title: Mouse liver lysosomes contain enzymatically active processed forms of Hyal-1.
abstract: It has long been known that liver lysosomes contain an endoglycosidase activity able to degrade the high molecular mass glycosaminoglycan hyaluronic acid (HA). The identification and cloning of a hyaluronidase with an acidic pH optimum, Hyal-1, suggested it might be responsible for this activity. However, we previously reported that this hydrolase could only be detected in pre-lysosomal compartments of the mouse liver using a zymography technique that allows the detection of Hyal-1 activity after SDS-PAGE ("renatured protein zymography"). Present work reveals that the activity highlighted by this technique belongs to a precursor form of Hyal-1 and that the lysosomal HA endoglycosidase activity of the mouse liver is accounted for by a proteolytically processed form of Hyal-1 that can only be detected using "native protein zymography". Indeed, the distribution of this form follows the distribution of β-galactosidase, a well-established lysosomal marker, after fractionation of the mouse liver in a linear sucrose density gradient. In addition, both activities shift toward the lower density region of the gradient when a specific decrease of the lysosomal density is induced by Triton WR-1339 injection. The fact that only native protein zymography but not renatured protein zymography is able to detect Hyal-1 activity in lysosomes points to a non-covalent association of Hyal-1 proteolytic fragments or the existence of closely linked partners supporting Hyal-1 enzymatic activity. The knockdown of Hyal-1 results in an 80% decrease of total acid hyaluronidase activity in the mouse liver, confirming that Hyal-1 is a key actor of HA catabolism in this organ.
authors.affiliation: URPhyM-Laboratoire de Chimie Physiologique, Narilis, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
authors.forename: Marielle
authors.initials: M
authors.lastname: Boonen
authors.affiliation: URPhyM-Laboratoire de Chimie Physiologique, Narilis, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
authors.forename: Emeline
authors.initials: E
authors.lastname: Puissant
authors.affiliation: URPhyM-Laboratoire de Chimie Physiologique, Narilis, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
authors.forename: Florentine
authors.initials: F
authors.lastname: Gilis
authors.affiliation: URPhyM-Laboratoire de Physiologie et Pharmacologie, Narilis, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
authors.forename: Bruno
authors.initials: B
authors.lastname: Flamion
authors.affiliation: URPhyM-Laboratoire de Chimie Physiologique, Narilis, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium. Electronic address: michel.jadot@unamur.be.
authors.forename: Michel
authors.initials: M
authors.lastname: Jadot
mesh_terms: D000818:Animals; D055785:Gene Knockdown Techniques; D006820:Hyaluronic Acid / Q000378:metabolism; D006821:Hyaluronoglucosaminidase / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008247:Lysosomes / Q000201:enzymology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D006820:Hyaluronic Acid; C469220:Hyal1 protein, mouse; D006821:Hyaluronoglucosaminidase
keywords: Fractionation; Hyal-1; Liver; Lysosome; Triton WR-1339; Zymography