Although histone H3 lysine 27 trimethylation (H3K27Me3) is associated with gene silencing, whether H3K27Me3 demethylation affects transcription and cell differentiation in vivo has remained elusive. To investigate this, we conditionally inactivated the two H3K27Me3 demethylases, Jmjd3 and Utx, in non-dividing intrathymic CD4+ T-cell precursors. Here we show that both enzymes redundantly promote H3K27Me3 removal at, and expression of, a specific subset of genes involved in terminal thymocyte differentiation, especially S1pr1, encoding a sphingosine-phosphate receptor required for thymocyte egress. Thymocyte expression of S1pr1 was not rescued in Jmjd3- and Utx-deficient male mice, which carry the catalytically inactive Utx homolog Uty, supporting the conclusion that it requires H3K27Me3 demethylase activity. These findings demonstrate that Jmjd3 and Utx are required for T-cell development, and point to a requirement for their H3K27Me3 demethylase activity in cell differentiation.
Two putative endocannabinoids, N-arachidonylethanolamine (AEA) and 2-arachidonylglycerol, are inactivated by removal from the extracellular environment by a process that has the features of protein-mediated facilitated diffusion. We have synthesized and studied 22 N-linked analogues of arachidonylamide for the purpose of increasing our understanding of the structural requirements for the binding of ligands to the AEA transporter. We have also determined the affinities of these analogues for both the CB 1 cannabinoid receptor and fatty acid amide hydrolase (FAAH). We have identified several structural features that enhance binding to the AEA transporter in cerebellar granule cells. We have confirmed the findings of others that replacing the ethanolamine head group with 4-hydroxybenzyl results in a high-affinity ligand for the transporter. However, we find that the same molecule is also a competitive inhibitor of FAAH. Similarly, replacement of the ethanolamine of AEA with 3-pyridinyl also results in a high-affinity inhibitor of both the transporter and FAAH. We conclude that the structural requirements for ligand binding to the CB 1 receptor and binding to the transporter are very different; however, the transporter and FAAH share most, but not all, structural requirements. Key Words: N-ArachidonylethanolamineEndocannabinoid-Fatty acid amide hydrolase-Cannabinoid receptor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.