Galectin-related protein: An integral member of the network of chicken galectins: 2. From expression profiling to its immunocyto- and histochemical localization and application as tool for ligand detection

Abstract

Background: Galectin-related protein (GRP), present in vertebrates, is special within this family of adhesion/growth-regulatory proteins due to its strong positive selection and loss of canonical lectin activity.

Methods: RT-PCR and Western blotting together with flow cytofluorimetry and immunocyto- and histochemistry monitor expression and localization of chicken GRP. The promoter sequence of the GRP gene is processed computationally to detect putative sites for binding transcription factors. The labeled protein is applied as probe to detect binding sites on cells and in sections, along with glycocompounds to test inhibition of the association.

Results: Expression of GRP in chicken is limited to bursa of Fabricius, immunohistochemically found in B cells, also in bursal epithelium and vessels. Presence in B cells is shared with only one canonical galectin, i.e. CG-8. Binding to a chicken lymphoma line was specific and saturable, not affected by lactose but completely blocked by heparin, as also seen in sections.

Conclusions: Expression monitoring initiated for GRP reveals a distinct site of localization in chicken, much more restricted than for any of its canonical galectins.

Keywords: B cells; Bursa; Lectin; Lymphocytes; Promoter.