Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Penn Cardiovascular Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA.
Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Penn Cardiovascular Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA.
Cell Stem Cell. 2021 May 6;28(5):938-954.e9. doi: 10.1016/j.stem.2020.12.016. Epub 2021 Feb 1.
Pathogenic mutations in LAMIN A/C (LMNA) cause abnormal nuclear structure and laminopathies. These diseases have myriad tissue-specific phenotypes, including dilated cardiomyopathy (DCM), but how LMNA mutations result in tissue-restricted disease phenotypes remains unclear. We introduced LMNA mutations from individuals with DCM into human induced pluripotent stem cells (hiPSCs) and found that hiPSC-derived cardiomyocytes, in contrast to hepatocytes or adipocytes, exhibit aberrant nuclear morphology and specific disruptions in peripheral chromatin. Disrupted regions were enriched for transcriptionally active genes and regions with lower LAMIN B1 contact frequency. The lamina-chromatin interactions disrupted in mutant cardiomyocytes were enriched for genes associated with non-myocyte lineages and correlated with higher expression of those genes. Myocardium from individuals with LMNA variants similarly showed aberrant expression of non-myocyte pathways. We propose that the lamina network safeguards cellular identity and that pathogenic LMNA variants disrupt peripheral chromatin with specific epigenetic and molecular characteristics, causing misexpression of genes normally expressed in other cell types.
核纤层蛋白 A/C（LMNA）中的致病突变可导致异常的核结构和核纤层病。这些疾病具有多种组织特异性表型，包括扩张型心肌病（DCM），但 LMNA 突变如何导致组织受限的疾病表型仍不清楚。我们将来自 DCM 患者的 LMNA 突变引入人类诱导多能干细胞（hiPSC）中，发现与肝细胞或脂肪细胞相比，hiPSC 衍生的心肌细胞表现出异常的核形态和外周染色质的特定破坏。破坏区域富含转录活跃的基因和 LAMIN B1 接触频率较低的区域。突变型心肌细胞中破坏的核层-染色质相互作用富含与非心肌谱系相关的基因，并与这些基因的更高表达相关。来自携带 LMNA 变体个体的心肌也表现出非心肌途径的异常表达。我们提出核层网络可保护细胞身份，而致病性 LMNA 变体可破坏具有特定表观遗传和分子特征的外周染色质，导致通常在其他细胞类型中表达的基因的异常表达。
