Functional screen for microcephaly genes Genetic screens are widely used to identify regulators in biological processes. Human screens are currently limited to two-dimensional cell cultures, which lack the ability to score tissue-dependent gene function. Esk et al. combined CRISPR-Cas9 screening with barcoded cellular lineage tracing to enable loss-of-function screening in three-dimensional human cerebral organoid tissue. By testing microcephaly candidate genes, the endoplasmic reticulum was found to control extracellular matrix protein secretion regulating tissue integrity and brain size. This genetic screen in human brain tissue implicates multiple pathways in microcephaly and provides a tool for systematic testing of genes in organoids. Science, this issue p. 935 A loss-of-function screen in human cerebral organoids identifies genes for brain-size control and microcephaly. Loss-of-function (LOF) screens provide a powerful approach to identify regulators in biological processes. Pioneered in laboratory animals, LOF screens of human genes are currently restricted to two-dimensional cell cultures, which hinders the testing of gene functions requiring tissue context. Here, we present CRISPR–lineage tracing at cellular resolution in heterogeneous tissue (CRISPR-LICHT), which enables parallel LOF studies in human cerebral organoid tissue. We used CRISPR-LICHT to test 173 microcephaly candidate genes, revealing 25 to be involved in known and uncharacterized microcephaly-associated pathways. We characterized IER3IP1, which regulates the endoplasmic reticulum (ER) function and extracellular matrix protein secretion crucial for tissue integrity, the dysregulation of which results in microcephaly. Our human tissue screening technology identifies microcephaly genes and mechanisms involved in brain-size control.

中文翻译：

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人体组织筛选将 ER 分泌的调节器识别为大脑大小的决定因素

小头畸形基因的功能筛选 遗传筛选被广泛用于识别生物过程中的调节因子。人类筛查目前仅限于二维细胞培养，缺乏对组织依赖性基因功能进行评分的能力。埃斯克等人。将 CRISPR-Cas9 筛选与条形码细胞谱系追踪相结合，能够在三维人类大脑类器官组织中进行功能丧失筛选。通过测试小头畸形候选基因，发现内质网控制细胞外基质蛋白分泌，调节组织完整性和大脑大小。人类脑组织中的这种遗传筛选涉及小头畸形的多种途径，并为系统测试类器官中的基因提供了工具。科学，这个问题 p。935 人类大脑类器官的功能丧失筛查确定了大脑大小控制和小头畸形的基因。功能丧失 (LOF) 筛选提供了一种强大的方法来识别生物过程中的调节剂。人类基因的 LOF 筛选在实验室动物中首创，目前仅限于二维细胞培养，这阻碍了需要组织环境的基因功能测试。在这里，我们在异质组织中以细胞分辨率呈现 CRISPR 谱系追踪 (CRISPR-LICHT)，这使得在人类大脑类器官组织中进行平行 LOF 研究成为可能。我们使用 CRISPR-LICHT 测试了 173 个小头畸形候选基因，揭示了 25 个参与已知和未表征的小头畸形相关通路。我们表征了 IER3IP1，它调节内质网 (ER) 功能和对组织完整性至关重要的细胞外基质蛋白分泌，其失调会导致小头畸形。我们的人体组织筛选技术可识别小头畸形基因和参与大脑大小控制的机制。