Abstract
BackgroundThe glycosylation of proteins on the surface of corneocytes is believed to play an important role in cellular adhesion in the stratum corneum (SC) of human skin. Mapping with accuracy the localization of glycans on the surface of corneocytes through traditional methods of immunohistochemistry and electron microscopy remains a challenging task as both approaches lack enough resolution or need to be performed in high vacuum conditions.Materials and methodsWe used an advanced mode of atomic force microscope (AFM), with simultaneous topography and recognition imaging to investigate the distribution of glycans on native (no chemical preparation) stripped samples of human SC. The AFM cantilever tips were functionalized with anti‐heparan sulfate antibody and the lectin wheat germ agglutinin (WGA) which binds specifically to N‐acetyl glucosamine and sialic acid.ResultsFrom the recognition imaging, we observed the presence of the sulfated glycosaminoglycan, heparan sulfate, and the glycans recognized by WGA on the surface of SC corneocytes in their native state. These glycans were found associated with bead‐like domains which represent corneodesmosomes in the SC layers. Glycan density was calculated to be ~1200 molecules/μm2 in lower layers of SC compared to an important decrease, (~106 molecules/μm2) closer to the surface due probably to corneodesmosome degradation.ConclusionGlycan spatial distribution and degradation is first observed on the surface of SC in native conditions and at high resolution. The method used can be extended to precisely localize the presence of other macromolecules on the surface of skin or other tissues where the maintenance of its native state is required.
Highlights
The glycosylation of cell membrane proteins plays an important role in cell-cell interactions, cell adhesion, proliferation, differentiation, morphogenesis, remodeling of the extracellular matrix, hydration, antimicrobial activity,[1,2] and modulation of inflammatory responses.[3]
In the stratum corneum of human skin (Figure 1), protein glycosylation has been postulated to play an important role in the desquamation process, the shedding of corneocytes from the surface of the skin, since glycan moieties have been demonstrated to protect the corneodesmosomes from proteolysis.[7]
The presence of heparan sulfate on the surface on corneocytes was investigated on stripped abdominal stratum corneum (SC) samples using single molecular recognition force spectroscopy,[14] for which the cantilever tips were functionalized with an anti-heparan sulfate antibody (Figure 2)
Summary
The glycosylation of cell membrane proteins plays an important role in cell-cell interactions, cell adhesion, proliferation, differentiation, morphogenesis, remodeling of the extracellular matrix, hydration, antimicrobial activity,[1,2] and modulation of inflammatory responses.[3]. The presence of heparan sulfate on the surface on corneocytes was investigated on stripped abdominal SC samples using single molecular recognition force spectroscopy,[14] for which the cantilever tips were functionalized with an anti-heparan sulfate antibody (Figure 2).
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