RET PLCγ Phosphotyrosine Binding Domain Regulates Ca2+ Signaling and Neocortical Neuronal Migration

The receptor tyrosine kinase RET plays an essential role during embryogenesis in regulating cell proliferation, differentiation, and migration. Upon glial cell line-derived neurotrophic factor (GDNF) stimulation, RET can trigger multiple intracellular signaling pathways that in concert activate various downstream effectors. Here we report that the RET receptor induces calcium (Ca2+) signaling and regulates neocortical neuronal progenitor migration through the Phospholipase-C gamma (PLCγ) binding domain Tyr1015. This signaling cascade releases Ca2+ from the endoplasmic reticulum through the inositol 1,4,5-trisphosphate receptor and stimulates phosphorylation of ERK1/2 and CaMKII. A point mutation at Tyr1015 on RET or small interfering RNA gene silencing of PLCγ block the GDNF-induced signaling cascade. Delivery of the RET mutation to neuronal progenitors in the embryonic ventricular zone using in utero electroporation reveal that Tyr1015 is necessary for GDNF-stimulated migration of neurons to the cortical plate. These findings demonstrate a novel RET mediated signaling pathway that elevates cytosolic Ca2+ and modulates neuronal migration in the developing neocortex through the PLCγ binding domain Tyr1015

Myeloperoxidase and urate in patients with heart failure and preserved ejection fraction

International audienceConference: Congress of the European-Society-of-Cardiology (ESC) Location: Rome, ITALY Date: AUG 27-31, 201

The major determinant of the heparin binding of glial cell-line-derived neurotrophic factor is near the N-terminus and is dispensable for receptor binding

GDNF (glial cell-line-derived neurotrophic factor), and the closely related cytokines artemin and neurturin, bind strongly to heparin. Deletion of a basic amino-acid-rich sequence of 16 residues N-terminal to the first cysteine of the transforming growth factor β domain of GDNF results in a marked reduction in heparin binding, whereas removal of a neighbouring sequence, and replacement of pairs of other basic residues with alanine had no effect. The heparin-binding sequence is quite distinct from the binding site for the high affinity GDNF polypeptide receptor, GFRα1 (GDNF family receptor α1), and heparin-bound GDNF is able to bind GFRα1 simultaneously. The heparin-binding sequence of GDNF is dispensable both for GFRα1 binding, and for activity for in vitro neurite outgrowth assay. Surprisingly, the observed inhibition of GDNF bioactivity with the wild-type protein in this assay was still found with the deletion mutant lacking the heparin-binding sequence. Heparin neither inhibits nor potentiates GDNF–GFRα1 interaction, and the extracellular domain of GFRα1 does not bind to heparin itself, precluding heparin cross-bridging of cytokine and receptor polypeptides. The role of heparin and heparan sulfate in GDNF signalling remains unclear, but the present study indicates that it does not occur in the first step of the pathway, namely GDNF–GFRα1 engagement

Hirschsprung associated GDNF mutations do not prevent RET activation

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