Role of MEF2C in the Endothelial Cells Derived from Human Induced Pluripotent Stem Cells. Role of MEF2C in the Endothelial Cells Derived from Human Induced Pluripotent Stem Cells

Human induced pluripotent stem cells (hiPSCs) not only provide an abundant source of vascular cells for potential therapeutic applications in vascular disease but also constitute an excellent model for understanding the mechanisms that regulate the differentiation and the functionality of vascular cells. Here, we reported that myocyte enhancer factor 2C (MEF2C) transcription factor, but not any other members of the MEF2 family, was robustly upregulated during the differentiation of vascular progenitors and endothelial cells (ECs) from hiPSCs. Vascular endothelial growth factors (VEGF) strongly induced MEF2C expression in endothelial lineage cells. The specific upregulation of MEF2C during the commitment of endothelial lineage was dependent on the extracellular signal regulated kinase (ERK). Moreover, knockdown of MEF2C with shRNA in hiPSCs did not affect the differentiation of ECs from these hiPSCs, but greatly reduced the migration and tube formation capacity of the hiPSC-derived ECs. Through a chromatin immunoprecipitation-sequencing, genome-wide RNA-sequencing, quantitative RT-PCR, and immunostaining analyses of the hiPSC-derived endothelial lineage cells with MEF2C inhibition or knockdown compared to control hiPSC-ECs, we identified TNF-related apoptosis inducing ligand (TRAIL) and transmembrane protein 100 (TMEM100) as novel targets of MEF2C. This study demonstrates an important role for MEF2C in regulating human EC functions and highlights MEF2C and its downstream effectors as potential targets to treat vascular malfunction-associated diseases. Overall design: Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for MEF2C in hiPSC-derived Ecs

人类诱导多能干细胞（human induced pluripotent stem cells，hiPSCs）不仅可为血管疾病的潜在治疗应用提供丰富的血管细胞来源，同时亦是解析调控血管细胞分化与功能机制的理想模型。本研究报道称，肌细胞增强因子2C（myocyte enhancer factor 2C，MEF2C）转录因子——而非MEF2家族的其他成员——在hiPSCs向血管祖细胞与内皮细胞（endothelial cells，ECs）分化过程中被显著上调。血管内皮生长因子（vascular endothelial growth factors，VEGF）可强力诱导内皮谱系细胞中MEF2C的表达。内皮谱系定向分化过程中MEF2C的特异性上调依赖于细胞外信号调节激酶（ERK）。此外，在hiPSCs中利用短发夹RNA（shRNA）敲低MEF2C，并不会影响这些hiPSCs向ECs的分化，但会大幅降低hiPSC来源ECs的迁移与管形成能力。通过对MEF2C抑制或敲低的hiPSC来源内皮谱系细胞以及对照hiPSC-ECs开展染色质免疫沉淀测序、全基因组RNA测序、定量逆转录聚合酶链反应及免疫染色分析，本研究鉴定出肿瘤坏死因子相关凋亡诱导配体（TNF-related apoptosis inducing ligand，TRAIL）与跨膜蛋白100（transmembrane protein 100，TMEM100）为MEF2C的新型靶基因。本研究证实了MEF2C在调控人内皮细胞功能中的重要作用，并提出MEF2C及其下游效应因子可作为治疗血管功能异常相关疾病的潜在靶点。
总体实验设计：针对hiPSC来源ECs中的MEF2C开展染色质免疫沉淀DNA测序（ChIP-seq）