LncRNA MALAT1 Regulates iPSC-derived Β-cell Differentiation by Targeting the miR-15b-5p/Ihh Axis

Abstract Background: iPSCs-derived β-like cell differentiation provides a novel strategy for type 1 diabetes treatment. Clarifying the regulatory mechanisms of lncRNAs in β-like cells derived from induced pluripotent stem cells (iPSCs) is not only significant for understanding the development of pancreas or pancreatic β cells, but also helpful for improving the quality of β-like cells for stem cell therapy.Methods: β-like cells derived from iPSCs followed a three-step protocol. RNA-sequencing was carried out to screen the differentially expressed lncRNAs which was probably involved in the differentiation of pancreatic β cells. Bioinformatics was performed to analyze the putative target genes of significantly differentially expressed lncRNAs. LncRNA Malat1 was chosen for further research. Lentivirus victor, siRNA victor, antagomir victor and mimic victor were constructed for overexpression of lncRNA Malat1, knockdown of lncRNA Malat1, knockdown of miR-15b-5p and overexpression of miR-15b-5p respectively. Quantitative Real-Time PCR (qRT-PCR), Western Blot and Immunofluorescence (IF) staining were carried out to detect the functions of pancreatic β cells at mRNA and protein level separately. Cytoplasmic and nuclear RNA fractionation and Fluorescence in situ hybridization (FISH) were to ventilate the subcellar location of lncRNA Malat1 in β-like cells. Flow cytometry and ELISA were performed to examine differentiation efficiency and function of insulin secretion from β-like cells after being stimulated with different concentrations of glucose. Structural interactions between lncRNA Malat1 and miR-15b-5p and between miR-15b-5p and Ihh were detected by Dual luciferase reporter assay (LRA).Results: We found that expression of lncRNA Malat1 was on the decline during the differentiation and overexpression of this lncRNA obviously impaired the differentiation and maturation of β-like cells derived from iPSCs in vitro and in vivo. Localized to the cytoplasm, lncRNA Malat1 could function as a competing endogenous RNA (ceRNA) of miR-15b-5p to regulate the expression of Ihh according the bioinformatic prediction, mechanistic analysis and downstream experiments.Conclusion: This study built an unreported regulatory network of lncRNA Malat1 and miR-15b-5p/Ihh axis during differentiation of iPSCs into β-like cells. Except for acting as a proverbial oncogene promoting tumorigenesis, lncRNA Malat1 may provide effective and novel molecule for diabetes cell therapy in the future.