Regulation of H19 and its encoded microRNA-675 in osteoarthritis and under anabolic and catabolic in vitro conditions

Abstract

Cartilage degeneration in the course of osteoarthritis (OA) is associated with an alteration in chondrocyte metabolism. In order to identify molecules representing putative key regulators for diagnosis and therapeutic intervention, we analyzed gene expression and microRNA (miR) levels in OA and normal knee cartilage using a customized cartilage cDNA array and quantitative RT-PCR. Among newly identified candidate molecules, H19, IGF2, and ITM2A were significantly elevated in OA compared to normal cartilage. H19 is an imprinted maternally expressed gene influencing IGF2 expression, whose transcript is a long noncoding (lnc) RNA of unknown biological function harboring the miR-675. H19 and IGF2 mRNA levels did not correlate significantly within cartilage samples suggesting that deregulation by imprinting effects are unlikely. A significant correlation was, however, observed for H19, COL2A1, and miR-675 expression levels in OA tissue, and functional regulation of these candidate molecules was assessed under anabolic and catabolic conditions. Culture of chondrocytes under hypoxic signaling showed co-upregulation of H19, COL2A1, and miRNA-675 levels in close correlation. Proinflammatory cytokines IL-1β and TNF-α downregulated COL2A1, H19, and miR-675 significantly without close statistical correlation. In conclusion, this is the first report demonstrating deregulation of an lncRNA and its encoded miR in the context of OA-affected cartilage. Stress-induced regulation of H19 expression by hypoxic signaling and inflammation suggests that lncRNA H19 acts as a metabolic correlate in cartilage and cultured chondrocytes, while the miR-675 may indirectly influence COL2A1 levels. H19 may not only be an attractive marker for cell anabolism but also a potential target to stimulate cartilage recovery.

Differential expression of long non-coding RNAs in bleomycin-induced lung fibrosis

“…In our microarray results, a vast majority of the differentially expressed lncRNAs in bleomycin-induced lung fibrosis have official names and clear functions, apart from H19, RNA component of mitochondrial RNA processing endoribonuclease (RMRP), and telomerase RNA component (TERC). A previous study demonstrated that H19 regulates biological processes on at least 3 separate levels of the highest significance: in imprinting, as an lncRNA transcript, and as the miR-675 host (23). Another study showed that it can affect the expression of IGF (24).…”

Significance of Epigenetic Landscape in Cartilage Regeneration from the Cartilage Development and Pathology Perspective

“…In an ischemic model, miR-210 also suppressed apoptosis in BMSCs through caspase-8-associated protein 2 [69]. Under hypoxic signaling, the culture of human chondrocytes showed that lncRNA H19 and its encoded miR-675 as well as COL2A1 were upregulated in close relation [70].…”

“…Both IL-1b and TNF-a downregulated H19, COL2A1, and miR-675 expression [70]. The stress-induced regulation of H19 by hypoxic signaling and inflammation suggested that H19 acted as a metabolic correlate in cartilage and cultured chondrocytes; there may be an indirect influence of miR-675 on COL2A1 levels in OA-affected cartilage [70].…”

Imprinted and X-linked non-coding RNAs as potential regulators of human placental function

“…Recent work suggests that H19 is a trans regulator of an imprinted gene network for growth and development 40 involving miRNAs hosted within the H19 transcript, 32,41,42 which may account for some of H19's bioactivity. Most recently, Keniry et al have described H19 as a developmental reservoir of miR-675 in the mouse.…”