CONSTRUCTION OF A LINEAGE REPORTER LIBRARY FOR STUDYING HUMAN EMBRYONIC DEVELOPMENT

Abstract

Human embryonic stem cells (hESCs) can provide insights into the development of inaccessible human tissues such as embryonic endoderm, mesoderm, ectoderm and further differentiated progenies. However, a lack of efficient methods for isolating pure populations of these cells has hindered the progression in this area. By using the transposon-mediated BAC reporter system, we have established a reporter library for different lineages of the three germ layers. These reporter lines allow us to identify, isolate and monitor the progenitors in vitro. We discover that LGR6, which is reported before as an adult stem cell marker of the hair follicle, shows relatively higher gene expression level in early cardiac mesoderm development. Depletion of LGR6 primes hESCs towards the mesoendodermal lineage, with upregulation of early mesoendodermal genes and few changes of most pluripotency genes except for NANOG. In addition, we find increased NANOG binding on the promoters of the early mesodendodermal genes in LGR6 KO cells. Together, we establish a resource library of multi-lineage reporter cell lines and uncover a novel function of LGR6 gene in the early mesoderm development.