The effect of HP1-gamma deficiency on primordial germ cells

We compared the gene expression profiles of the HP1 gamma -/- vs wild-type PGCs to examine the molecular mechanisms of HP1g in PGC development. Although HP1g is suggested to be involved in PGC proliferation, our microarray data indicated that HP1g does not directly control PGC cell-cycle progression by regulating cell cycle-related genes. However, many genes acting on differentiated tissues were up-regulated in the HP1g-/- PGCs. The mVenus-positive cells from the E11.5 genital ridges were isolated by flow cytometry (JSAN, Bay Bioscience). The total RNA was then prepared from the sorted primordial germ cells (about 500-3,500 cells per embryo) of wild-type or HP1γ-/- embryos with an RNeasy micro kit (Qiagen). The RNA samples were pooled from 5 or 6 embryos of each genotype. Two independent pooled RNA samples of each genotypes were used to verify the reproducibility of the microarray analyses.