Differentiation-dependent glycosylation of cells in squamous cell epithelia detected by a mammalian lectin.
The squamous stratified epithelia contain a proliferative (harboring mitotic activity) and a differentiating compartment. Due to the potential of protein-carbohydrate interactions to regulate cellular activities we introduced a mammalian lectin to cyto- and histochemical analysis. We answer the questions of whether and to what extent this new probe can pinpoint differentiation-dependent glycosylation changes in sections and in culture of keratinocytes.


METHODS
Purification and labeling enabled monitoring of galectin-3 reactivity in frozen sections of human and pig epidermis and basal cell carcinomas as well as in culture of keratinocytes. The staining pattern of the lectin was correlated with the staining profile of other cell markers including desmosomal proteins, beta(1) integrin, and the proliferation marker Ki-67. The Dolichos biflorus agglutinin (DBA) sharing binding reactivity of galectin-3 to the A type histoblood group epitope was used for comparison.


RESULTS
Both lectins exhibit suprabasal binding. However, their profiles were not identical, substantiated by lack of coinhibition. Strong DBA reactivity was also observed in a limited number of basal layer cells, namely in cells without the expression of the proliferation marker Ki-67. Cultured mitotic epidermal cells have no reactivity for DBA. Presence of ligands for this plant lectin was connected with decreased positivity of nuclei for Ki-67 and the occurrence of ring-shaped nucleoli, micronucleoli or absence of nucleoli. Considering colocalization the pattern of galectin-3-binding sites coincided with the presence of desmosomal proteins such as desmoplakin-1 and desmoglein but not beta(1) integrin, a potential ligand. Interestingly, studied basal cell carcinomas expressed no binding sites for galectin-3, while a limited number of cells were DBA-reactive.


CONCLUSIONS
The expression of galectin-3-binding sites and also DBA-reactive glycoligands correlates with an increased level of differentiation and/or cessation of proliferation in the examined squamous stratified epithelia. Further application of tissue lectins for characterizing ligand expression and its modulation is an important step to reveal functional relevance.
Plzák
Jan
J
Institute of Anatomy, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
Holíková
Zuzana
Z
Smetana
Karel
K
Dvoránková
Barbora
B
Hercogová
Jana
J
Kaltner
Herbert
H
Motlík
Jan
J
Gabius
Hans-Joachim
HJ
D000818:Animals; D001665:Binding Sites; D002280:Basal Cell Carcinoma / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D051182:Desmogleins; D051180:Desmoplakins; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D004848:Epithelium / Q000502:physiology*; D037502:Galectin 3 / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1 / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D051379:Mice; D037121:Plant Lectins / Q000378:metabolism; D011485:Protein Binding; D012878:Skin Neoplasms / Q000378:metabolism; D013552:Swine
D003598:Cytoskeletal Proteins; C495294:DSP protein, human; D051182:Desmogleins; D051180:Desmoplakins; C495295:Dsp protein, mouse; D037502:Galectin 3; D019012:Integrin beta1; D019394:Ki-67 Antigen; D037121:Plant Lectins; C036554:dolichos biflorus agglutinin; D007633:Keratins