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Senescent cells accumulate in various peripheral tissues during aging and have been shown to exacerbate age-related inflammatory responses. We recently showed that exposure to neurotoxic amyloid β (Aβ1-42) oligomers can readily induce a senescence phenotype in human brain microvascular endothelial cells (HBMECs). In the present work, we used atomic force microscopy (AFM) to further characterize the morphological properties such as cell membrane roughness and cell height and nanomechanical properties such as Young's modulus of the membrane (membrane stiffness) and adhesion resulting from the interaction between AFM tip and cell membrane in Aβ1-42 oligomer-induced senescent human brain microvascular endothelial cells. Morphological imaging studies showed a flatter and spread-out nucleus in the senescent HBMECs, both characteristic features of a senescent phenotype. Furthermore, the mean cell body roughness and mean cell height were lower in senescent HBMECs compared to untreated normal HBMECs. We also observed increased stiffness and alterations in the adhesion properties in Aβ1-42 oligomer-induced senescent endothelial cells compared to the untreated normal HBMECs suggesting dynamic reorganization of cell membrane. We then show that vascular endothelial growth factor receptor 1 (VEGFR-1) knockdown or overexpression of Rho GTPase Rac 1 in the endothelial cells inhibited senescence and reversed these nanomechanical alterations, confirming a direct role of these pathways in the senescent brain endothelial cells. These results illustrate that nanoindentation and topographic analysis of live senescent brain endothelial cells can provide insights into cerebrovascular dysfunction in neurodegenerative diseases such as Alzheimer's disease.
This article was published in the following journal.
Name: Biochimica et biophysica acta. Biomembranes
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A type of extracellularly deposited substance composed of an amyloid protein and additional components including HEPARAN SULFATE PROTEOGLYCAN; LAMININ; COLLAGEN TYPE IV; SERUM AMYLOID P-COMPONENT; and APOLIPOPROTEINS E which together form characteristic amyloid fibrils. The core of amyloid fibrils is formed by the stacking of overlapping beta-pleated sheet domains of the amyloid protein. There are many different amyloid proteins that have been found forming the core of the fibrils in vivo. However, amyloid can be formed from any protein that exposes beta-pleated strand conformations during unfolding or refolding. A common characteristic of amyloid is the ability to bind such dyes as CONGO RED and thioflavine.
A precursor to the AMYLOID BETA-PROTEIN (beta/A4). Alterations in the expression of the amyloid beta-protein precursor (ABPP) gene, located on chromosome 21, plays a role in the development of the neuropathology common to both ALZHEIMER DISEASE and DOWN SYNDROME. ABPP is associated with the extensive extracellular matrix secreted by neuronal cells. Upon cleavage, this precursor produces three proteins of varying amino acid lengths: 695, 751, and 770. The beta/A4 (695 amino acids) or beta-amyloid protein is the principal component of the extracellular amyloid in senile plaques found in ALZHEIMER DISEASE; DOWN SYNDROME and, to a limited extent, in normal aging.
Peptides generated from AMYLOID BETA-PEPTIDES PRECURSOR. An amyloid fibrillar form of these peptides is the major component of amyloid plaques found in individuals with Alzheimer's disease and in aged individuals with trisomy 21 (DOWN SYNDROME). The peptide is found predominantly in the nervous system, but there have been reports of its presence in non-neural tissue.
A pancreatic beta-cell hormone that is co-secreted with INSULIN. It displays an anorectic effect on nutrient metabolism by inhibiting gastric acid secretion, gastric emptying and postprandial GLUCAGON secretion. Islet amyloid polypeptide can fold into AMYLOID FIBRILS that have been found as a major constituent of pancreatic AMYLOID DEPOSITS.
Endopeptidases that are specific for AMYLOID PROTEIN PRECURSOR. Three secretase subtypes referred to as alpha, beta, and gamma have been identified based upon the region of amyloid protein precursor they cleave.
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