The transcription factor PU.1 is an important regulator of hematopoiesis; precise expression levels are critical for normal hematopoietic development and suppression of leukemia. We show here that noncoding antisense RNAs are important modulators of proper dosages of PU.1. Antisense and sense RNAs are regulated by shared evolutionarily conserved cis-regulatory elements, and we can show that antisense RNAs inhibit PU.1 expression by modulating mRNA translation. We propose that such antisense RNAs will likely be important in the regulation of many genes and may be the reason for the large number of overlapping complementary transcripts with so far unknown function.[Keywords: Noncoding antisense RNA; upstream and intronic regulatory elements; coordinated expression of the target and regulator; translation stalling] Supplemental material is available at http://www.genesdev.org.

Targeted disruption of a highly conserved distal enhancer reduces expression of the PU.1 transcription factor by 80% and leads to acute myeloid leukemia (AML) with frequent cytogenetic aberrations in mice. Here we identify a SNP within this element in humans that is more frequent in AML with a complex karyotype, leads to decreased enhancer activity, and reduces PU.1 expression in myeloid progenitors in a developmentdependent manner. This SNP inhibits binding of the chromatin-remodeling transcriptional regulator special AT-rich sequence binding protein 1 (SATB1). Overexpression of SATB1 increased PU.1 expression, and siRNA inhibition of SATB1 downregulated PU.1 expression. Targeted disruption of the distal enhancer led to a loss of regulation of PU.1 by SATB1. Interestingly, disruption of SATB1 in mice led to a selective decrease of PU.1 RNA in specific progenitor types (granulocyte-macrophage and megakaryocyte-erythrocyte progenitors) and a similar effect was observed in AML samples harboring this SNP. Thus we have identified a SNP within a distal enhancer that is associated with a subtype of leukemia and exerts a deleterious effect through remote transcriptional dysregulation in specific progenitor subtypes.

Marked knowledge deficits in transfusion medicine were noted. If the results of this study could be reproduced at other training institutions, medical schools may be willing to donate more resources into transfusion medicine education.

SUMMARYCoactivator-associated arginine methyltransferase I (CARM1; PRMT4) regulates gene expression by multiple mechanisms including methylation of histones and coactivation of steroid receptor transcription. Mice lacking CARM1 are small, fail to breathe and die shortly after birth, demonstrating the crucial role of CARM1 in development. In adults, CARM1 is overexpressed in human grade-III breast tumors and prostate adenocarcinomas, and knockdown of CARM1 inhibits proliferation of breast and prostate cancer cell lines. Based on these observations, we hypothesized that loss of CARM1 in mouse embryos would inhibit pulmonary cell proliferation, resulting in respiratory distress. By contrast, we report here that loss of CARM1 results in hyperproliferation of pulmonary epithelial cells during embryonic development. The lungs of newborn mice lacking CARM1 have substantially reduced airspace compared with their wild-type littermates. In the absence of CARM1, alveolar type II cells show increased proliferation. Electron microscopic analyses demonstrate that lungs from mice lacking CARM1 have immature alveolar type II cells and an absence of alveolar type I cells. Gene expression analysis reveals a dysregulation of cell cycle genes and markers of differentiation in the Carm1 knockout lung. Furthermore, there is an overlap in gene expression in the Carm1 knockout and the glucocorticoid receptor knockout lung, suggesting that hyperproliferation and lack of maturation of the alveolar cells are at least in part caused by attenuation of glucocorticoid-mediated signaling. These results demonstrate for the first time that CARM1 inhibits pulmonary cell proliferation and is required for proper differentiation of alveolar cells. ) are small and have defects in the differentiation of multiple cell types including T cells and adipocytes (Kim et al., 2004;Yadav et al., 2008;Yadav et al., 2003). Recently, it has been shown that mice carrying the enzyme-dead form of CARM1 phenocopy the Carm1 knockout, suggesting that CARM1 requires enzymatic activity for its known cellular functions (Kim et al., 2009). Carm1 knockout animals die shortly after birth and suffer from respiratory distress. Carm1/ animals fail to inflate their lungs after birth, and have reduced alveolar air space compared with wild-type littermates. These observations suggest that CARM1 is an important regulator of lung development. However, detailed studies of CARM1 expression and function in lung have not been described. Development of the distal lung and alveolar sacculation are tightly regulated by a myriad of hormone signals and a cascade of interacting transcription factor pathways that are just beginning to be elucidated (Cardoso and Lu, 2006;Maeda et al., 2007). Progenitor cells in the distal lung differentiate to multiple types including Clara bronchiole epithelial cells and alveolar type II (AT2) cells. AT2 cells are cuboidal and located in the alveolar sacs that produce the surfactant required to reduce surface tension for these sacs to fill with air. AT2 cell...