Identification of microRNA-181a-5p and microRNA-4454 as mediators of facet cartilage degeneration
Akihiro Nakamura, … , Igor Jurisica, Mohit Kapoor
Akihiro Nakamura, … , Igor Jurisica, Mohit Kapoor
Published August 4, 2016
Citation Information: JCI Insight. 2016;1(12):e86820. https://doi.org/10.1172/jci.insight.86820.
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Research Article Cell biology

Identification of microRNA-181a-5p and microRNA-4454 as mediators of facet cartilage degeneration

Abstract

Osteoarthritis (OA) of spine (facet joints [FJs]) is one of the major causes of severe low back pain and disability worldwide. The degeneration of facet cartilage is a hallmark of FJ OA. However, endogenous mechanisms that initiate degeneration of facet cartilage are unknown, and there are no disease-modifying therapies to stop FJ OA. In this study, we have identified microRNAs (small noncoding RNAs) as mediators of FJ cartilage degeneration. We first established a cohort of patients with varying degrees of facet cartilage degeneration (control group: normal or mild facet cartilage degeneration; FJ OA group: moderate to severe facet cartilage degeneration) and then screened 2,100 miRNAs and identified 2 miRNAs (miR-181a-5p and miR-4454) that were significantly elevated in FJ OA cartilage compared with control facet cartilage. We further explored their role, function, and signaling mechanisms using computational, in vitro functional, and in vivo studies. We specifically indicate that miR-181a-5p and miR-4454 are involved in promoting inflammatory, catabolic, and cell death activity in FJ chondrocytes. This is the first report to our knowledge that identifies miR-181a-5p and miR-4454 as mediators of cartilage degeneration in FJs and potential therapeutic targets for stopping cartilage degeneration.

Authors

Akihiro Nakamura, Y. Raja Rampersaud, Anirudh Sharma, Stephen J. Lewis, Brian Wu, Poulami Datta, Kala Sundararajan, Helal Endisha, Evgeny Rossomacha, Jason S. Rockel, Igor Jurisica, Mohit Kapoor

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Figure 5

miR-181a-5p mimic promotes cartilage degeneration in vivo.

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miR-181a-5p mimic promotes cartilage degeneration in vivo. (A) Schematic...
(A) Schematic of miR-181a-5p mimic injection in facet joints (FJs) of rats of miR-181a-5p mimic (right side; n = 7) or control mimic (left side; n = 7 were injected into 2 lumbar spinal FJs, L4/5 and L5/6), using a 26-gauge Hamilton syringe under surgical microscope. (B–H) Rat FJs (L4/5 and L5/6) were stained with Safranin O/fast green stain. miR-181a-5p mimic injection resulted in a FJ OA–like phenotype associated with loss of chondrocyte cellularity, proteoglycan depletion, and cartilage degeneration in vivo. (B) Sham — without injection. (C and F) L4/5 FJ treated with control mimic. (D and G) L4/5 FJ treated with miR-181a-5p mimic. (E and H) L5/6 FJ treated with miR-181a-5p mimic. (B–E: original magnification, ×4; F–H: original magnification, ×20). (I) Histomorphometric analysis of FJs treated with miR-181a-5p or control mimic was scored by Osteoarthritis Research Society International (OARSI) scoring. Facet chondrocyte cellularity per area was calculated in FJs treated with miR-181a-5p or control mimic (n = 7/each group). (J–P) Representative images of FJ cartilage sections analyzed by immunohistochemistry for poly (ADP-ribose) polymerase (PARP) p85 or matrix metallopeptidase 13 (MMP13) (n = 7/each group). (P) Immuno-positive cells and total cells in FJ cartilage were counted and expressed as a percentage of PARP p85– and MMP13-positive cells. (L and O) Rabbit IgG-HRP was used as an isotype negative control (original magnification, ×20). (I and P) For data presented as box-and-whiskers plots, horizontal lines and cross marks indicate the medians and the means, boxes indicate 25th to 75th percentiles, and whiskers indicate minimum and maximum values of the data set. **P < 0.01, as determined by 2-tailed Student’s t tests.