Abstract: Objective To observe the effects of long-chain noncoding RNA X-inactive specific transcripts (LncRNA XIST, XIST) and miR-150-5p on the proliferation and apoptosis of mesangial cells in lupus nephritis (LN) and to explore its mechanism of action. 
Methods Mesangial cells from LN mice and normal mice were isolated and cultured. pcDNA group (transfected empty vector), pcDNA-XIST group (transfected pcDNA-XIST), antagomiRNA group (transfected antagomiRNA), antagomiR-150-5p group (transfected antagomiR-150-5p), pcDNA-XIST + agomiRNA group (co-transfected pcDNA-XIST and agomiRNA), pcDNA-XIST + agomiR-150-5p group (co-transfected pcDNA-XIST and agomiR-150-5p) were transfected into mesangial cells of LN by liposome method. Real time fluorescence quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to detect the expression of XIST and miR-150-5p. Dual luciferase assay was used to detect the fluorescence activity of cells, and cell counting kit (CCK8) and annexin V-fluorescein isothiocyanate propidium iodide (annexin V-FITC/PI) were used to detect cell proliferation and apoptosis. Protein expressions of cyclin-dependent kinase inhibitor 1A (p21), proliferating cell nuclear antigen (PCNA), B-cell lymphoma-2 (Bcl-2) and BCL2-associated X protein (Bax) were detected by Western blotting (WB) . 
Results Compared with normal mouse renal tissue or mesangial cells, the expression of XIST significantly increased and the expression of miR-150-5p significantly decreased in renal tissue or mesangial cells of LN mice (P＜0.001). Overexpression of XIST or inhibition of miR-150-5p significantly facilitated the proliferation and inhibited apoptosis, up-regulated the expression of PCNA and Bcl-2 protein, and down-regulated the expression of p21 and Bax protein of mesangial cells of LN (P＜0.001). MiR-150-5p significantly inhibited the fluorescence activity of wild-type XIST cells and negatively regulated XIST (P＜0.001). Overexpression of miR-150-5p significantly inhibited the effect of overexpression of XIST on the proliferation and apoptosis of mesangial cells of LN (P＜0.001). 
Conclusion LncRNA XIST can promote the proliferation and inhibit apoptosis of mesangial cells of LN, and its mechanism may be related to directly targeting miR-150-5p. 

Key words: lupus nephritis, mesangial cells, apoptosis