How adhesion/growth-regulatory galectins-1 and -3 attain cell specificity: case study defining their target on neuroblastoma cells (SK-N-MC) and marked affinity regulation by affecting microdomain organization of the membrane.
Galectins are potent effectors with conspicuous cell-type-specific activity profile. Its occurrence poses the question on the nature of the underlying biochemical determinants, in human SK-N-MC neuroblastoma cells involved in negative growth regulation. Since increase of surface presentation of ganglioside GM1 and homodimeric galectin-1 precedes growth inhibition, a direct interaction is suggested. We thus examined cell binding depending on glucosylceramide synthesis. It was drastically reduced by N-butyldeoxynojirimycin and threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, adding decisive evidence for the assumed galectin/ganglioside binding. Glycoproteins do not compensate ganglioside depletion which was verified by measuring lipid-bound sialic acid. Binding affinity is significantly lowered by disrupting microdomain integrity, also effective for the competitive inhibitor galectin-3. This was caused by cell treatment with either 2-hydroxypropyl-beta-cyclodextrin or filipin III. In this cell system, target specificity and topology of ligand presentation act together to enable high-affinity binding.
Kopitz
Jürgen
J
Pathologisches Institut, Abteilung für Angewandte Tumorbiologie, Ruprecht-Karls-Universität, Im Neuenheimer Feld 220, Heidelberg, Germany. juergen.kopitz@med.uni-heidelberg.de
Bergmann
Marion
M
Gabius
Hans-Joachim
HJ
D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives / Q000494:pharmacology; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002448:Cell Adhesion; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005079:Excipients / Q000494:pharmacology; D005372:Filipin / Q000494:pharmacology; D005677:G(M1) Ganglioside / Q000378:metabolism; D037483:Galectin 1 / Q000378:metabolism*; D037502:Galectin 3 / Q000378:metabolism*; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009447:Neuroblastoma / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D047392:beta-Cyclodextrins / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D005079:Excipients; D037483:Galectin 1; D037502:Galectin 3; D065089:Glycoside Hydrolase Inhibitors; C445499:LGALS1 protein, human; D009025:Morpholines; D047392:beta-Cyclodextrins; D017485:1-Deoxynojirimycin; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D005677:G(M1) Ganglioside; C033110:RV 538; D005372:Filipin; C059896:miglustat