Response to Comment on "Oxytocin-mediated GABA inhibition during delivery attenuates autism pathogenesis in rodent offspring".

Bambini-Junior et al. questioned whether our treatment in two rodent models of autism has a long-lasting effect into adulthood. In response, we show that bumetanide treatment around delivery attenuates autistic behavioral features in adult offspring. Therefore, the polarity of γ-aminobutyric acid (GABA) actions during delivery exerts long-lasting priming actions after birth.

Lebectin, a Macrovipera lebetina venom-derived C-type lectin, inhibits angiogenesis both in vitro and in vivo.

Integrins play an essential role in endothelial cell motility processes during angiogenesis and thus present interesting targets for the development of new anti-angiogenic agents. Snake venoms naturally contain a variety of proteins that can affect integrin-ligand interactions. Recently, the C-type lectin proteins (CLPs) have been characterized as efficient modulators of integrin functions. In this study, we investigated the anti-angiogenic activity of lebectin, a newly discovered CLP from Macrovipera lebetina venom. Human brain microvascular endothelial cells (HBMEC), used as an in vitro model, express alphavbeta3, alphavbeta5, and alpha5beta1 integrins, as well as the alpha2, alpha3, alpha6, and beta4 subunits. Our data show that lebectin acts as a very potent inhibitor (IC(50) approximately 0.5 nM) of HBMEC adhesion and migration on fibronectin by blocking the adhesive functions of both the alpha5beta1 and alphaV integrins. In addition, lebectin strongly inhibits both HBMEC in vitro tubulogenesis on Matrigel trade mark (IC(50) = 0.4 nM) and proliferation. Finally, using both a chicken CAM assay and a Matrigel trade mark Plug assay in nude mice, our results show that lebectin displays potent anti-angiogenic activity in vivo. Lebectin thus represents a new C-type lectin with anti-angiogenic properties with great potential for the treatment of angiogenesis-related diseases.

Down-regulation of alpha v/beta 3 integrin via misrouting to lysosomes by overexpression of a beta 3Lamp1 fusion protein.

We present a general strategy for the dominant negative reduction in the levels of type-1 membrane-bound heterodimeric proteins within the secretory pathway through fusion of the soluble ectodomain of one of the partners to the transmembrane-cytosolic tail of the lysosomal protein Lamp1. Thus, in human embryonic kidney (HEK)-293 cells, overexpression of an integrin beta 3Lamp1 chimera resulted in a drastic reduction of its endogenous partner, the integrin alpha v subunit. The mechanism involves the formation in the endoplasmic reticulum of a alpha v/beta 3Lamp1 complex that is subsequently sorted towards a lysosomal/endosomal degradation pathway. The specificity of this approach is afforded by the invariance in the levels of the endogenous integrins alpha 5 and beta1 as compared with control cells. Conversely overexpression of integrin beta 3 in HEK-293 cells led to an increased level of alpha v beta 3 at the cell surface. Functionally beta 3Lamp1 and beta 3 overexpressors exhibit decreased and increased adhesion to vitronectin, respectively, as well as diminished cellular aggregation. The application of this technology should enable the analysis of the functional importance of homodimers or heterodimers in the cell types of choice and the identification of novel partner proteins by proteomic approaches.