Up-Regulated Expression of Pro-Apoptotic Long Noncoding RNA lincRNA-p21 in Lupus Nephritis Patients and an Experimental Mouse Model

Abstract Background: Accelerated cell apoptosis is a crucial pathogenic mechanism in lupus nephritis (LN) with dysregulated expression levels of long noncoding RNAs (lncRNAs). The expression of pro-apoptotic lincRNA-p21 and its competing endogenous RNA target miR-181a were studied in LN patients, human kidney cell and T-lymphocyte lines with CRISPR interference-conducted repression and lentiviral vector-mediated overexpression of lincRNA-p21, and a mouse LN model. Methods: Clinical samples were collected from LN patients with higher disease activity and control subjects including lupus patients without renal involvement and age/sex-matched healthy controls (HCs). The expression of lincRNA-p21, H19 (anti-apoptotic lncRNA) and miR-181a were examined in peripheral blood mononuclear cells (PBMNCs) and urine cells, and analyzed for clinical correlation. Cell lines were treated with doxorubicin (Dox) to induce apoptosis and evaluate for the expression of lincRNA-p21, caspase 3 and p21. LincRNA-p21-silened HEK 293T and Jurkat transfectants were examined for apoptosis and miR-181a expression. LincRNA-p21-overexpressed HK-2 cells were examined for apoptosis and p53-related down-stream molecules levels. Female Balb/C mice were injected with pristane to induce LN, and examined for the expression of anti-DNA, proteinuria, lincRNA-p21, caspase 3 and p21 as well as in situ apoptosis. Results: Up-regulated expression of lincRNA-p21 rather than H19 were identified in PBMNCs from LN patients, positively correlated with disease activity and proteinuria amount. Higher lincRNA-p21 levels were identified in LN CD4+T cells than other subpopulations. LN urine cells had greater lincRNA-p21 levels than HCs. There were lower miR-181a levels in PBMNCs from LN patients, negatively correlated with disease activity. Dox-induced apoptotic cell lines had up-regulated levels of lincRNA-p21, caspase 3 and p21, whereas down-regulated miR-181a expression with decreased TCRζchain and IL-2 levels was identified in Jurkat cells. LincRNA-p21-silenced transfectants displayed reduced apoptosis with up-regulated miR-181a expression. LincRNA-p21-overexpressed HK-2 cells revealed enhanced apoptosis with up-regulated expression of downstream PUMA and Bax molecules. LN mice had in situ apoptosis and progressively increased anti-dsDNA, proteinuria and renal lincRNA-p21 levels with up-regulated expression of caspase 3 and p21.Conclusions: By using clinical samples, human cell lines and a mouse model, we demonstrate up-regulated expression of lincRNA-p21 in LN, implicating a potential activity biomarker and therapeutic target.