UNIVERSITY OF MASSACHUSETTS
This award, received in just the last 7-10 days, is for supplemental funds ($75,000 direct costs for one year) to support use of human iPS cells to study the fundamental aspects of X-chromosome inactivation in human females. The title of the parent R01 grant (GM 054234) is 'Nuclear and Chromatin Packaging of Mammalian X-Chromosome'. X-inactivation is an exceptionally valuable model for epigenetic regulation of the mammalian genome, particularly as it concerns formation of facultative heterochromatin. X-inactivation begins just as pluripotent embryonic cells (ES cells or iPS cells) first transition to cell type committment, in the very early embryo. Thus, to study the initial formation of the inactive X chromosome, induced by the non-coding XIST RNA, it would be of upmost value to have a cultured cell system that recapitulates the genomic programming behavior of early embryonic cells. Thus our goals include analysis of 'reverse programming' of the inactive X chromsome that is likely reactivated when iPS cells are created, and to generate a tractable XIST-inducible iPS cells system to study human X-inactivation in human embryonic-like or 'induced pluripotent' cells. The use of iPS cells circumvents the ethical concerns raised by creation of new embyronic stem cell lines from embryos.