Revealing Advanced Glycation End Products Associated Structural Changes in Serum Albumin

Abstract

Structural alterations in proteins have a significant impact on their function and body physiology. Glycation via nonenzymatic forms of cross-linking leads to proteins’ conformational changes, the macromolecule being recognized as a stable fibrillary structure, oligomerization, and becoming advanced glycation end products (AGEs). Protein that undergoes glycation-related modifications, namely, β-sheet enriched structural changes, are recognized as amyloid. In the current study, we characterized a single protein modified in vitro under physiological conditions to represent a protein glycation model. The glycation altered the helical conformation of serum albumin (SA) and promoted the formation of a β-sheet enriched with amyloid fibrils detected at multidimensional levels. The nanoscale resolution by spectroscopy in the presence of thioflavin-T (ThT) and 8-anilinonaphthalene-1-sulfonic acid (8-ANS) showed binding of the fibrils formed in the presence of glucose (GLU) and the carbonyl metabolites methylglyoxal (MGO) and glycolaldehyde (GAD). In the presence of MGO and GAD, the SA becomes insoluble aggregates, demonstrated by TEM microscopy and dynamic light scattering (DLS). The protein oligomerization was visualized when separated via SDS gel electrophoresis and mass photometry (MP) assays. Following the glycation, eventually, the material polymerized and became stiffer. The level of stiffness was analyzed by a rheometer that revealed a quick alteration under MGO and GAD. This is the first study to combine multiple spectroscopy assays, imaging, and rheology measurements of SA and to demonstrate a resolution on a nanoscale structural toward better resolution of the conformational changes of glycated SA, oligomerization, and protein aggregations under physiological conditions.

Neutrophil Activation by Mineral Microparticles Coated with Methylglyoxal-Glycated Albumin

“…Oligomerization can be accompanied by significant conformational changes which are significant for RAGE-dependent neutrophil responses. Thus, lately it was shown that modification of BSA influences the stiffness and formation of β-rich fibrils [ 39 ], which are well-known RAGE agonists [ 1 ].…”

Nutrition Alters the Stiffness of Adipose Tissue and Cell Signaling

“…Alterations in the ECM protein’s profile and structural changes can be facilitated by forming advanced glycation products (AGEs) from protein cross-linking via a non-enzymatic glycation process [ 11 ]. As we recently reported for serum albumin, the formation of AGEs and subsequent protein cross-linking increases the stiffness of the protein [ 12 ]. In cellular models and tissues, the accumulation of AGEs affects their activity, signaling pathways, and function [ 13 ].…”

“…Dissected VAT from CHD and HFD-fed mice were measured as was previously described [ 12 ]. The tissues were measured on an HR-3 hybrid Rheometer (TA Instruments, New Castle, DE, USA) used a 8-mm diameter parallel Peltier plate at 25 °C or 37 °C according to ISO 6721-1 method to measure the viscoelasticity and determine the rheological properties of VAT.…”

RAGE signaling regulates the progression of diabetic complications

“…Modification of lysine and arginine during AGE formation renders the protein surface negatively charged, which enables binding to RAGE and amplifies RAGE–mediated inflammation and adhesion. Recently, Nafty et al demonstrated that glycation alters the helical conformation of serum albumin and promotes the formation of β–sheets enriched with amyloid fibrils ( Naftaly et al, 2021 ). Serum albumin becomes insoluble and aggregates during co–incubation with methylglyoxal, glycolaldehyde ( Naftaly et al, 2021 ) and ribose–modified albumin, thereby forming amyloid–like aggregates that induce cytotoxicity ( Wei et al, 2009 ), which is linked to the development of Alzheimer’s disease ( Tu et al, 2016 ).…”

“…Recently, Nafty et al demonstrated that glycation alters the helical conformation of serum albumin and promotes the formation of β–sheets enriched with amyloid fibrils ( Naftaly et al, 2021 ). Serum albumin becomes insoluble and aggregates during co–incubation with methylglyoxal, glycolaldehyde ( Naftaly et al, 2021 ) and ribose–modified albumin, thereby forming amyloid–like aggregates that induce cytotoxicity ( Wei et al, 2009 ), which is linked to the development of Alzheimer’s disease ( Tu et al, 2016 ). There are a wide variety of pathways involved in the formation of AGEs and the other RAGE ligands.…”