Charcot-Leyden Crystal Protein/Galectin-10 Interacts with Cationic Ribonucleases and is Required for Eosinophil Granulogenesis.

Charcot-Leyden Crystal Protein/Galectin-10 Interacts with Cationic Ribonucleases and is Required for Eosinophil Granulogenesis.:

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Charcot-Leyden Crystal Protein/Galectin-10 Interacts with Cationic Ribonucleases and is Required for Eosinophil Granulogenesis.

J Allergy Clin Immunol. 2020 Jan 23;:

Authors: Grozdanovic MM, Doyle CB, Liu L, Maybruck B, Kwatia MA, Thiyagarajan N, Acharya KR, Ackerman SJ

Abstract

BACKGROUND: The human eosinophil Charcot-Leyden Crystal (CLC) protein is a member of the Galectin superfamily and is also known as Galectin-10 (Gal-10). CLC/Gal-10 forms the distinctive hexagonal bipyramidal crystals considered hallmarks of eosinophil participation in allergic responses and related inflammatory reactions; however, the glycan-containing ligands of CLC/Gal-10, its cellular function(s), and its role(s) in allergic diseases are unknown.

OBJECTIVE: We sought to determine the binding partners of CLC/Gal-10 and elucidate its role in eosinophil biology.

METHODS: Intracellular binding partners were determined by ligand blotting with CLC/Gal-10, followed by co-immunoprecipitation and co-affinity purifications. The role of CLC/Gal-10 in eosinophil function was determined by employing enzyme activity assays, confocal microscopy, and shRNA knock-out of CLC/Gal-10 expression in human CD34+ cord blood hematopoietic progenitors differentiated to eosinophils.

RESULTS: CLC/Gal-10 interacts with both human eosinophil granule cationic ribonucleases, eosinophil-derived neurotoxin (EDN, RNS2) and eosinophil cationic protein (ECP, RNS3) , and with murine eosinophil-associated ribonucleases. The interaction is independent of glycosylation and is not inhibitory toward endoribonuclease activity. Activation of eosinophils with INF-γ induces the rapid co-localization of CLC/Gal-10 with EDN/RNS2 and CD63. ShRNA knock-down of CLC/Gal-10 in human cord blood-derived CD34+ progenitor cells impairs eosinophil granulogenesis.

CONCLUSIONS: CLC/Gal-10 functions as a carrier for the sequestration and vesicular transport of the potent eosinophil granule cationic ribonucleases during both differentiation and degranulation, enabling their intracellular packaging and extracellular functions in allergic inflammation.

PMID: 31982451 [PubMed - as supplied by publisher]