48 research outputs found
Eps8 regulates axonal filopodia in hippocampal neurons in response to BDNF
The regulation of filopodia plays a crucial role during neuronal development and
synaptogenesis. Axonal filopodia, which are known to originate presynaptic
specializations, are regulated in response to neurotrophic factors. The structural
components of filopodia are actin filaments, whose dynamics and organization are
controlled by ensembles of actin binding proteins. How neurotrophic factors regulate
these latter proteins remains, however, poorly defined.
Here, using a combination of mouse genetic, biochemical and cell biological assays,
we show that genetic removal of Eps8, an actin-binding and regulatory protein
enriched in the growth cones and developing processes of neurons, significantly
augments the number and density of VASP-dependent axonal filopodia. The
reintroduction of Eps8 WT, but not an Eps8 capping-defective mutant into primary
hippocampal neurons restored axonal filopdia to wild type levels. We further show
that the actin barbed end capping activity of Eps8 is inhibited by BDNF treatment
through MAPK-dependent phosphorylation of Eps8 residues S624 and T628.
Additionally, an Eps8 mutant, impaired in the MAPK target sites (S624A/T628A),
displays increased association to actin-rich structures, is resistant to BDNF-mediated
release from microfilaments, and inhibits BDNF-induced filopodia. The opposite is
observed for a phosphomimetic Eps8 (S624E/T628E) mutant.
Thus, collectively, our data identify Eps8 as a critical capping protein in the
regulation of axonal filopodia and delineate a molecular pathway by which BDNF,
through MAPK-dependent phosphorylation of Eps8, stimulates axonal filopodia
formation, a process with crucial impacts on neuronal development and synapse
formation
Late Oligocene to Early Miocene foraminifers and ostracods from Karben (Wetterau, Hesse State, Germany): stratigraphic occurrence and palaeoecological implications
Observation of B meson decays to b(1)pi and b(1)K
We present the results of searches for decays of B mesons to final states with a b(1) meson and a charged pion or kaon. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 382x10(6) B(B)over bar pairs produced in e(+)e(-) annihilation. The results for the branching fractions are, in units of 10(-6), B(B+ -> b(1)(0)pi(+)) = 6.7 +/- 1.7 +/- 1.0, B(B+ -> b(1)(0)K(+)) = 9.1 +/- 1.7 +/- 1.0, B(B-0 -> b(1)(-/+)pi +/- ) = 10.9 +/- 1.2 +/- 0.9, and B(B-0 -> b(1)(-)K(+)) = 7.4 +/- 1.0 +/- 1.0, with the assumption that B(b(1) -> omega pi) = 1. We also measure charge and flavor asymmetries A(ch)(B+ -> b(1)(0)pi(+)) = 0.05 +/- 0.16 +/- 0.02, A(ch)(B+ -> b(1)(0)K(+)) = -0.46 +/- 0.20 +/- 0.02, A(ch)(B-0 -> b(1)(-/+)pi +/- ) = -0.05 +/- 0.10 +/- 0.02, C(B-0 -> b(1)(-/+)pi +/- ) = -0.22 +/- 0.23 +/- 0.05, Delta C(B-0 -> b(1)(-/+)pi +/- ) = -1.04 +/- 0.23 +/- 0.08, and A(ch)(B-0 -> b(1)(-)K(+)) = -0.07 +/- 0.12 +/- 0.02. The first error quoted is statistical, and the second systematic
Amplitude analysis of the decay D0→K-K+π0
Using 385 fb(-1) of e(+)e(-) collisions, we study the amplitudes of the singly Cabibbo-suppressed decay D-0 -> K-K+pi(0). We measure the strong phase difference between the (D) over bar (0) and D-0 decays to K-*(892)K-+(-) to be -35.5 degrees +/- 1.9 degrees(stat)+/- 2.2 degrees(syst), and their amplitude ratio to be 0.599 +/- 0.013(stat)+/- 0.011(syst). We observe contributions from the K pi and K-K+ scalar and vector amplitudes, and analyze their angular moments. We find no evidence for charged kappa, nor for higher spin states. We also perform a partial-wave analysis of the K-K+ system in a limited mass range