Glycolipid biointerface to decipher disease-implicated ganglioside-protein interactions

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Glycolipid biointerface to decipher disease-implicated ganglioside-protein interactions All cells in the human body, including neurons, immune cells, epithelial cells, and blood cells, are coated with a dense layer of glycoproteins and glycolipids known as the glycocalyx. The extraordinary complexity in structural organization and biosynthesis of the glycocalyx has made it very difficult to comprehend the precise roles it plays in various cellular processes and thus limited its potential as therapeutic target. An important family of molecules of the glycocalyx is gangliosides, which participate in a wide array of intercellular events such as modulating killer cell toxicity, controlling neural regeneration, and promoting cell adhesion during inflammation. Gangliosides are found to play important roles in altering and mediating affinity properties of the membrane proteins in certain cancers, and are clearly implicated in insulin-resistant type 2 diabetes. However, the biochemical mechanisms of gangliosides’ effect on tumor and type 2 diabetes appear to be extremely complex, and a major portion of ganglioside pathology remains elusive. Lack of suitable techniques is a main obstacle that has principally limited the research on gangliosides and restricted our ability to understand their roles on protein function. We propose to build a highly effective, glyco-diverse, biomimetic membrane interface system and a new bioanalytical platform to study the ganglioside-protein interactions implicated in several diseases at the molecular level. A ganglioside library will be created for construction of interface mimics with precisely controlled glycan moiety, composition and packing biophysics as observed in those disease states. The proposed approach bypasses complex endogenous synthesis of gangliosides, and creates a novel hosting environment with programmed tuning in ganglioside makeups for elucidating structure- function relationships with the membrane proteins. The effect of gangliosides on protein interactions will be primarily investigated by surface plasmon resonance (SPR) spectroscopy, which quantifies molecular binding and affinity changes under systematically varied composition and headgroup moiety (Aim 1). We will then study and understand the inhibitory/promoting function of gangliosides on proteins EGFR and VEGFR, angiogenic activators linked to progression of cancer (Aim 2), and on interactions of insulin, insulin receptor and caveolin-1 (Aim 3), a key system implicated in insulin-resistant type 2 diabetes.