title: Smoothened-antagonists reverse homogentisic acid-induced alterations of Hedgehog signaling and primary cilium length in alkaptonuria.
abstract: Alkaptonuria (AKU) is an ultra-rare genetic disease, in which the accumulation of a toxic metabolite, homogentisic acid (HGA) leads to the systemic development of ochronotic aggregates. These aggregates cause severe complications mainly at the level of joints with extensive degradation of the articular cartilage. Primary cilia have been demonstrated to play an essential role in development and the maintenance of articular cartilage homeostasis, through their involvement in mechanosignaling and Hedgehog signaling pathways. Hedgehog signaling has been demonstrated to be activated in osteoarthritis (OA) and to drive cartilage degeneration in vivo. The numerous similarities between OA and AKU suggest that primary cilia Hedgehog signaling may also be altered in AKU. Thus, we characterized an AKU cellular model in which healthy chondrocytes were treated with HGA (66 µM) to replicate AKU cartilage pathology. We investigated the degree of activation of the Hedgehog signaling pathway and how treatment with inhibitors of the receptor Smoothened (Smo) influenced Hedgehog activation and primary cilia structure. The results obtained in this work provide a further step in the comprehension of the pathophysiological features of AKU, suggesting a potential therapeutic approach to modulate AKU cartilage degradation processes through manipulation of the Hedgehog pathway.
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Gambassi
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Geminiani
authors.affiliation: Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd, London, United Kingdom.
authors.forename: Stephen D
authors.identifier: http://orcid.org/0000-0002-4707-7756
authors.initials: SD
authors.lastname: Thorpe
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Bernardini
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Lia
authors.initials: L
authors.lastname: Millucci
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Braconi
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Orlandini
authors.affiliation: Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd, London, United Kingdom.
authors.forename: Clare L
authors.initials: CL
authors.lastname: Thompson
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Petricci
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Manetti
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Taddei
authors.affiliation: Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd, London, United Kingdom.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Knight
authors.affiliation: Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Santucci
mesh_terms: D000474:Alkaptonuria / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D000813:Anilides / Q000494:pharmacology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D002923:Cilia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D053823:Hedgehog Proteins / Q000378:metabolism*; D006713:Homogentisic Acid / Q000633:toxicity*; D006801:Humans; D017495:Hyperpigmentation / Q000139:chemically induced / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D000072086:Smoothened Receptor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014704:Veratrum Alkaloids / Q000494:pharmacology*; D000071676:Zinc Finger Protein GLI1 / Q000378:metabolism
chemical_list: D000813:Anilides; C400551:GLI1 protein, human; D053823:Hedgehog Proteins; C538724:HhAntag691; D011725:Pyridines; C491023:SMO protein, human; D000072086:Smoothened Receptor; D014704:Veratrum Alkaloids; D000071676:Zinc Finger Protein GLI1; D006713:Homogentisic Acid; C000541:cyclopamine
keywords: acetylated α-tubulin; chondrocytes; confocal microscopy; ochronosis