Embryonic stem cells (ESCs) are pluripotent cells capable of differentiating into any of the 200 or so different cell types in the body. Maintaining ESCs in their pluripotent state requires pluripotency factors and Tet enzymes, which regulate gene expression and differentiation programs. In a study involving mouse embryonic stem cells, Meelad Dawlaty, Ph.D., and colleagues have found that a nuclear protein known as Rinf (retinoid inducible nuclear factor) positively regulates the transcription of pluripotency genes and Tet enzymes to ensure the proper differentiation of ESCs. The researchers found that loss of Rinf compromises gene expression and differentiation programs in ESCs. Rinf was known to be expressed in ESCs, but its roles in regulating gene expression and ESC biology had not been defined. The findings were published online on August 20 in Cell Reports. Dr. Dawlaty is an assistant professor of genetics and member of the Einstein Stem Cell Institute at Einstein.