Monoclonal Antibody DL11C8 Identifies ADAM23 as a Component of Lipid Raft Microdomains

Abstract

A disintegrin and metalloprotease protein 23 (ADAM23) is a transmembrane type I glycoprotein involved with the development and maintenance of the nervous system, including neurite outgrowth, neuronal adhesion and differentiation and regulation of synaptic transmission. In addition, ADAM23 seems to participate in immune response and tumor establishment through interaction with different members of integrin receptors. Here, we describe a novel monoclonal antibody (DL11C8) that specifically recognizes the cysteine-rich domain of both pre-protein (100 kDa) and mature (70 kDa) forms of ADAM23 from different species, including human, rodents and avian orthologs. Using this antibody, we detected both forms of ADAM23 on the cell surface of three neuronal cell lineages (Neuro-2a, SH-SY5Y and CHLA-20), with a higher relative content of ADAM23^{100 kDa}. Furthermore, we demonstrate for the first time that a catalytically inactive member of the ADAM family is present in the membrane signaling platforms, namely lipid rafts. Indeed, the mature ADAM23^{70 kDa} partitions between raft and non-raft membrane domains, while the pro-protein ADAM23^{100 kDa} is mainly expressed in non-raft domains. These membranous distributions were observed in both different brain regions homogenates and primary cultured neurons lysates from mouse cortex and cerebellum. Taken together, these findings point out ADAM23 as a lipid raft molecular component.

Keywords: ADAM23; disintegrins; integrin; lipid rafts; monoclonal antibody; prion protein.