A novel circRNA, circRACGAP1, hampers the progression of systemic lupus erythematosus via miR-22-3p-mediated AKT signalling.

BACKGROUND: Systemic lupus erythematosus (SLE) is defined as a multisystem autoimmune disease involving various organs, of which exact molecular mechanisms remain elusive. Here, we aimed to investigate a novel circular RNA (circRNA), circRACGAP1, abnormally expressed in SLE and explored its underlying regulatory network. METHODS: The expression patterns of circRACGAP1 were determined in patients diagnosed with SLE by using a qRT-PCR assay. Spearman correlation analysis was employed to evaluate the correlation between circRACGAP1 and clinicopathological variables in patients with SLE. Flow cytometry and TUNEL assays were subjected to assess the cell apoptosis. Nuclear-cytoplasmic fractionation and luciferase reporter assay was used to verify the circRACGAP1/miR-22-3p/PTEN axis. Western blot analysis was performed to measure the PTEN/AKT signalling-related proteins and apoptotic-related biomarkers. RESULTS: Down-regulated circRACGAP1 was observed and correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score, anti-double-stranded (ds) DNA, and complement C3 level in patients with SLE. Overexpression of circRACGAP1 significantly alleviated cell apoptosis in Jurkat cells within UVB exposure. Mechanistic investigation revealed that circRACGAP1 could serve as a sponge of miR-22-3p to regulate PTEN/AKT signalling. CONCLUSIONS: Collectively, circRACGAP1 regulated the AKT signalling pathway via binding to miR-22-3p in the progression of SLE, suggesting therapeutic targets for SLE treatment.

Oestradiol ameliorates monocrotaline pulmonary hypertension via NO, prostacyclin and endothelin-1 pathways.

Pulmonary hypertension continues to be a serious clinical problem with high mortality. As oestrogen is a potential vasodilator of the pulmonary circulation, this study examined the mechanisms by which 17ß-oestradiol improves monocrotaline (MCT)-induced pulmonary hypertension. Female Sprague-Dawley rats underwent bilateral ovariectomy or sham operations. The rats received MCT (50 mg·kg(-1)) and were treated with 17ß-oestradiol (1 mg·kg(-1) per day) for either 5 weeks or only from week 4 to week 5. Plasma 17ß-oestradiol concentrations were decreased in sham-operated, MCT-treated rats when compared with sham-operated rats (17.7 ± 4.7 versus 50.3 ± 15.4 pg·mL(-1); p=0.029). The 17ß-oestradiol anabolic enzyme cytochrome P450 (CYP)-19 was decreased by MCT treatment, while the catabolic enzymes CYP-1A1 and -1B1 were increased. Ovariectomised and MCT-treated rats had more severe pulmonary hypertension. 17ß-oestradiol suppressed pulmonary arterial smooth muscle cell proliferation and macrophage infiltration, and enhanced apoptosis by increasing nitric oxide (NO) and prostacyclin (prostaglandin (PG)I2) levels and reducing endothelin (ET)-1 levels. Phosphoinositide-3-kinase (PI3K) and Akt phosphorylations were markedly increased, but were inhibited by 17ß-oestradiol treatment in rats with pulmonary hypertension. Oestrogen deficiency may aggravate development of pulmonary hypertension. 17ß-oestradiol improved pulmonary hypertension via activation of the PI3K/Akt pathway to regulate NO, PGI2 and ET-1 expression.