Molecular maps of the Lamin B1-associated genomic regions in oligodendrocyte lineage cells

This study addresses the mechanisms regulating the identity of oligodendrocyte progenitor cells (OPC) in physiological conditions and the pathological mechanisms leading to autosomal  adrenoleukodystrophy (ADLD), a disease caused by persistence of lamin B1 (LMNB1) expression in oligodendrocytes (OL).  Using mouse primary OPCs and a novel technique for the study of DNA-protein interaction, we identify the genomic regions showing dynamic interactions with LMNB1.  The transition from ESC to OPC revealed increased association of gene involved in pluripotency and neuronal function and decreased association of gene categories associated with the differentiation of OPC into OL (including genes regulating epigenetic modifiers, RNA processing and protein phosphorylation).  Since LMNB1 declines during the transition from OPC to OL, and its persistent expression has been linked to pathological conditions, such as ADLD, we further identified the molecular maps of genome-lamina reorganization in OPC differentiating into OL which continue to express LMNB1 (mOLLMNB1).  The transition from OPC to mOLLMNB1 revealed increased association to LMNB1 of genomic regions encoding for lipid metabolism and protein phosphorylation, and decreased association of genes negatively regulating differentiation. These data highlight the importance of LMNB1 in physiological conditions and identify mechanisms responsible for late onset ADLD. Quantifying laminB-DNA association through DamID high throughout sequencing

本研究聚焦于生理状态下少突胶质前体细胞（oligodendrocyte progenitor cells, OPC）的身份调控机制，以及由少突胶质细胞（oligodendrocytes, OL）中核纤层蛋白B1（laminin B1, LMNB1）表达持续异常所引发的常染色体肾上腺脑白质营养不良（autosomal adrenoleukodystrophy, ADLD）的病理机制。本研究使用小鼠原代少突胶质前体细胞，以及一种全新的DNA-蛋白质相互作用研究技术，成功鉴定出与LMNB1发生动态相互作用的基因组区域。从胚胎干细胞（ESC）向少突胶质前体细胞的转化过程中，多能性与神经元功能相关基因所在的基因组区域与LMNB1的结合丰度显著升高，而与少突胶质前体细胞向少突胶质细胞分化相关的基因类别（包括表观遗传调控因子、RNA加工及蛋白质磷酸化相关基因）所在的基因组区域与LMNB1的结合丰度则显著降低。鉴于LMNB1在少突胶质前体细胞向少突胶质细胞的转化过程中表达下调，且其持续表达与ADLD等病理状态密切相关，本研究进一步鉴定了持续表达LMNB1的少突胶质细胞（mOLLMNB1）在由少突胶质前体细胞分化而来的过程中，基因组-核纤层结构重组的分子图谱。少突胶质前体细胞向持续表达LMNB1的少突胶质细胞转化过程中，编码脂质代谢与蛋白质磷酸化相关蛋白的基因组区域与LMNB1的结合丰度显著升高，而负向调控分化的基因所在的基因组区域与LMNB1的结合丰度则显著降低。本研究结果阐明了LMNB1在生理状态下的重要作用，并明确了迟发性常染色体肾上腺脑白质营养不良的致病机制。本研究通过DamID高通量测序技术对核纤层蛋白B与DNA的结合情况进行定量分析。