This $620,940 Project Grant award from the National Institute of Environmental Health Sciences (NIEHS) under the Environmental Health (CFDA 93.113) federal grant program supports research to investigate the impact of environmental chemicals on the epigenetic silencing of the endogenous retrovirus HML-2 in human primordial germ cells (PGCs). The research aims to determine how impairment of HML-2 epigenetic silencing during PGC development may predispose the next generation to cancer. The work involves exposing human PGC-like cells in a xenogeneic reconstituted testis (XRTestis) organoid culture to various toxicants, analyzing the transcriptional and epigenetic states of HML-2 loci, and using CRISPR to disrupt HML-2 silencing. A humanized mouse model will also be created to study multi-generational effects. The project will perform computational analysis to identify similarities and differences in HML-2 activation across human cancers and PGCs. The University of California Irvine received a sub-award under this grant to provide mice and CRISPR tools, as well as conduct chemical exposure studies and collect PGC samples for analysis by the prime awardee, the Massachusetts General Hospital.