Molecular and cellular characterization of essential human genes.

我们建议生成条形码和条件空 细胞系统中的等位基因可以模拟早期人类发育和广泛的人类 疾病。我们将建立数据生产研发中心，以应对 RFA-HG-21-029：细胞中空等位基因的分子表型(形态)第一阶段，旨在 为最终每个人类基因建立空等位基因的分子和细胞表型目录， 使用体外多细胞系统。我们的中心将利用化学诱导和可逆系统 这使得目标蛋白质能够迅速耗尽。这种方法允许对蛋白质进行时间控制 水平，以研究零等位基因的后果。我们会如此迅速地使用一个超级敏感的降落物 对低剂量的生长素(一种可扩散的细胞膜)的反应降解目标蛋白 小的化学植物激素。我们将结合基于CRISPR的目标轨迹工程来 在targe基因末端敲入一个由生长素诱导的微小降解基因(MAID)，以创造一个 在开放获取的人类诱导的多能干细胞中化学可控的开关来产生零等位基因 (HiPSC)细胞，可分化为各种细胞谱系和多细胞类器官进行建模 人类发展和疾病。值得注意的是，每个AID-degron还将包含基因特定的条形码， 允许跟踪数十万无效等位基因的命运，当这些设计的无效等位基因 是汇集在一起的。 所提出的方法具有通用性，可以快速耗尽不同编码的目标蛋白。 人类基因的类别。我们的策略对研究零将是特别有利和关键的 必需基因的表型，不能用遗传学方法通过慢性耗竭来研究 (如CRISPR KO)，因为敲入会导致细胞死亡。因此，要突出 我们的策略是，我们优先通过CRISPR介导的敲入过程来引入零等位基因 250个必需基因中的条形码AID降解。我们选择了与人类疾病有牵连且不可行的基因 国际小鼠表型鉴定联盟(IMPC)的表型。我们建议编目 细胞表型(存活、增殖、有丝分裂功能和分化)和分子 音型，包括基因表达和选择空等位基因的染色质可及性。这 信息将为这些对发育至关重要的细胞的生物学功能提供独特的见解 基因。它将强调建立化学诱导降解系统作为一种 形态联合体目标的概括策略。创建的条形码和条形码 零等位基因资源将提供一个独特的机会，在时间上控制零等位基因的时间 多能干细胞状态与多种终末分化细胞类型或多细胞类器官系统 它可以从多能干细胞中产生。

We propose to generate barcoded and conditional null alleles in a cellular system that can model early human development and a broad range of human diseases. We will establish a data production research and development center in response to the RFA-HG-21-029: Molecular Phenotypes of Null Alleles in Cells (MorPhiC) Phase 1, which aims to establish a catalog of molecular and cellular phenotypes of null alleles for ultimately every human gene, using in vitro multicellular systems. Our center will utilize a chemically inducible and reversible system that enables the rapid depletion of target proteins. The approach permits temporal control of protein levels to study the consequences of null alleles. We will utilize a super sensitive degron that rapidly degrades the target protein of interest in response to a low dose of auxin, a cell membrane diffusible small chemical plant hormone. We will combine CRISPR-based targeted locus engineering to homozygous knock-in a mini auxin-inducible degron (mAID) at the end of the targe gene to create a chemically controllable switch to create null-alleles in an open-access human induced pluripotent stem (hiPSC) cell, which can be differentiated into various cell lineages and multicellular organoids to model human development and diseases. Notably, each AID-degron will also contain gene-specific barcodes, allowing tracking the fate of hundreds of thousands of null alleles when these engineered null alleles are pooled. The proposed approach is generalizable and can rapidly deplete target proteins codded by various classes of human genes. Our strategy will be particularly advantageous and critical to study the null phenotypes of essential genes, which cannot be studied by chronic depletion using genetic approaches (such as CRISPR KO) because the knock-in results in cell death. Therefore, to highlight the utility of our strategy, we prioritize creating null alleles by CRISPR mediated knock-in process to introduce barcoded AID degron in 250 essential genes. We chose genes implicated in human diseases and subviable phenotypes in the International Mouse Phenotyping Consortium (IMPC). We propose to catalog the cellular phenotypes (survival, proliferation, mitotic function, and differentiation) and molecular phonotypes, including gene expression and chromatin accessibility for select null alleles. This information will provide unique insights into the biological function of these developmentally critical genes. It will highlight the utility of establishing the chemically inducible degron system as a generalizable strategy for the goals of the MorPhiC consortium. The created barcoded and conditional null allele resource will provide a unique opportunity to temporally control the timing of null alleles in pluripotent stem state and various terminally differentiated cell types or multicellular organoid systems that can be generated from the pluripotent stem cells.