Project description:Protein arginine methyltransferase 5 (PRMT5) catalyzes the symmetric di-methylation of arginine residues in histones H3 and H4, marks generally associated with transcriptional repression. However, we found that PRMT5 inhibition (or depletion) led to more genes being down-regulated than up-regulated, indicating that PRMT5 can also act as a transcriptional activator. Indeed, the global level of histone H3K27me3 increases in PRMT5 deficient cells. Although PRMT5 does not directly affect PRC2 enzymatic activity, methylation of histone H3 by PRMT5 abrogates its subsequent methylation by PRC2. Treating AML cells with an EZH2 inhibitor partially restored the expression of approximately 50% of the genes that are initially down-regulated by PRMT5 inhibition, suggesting that the increased H3K27me3 contributes to the transcription repression of these genes. Interestingly, the growth inhibitory effect of PRMT5 inhibition was also partially rescued by combined treatment with EZH2 inhibitor in several leukemia cell lines. Thus, PRMT5-mediated crosstalk between histone marks contributes to its functional effects.
Project description:Protein arginine methyltransferase 5 (PRMT5) catalyzes the symmetric di-methylation of arginine residues in histones H3 and H4, marks generally associated with transcriptional repression. However, we found that PRMT5 inhibition (or depletion) led to more genes being down-regulated than up-regulated, indicating that PRMT5 can also act as a transcriptional activator. Indeed, the global level of histone H3K27me3 increases in PRMT5 deficient cells. Although PRMT5 does not directly affect PRC2 enzymatic activity, methylation of histone H3 by PRMT5 abrogates its subsequent methylation by PRC2. Treating AML cells with an EZH2 inhibitor partially restored the expression of approximately 50% of the genes that are initially down-regulated by PRMT5 inhibition, suggesting that the increased H3K27me3 contributes to the transcription repression of these genes. Interestingly, the growth inhibitory effect of PRMT5 inhibition was also partially rescued by combined treatment with EZH2 inhibitor in several leukemia cell lines. Thus, PRMT5-mediated crosstalk between histone marks contributes to its functional effects.
Project description:Branching morphogenesis is essential for the successful development of a functional lung to accomplish its gas exchange function. Although many studies have highlighted requirements for the bone morphogenetic protein (BMP) signaling pathway during branching morphogenesis, little is known about how BMP signalingis regulated. Here we report that the protein arginine methyltransferase 5 (Prmt5) and symmetric dimethylation at histone H4 arginine 3 (H4R3sme2) directly associate with chromatin of Bmp4 to suppress its transcription. Inactivation of Prmt5 in the lung epithelium results in halted branching morphogenesis, altered epithelial cell differentiation and neonatal lethality. These defects are accompanied by increased apoptosis and reduced proliferation of lung epithelium, as a consequence of elevated canonical BMP-Smad1/5/9 signaling. Inhibition of BMP signaling by Noggin rescues the lung branching defects of Prmt5 mutant in vitro. Taken together, our results identify a novel mechanism through which Prmt5-mediated histone arginine methylation represses canonical BMP signaling to regulate lung branching morphogenesis.
