81 research outputs found
PRMT5 is required for cell-cycle progression and p53 tumor suppressor function
Protein arginine methyltransferases (PRMTs) mediate the transfer of methyl groups to arginines in proteins involved in signal transduction, transcriptional regulation and RNA processing. Tumor suppressor p53 coordinates crucial cellular processes, including cell-cycle arrest and DNA repair, in response to stress signals. Post-translational modifications and interactions with co-factors are important to regulate p53 transcriptional activity. To explore whether PRMTs modulate p53 function, we generated multiple cell lines in which PRMT1, CARM1 and PRMT5 are inducibly knocked down. Here, we showed that PRMT5, but not PRMT1 or CARM1, is essential for cell proliferation and PRMT5 deficiency triggers cell-cycle arrest in G1. In addition, PRMT5 is required for p53 expression and induction of p53 targets MDM2 and p21 upon DNA damage. Importantly, we established that PRMT5 knockdown prevents p53 protein synthesis. Furthermore, we found that PRMT5 regulates the expression of translation initiation factor eIF4E and growth suppression mediated upon PRMT5 knockdown is independent of p53 but is dependent on eIF4E. Taken together, we uncovered that arginine methyltransferase PRMT5 is a major pro-survival factor regulating eIF4E expression and p53 translation
Over-Expression of LSD1 Promotes Proliferation, Migration and Invasion in Non-Small Cell Lung Cancer
Background: Lysine specific demethylase 1 (LSD1) has been identified and biochemically characterized in epigenetics, but the pathological roles of its dysfunction in lung cancer remain to be elucidated. The aim of this study was to evaluate the prognostic significance of LSD1 expression in patients with non-small cell lung cancer (NSCLC) and to define its exact role in lung cancer proliferation, migration and invasion. Methods: The protein levels of LSD1 in surgically resected samples from NSCLC patients were detected by immunohistochemistry or Western blotting. The mRNA levels of LSD1 were detected by qRT-PCR. The correlation of LSD1 expression with clinical characteristics and prognosis was determined by statistical analysis. Cell proliferation rate was assessed by MTS assay and immunofluorescence. Cell migration and invasion were detected by scratch test, matrigel assay and transwell invasion assay. Results: LSD1 expression was higher in lung cancer tissue more than in normal lung tissue. Our results showed that overexpression of LSD1 protein were associated with shorter overall survival of NSCLC patients. LSD1 was localized mainly to the cancer cell nucleus. Interruption of LSD1 using siRNA or a chemical inhibitor, pargyline, suppressed proliferation, migration and invasion of A549, H460 and 293T cells. Meanwhile, over-expression of LSD1 enhanced cell growth. Finally, LSD1 was shown to regulate epithelial-to-mesenchymal transition in lung cancer cells
p53 Interaction with JMJD3 Results in Its Nuclear Distribution during Mouse Neural Stem Cell Differentiation
Conserved elements of apoptosis are also integral components of cellular differentiation. In this regard, p53 is involved in neurogenesis, being required for neurite outgrowth in primary neurons and for axonal regeneration in mice. Interestingly, demethylases regulate p53 activity and its interaction with co-activators by acting on non-histone proteins. In addition, the histone H3 lysine 27-specific demethylase JMJD3 induces ARF expression, thereby stabilizing p53 in mouse embryonic fibroblasts. We hypothesized that p53 interacts with key regulators of neurogenesis to redirect stem cells to differentiation, as an alternative to cell death. Specifically, we investigated the potential cross-talk between p53 and JMJD3 during mouse neural stem cell (NSC) differentiation. Our results demonstrated that JMJD3 mRNA and protein levels were increased early in mouse NSC differentiation, when JMJD3 activity was readily detected. Importantly, modulation of JMJD3 in NSCs resulted in changes of total p53 protein, coincident with increased ARF mRNA and protein expression. ChIP analysis revealed that JMJD3 was present at the promoter and exon 1 regions of ARF during neural differentiation, although without changes in H3K27me3. Immunoprecipitation assays demonstrated a direct interaction between p53 and JMJD3, independent of the C-terminal region of JMJD3, and modulation of p53 methylation by JMJD3-demethylase activity. Finally, transfection of mutant JMJD3 showed that the demethylase activity of JMJD3 was crucial in regulating p53 cellular distribution and function. In conclusion, JMJD3 induces p53 stabilization in mouse NSCs through ARF-dependent mechanisms, directly interacts with p53 and, importantly, causes nuclear accumulation of p53. This suggests that JMJD3 and p53 act in a common pathway during neurogenesis
A chemical biology toolbox to study protein methyltransferases and epigenetic signaling
© 2019, The Author(s). Protein methyltransferases (PMTs) comprise a major class of epigenetic regulatory enzymes with therapeutic relevance. Here we present a collection of chemical probes and associated reagents and data to elucidate the function of human and murine PMTs in cellular studies. Our collection provides inhibitors and antagonists that together modulate most of the key regulatory methylation marks on histones H3 and H4, providing an important resource for modulating cellular epigenomes. We describe a comprehensive and comparative characterization of the probe collection with respect to their potency, selectivity, and mode of inhibition. We demonstrate the utility of this collection in CD4 + T cell differentiation assays revealing the potential of individual probes to alter multiple T cell subpopulations which may have implications for T cell-mediated processes such as inflammation and immuno-oncology. In particular, we demonstrate a role for DOT1L in limiting Th1 cell differentiation and maintaining lineage integrity. This chemical probe collection and associated data form a resource for the study of methylation-mediated signaling in epigenetics, inflammation and beyond
KDM1A microenvironment, its oncogenic potential, and therapeutic significance
The lysine-specific histone demethylase 1A (KDM1A) was the first demethylase to challenge the concept of the irreversible nature of methylation marks. KDM1A, containing a flavin adenine dinucleotide (FAD)-dependent amine oxidase domain, demethylates histone 3 lysine 4 and histone 3 lysine 9 (H3K4me1/2 and H3K9me1/2). It has emerged as an epigenetic developmental regulator and was shown to be involved in carcinogenesis. The functional diversity of KDM1A originates from its complex structure and interactions with transcription factors, promoters, enhancers, oncoproteins, and tumor-associated genes (tumor suppressors and activators). In this review, we discuss the microenvironment of KDM1A in cancer progression that enables this protein to activate or repress target gene expression, thus making it an important epigenetic modifier that regulates the growth and differentiation potential of cells. A detailed analysis of the mechanisms underlying the interactions between KDM1A and the associated complexes will help to improve our understanding of epigenetic regulation, which may enable the discovery of more effective anticancer drugs
Protein methylation, a new mechanism of p53 tumor suppressor regulation
The tumor suppressor p53 is the most
frequently inactivated gene in human cancers. The p53
protein functions as a sequence-specific transcription
factor to regulate key cellular processes, including cellcycle
arrest, DNA repair, apoptosis, and senescence in
response to stress signals. P53 is maintained at a low
level in the cell, but becomes rapidly stabilized and
activated in response to DNA damage, hypoxia,
hyperproliferation, and other types of cellular stresses.
The stability and transcriptional activity of p53 are
tightly regulated through multiple post-translational
modifications, such as phosphorylation, acetylation, and
ubiquitination. Within the past few years, several studies
have established that protein methylation is a novel
mechanism by which p53 is regulated. Indeed, histone
lysine methyltransferases KMT5 (Set9), KMT3C
(Smyd2), and KMT5A (Set8) methylate p53 at specific
C-terminal lysines. Lysine methylation enhances or
suppresses p53 transcriptional activity depending on the
methylation site. Furthermore, the lysine-specific
demethylase KDM1 (LSD1) mediates p53 demethylation, which prevents p53 interaction with its
co-activator 53BP1 to induce apoptosis. Finally, protein
arginine methyltransferases CARM1 and PRMT1 are coactivators
of p53 involved in the methylation of histones
H3 and H4 to facilitate p53-mediated transcription. In
response to cellular stresses, the interplay between p53
methylation, demethylation, and other post-translational
modifications fine-tunes the activity of p53 to ultimately
prevent tumor formation
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