p16INK4a and its regulator miR-24 link senescence and chondrocyte terminal differentiation-associated matrix remodeling in osteoarthritis
- Equal contributors
1 INSERM U844, CHU St Eloi, Bat INM, 80 av A. Fliche, 34298 Montpellier, cedex 05, France
2 Université de Montpellier-1, UFR de Medecine, F-34000, Montpellier, France
3 Laboratorio di immunoreumatologia e rigenerazione tissutale, IOR, Istituto di ricerca Codivilla Putti, I-40136 Bologna, Italy
4 Service de Medecine légale CHU La Peyronie, F34000 Montpellier, France
5 Unité clinique, thérapeutiques des maladies des os et articulations, CHU Lapeyronie, F34000 Montpellier, France
6 UMR5237, CNRS, CRBM, 1919 route de Mende, F34295 Montpellier, France
Arthritis Research & Therapy 2014, 16:R58 doi:10.1186/ar4494Published: 27 February 2014
Recent evidence suggests that tissue accumulation of senescent p16INK4a-positive cells during the life span would be deleterious for tissue functions and could be the consequence of inherent age-associated disorders. Osteoarthritis (OA) is characterized by the accumulation of chondrocytes expressing p16INK4a and markers of the senescence-associated secretory phenotype (SASP), including the matrix remodeling metalloproteases MMP1/MMP13 and pro-inflammatory cytokines interleukin-8 (IL-8) and IL-6. Here, we evaluated the role of p16INK4a in the OA-induced SASP and its regulation by microRNAs (miRs).
We used IL-1-beta-treated primary OA chondrocytes cultured in three-dimensional setting or mesenchymal stem cells differentiated into chondrocyte to follow p16INK4a expression. By transient transfection experiments and the use of knockout mice, we validate p16INK4a function in chondrocytes and its regulation by one miR identified by means of a genome-wide miR-array analysis.
p16INK4a is induced upon IL-1-beta treatment and also during in vitro chondrogenesis. In the mouse model, Ink4a locus favors in vivo the proportion of terminally differentiated chondrocytes. When overexpressed in chondrocytes, p16INK4a is sufficient to induce the production of the two matrix remodeling enzymes, MMP1 and MMP13, thus linking senescence with OA pathogenesis and bone development. We identified miR-24 as a negative regulator of p16INK4a. Accordingly, p16INK4a expression increased while miR-24 level was repressed upon IL-1-beta addition, in OA cartilage and during in vitro terminal chondrogenesis.
We disclosed herein a new role of the senescence marker p16INK4a and its regulation by miR-24 during OA and terminal chondrogenesis.