21 These MAPKs are induced by cytokines and stressors. Further down in the signal transduction cascade, transcription factors like

nuclear factor-kappaB are also activated. Therefore, ligand-RAGE interaction activates NF-κB through these MAPKs signalling pathway. The SRT1720 mouse cascade of signal transduction depends on the binding of AGEs to RAGE, as blocking RAGE with either an excess of sRAGE or anti-RAGE antibody prevents cellular activation.22 The RAGE is composed of 404 AA.23 It contains an extracellular part with 320 AA, a single transmembrane domain with 21 AA and a short cytoplasmic Inhibitors,research,lifescience,medical domain with 40 AA.24 The extracellular part is composed of a variable domain and two constant (C) domains.25 It has 94 AA in Ig-like V-type domain, 98 AA in Ig-like C2-type 1 domain and 91 AA in Ig-like C2-type 2 domain. Alternative

splicing plays a major role in the production of different RAGE isoforms.23 Inhibitors,research,lifescience,medical During alternative RNA splicing, exons Inhibitors,research,lifescience,medical or introns could be retained or removed in different combinations. This process produces different proteins with unique characteristics.26 Over 20 different splice variants of human RAGE have been identified to date.27 Generally there are four main RAGE isoforms: full length -RAGE, N-terminal truncated -RAGE,endogenous secretary (Es)-RAGE, and soluble (s)-RAGE (figure 2). These isoforms are the product of alternative splicing. Different splice variants of RAGE in human brain 28 are shown in figure 2. Soluble-RAGE and Es-RAGE have similar patterns; however, Inhibitors,research,lifescience,medical s-RAGE may have some differences compared with Es-RAGE in some AA. Soluble-RAGE is also a product of recombinant technology as well as the cleavage of cell surface RAGE by extracellular metalloproteinases.29 Soluble-RAGE and Es-RAGE do not have the cytoplasmic and transmembrane domains of FL-RAGE.30,31 This intron includes a stop codon in the sequence. Inhibitors,research,lifescience,medical Because of this stop codon, s-RAGE lacks exon 10 and 11. This sequence encodes the transmembrane domain of FL-RAGE;

therefore, s-RAGE lacks the transmembrane and cytoplasmic domain. Soluble-RAGE contains V, C1 and C2 domains.32 The Nt-RAGE mRNA contains intron 1. Intron 1 contains a stop codon. This stop codon results in the loss of exon 1 and 2. Hence, it lacks the V-type domain unless of FL-RAGE. It cannot act as a FL-RAGE and different ligands cannot bind to Nt-RAGE.28 The ligands of RAGE such as amphoterin, S100B and Aβ oligomer bind to V domain, however, some ligands such as Aβ also bind to C domain.33 Moreover, there are two N-glycosylation sites in and close to the AGE binding domain. Osawa et al,34 showed that a G82S mutation in the second N-glycosylation motif increased the AGEs affinity in COS-7 cells.