In chronic immune thrombocytopenic purpura (ITP), autoantibodies bind to platelet surface proteins, particularly alphaIIb, resulting in platelet destruction by the reticulo-endothelial system. In order to better localize the autoepitopes on alphaIIb, we studied the binding of antibodies to Chinese hamster ovary (CHO) cells expressing either alphaIIbbeta3 or alphaIIb-alphavbeta3 chimaeras in which a segment of alphaIIb (either amino acids L1-Q459, L1-F223 or F223-Q459) was substituted for that portion of alphav. We evaluated platelet-associated autoantibodies from 14 ITP patients with alphaIIb-dependent antibodies. Ten of 14 bound to alphaIIb (L1-Q459)-alphavbeta3, showing that autoepitopes were often localized to this region of alphaIIb. In addition, each of the autoantibodies binding to alphaIIb (L1-Q459)-alphavbeta3, also bound to CHO cells expressing either alphaIIb(L1-F223)-alphavbeta3 or alphaIIb(F223-Q459)-alphavbeta3). In two of the three eluates tested, > 95% of the autoantibody binding to alphaIIb could be adsorbed using CHO cells expressing any of the three chimaeras, showing that the epitope(s) have contact points on either side of amino acid F223; in the third eluate, only a portion ( approximately 40%) could be adsorbed by the chimaeric cell lines showing that, in this patient, an additional antibody was also present, directed to a site distal to amino acid Q459. The remaining four eluates bound to CHO cells expressing alphaIIbbeta3 but to none of the chimaeras, suggesting that these epitopes are also distal to amino acid Q459. We conclude that the binding of many anti-alphaIIbbeta3 autoantibodies is dependent on the presence of alphaIIb amino acids L1-Q459.

Download full-text PDF

Source
http://dx.doi.org/10.1046/j.1365-2141.2002.03751.xDOI Listing

Publication Analysis

Top Keywords

cho cells
16
cells expressing
16
alphaiib amino
12
amino acids
12
amino acid
12
alphaiib
9
chronic immune
8
immune thrombocytopenic
8
thrombocytopenic purpura
8
expressing alphaiibbeta3
8

Similar Publications

Unlabelled: Engineered three-dimensional (3D) tissue culture platforms are useful for reproducing and elucidating complex in vivo biological phenomena. Spheroids, 3D aggregates of living cells, are produced based on physicochemical or microfabrication technologies and are commonly used even in cancer pathology research. However, conventional methods have difficulties in constructing 3D structures depending on the cell types, and require specialized techniques/lab know-how to reproducibly control the spheroid size and shape.

View Article and Find Full Text PDF

Protective effect of CK2 against endoplasmic reticulum stress in pancreatic β cells.

Diabetol Int

January 2025

Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, 7-5-2, Kusunoki-cho, Chuo-ku, Kobe, 650-0017 Japan.

Unlabelled: Endoplasmic reticulum (ER) stress due to obesity or systemic insulin resistance is an important pathogenic factor that could lead to pancreatic β-cell failure. We have previously reported that CCAAT/enhancer-binding protein β (C/EBPβ) is highly induced by ER stress in pancreatic β cells. Moreover, its accumulation hampers the response of these cells to ER stress by inhibiting the induction of the molecular chaperone 78 kDa glucose-regulated protein (GRP78).

View Article and Find Full Text PDF

Alzheimer's disease (AD) is a debilitating neurodegenerative disease that is marked by profound neurovascular dysfunction and significant cell-specific alterations in the brain vasculature. Recent advances in high throughput single-cell transcriptomics technology have enabled the study of the human brain vasculature at an unprecedented depth. Additionally, the understudied niche of cerebrovascular cells, such as endothelial and mural cells, and their subtypes have been scrutinized for understanding cellular and transcriptional heterogeneity in AD.

View Article and Find Full Text PDF

Lysophagy eliminates damaged lysosomes and is crucial to cellular homeostasis; however, its underlying mechanisms are not entirely understood. We screen a ubiquitination-related compound library and determine that the substrate recognition component of the SCF-type E3 ubiquitin ligase complex, SCF(FBXO3), which is a critical lysophagy regulator. Inhibition of FBXO3 reduces lysophagy and lysophagic flux in response to L-leucyl-L-leucine methyl ester (LLOMe).

View Article and Find Full Text PDF

Mangiferin Protects Mesenchymal Stem Cells Against DNA Damage and Cellular Aging via SIRT1 Activation.

Mech Ageing Dev

January 2025

Department of Biological Science, College of Natural Science, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea; BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Republic of Korea; The Basic Science Institute of Chosun University, Chosun University, Gwangju 61452, Republic of Korea. Electronic address:

The protective effects of mangiferin (MAG) against etoposide- and high glucose (HG)-induced DNA damage and aging were investigated in human bone marrow-mesenchymal stem cells (hBM-MSCs). Etoposide, a topoisomerase II inhibitor, was used to induce double-strand breaks (DSBs) in hBM-MSCs, resulting in increased genotoxicity, elevated levels of the DNA damage sensor ATM and CDKN1A, and decreased levels of the aging markers H3 and H4. MAG activated AMPK and SIRT1, thus protecting against DSB-induced damage.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!