Figure 3. HOTAIR binds to miR-221-3p and consequently down-regulates its expression. Subcellular localization of HOTAIR in MN9D cells detected by FISH assay. (A) The prediction of downstream miRNAs regulated by HOTAIR in starBase and RNA22 etc.. (B) The expression patterns of the 4 screened miRNAs measured using RT-qPCR, *p < 0.05 vs. MN9D cells treated with sh-NC. (C) The expression patterns of miR-221-3p in the SNc tissues (n = 10) of PD mouse models and PD cell models determined by RT-qPCR, *p < 0.05 vs. mice injected with normal saline or cells treated with PBS. (D) Pearson’s correlation analysis of the expressions of HOTAIR and miR-221-3p in the SNc tissues of PD mouse models. (E) The expression patterns of HOTAIR in PD cell models determined by RT-qPCR, *p < 0.05 vs. cells treated with mimic NC. #p < 0.05 vs. cells treated with inhibitor NC. (F) The complementary base paring diagram of HOTAIR and miR-221-3p sequences predicted online. (G) The binding of HOTAIR to miR-221-3p measured by dual-luciferase reporter gene assay, *p < 0.05 vs. the cells treated with NC mimic. (H) The binding of miR-221-3p and HOTAIR assessed by the RIP assay, *p < 0.05 vs. cells treated with anti-IgG. (I) Data (mean ± standard deviation) between two groups were compared using unpaired t-test. The experiment was repeated three times. HOTAIR, HOX transcript antisense intergenic RNA; PD, Parkinson’s disease; miR-221-3p, microRNA-221-3p; FISH, fluorescence in situ hybridization; RT-qPCR, reverse transcription quantitative polymerase chain reaction; SNc, substantia nigra compact; PBS, phosphate buffered saline; wt, wild type; mut, mutase; NC, negative control; RIP, RNA binding protein immunoprecipitation assay.