Galectin 3 Deficiency Alters Chondrocyte Primary Cilium Formation and Exacerbates Cartilage Destruction via Mitochondrial Apoptosis.

Narjès Hafsia,Narjès Hafsia,Félix Renaudin,Félix Renaudin,Frédéric Lioté,Frédéric Lioté,Frédéric Lioté,Frédéric Lioté,Françoise Poirier,Marine Forien,Marine Forien,Peter Van Lent,Françoise Poirier,Martine Cohen-Solal,Martine Cohen-Solal,Martine Cohen-Solal,Martine Cohen-Solal,Françoise Poirier,Pascal Reboul,Pascal Reboul,Hang Korng Ea,Delphine Delacour,Delphine Delacour,Delphine Delacour,Delphine Delacour,Delphine Delacour,Françoise Poirier,Françoise Poirier

doi:10.3390/ijms21041486

Abstract

Mechanical overload and aging are the main risk factors of osteoarthritis (OA). Galectin 3 (GAL3) is important in the formation of primary cilia, organelles that are able to sense mechanical stress. The objectives were to evaluate the role of GAL3 in chondrocyte primary cilium formation and in OA in mice. Chondrocyte primary cilium was detected in vitro by confocal microscopy. OA was induced by aging and partial meniscectomy of wild-type (WT) and Gal3-null 129SvEV mice (Gal3−/−). Primary chondrocytes were isolated from joints of new-born mice. Chondrocyte apoptosis was assessed by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), caspase 3 activity and cytochrome c release. Gene expression was assessed by qRT-PCR. GAL3 was localized at the basal body of the chondrocyte primary cilium. Primary cilia of Gal3−/− chondrocytes were frequently abnormal and misshapen. Deletion of Gal3 triggered premature OA during aging and exacerbated joint instability-induced OA. In both aging and surgery-induced OA cartilage, levels of chondrocyte catabolism and hypertrophy markers and apoptosis were more severe in Gal3−/− than WT samples. In vitro, Gal3 knockout favored chondrocyte apoptosis via the mitochondrial pathway. GAL3 is a key regulator of cartilage homeostasis and chondrocyte primary cilium formation in mice. Gal3 deletion promotes OA development.

Highlights

Osteoarthritis (OA) is a multifaceted joint disease characterized by cartilage degradation, bone modifications and mild synovial inflammation
We observed that Galectin 3 (GAL3) was a key regulator of cartilage homeostasis in mice, in response to mechanical stress induced by joint instability
The cartilages of old (14 months) and young (3 months) wild-type (WT) and Gal3−/− mice were compared after safranin-O staining of knee sections (Figures 1A and 2A)

Summary

Introduction

Osteoarthritis (OA) is a multifaceted joint disease characterized by cartilage degradation, bone modifications and mild synovial inflammation. OA cartilage displays extracellular matrix and cell modifications including increased production of metalloproteases (MMPs) and aggrecanases (ADAMTS-4 and 5, A Disintegrin And Metalloprotease with ThromboSpondin-like repeat) and increased chondrocyte catabolic and hypertrophic differentiation [1,2]. Chondrocytes isolated from mice with mutant Polaris/intraflagellar transport (ITF) 88, a protein necessary for cilium formation, fail to increase intracellular Ca2+ under mechanical stimulation [11]. Loss of primary cilia in chondrocytes reduces cartilage mechanical properties in Col2Cre/Ift88ft/ft transgenic mice and promotes OA development characterized by increased expression of MMP13, ADAMTS5, COLX and RUNX2 [12,13]. Mice mutant for Bardet-Biedl syndrome 1 (Bbs1−/−), Bbs2−/− or Bbs6−/−, a family of proteins involved in primary cilium formation/functions, develop OA-like cartilage abnormalities including proteoglycan loss, small surface fibrillations, reduced cartilage thickness and increased MMP13 expression [14,15]

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Conclusion