Involved in the reprogramming of X-chromosome inactivation during the acquisition of pluripotency. Required for efficient elongation of TSIX, a non-coding RNA antisense to XIST. Binds DXPas34 enhancer within the TSIX promoter. Involved in ES cell self-renewal. Restricted to testis, to germ cells in the early stages of spermatogenesis. Not expressed in spermatids, nor spermatozoa. Expressed in embryonic stem (ES) cells. Expressed in the inner cell mass of 4.5 dpc blastocysts, as well as in the polar trophoblast. At 6 dpc, abundant in the extraembryonic ectoderm and the ectoplacental cone. At this stage, not detected in the embryonic ectoderm. At 7 dpc, restricted to the extraembryonic ectoderm and the ectoplacental cone. Also expressed in the placenta. Expressed in male germ cells undergoing meiosis. Up-regulated by NANOG, up-regulation which is increased by SOX2 and POU5F1. Up-regulated by nicotine; up-regulation which is prevented with tubocurarine, a nicotinic acetylcholine receptor antagonist. Down-regulated by sodium vanadate and retinoic acid (RA). In ES cells, down-regulation correlates with differentiation. Polyubiquitinated by RNF12, leading to proteasomal degradation. Belongs to the krueppel C2H2-type zinc-finger protein family.