Red Blood Cell Deformability Is Expressed by a Set of Interrelated Membrane Proteins

Abstract

Red blood cell (RBC) deformability, expressing their ability to change their shape, allows them to minimize their resistance to flow and optimize oxygen delivery to the tissues. RBC with reduced deformability may lead to increased vascular resistance, capillary occlusion, and impaired perfusion and oxygen delivery. A reduction in deformability, as occurs during RBC physiological aging and under blood storage, is implicated in the pathophysiology of diverse conditions with circulatory disorders and anemias. The change in RBC deformability is associated with metabolic and structural alterations, mostly uncharacterized. To bridge this gap, we analyzed the membrane protein levels, using mass spectroscopy, of RBC with varying deformability determined by image analysis. In total, 752 membrane proteins were identified. However, deformability was positively correlated with the level of only fourteen proteins, with a highly significant inter-correlation between them. These proteins are involved in membrane rafting and/or the membrane-cytoskeleton linkage. These findings suggest that the reduction of deformability is a programmed (not arbitrary) process of remodeling and shedding of membrane fragments, possibly mirroring the formation of extracellular vesicles. The highly significant inter-correlation between the deformability-expressing proteins infers that the cell deformability can be assessed by determining the level of a few, possibly one, of them.

Keywords: RBC deformability; lipid rafts; membrane proteins; membrane remodeling; membrane vesicles; red blood cells.

Figure 1

Correlation between the level of ezrin (expressed by the value of Ln (LFQ)) in RBC membrane and cell deformability, expressed by the average elongation ratio (AER). r = 0.83; p = 0.00006.

Figure 2

Distribution of the deformability (AER, (A)) and the membrane ezrin level (B) in the RBC samples.

Figure 3

RBC deformability, expressed by AER measured directly by the image analysis (by the CFA) vs. AER calculated by the cell membrane ezrin level. r = 0.83, p = 0.00006.

Figure 4

RBC deformability, expressed by AER, measured directly by image analysis (using the CFA) vs. AER calculated by the combined levels of ezrin and protein 4.1 in the cell membrane (using a two-parametric linear regression model). r = 0.877, p = 0.00006.

Figure 5

Scheme of the Cell Flow-properties Analyzer (CFA).