Itch, a C2-WW-HECT domain ubiquitin E3 ligase, plays an important role in various biological processes. However, its role in embryonic stem cells (ESCs) remains unknown. Here, we report that Itch interacts with and targets pluripotency-associated transcription factor Oct4 for ubiquitination. Moreover, Itch enhances Oct4 transcriptional activities and controls Oct4 protein stability dependent on its catalytic activity. Importantly, silencing Itch expression compromises ESC self-renewal capacity and somatic cell reprogramming efficiency. Taken together, our study identifies Itch as a regulator of Oct4 stability and transcriptional activity, establishing a functional link between an E3 ligase and the regulation of pluripotency. J. Cell. Physiol. © 2012 Wiley Periodicals, Inc.