The receptor for advanced glycation end-products (RAGE) is a single-transmembrane, multiligand receptor of the immunoglobulin superfamily. RAGE up-regulation is implicated in numerous pathological states including vascular disease, diabetes, cancer, and neurodegeneration. The understanding of the regulation of RAGE is important in both disease pathogenesis and normal homeostasis. Here, we demonstrate the characterization and identification of human RAGE splice variants by analysis of RAGE cDNA from tissue and cells. We identified a vast range of splice forms that lead to changes in the protein coding region of RAGE, which we have classified according to the Human Gene Nomenclature Committee (HGNC). These resulted in protein changes in the ligand-binding domain of RAGE or the removal of the transmembrane domain and cytosolic tail. Analysis of splice variants for premature termination codons reveals approximately 50% of identified variants are targeted to the nonsense-mediated mRNA decay pathway. Expression analysis revealed the RAGE_v1 variant to be the primary secreted soluble isoform of RAGE. Taken together, identification of functional splice variants of RAGE underscores the biological diversity of the RAGE gene and will aid in the understanding of the gene in the normal and pathological state.

Cellular migration is a fundamental process linked to diverse pathological states such as diabetes and its complications, atherosclerosis, inflammation, and cancer. The receptor for advanced glycation end products (RAGE) is a multiligand cell surface macromolecule which binds distinct ligands that accumulate in these settings. RAGE-ligand interaction evokes central changes in key biological properties of cells, including proliferation, generation of inflammatory mediators, and migration. Although RAGE-dependent signal transduction is critically dependent on its short cytoplasmic domain, to date the proximate mechanism by which this RAGE domain engages and stimulates cytoplasmic signaling pathways has yet to be identified. Here we show that the RAGE cytoplasmic domain interacts with Diaphanous-1 (Dia-1) both in vitro and in vivo. We employed the human RAGE cytoplasmic domain as "bait" in the yeast two-hybrid assay and identified the formin homology (FH1) domain of Dia-1 as a potential binding partner of this RAGE domain. Immunoprecipitation studies revealed that the RAGE cytoplasmic domain interacts with the FH1 domain of Dia-1. Down-regulation of Dia-1 expression by RNA interference blocks RAGE-mediated activation of Rac-1 and Cdc42 and, in parallel, RAGE ligand-stimulated cellular migration. Taken together, these findings indicate that the interaction of the RAGE cytoplasmic domain with Dia-1 is required to transduce extracellular environmental cues evoked by binding of RAGE ligands to their cell surface receptor, a chief consequence of which is Rac-1 and Cdc42 activation and cellular migration. Because RAGE and Dia-1 are implicated in the regulation of inflammatory, vascular, and transformed cell migration, these findings highlight this interaction as a novel target for therapeutic intervention in inflammation, atherosclerosis, diabetes, and cancer.The receptor for advanced glycation end products (RAGE) 5 is a multiligand cell surface macromolecule of the immunoglobulin superfamily which binds diverse ligands, including advanced glycation end products (1), S100/calgranulins (2), high mobility group Box-1 (HMGB1) (3), amyloid-␤ peptide (A␤), and ␤-sheet fibrils (4). RAGE-ligand interaction evokes central changes in cellular properties including stimulation of cellular migration (2, 5-7). Extensive evidence suggests that pharmacological antagonism or genetic modulation of RAGE exerts protection against disease states characterized by up-regulation and accumulation of RAGE ligands, such as the complications of diabetes, atherosclerosis, inflammation, and tumors (2, 7-9).Our studies have definitively shown that the ligands of RAGE are not simply tethered to this receptor. Rather, studies in vitro and in vivo indicate that RAGE is a signal transduction receptor for these ligand families (6, 9, 10). Both in vitro and in vivo experiments reveal that deletion of the short cytoplasmic domain of RAGE exerts a "dominant negative" (DN) effect in which the signal transduction response to RAGE ligand is blunted (5-7). Stu...

The alternative splicing of pre-mRNAs is a critical mechanism in genomic complexity, disease, and development. Studies of the receptor for advanced glycation end-products (RAGE) indicate that this gene undergoes a variety of splice events in humans. However, no studies have extensively analyzed the tissue distribution in other species or compared evolutionary differences of RAGE isoforms. Because the majority of studies probing RAGE function have been performed in murine models, we therefore performed studies to identify and characterize the splice variants of the murine RAGE gene, and we compared these to human isoforms. Here, using mouse tissues, we identified numerous splice variants including changes in the extracellular domain or the removal of the transmembrane and cytoplasmic domains, which produce soluble splice isoforms. Comparison of splice variants between humans and mice revealed homologous regions in the RAGE gene that undergo splicing as well as key species-specific mechanisms of splicing. Further analysis of tissue splice variant distribution in mice revealed major differences between lung, kidney, heart, and brain. To probe the potential impact of disease-like pathological states, we studied diabetic mice and report that RAGE splice variation changed dramatically, resulting in an increase in production of soluble RAGE (sRAGE) splice variants, which were not associated with detectable levels of sRAGE in murine plasma. In conclusion, we have determined that the murine RAGE gene undergoes extensive splicing with distinct splice isoforms being uniquely distributed in different tissues. These differences in RAGE splicing in both physiological and pathogenic states further expand our understanding of the biological repertoire of this receptor in health and disease.

Interleukin-1β (IL-1β) is a pleiotropic cytokine that exerts multiple roles in both physiological and pathological conditions. It is produced by different cell subsets, and drives a wide range of inflammatory responses in numerous target cells. Enhanced IL-1β signaling is a common event in patients of hematological malignancies. Recent body of evidence obtained in preclinical models shows the pathogenic role of these alterations, and the promising therapeutic value of IL-1 targeting. In this review, we further highlight a potential contribution of IL-1β linking to complications and autoimmune disease that should be investigated in future studies. Hence, drugs that target IL-1 may be helpful to improve outcome or reduce morbidity in patients. Some of them are FDA-approved, and used efficiently against autoimmune diseases, like IL-1 receptor antagonist. In the clinic, however, this agent seems to have limited properties. Current improved drugs will allow to determine the true potential of IL-1 and IL-1β targeting as therapy in hematological malignancies and their related complications.

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