TY - JOUR
T1 - Spire and Formin 2 synergize and antagonize in regulating actin assembly in meiosis by a ping-pong mechanism
AU - Montaville, Pierre
AU - Jégou, Antoine
AU - Pernier, Julien
AU - Compper, Christel
AU - Guichard, Bérengère
AU - Mogessie, Binyam
AU - Schuh, Melina
AU - Romet-Lemonne, Guillaume
AU - Carlier, Marie-France
PY - 2014/2
Y1 - 2014/2
N2 - In mammalian oocytes, three actin binding proteins, Formin 2 (Fmn2), Spire, and profilin, synergistically organize a dynamic cytoplasmic actin meshwork that mediates translocation of the spindle toward the cortex and is required for successful fertilization. Here we characterize Fmn2 and elucidate the molecular mechanism for this synergy, using bulk solution and individual filament kinetic measurements of actin assembly dynamics. We show that by capping filament barbed ends, Spire recruits Fmn2 and facilitates its association with barbed ends, followed by rapid processive assembly and release of Spire. In the presence of actin, profilin, Spire, and Fmn2, filaments display alternating phases of rapid processive assembly and arrested growth, driven by a "ping-pong" mechanism, in which Spire and Fmn2 alternately kick off each other from the barbed ends. The results are validated by the effects of injection of Spire, Fmn2, and their interacting moieties in mouse oocytes. This original mechanism of regulation of a Rho-GTPase-independent formin, recruited by Spire at Rab11a-positive vesicles, supports a model for modulation of a dynamic actin-vesicle meshwork in the oocyte at the origin of asymmetric positioning of the meiotic spindle.
AB - In mammalian oocytes, three actin binding proteins, Formin 2 (Fmn2), Spire, and profilin, synergistically organize a dynamic cytoplasmic actin meshwork that mediates translocation of the spindle toward the cortex and is required for successful fertilization. Here we characterize Fmn2 and elucidate the molecular mechanism for this synergy, using bulk solution and individual filament kinetic measurements of actin assembly dynamics. We show that by capping filament barbed ends, Spire recruits Fmn2 and facilitates its association with barbed ends, followed by rapid processive assembly and release of Spire. In the presence of actin, profilin, Spire, and Fmn2, filaments display alternating phases of rapid processive assembly and arrested growth, driven by a "ping-pong" mechanism, in which Spire and Fmn2 alternately kick off each other from the barbed ends. The results are validated by the effects of injection of Spire, Fmn2, and their interacting moieties in mouse oocytes. This original mechanism of regulation of a Rho-GTPase-independent formin, recruited by Spire at Rab11a-positive vesicles, supports a model for modulation of a dynamic actin-vesicle meshwork in the oocyte at the origin of asymmetric positioning of the meiotic spindle.
KW - Actins
KW - Animals
KW - Cells, Cultured
KW - Feedback, Physiological
KW - Humans
KW - Kinetics
KW - Meiosis
KW - Mice
KW - Microfilament Proteins
KW - Nuclear Proteins
KW - Oocytes
KW - Profilins
KW - Protein Binding
KW - Protein Multimerization
KW - Journal Article
KW - Research Support, Non-U.S. Gov't
U2 - 10.1371/journal.pbio.1001795
DO - 10.1371/journal.pbio.1001795
M3 - Article (Academic Journal)
C2 - 24586110
VL - 12
SP - e1001795
JO - PLoS Biology
JF - PLoS Biology
SN - 1544-9173
IS - 2
ER -