Pre-B cell receptor acts as a selectivity switch for Galectin-1 at the pre-B cell surface

Touarin, P.; Serrano, B.; Courbois, A.; Bornet, O.; Chen, Q.; Scott, L. G.; Mancini, S. J. C.; Williamson, J. R.; Sebban-Kreuzer, C.; Elantak, L.

doi:10.1101/2022.02.08.479506

bioRxiv · 10.1101/2022.02.08.479506

Pre-B cell receptor acts as a selectivity switch for Galectin-1 at the pre-B cell surface

Touarin, P.·Serrano, B.·Courbois, A.·Bornet, O.·Chen, Q.·Scott, L. G.·Mancini, S. J. C.·Williamson, J. R.·Sebban-Kreuzer, C.·Elantak, L.

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Abstract

Galectins are glycan binding proteins translating the sugar-encoded information of cellular glycoconjugates into many physiological activities including immunity, cell migration, and signaling. During early B lymphocytes (BL) development at the pre-B cell stage, BL express the pre-B cell receptor (pre-BCR) and are supported by mesenchymal stromal cells secreting Galectin-1 (Gal-1). Gal-1 interacts with glycosylated receptors from stromal and pre-B cell surfaces but also with the pre-BCR through a direct carbohydrate-independent contact. How this interaction might interplay with the glycan-decoding function of Gal-1 is unknown. Here, we investigated Gal-1 binding to cell surface ligands using NMR spectroscopy on native membranes. We showed that pre-BCR regulates Gal-1 binding to specifically target 2,3-sialylated receptors on pre-B cells. Upon pre-BCR interaction, dynamic changes resulted in additional contacts with 2,3-sialylated glycans converting Gal-1 from an exo- to an endo-type lectin. Remarkably, this selectivity switch is able to promote pre-B cell survival. Altogether, we shed light on a new mechanism allowing fine-tuning of Galectin specificity at the cell surfaces.

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Touarin, P., Serrano, B., Courbois, A., Bornet, O., Chen, Q., Scott, L. G., Mancini, S. J. C., Williamson, J. R., Sebban-Kreuzer, C., Elantak, L.. 2022-02-08. Pre-B cell receptor acts as a selectivity switch for Galectin-1 at the pre-B cell surface. https://doi.org/10.1101/2022.02.08.479506

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