CHO cell aggregation induced by fibronectin-coated beads. Differences between wild-type and adhesion-variant cells

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• Chinese Hamster Ovary (CHO) cells are a common host for recombinant protein production.
• Fibronectin (Fn) is a key extracellular matrix protein involved in cell adhesion and signaling.
• ADvF11 is a CHO cell variant exhibiting defective adhesion to fibronectin-coated surfaces.

Purpose of the Study:

• To investigate the mechanism underlying the fibronectin (Fn) aggregation defect in ADvF11 (F11) cells.
• To determine if the defect in F11 cells is related to initial fibronectin binding or subsequent cellular processes.

Main Methods:

• Comparing fibronectin (Fn) bead binding and aggregation between F11 and wild-type (WT) CHO cells.
• Assessing the effect of temperature, formaldehyde fixation, and pharmacological inhibitors (colchicine, tetracaine, cytochalasin B) on Fn-mediated aggregation.

Main Results:

• Both F11 and WT cells demonstrated similar binding of 3H-Fn beads.
• Only WT cells, not F11 cells, aggregated in the presence of Fn beads, indicating an aggregation defect.
• Fn-bead-mediated aggregation was temperature-dependent and required viable cells, but was not blocked by tested inhibitors.
• Both cell types aggregated similarly with lectins.

Conclusions:

• ADvF11 (F11) cells possess functional surface membrane-binding sites for fibronectin (Fn).
• The aggregation defect in F11 cells occurs downstream of initial Fn binding but upstream of the cytoskeletal rearrangements necessary for adhesion.
• This highlights a specific defect in Fn-mediated cell-cell interactions in the F11 variant.