PRKACB Attenuates Chondrocyte Loss and Inflammation in Osteoarthritis

TL;DR

This study shows that PRKACB helps protect cartilage cells from inflammation and damage in osteoarthritis by activating a specific signaling pathway.

Contribution

The study identifies PRKACB as a novel therapeutic target for osteoarthritis by revealing its protective role via the PKA/CREB pathway.

Findings

PRKACB expression is reduced in inflammatory chondrocytes and restoring it improves cell survival.

PRKACB suppresses inflammation and cartilage degradation by activating the PKA/CREB signaling pathway.

Blocking PKA reverses the protective effects of PRKACB, confirming its role in the pathway.

Abstract

Previous work revealed that protein kinase cAMP‐dependent catalytic β (PRKACB) may play a crucial role in osteoarthritis (OA) development. However, the mechanism by which PRKACB plays a role in OA still needs to be further investigated. Our aim was to explore the mechanism of PRKACB in a human chondrocyte inflammatory injury model.

Human CHON‐001 chondrocytes were treated with 10 ng/mL IL‐1β for 12 h to establish an in vitro model of chondrocyte inflammatory injury. Cell viability was determined by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. Flow cytometry (FCM) was conducted to assess apoptosis. Western blot assays were carried out to measure cleaved caspase‐3, caspase‐3, PRKACB, collagen II, aggrecan, phosphorated protein kinase A (p‐PKA), PKA, cAMP response element‐binding protein (CREB) and p‐CREB protein expression levels. Reverse transcription quantitative polymerase chain reaction (RT‐qPCR) assay was used to measure PRKACB gene expression. Interleukin 6 (IL‐6), IL‐1β, and tumor necrosis factor alpha (TNF‐α) levels were measured by enzyme‐linked immunosorbent assay (ELISA).

PRKACB expression was decreased in IL‐1β‐treated CHON‐001 cells. Transfection of a PRKACB plasmid increased PRKACB expression in CHON‐001 cells. IL‐1β significantly inhibited CHON‐001 cell viability; induced apoptosis; increased cleaved caspase‐3 expression and the cleaved caspase‐3/caspase‐3 ratio; promoted TNF‐α, IL‐6 and IL‐8 secretion; and decreased the expression levels of collagen II and aggrecan. However, these effects could be suppressed by the PRKACB plasmid. Moreover, we also found that PRKACB activated the PKA/CREB signaling pathway. H89 (a PKA inhibitor) distinctly reversed the effect of PRKACB on IL‐1β‐induced CHON‐001 cells.

PRKACB can increase cell viability and reduce inflammation by activating the PKA/CREB signaling pathway, and PRKACB is a novel target for OA treatment.

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