title: Teaming up synthetic chemistry and histochemistry for activity screening in galectin-directed inhibitor design.
abstract: A hallmark of endogenous lectins is their ability to select a few distinct glycoconjugates as counterreceptors for functional pairing from the natural abundance of cellular glycoproteins and glycolipids. As a consequence, assays to assess inhibition of lectin binding should necessarily come as close as possible to the physiological situation, to characterize an impact of a synthetic compound on biorelevant binding with pharmaceutical perspective. We here introduce in a proof-of-principle manner work with sections of paraffin-embedded tissue (jejunum, epididymis) and labeled adhesion/growth-regulatory galectins, harboring one (galectin-1 and galectin-3) or two (galectin-8) types of lectin domain. Six pairs of synthetic lactosides from tailoring of the headgroup (3'-O-sulfation) and the aglycone (β-methyl to aromatic S- and O-linked extensions) as well as three bi- to tetravalent glycoclusters were used as test compounds. Varying extents of reduction in staining intensity by synthetic compounds relative to unsubstituted/free lactose proved the applicability and sensitivity of the method. Flanking cytofluorimetric assays on lectin binding to native cells gave similar grading, excluding a major impact of tissue fixation. The experiments revealed cell/tissue binding of galectin-8 preferentially via one domain, depending on the cell type so that the effect of an inhibitor in a certain context cannot be extrapolated to other cells/tissues. Moreover, the work with the other galectins attests that this assay enables comprehensive analysis of the galectin network in serial tissue sections to determine overlaps and regional differences in inhibitory profiles.
authors.affiliation: Pharmaqam and Nanoqam, Department of Chemistry, University du Québec à Montréal, P.O. Box 8888, Succ. Centre-Ville, Montreal, QC, H3C 3P8, Canada. roy.rene@uqam.ca.
authors.forename: René
authors.initials: R
authors.lastname: Roy
authors.affiliation: Pharmaqam and Nanoqam, Department of Chemistry, University du Québec à Montréal, P.O. Box 8888, Succ. Centre-Ville, Montreal, QC, H3C 3P8, Canada.
authors.forename: Yihong
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Faculty of Veterinary Medicine, Institute of Physiological Chemistry, Ludwig-Maximilians-University Munich, Veterinärstr. 13, 80539, Munich, Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: Kaltner
authors.affiliation: Pharmaqam and Nanoqam, Department of Chemistry, University du Québec à Montréal, P.O. Box 8888, Succ. Centre-Ville, Montreal, QC, H3C 3P8, Canada.
authors.forename: Naresh
authors.initials: N
authors.lastname: Kottari
authors.affiliation: Pharmaqam and Nanoqam, Department of Chemistry, University du Québec à Montréal, P.O. Box 8888, Succ. Centre-Ville, Montreal, QC, H3C 3P8, Canada.
authors.forename: Tze Chieh
authors.initials: TC
authors.lastname: Shiao
authors.affiliation: Pharmaqam and Nanoqam, Department of Chemistry, University du Québec à Montréal, P.O. Box 8888, Succ. Centre-Ville, Montreal, QC, H3C 3P8, Canada.
authors.forename: Karima
authors.initials: K
authors.lastname: Belkhadem
authors.affiliation: Faculty of Veterinary Medicine, Institute of Physiological Chemistry, Ludwig-Maximilians-University Munich, Veterinärstr. 13, 80539, Munich, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.affiliation: Faculty of Veterinary Medicine, Institute of Physiological Chemistry, Ludwig-Maximilians-University Munich, Veterinärstr. 13, 80539, Munich, Germany.
authors.forename: Joachim C
authors.initials: JC
authors.lastname: Manning
authors.affiliation: School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland.
authors.forename: Paul V
authors.initials: PV
authors.lastname: Murphy
authors.affiliation: Faculty of Veterinary Medicine, Institute of Physiological Chemistry, Ludwig-Maximilians-University Munich, Veterinärstr. 13, 80539, Munich, Germany. gabius@tiph.vetmed.uni-muenchen.de.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
mesh_terms: D005434:Flow Cytometry; D037161:Galectins / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*; D006027:Glycosides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D037102:Lectins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding
chemical_list: D037161:Galectins; D006027:Glycosides; D037102:Lectins; C008245:lactosides
keywords: Agglutinin; Glycocluster; Glycoprotein; Glycosylation; Lectin