Profilin enhances Cdc42-induced nucleation of actin polymerization

被引:106
作者
Yang, CS
Huang, MZ
DeBiasio, J
Pring, M
Joyce, M
Miki, H
Takenawa, T
Zigmond, SH [1 ]
机构
[1] Univ Penn, Dept Biol, Philadelphia, PA 19104 USA
[2] Univ Penn, Dept Physiol, Philadelphia, PA 19104 USA
[3] Univ Tokyo, Inst Med Sci, Dept Biochem, Tokyo 1088639, Japan
关键词
actin polymerization; nucleation; Cdc42; leukocytes; profilin;
D O I
10.1083/jcb.150.5.1001
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
We find that profilin contributes in several ways to Cdc42-induced nucleation of actin filaments in high speed supernatant of lysed neutrophils. Depletion of profilin inhibited Cdc42-induced nucleation; re-addition of profilin restored much Of the activity. Mutant profilins with a decreased affinity for either actin or poly-L-proline were less effective at restoring activity. Whereas Cdc42 must activate Wiskott-Aldrich Syndrome protein (WASP) to stimulate nucleation by the Arp2/3 complex, VCA (verpolin homology, cofilin, and acidic domain contained in the COOH-terminal fragment of N-WASP) constitutively activates the Arp2/3 complex. Nucleation by VCA was not inhibited by profilin depletion. With purified N-WASP and Arp2/3 complex, Cdc42-induced nucleation did not require profilin but was enhanced by profilin, wild-type profilin being more effective than mutant profilin with reduced affinity for poly-L-proline. Nucleation by the Arp2/3 complex is a function of the free G-actin concentration. Thus, when profilin addition decreased the free G-actin concentration, it inhibited Cdc42- and VCA-induced nucleation. However, when profilin was added with G-actin in a ratio that maintained the initial free G-actin concentration, it increased the rate of both Cdc42- and VCA-induced nucleation. This enhancement, also seen with purified proteins, was greatest when the free G-actin concentration was low. These data suggest that under conditions present in intact cells, profilin enhances nucleation by activated Arp2/3 complex.
引用
收藏
页码:1001 / 1012
页数:12
相关论文
共 53 条
[31]   Scar, a WASp-related protein, activates nucleation of actin filaments by the Arp2/3 complex [J].
Machesky, LM ;
Mullins, RD ;
Higgs, HN ;
Kaiser, DA ;
Blanchoin, L ;
May, RC ;
Hall, ME ;
Pollard, TD .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1999, 96 (07) :3739-3744
[32]   Scar1 and the related Wiskott-Aldrich syndrome protein, WASP, regulate the actin cytoskeleton through the Arp2/3 complex [J].
Machesky, LM ;
Insall, RH .
CURRENT BIOLOGY, 1998, 8 (25) :1347-1356
[33]   Interactions of drebrin and gephyrin with profilin [J].
Mammoto, A ;
Sasaki, T ;
Asakura, T ;
Hotta, I ;
Imamura, H ;
Takahashi, K ;
Matsuura, Y ;
Shirao, T ;
Takai, Y .
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 1998, 243 (01) :86-89
[34]   WAVE, a novel WASP-family protein involved in actin reorganization induced by Rac [J].
Miki, H ;
Suetsugu, S ;
Takenawa, T .
EMBO JOURNAL, 1998, 17 (23) :6932-6941
[35]   Induction of filopodium formation by a WASP-related actin-depolymerizing protein N-WASP [J].
Miki, H ;
Sasaki, T ;
Takai, Y ;
Takenawa, T .
NATURE, 1998, 391 (6662) :93-96
[36]   N-WASP, a novel actin-depolymerizing protein, regulates the cortical cytoskeletal rearrangement in a PIP2-dependent manner downstream of tyrosine kinases [J].
Miki, H ;
Miura, K ;
Takenawa, T .
EMBO JOURNAL, 1996, 15 (19) :5326-5335
[37]   Cdc42 is required for membrane dependent actin polymerization in vitro [J].
Moreau, V ;
Way, M .
FEBS LETTERS, 1998, 427 (03) :353-356
[38]   Rho-family GTPases require the Arp2/3 complex to stimulate actin polymerization in Acanthamoeba extracts [J].
Mullins, RD ;
Pollard, TD .
CURRENT BIOLOGY, 1999, 9 (08) :405-415
[39]   Arp2/3 complex from Acanthamoeba finds profilin and cross-links actin filaments [J].
Mullins, RD ;
Kelleher, JF ;
Xu, J ;
Pollard, TD .
MOLECULAR BIOLOGY OF THE CELL, 1998, 9 (04) :841-852
[40]   Collagen induces tyrosine phosphorylation of Wiskott-Aldrich syndrome protein in human platelets [J].
Oda, A ;
Ochs, HD ;
Druker, BJ ;
Ozaki, K ;
Watanabe, C ;
Handa, M ;
Miyakawa, Y ;
Ikeda, Y .
BLOOD, 1998, 92 (06) :1852-1858