocation of cytohesin- 2/ARNO did not require phosphoinositide 3-kinase activation. Together, these data demonstrate that ARL4D acts as a novel upstream regulator of cytohesin-2/ARNO to promote ARF6 activation and modulate actin remodeling.
Subjects
GUANINE-NUCLEOTIDE-EXCHANGE
ADP-RIBOSYLATION FACTOR
PLECKSTRIN-HOMOLOGY DOMAINS
GTP-BINDING PROTEINS
PLASMA-MEMBRANE
SEC7 DOMAIN