A human tissue screen identifies a regulator of ER secretion as a brain size determinant

A human tissue screen identifies a regulator of ER secretion as a brain size determinant. Abstract: 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 (2D) cell culture hindering testing of gene functions requiring tissue context. Here we present CRISPR-LIneage tracing at Cellular resolution in Heterogenous Tissue (CRISPR-LICHT), enabling 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 Immediate Early Response 3 Interacting Protein 1 (IER3IP1) regulating the unfolded protein response (UPR) and extracellular matrix (ECM) protein secretion crucial for tissue integrity, with dysregulation resulting in microcephaly. Our human tissue screening technology identifies microcephaly genes and mechanisms involved in brain size control.

人体组织筛选鉴定出内质网（Endoplasmic Reticulum）分泌调控因子作为脑尺寸决定因子。摘要：功能丧失（Loss-of-function, LOF）筛选是鉴定生物学过程调控因子的有力手段。尽管该方法最初在实验动物中建立，但当前人类基因的功能丧失筛选仅局限于二维（2D）细胞培养体系，这一局限阻碍了对依赖组织微环境的基因功能的验证。本研究报道了异质性组织细胞分辨率CRISPR谱系示踪技术（CRISPR-LIneage tracing at Cellular resolution in Heterogenous Tissue，简称CRISPR-LICHT），可实现在人类大脑类器官组织中并行开展功能丧失研究。我们利用该技术对173个小头畸形候选基因进行筛选，鉴定出25个基因参与已知及未被阐明的小头畸形相关通路。我们对即刻早期反应3互作蛋白1（Immediate Early Response 3 Interacting Protein 1, IER3IP1）进行了功能表征，发现其可调控未折叠蛋白反应（Unfolded Protein Response, UPR）及对维持组织完整性至关重要的细胞外基质（Extracellular Matrix, ECM）蛋白分泌，该蛋白的调控异常可导致小头畸形。本研究开发的人体组织筛选技术可鉴定出参与脑尺寸调控的小头畸形相关基因及作用机制。