Husser, M. C. | bioRxiv Science

bioRxiv2023

Endogenous tagging using split mNeonGreen in human iPSCs for live imaging studies

Endogenous tags have become invaluable tools to visualize and study native proteins in live cells. However, generating human cell lines carrying endogenous tags is difficult due to the low efficiency of homology-directed repair. Recently, an engineered split mNeonGreen protein was used to generate a large-scale endogenous tag library in HEK293 cells. Using split mNeonGreen for large-scale endogenous tagging in human iPSCs would open the door to studying protein function in healthy cells and across differentiated cell types. We engineered an iPS cell line to express the large fragment of the split mNeonGreen protein (mNG21-10) and showed that it enables fast and efficient endogenous tagging of proteins with the short fragment (mNG211). We also demonstrate that neural network-based image restoration enables live imaging studies of highly dynamic cellular processes such as cytokinesis in iPSCs. This work represents the first step towards a genome-wide endogenous tag library in human stem cells.

cell biology↗

bioRxiv2022

Imaging tools generated by CRISPR/Cas9 tagging reveal cytokinetic diversity in mammalian cells

Cytokinesis is required to physically separate the daughter cells at the end of mitosis. This process occurs via the ingression of an actomyosin ring that assembles in anaphase and pulls in the overlying plasma membrane as it constricts. Mechanistic studies have uncovered different pathways that regulate the assembly and position of the ring in mammalian cells, but the majority of these studies were done using HeLa cells with overexpressed transgenes, and the relative requirement for these mechanisms among the majority of cell types is not known. Here, we used CRISPR/Cas9 gene editing to endogenously tag cytokinesis proteins, anillin, Ect2 and RhoA, as well as other cellular components, with fluorescent proteins. These tools enabled the visualization of cytokinesis by live imaging to quantitatively study these proteins at endogenous levels. As a proof-of-concept, tagging anillin in multiple mammalian cell lines revealed cytokinetic diversity, which will be useful for studies of how mechanisms controlling cytokinesis vary among cell types. We also successfully tagged multiple cellular components in the same cell line, demonstrating the versatility of these tagging tools.

cell biology↗