N-Cadherin Prodomain Processing Regulates Synaptogenesis

Abstract

Classical cadherins, which are adhesion molecules functioning at the CNS synapse, are synthesized as adhesively inactive precursor proteins in the endoplasmic reticulum (ER). Signal sequence and prodomain cleavage in the ER and Golgi apparatus, respectively, activates their adhesive properties. Here, we provide the first evidence for sorting of nonadhesive precursor N-cadherin (ProN) to the neuronal surface, where it coexists with adhesively competent mature N-cadherin (N-cad), generating a spectrum of adhesive strengths. In cultured hippocampal neurons, a high ProN/N-cad ratio downregulates synapse formation. Neurons expressing genetically engineered uncleavable ProN make markedly fewer synapses. The synapse number can be rescued to normality by depleting surface ProN levels through prodomain cleavage by an exogenous protease. Finally, prodomain processing is developmentally regulated in the rat hippocampus. We conclude that it is the ProN/N-cad ratio and not mature N-cad alone that is critical for regulation of adhesion during synaptogenesis.

MT5-MMP Promotes Alzheimer’s Pathogenesis in the Frontal Cortex of 5xFAD Mice and APP Trafficking in vitro

“…This “soluble fraction” contained cytosolic proteins and proteins easy to solubilize. Cell pellets were resuspended in 25% w/v of 50 mM Tris-HCl pH 7.5 buffer containing 2% SDS, then sonicated and centrifuged at 10000× g for 10 min at 4°C to obtain an “insoluble fraction” containing more insoluble proteins, among which an important part of membrane proteins (Reinés et al, 2012). Protein concentrations were determined using a Bio-Rad DC TM protein assay kit (Bio-Rad, Marnes-La-Coquette, France) and 50 μg of protein were run on 10%–15% SDS-PAGE gels and transferred to nitrocellulose membranes (Amersham Bioscience, Velizy-Villacoublay, France; Py et al, 2014).…”

Cadherins and catenins in dendrite and synapse morphogenesis

“…Contrary to the expectation that proN-cadherin is not localized to cell surface, recent data indicate that not only is proN-cadherin localized to cell surfaces in hippocampal neurons, but also is a critical regulator of synapse formation. 54 Overexpression of a proN-cadherin form inhibits synapse formation concomitant with a reduction in synaptic function.…”

δ-Catenin Regulates Spine Architecture via Cadherin and PDZ-dependent Interactions

“…Given the known role of N-cadherin in regulating synaptic architecture (37)(38)(39) and spine plasticity (40 -42), we examined if ␦-catenin cooperates with N-cadherin to regulate spine architecture. We examined the colocalization of endogenous N-cadherin with EGFP and EGFP-tagged ␦-catenin in cultured rat hippocampal neurons by transfecting EGFP or EGFP-␦-catenin, immunostaining with N-cadherin and confocal microscopy.…”