RNA-seq analysis of human forebrain organoids irradiated with moderate to high doses of ionizing radiation

Prenatal irradiation can cause neurodevelopmental defects which are characterized by a reduction in brain size (microcephaly). The underlying molecular mechanisms in humans have so far not been studied. Here, we leveraged human forebrain organoids as a model for human embryonic brain development to investigate time- and dose-dependent effects of radiation on organoid growth. For this, organoids of 14 days and 56 days old were irradiated with acute X-ray doses of 0.5 Gy or 2 Gy and compared to controls. Using bulk RNA-seq at different early (6 h and 24 h) and late (14 days) time points after irradiation, we investigated mechanisms of radiation-induced growth defects which resulted from activation of the DNA damage response (cell cycle arrest, DNA repair, apoptosis), premature differentiation and the coordinated repression of primary microcephaly genes.

产前辐射可引发以脑容量缩减为特征的神经发育缺陷，即小头畸形（microcephaly）。截至目前，学界尚未针对人类该类缺陷的潜在分子机制展开相关研究。本研究以人类前脑类器官（human forebrain organoids）作为人类胚胎脑发育的体外模型，探究辐射对类器官生长的时间依赖性与剂量依赖性效应。为此，我们对培养14天及56天的类器官分别施加0.5 Gy或2 Gy的急性X射线辐射，并设置未辐射对照组进行对照。我们在辐射后的不同早期节点（6小时与24小时）及晚期节点（14天）开展批量RNA测序（bulk RNA-seq），解析了辐射诱导生长缺陷的分子机制：该缺陷由DNA损伤应答（DNA damage response，涵盖细胞周期阻滞、DNA修复与细胞凋亡）的激活、细胞过早分化，以及原发性小头畸形相关基因的协同抑制所共同介导。