Mechanisms to maintain the self-renewal and genetic stability of human embryonic stem cells

Mechanisms to maintain the self-renewal and genetic stability of human embryonic stem cells

Funding Type: 
Comprehensive Grant
Grant Number: 
RC1-00148
Award Value: 
$2,467,200
Disease Focus: 
Cancer
Genetic Disorder
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
Status: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 

Year 1

The goal of this proposal is to investigate the mechanisms that maintain the genomic stability of human ES cells (hESCs). We are focusing on the tumor suppression pathways ATM and p53, which are well established guardians of the genome in differentiated cells. In addition, we are investigating the pathways that govern the self-renewal of hESCs, which might be coordinated with DNA damage responses to maintain the genomic stability in hESCs. During the reporting period, we made significant progress towards our goals. First, we developed high efficiency homologous recombination technology to successfully disrupted ATM and p53 in hESCs. Analysis of the mutant ES cells indicate the roles of ATM and p53 in maintaining genomic stability in hESCs. Second, we identified pathways that are important for the self-renewal of hESCs. Third, we employed the knock-in tech

Year 2

The goal of this proposal is to investigate the mechanisms that maintain the genomic stability of human ES cells (hESCs). We are focusing on the tumor suppression pathways ATM and p53, which are well established guardians of the genome in differentiated cells. In addition, we are investigating the pathways that govern the self-renewal of hESCs, which might be coordinated with DNA damage responses to maintain the genomic stability in hESCs. During the reporting period, we made significant progress towards our goals. First, we developed a bacterial artificial chromosome based gene targeting technology that allows high efficiency homologous recombination in hESCs, and published the first homozygous knockout mutant hESCs in the world (Aims 1 and 3). This achievement, which was described in a publication in the top stem cell journal Cell Stem Cell, has attracted worldwide attention and will help to open up the entire field of hESCs (Song et al., 2010, Cell Stem Cell 6, 180-189). We employed the same technology to generate homozygous phosphorylation site knock-in mutant hESCs to study the mechanism underlying ATM activation in hESCs (Aim 3). Second, we identified a novel Pin1-Nanog pathway that is critical for the self-renewal of hESCs (Aim 2). Using small molecule compounds that inhibit this pathway, we were able to suppress the potential of ES cells to form teratomas. This finding, which is published in the Proceeding National Academy of Science, provides a druggable target to address the teratomas risk associated with the human ES cell based therapy (Moretto-Zita et al., 2010, PNAS, Epub 7/9). Third, to identify ES cell-specific DNA repair pathways, we have identified several ES cell-specific interaction between proteins and DNA breaks (Aim 3).

Year 3

We have made several significant progresses during the past year. We found the important roles of p53 in the differentiation of hESCs. We also identified that Nanog is a major coordinator of the self-renewal and proliferation of ES cells. We found that ATM is important to maintain the genetic stability of cells differentiated from hESCs. In addition, we identified an important phosphorylation event in activating ATM in hESCs. Finally, we identified a novel pathway to activate DNA damage in ES cells.

© 2013 California Institute for Regenerative Medicine