Functional interplay between ganglioside GM1 and cross-linking galectin-1 induces axon-like neuritogenesis via integrin-based signaling and TRPC5-dependent Ca2+ influx

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Abstract

Axon-like neuritogenesis in neuroblastoma (NG108–15) cells and primary cerebellar granular neurons is furthered by the presence of ganglioside GM1. We describe here that galectin-1 (Gal-1), a homobivalent endogenous lectin, is an effector by cross-linking the ganglioside and its associated glycoprotein α5β1-integrin. The thereby triggered signaling cascade involves autophosphorylation of focal adhesion kinase and activation of phospholipase Cγ and phosphoinositide-3 kinase. This leads to a transient increase in the intracellular Ca2+ concentration by opening of TRPC5 channels, which belong to the signal transduction-gated cation channels. Controls with GM1-defective cells (NG-CR72 and neurons from ganglio-series KO mice) were retarded in axonal growth, underscoring the relevance of GM1 as functional counterreceptor for Gal-1. The lectin's presence was detected in the NG108–15 cells, suggesting an autocrine mechanism of action, and in astrocytes in situ. Gal-1, as cross-linking lectin, can thus translate metabolic conversion of ganglioside GD1a to GM1 by neuraminidase action into axon growth.

Galectin-1 (Gal-1) was shown an effector of axonogenesis in cerebellar granule neurons (CGNs) and NG108–15 cells by cross-linking GM1 ganglioside and its associated glycoprotein α5β1-integrin. The resulting signaling led to a transient increase in intracellular Ca2+ by opening TRPC5 channels. CGNs deficient in GM1 showed retarded axonogenesis, underscoring the relevance of GM1 as functional counterreceptor for Gal-1 in this process. This Gal-1/GM1-induced signaling was manifest only at the earliest, initiating stage of axon development.

Galectin-1 (Gal-1) was shown an effector of axonogenesis in cerebellar granule neurons (CGNs) and NG108–15 cells by cross-linking GM1 ganglioside and its associated glycoprotein α5β1-integrin. The resulting signaling led to a transient increase in intracellular Ca2+ by opening TRPC5 channels. CGNs deficient in GM1 showed retarded axonogenesis, underscoring the relevance of GM1 as functional counterreceptor for Gal-1 in this process. This Gal-1/GM1-induced signaling was manifest only at the earliest, initiating stage of axon development.

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