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Updated: Jul 5, 2026
Determining Cell-surface Expression and Endocytic Rate of Proteins in Primary Astrocyte Cultures Using Biotinylation
Published on: July 3, 2017
Detection of a hypersialylated beta1 integrin endogenously expressed in the human astrocytoma cell line A172
Petr Bartik1, Anne Maglott, Gustav Entlicher
1Département de Pharmacologie et Physicochimie, UMR 7175 CNRS, Université Louis Pasteur-Strasbourg I, Faculté de Pharmacie, BP 60024, 67401 Illkirch, France.
Abstract:
Gliomas are the most common deadly brain tumors. Human cerebral tumors express high level of alpha5beta1 integrins. As a potential new target, alpha5beta1 was investigated here in two human astrocytoma cell lines, A172 and U87MG. We found that a hypersialylated beta1 integrin was endogenously expressed in A172 cells. It forms heterodimers with alpha5 subunits, localizes at the cell membrane and allows adhesion to fibronectin. This form of beta1 integrin was only recognized by the 9EG7 anti-beta1 antibody and appeared devoid of other specific antibody epitopes (12G10, TS2/16 and mAb13 shown here to be N-glycosylation sensitive). Overexpression of the beta1 integrin subunit in A172 cells not only increased the hypersialylated form but also led to the appearance of a non-hypersialylated beta1 form also addressed to the cell surface. Compared to wild-type A172 cells, beta1-A172 cells showed increased adhesion to fibronectin and decreased sensitivity to SJ749, a non-peptidic alpha5beta1 antagonist. In addition, beta1-A172 cells exhibited increased matrix dependence for normal cell cycling. Collectively, the data add new evidence for the role of beta1 glycosylation/sialylation in the regulation of integrin functions.
Insights
Altered beta1 integrin glycosylation in brain tumor cells affects fibronectin adhesion and cell cycling. This research highlights beta1 integrin sialylation as a key regulator of integrin function in gliomas.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Gliomas are aggressive brain tumors with limited treatment options.
- Alpha5beta1 integrins are highly expressed in human brain tumors, presenting a potential therapeutic target.
- Integrin function is modulated by post-translational modifications, including glycosylation.
Purpose of the Study:
- To investigate the role of alpha5beta1 integrins in human astrocytoma cell lines.
- To characterize the expression and function of a hypersialylated beta1 integrin in A172 cells.
- To explore the impact of beta1 integrin overexpression on cell adhesion and proliferation.
Main Methods:
- Utilized human astrocytoma cell lines (A172, U87MG).
- Analyzed beta1 integrin expression and glycosylation using specific antibodies (9EG7, 12G10, TS2/16, mAb13).
- Assessed cell adhesion to fibronectin and sensitivity to alpha5beta1 antagonist SJ749.
- Investigated matrix dependence for cell cycling.
Main Results:
- A hypersialylated beta1 integrin, recognized by 9EG7, was endogenously expressed in A172 cells and localized to the cell membrane.
- Overexpression of beta1 integrin in A172 cells increased both hypersialylated and non-hypersialylated forms at the cell surface.
- Beta1-overexpressing cells showed enhanced fibronectin adhesion, reduced sensitivity to an alpha5beta1 antagonist, and increased matrix dependence for cell cycling.
Conclusions:
- Beta1 integrin glycosylation/sialylation significantly regulates alpha5beta1 integrin function.
- Hypersialylated beta1 integrin plays a role in glioma cell adhesion and matrix interactions.
- Targeting beta1 integrin glycosylation may offer a novel therapeutic strategy for gliomas.
