RESUMO
Metabolic reprogramming is a hallmark of cancer. However, mechanisms underlying metabolic reprogramming and how altered metabolism in turn enhances tumorigenicity are poorly understood. Here, we report that arginine levels are elevated in murine and patient hepatocellular carcinoma (HCC), despite reduced expression of arginine synthesis genes. Tumor cells accumulate high levels of arginine due to increased uptake and reduced arginine-to-polyamine conversion. Importantly, the high levels of arginine promote tumor formation via further metabolic reprogramming, including changes in glucose, amino acid, nucleotide, and fatty acid metabolism. Mechanistically, arginine binds RNA-binding motif protein 39 (RBM39) to control expression of metabolic genes. RBM39-mediated upregulation of asparagine synthesis leads to enhanced arginine uptake, creating a positive feedback loop to sustain high arginine levels and oncogenic metabolism. Thus, arginine is a second messenger-like molecule that reprograms metabolism to promote tumor growth.
Assuntos
Arginina , Carcinoma Hepatocelular , Neoplasias Hepáticas , Animais , Humanos , Camundongos , Arginina/metabolismo , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Metabolismo dos Lipídeos , Neoplasias Hepáticas/metabolismoRESUMO
In eukaryotic cells, organelle biogenesis is pivotal for cellular function and cell survival. Chloroplasts are unique organelles with a complex internal membrane network. The mechanisms of the migration of imported nuclear-encoded chloroplast proteins across the crowded stroma to thylakoid membranes are less understood. Here, we identified two Arabidopsis ankyrin-repeat proteins, STT1 and STT2, that specifically mediate sorting of chloroplast twin arginine translocation (cpTat) pathway proteins to thylakoid membranes. STT1 and STT2 form a unique hetero-dimer through interaction of their C-terminal ankyrin domains. Binding of cpTat substrate by N-terminal intrinsically disordered regions of STT complex induces liquid-liquid phase separation. The multivalent nature of STT oligomer is critical for phase separation. STT-Hcf106 interactions reverse phase separation and facilitate cargo targeting and translocation across thylakoid membranes. Thus, the formation of phase-separated droplets emerges as a novel mechanism of intra-chloroplast cargo sorting. Our findings highlight a conserved mechanism of phase separation in regulating organelle biogenesis.
Assuntos
Arabidopsis/metabolismo , Transporte Proteico/fisiologia , Sistema de Translocação de Argininas Geminadas/metabolismo , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Membranas Intracelulares/metabolismo , Proteínas de Membrana/metabolismo , Biogênese de Organelas , Organelas/metabolismo , Transição de Fase , Proteínas de Plantas/metabolismo , Tilacoides/metabolismo , Sistema de Translocação de Argininas Geminadas/fisiologiaRESUMO
Cytoplasmic FUS aggregates are a pathological hallmark in a subset of patients with frontotemporal dementia (FTD) or amyotrophic lateral sclerosis (ALS). A key step that is disrupted in these patients is nuclear import of FUS mediated by the import receptor Transportin/Karyopherin-ß2. In ALS-FUS patients, this is caused by mutations in the nuclear localization signal (NLS) of FUS that weaken Transportin binding. In FTD-FUS patients, Transportin is aggregated, and post-translational arginine methylation, which regulates the FUS-Transportin interaction, is lost. Here, we show that Transportin and arginine methylation have a crucial function beyond nuclear import-namely to suppress RGG/RG-driven phase separation and stress granule association of FUS. ALS-associated FUS-NLS mutations weaken the chaperone activity of Transportin and loss of FUS arginine methylation, as seen in FTD-FUS, promote phase separation, and stress granule partitioning of FUS. Our findings reveal two regulatory mechanisms of liquid-phase homeostasis that are disrupted in FUS-associated neurodegeneration.
Assuntos
Arginina/química , Proteína FUS de Ligação a RNA/química , beta Carioferinas/química , Transporte Ativo do Núcleo Celular , Motivos de Aminoácidos , Citoplasma/metabolismo , Metilação de DNA , DNA Complementar/metabolismo , Densitometria , Degeneração Lobar Frontotemporal/metabolismo , Células HeLa , Homeostase , Humanos , Carioferinas/química , Espectroscopia de Ressonância Magnética , Metilação , Chaperonas Moleculares/química , Mutação , Doenças Neurodegenerativas/metabolismo , Ligação Proteica , Domínios ProteicosRESUMO
Reversible phase separation underpins the role of FUS in ribonucleoprotein granules and other membrane-free organelles and is, in part, driven by the intrinsically disordered low-complexity (LC) domain of FUS. Here, we report that cooperative cation-π interactions between tyrosines in the LC domain and arginines in structured C-terminal domains also contribute to phase separation. These interactions are modulated by post-translational arginine methylation, wherein arginine hypomethylation strongly promotes phase separation and gelation. Indeed, significant hypomethylation, which occurs in FUS-associated frontotemporal lobar degeneration (FTLD), induces FUS condensation into stable intermolecular ß-sheet-rich hydrogels that disrupt RNP granule function and impair new protein synthesis in neuron terminals. We show that transportin acts as a physiological molecular chaperone of FUS in neuron terminals, reducing phase separation and gelation of methylated and hypomethylated FUS and rescuing protein synthesis. These results demonstrate how FUS condensation is physiologically regulated and how perturbations in these mechanisms can lead to disease.
Assuntos
Arginina/química , Chaperonas Moleculares/química , Proteína FUS de Ligação a RNA/química , Esclerose Lateral Amiotrófica/metabolismo , Animais , Cátions , Metilação de DNA , Demência Frontotemporal/metabolismo , Degeneração Lobar Frontotemporal/metabolismo , Humanos , Microscopia de Força Atômica , Microscopia de Fluorescência , Ligação Proteica , Domínios Proteicos , Processamento de Proteína Pós-Traducional , Estrutura Secundária de Proteína , Proteína FUS de Ligação a RNA/metabolismo , Tirosina/química , Xenopus laevisRESUMO
Many types of human cancers suppress the expression of argininosuccinate synthase 1 (ASS1), a rate-limiting enzyme for arginine production. Although dependency on exogenous arginine can be harnessed by arginine-deprivation therapies, the impact of ASS1 suppression on the quality of the tumor proteome is unknown. We therefore interrogated proteomes of cancer patients for arginine codon reassignments (substitutants) and surprisingly identified a strong enrichment for cysteine (R>C) in lung tumors specifically. Most R>C events did not coincide with genetically encoded R>C mutations but were likely products of tRNA misalignments. The expression of R>C substitutants was highly associated with oncogenic kelch-like epichlorohydrin (ECH)-associated protein 1 (KEAP1)-pathway mutations and suppressed by intact-KEAP1 in KEAP1-mutated cancer cells. Finally, functional interrogation indicated a key role for R>C substitutants in cell survival to cisplatin, suggesting that regulatory codon reassignments endow cancer cells with more resilience to stress. Thus, we present a mechanism for enriching lung cancer proteomes with cysteines that may affect therapeutic decisions.
Assuntos
Arginina , Cisteína , Proteína 1 Associada a ECH Semelhante a Kelch , Neoplasias Pulmonares , Proteoma , Humanos , Cisteína/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/patologia , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Proteoma/metabolismo , Arginina/metabolismo , Mutação , Argininossuccinato Sintase/metabolismo , Argininossuccinato Sintase/genética , Cisplatino/farmacologia , Linhagem Celular Tumoral , Proteômica/métodos , Regulação Neoplásica da Expressão Gênica , Sobrevivência Celular/efeitos dos fármacos , RNA de Transferência/metabolismo , RNA de Transferência/genéticaRESUMO
Metabolic activity is intimately linked to T cell fate and function. Using high-resolution mass spectrometry, we generated dynamic metabolome and proteome profiles of human primary naive T cells following activation. We discovered critical changes in the arginine metabolism that led to a drop in intracellular L-arginine concentration. Elevating L-arginine levels induced global metabolic changes including a shift from glycolysis to oxidative phosphorylation in activated T cells and promoted the generation of central memory-like cells endowed with higher survival capacity and, in a mouse model, anti-tumor activity. Proteome-wide probing of structural alterations, validated by the analysis of knockout T cell clones, identified three transcriptional regulators (BAZ1B, PSIP1, and TSN) that sensed L-arginine levels and promoted T cell survival. Thus, intracellular L-arginine concentrations directly impact the metabolic fitness and survival capacity of T cells that are crucial for anti-tumor responses.
Assuntos
Arginina/metabolismo , Linfócitos T CD4-Positivos/imunologia , Imunomodulação , Ativação Linfocitária , Melanoma Experimental/imunologia , Neoplasias Cutâneas/imunologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Linfócitos T CD4-Positivos/metabolismo , Proteínas de Ligação a DNA/metabolismo , Técnicas de Inativação de Genes , Glicólise , Humanos , Memória Imunológica , Metaboloma , Camundongos , Camundongos Endogâmicos BALB C , Fosforilação Oxidativa , Proteoma , Fatores de Transcrição/metabolismo , Transcrição GênicaRESUMO
Transcription factors (TFs) orchestrate the gene expression programs that define each cell's identity. The canonical TF accomplishes this with two domains, one that binds specific DNA sequences and the other that binds protein coactivators or corepressors. We find that at least half of TFs also bind RNA, doing so through a previously unrecognized domain with sequence and functional features analogous to the arginine-rich motif of the HIV transcriptional activator Tat. RNA binding contributes to TF function by promoting the dynamic association between DNA, RNA, and TF on chromatin. TF-RNA interactions are a conserved feature important for vertebrate development and disrupted in disease. We propose that the ability to bind DNA, RNA, and protein is a general property of many TFs and is fundamental to their gene regulatory function.
Assuntos
RNA , Fatores de Transcrição , Fatores de Transcrição/metabolismo , RNA/metabolismo , Sítios de Ligação , Ligação Proteica , DNA/genéticaRESUMO
Hv1 is a voltage-gated proton-selective channel that plays critical parts in host defense, sperm motility, and cancer progression. Hv1 contains a conserved voltage-sensor domain (VSD) that is shared by a large family of voltage-gated ion channels, but it lacks a pore domain. Voltage sensitivity and proton conductivity are conferred by a unitary VSD that consists of four transmembrane helices. The architecture of Hv1 differs from that of cation channels that form a pore in the center among multiple subunits (as in most cation channels) or homologous repeats (as in voltage-gated sodium and calcium channels). Hv1 forms a dimer in which a cytoplasmic coiled coil underpins the two protomers and forms a single, long helix that is contiguous with S4, the transmembrane voltage-sensing segment. The closed-state structure of Hv1 was recently solved using X-ray crystallography. In this article, we discuss the gating mechanism of Hv1 and focus on cooperativity within dimers and their sensitivity to metal ions.
Assuntos
Canais Iônicos/química , Canais Iônicos/metabolismo , Animais , Cristalografia por Raios X , Humanos , Modelos MolecularesRESUMO
The twin-arginine translocation (Tat) system, found in prokaryotes, chloroplasts, and some mitochondria, allows folded proteins to be moved across membranes. How this transport is achieved without significant ion leakage is an intriguing mechanistic question. Tat transport is mediated by complexes formed from small integral membrane proteins from just two protein families. Atomic-resolution structures have recently been determined for representatives of both these protein families, providing the first molecular-level glimpse of the Tat machinery. I review our current understanding of the mechanism of Tat transport in light of these new structural data.
Assuntos
Transporte Proteico , Sistema de Translocação de Argininas Geminadas/metabolismo , Archaea/classificação , Archaea/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Cloroplastos/metabolismo , Mitocôndrias/metabolismo , Células Procarióticas/metabolismo , Força Próton-Motriz , Sistema de Translocação de Argininas Geminadas/químicaRESUMO
Accurate control of innate immune responses is required to eliminate invading pathogens and simultaneously avoid autoinflammation and autoimmune diseases. Here, we demonstrate that arginine monomethylation precisely regulates the mitochondrial antiviral-signaling protein (MAVS)-mediated antiviral response. Protein arginine methyltransferase 7 (PRMT7) forms aggregates to catalyze MAVS monomethylation at arginine residue 52 (R52), attenuating its binding to TRIM31 and RIG-I, which leads to the suppression of MAVS aggregation and subsequent activation. Upon virus infection, aggregated PRMT7 is disabled in a timely manner due to automethylation at arginine residue 32 (R32), and SMURF1 is recruited to PRMT7 by MAVS to induce proteasomal degradation of PRMT7, resulting in the relief of PRMT7 suppression of MAVS activation. Therefore, we not only reveal that arginine monomethylation by PRMT7 negatively regulates MAVS-mediated antiviral signaling in vitro and in vivo but also uncover a mechanism by which PRMT7 is tightly controlled to ensure the timely activation of antiviral defense.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Arginina/metabolismo , Interações Hospedeiro-Patógeno/fisiologia , Imunidade Inata/fisiologia , Proteína-Arginina N-Metiltransferases/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Proteína DEAD-box 58/metabolismo , Fibroblastos/virologia , Células HEK293 , Herpes Simples/imunologia , Herpes Simples/metabolismo , Herpes Simples/virologia , Humanos , Metilação , Camundongos , Camundongos Knockout , Alcamidas Poli-Insaturadas , Proteína-Arginina N-Metiltransferases/antagonistas & inibidores , Proteína-Arginina N-Metiltransferases/genética , Proteína-Arginina N-Metiltransferases/imunologia , Receptores Imunológicos/metabolismo , Infecções por Respirovirus/imunologia , Infecções por Respirovirus/metabolismo , Infecções por Respirovirus/virologia , Proteínas com Motivo Tripartido/genética , Proteínas com Motivo Tripartido/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Aberrant cell proliferation is a hallmark of cancer, including glioblastoma (GBM). Here we report that protein arginine methyltransferase (PRMT) 6 activity is required for the proliferation, stem-like properties, and tumorigenicity of glioblastoma stem cells (GSCs), a subpopulation in GBM critical for malignancy. We identified a casein kinase 2 (CK2)-PRMT6-regulator of chromatin condensation 1 (RCC1) signaling axis whose activity is an important contributor to the stem-like properties and tumor biology of GSCs. CK2 phosphorylates and stabilizes PRMT6 through deubiquitylation, which promotes PRMT6 methylation of RCC1, which in turn is required for RCC1 association with chromatin and activation of RAN. Disruption of this pathway results in defects in mitosis. EPZ020411, a specific small-molecule inhibitor for PRMT6, suppresses RCC1 arginine methylation and improves the cytotoxic activity of radiotherapy against GSC brain tumor xenografts. This study identifies a CK2α-PRMT6-RCC1 signaling axis that can be therapeutically targeted in the treatment of GBM.
Assuntos
Neoplasias Encefálicas , Carcinogênese , Proteínas de Ciclo Celular , Glioblastoma , Fatores de Troca do Nucleotídeo Guanina , Mitose/efeitos da radiação , Proteínas de Neoplasias , Proteínas Nucleares , Proteína-Arginina N-Metiltransferases , Animais , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/radioterapia , Carcinogênese/genética , Carcinogênese/metabolismo , Carcinogênese/efeitos da radiação , Caseína Quinase II/genética , Caseína Quinase II/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Feminino , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/radioterapia , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Células HEK293 , Humanos , Masculino , Camundongos , Mitose/genética , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteína-Arginina N-Metiltransferases/genética , Proteína-Arginina N-Metiltransferases/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/efeitos da radiação , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Arginine methylation is an influential post-translational modification occurring on histones, RNA binding proteins, and many other cellular proteins, affecting their function by altering their protein-protein and protein-nucleic acid interactions. Recently, a wealth of information has been gathered, implicating protein arginine methyltransferases (PRMTs), enzymes that deposit arginine methylation, in transcription, pre-mRNA splicing, DNA damage signaling, and immune signaling with major implications for cancer therapy, especially immunotherapy. This review summarizes this recent progress and the current state of PRMT inhibitors, some in clinical trials, as promising drug targets for cancer.
Assuntos
Arginina/química , Metilação , Neoplasias/metabolismo , Processamento de Proteína Pós-Traducional , Proteína-Arginina N-Metiltransferases/antagonistas & inibidores , Processamento Alternativo , Animais , Antígeno B7-H1/metabolismo , Sistemas CRISPR-Cas , Comunicação Celular , Linhagem Celular Tumoral , Dano ao DNA , Reparo do DNA , Inibidores Enzimáticos/farmacologia , Epigênese Genética , Histonas , Humanos , Sistema Imunitário , Imunoterapia/métodos , Camundongos , Camundongos Knockout , Proteína-Arginina N-Metiltransferases/química , Splicing de RNA , RNA Mensageiro/metabolismo , Transdução de SinaisRESUMO
PRMT5 is an essential arginine methyltransferase and a therapeutic target in MTAP-null cancers. PRMT5 uses adaptor proteins for substrate recruitment through a previously undefined mechanism. Here, we identify an evolutionarily conserved peptide sequence shared among the three known substrate adaptors (CLNS1A, RIOK1, and COPR5) and show that it is necessary and sufficient for interaction with PRMT5. We demonstrate that PRMT5 uses modular adaptor proteins containing a common binding motif for substrate recruitment, comparable with other enzyme classes such as kinases and E3 ligases. We structurally resolve the interface with PRMT5 and show via genetic perturbation that it is required for methylation of adaptor-recruited substrates including the spliceosome, histones, and ribosomal complexes. Furthermore, disruption of this site affects Sm spliceosome activity, leading to intron retention. Genetic disruption of the PRMT5-substrate adaptor interface impairs growth of MTAP-null tumor cells and is thus a site for development of therapeutic inhibitors of PRMT5.
Assuntos
Proteína-Arginina N-Metiltransferases/metabolismo , Proteína-Arginina N-Metiltransferases/fisiologia , Animais , Linhagem Celular Tumoral , Citoplasma/metabolismo , Feminino , Células HCT116 , Células HEK293 , Histonas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Canais Iônicos/metabolismo , Masculino , Metilação , Camundongos , Camundongos Nus , Proteínas Nucleares/metabolismo , Peptídeos/genética , Ligação Proteica , Processamento de Proteína Pós-Traducional , Proteínas Serina-Treonina Quinases/metabolismo , Proteína-Arginina N-Metiltransferases/genética , Spliceossomos/metabolismoRESUMO
Macrophage polarization is accompanied by drastic changes in L-arginine metabolism. Two L-arginine catalytic enzymes, iNOS and arginase 1, are well-characterized hallmark molecules of classically and alternatively activated macrophages, respectively. The third metabolic fate of L-arginine is the generation of creatine that acts as a key source of cellular energy reserve, yet little is known about the role of creatine in the immune system. Here, genetic, genomic, metabolic, and immunological analyses revealed that creatine reprogrammed macrophage polarization by suppressing M(interferon-γ [IFN-γ]) yet promoting M(interleukin-4 [IL-4]) effector functions. Mechanistically, creatine inhibited the induction of immune effector molecules, including iNOS, by suppressing IFN-γ-JAK-STAT1 transcription-factor signaling while supporting IL-4-STAT6-activated arginase 1 expression by promoting chromatin remodeling. Depletion of intracellular creatine by ablation of the creatine transporter Slc6a8 altered macrophage-mediated immune responses in vivo. These results uncover a previously uncharacterized role for creatine in macrophage polarization by modulating cellular responses to cytokines such as IFN-γ and IL-4.
Assuntos
Arginina/metabolismo , Creatina/metabolismo , Cirrose Hepática/metabolismo , Macrófagos/fisiologia , Proteínas de Membrana Transportadoras/metabolismo , Animais , Diferenciação Celular , Células Cultivadas , Reprogramação Celular , Humanos , Imunidade Celular , Interferon gama/metabolismo , Cirrose Hepática/induzido quimicamente , Proteínas de Membrana Transportadoras/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Transdução de Sinais , TetracloroetilenoRESUMO
Neurogenesis in the developing and adult brain is intimately linked to remodeling of cellular metabolism. However, it is still unclear how distinct metabolic programs and energy sources govern neural stem cell (NSC) behavior and subsequent neuronal differentiation. Here, we found that adult mice lacking the mitochondrial urea metabolism enzyme, Arginase-II (Arg-II), exhibited NSC overactivation, thereby leading to accelerated NSC pool depletion and decreased hippocampal neurogenesis over time. Mechanistically, Arg-II deficiency resulted in elevated L-arginine levels and induction of a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) caused by impaired attachment of hexokinase-I to mitochondria. Notably, selective inhibition of OXPHOS ameliorated NSC overactivation and restored abnormal neurogenesis in Arg-II deficient mice. Therefore, Arg-II-mediated intracellular L-arginine homeostasis directly influences the metabolic fitness of neural stem cells that is essential to maintain neurogenesis with age.
Assuntos
Células-Tronco Neurais , Camundongos , Animais , Proliferação de Células , Células-Tronco Neurais/metabolismo , Neurogênese/fisiologia , Glicólise , Homeostase , Arginina/metabolismoRESUMO
Enteropathogenic E. coli NleB and related type III effectors catalyze arginine GlcNAcylation of death domain (DD) proteins to block host defense, but the underlying mechanism is unknown. Here we solve crystal structures of NleB alone and in complex with FADD-DD, UDP, and Mn2+ as well as NleB-GlcNAcylated DDs of TRADD and RIPK1. NleB adopts a GT-A fold with a unique helix-pair insertion to hold FADD-DD; the interface contacts explain the selectivity of NleB for certain DDs. The acceptor arginine is fixed into a cleft, in which Glu253 serves as a base to activate the guanidinium. Analyses of the enzyme-substrate complex and the product structures reveal an inverting sugar-transfer reaction and a detailed catalytic mechanism. These structural insights are validated by mutagenesis analyses of NleB-mediated GlcNAcylation in vitro and its function in mouse infection. Our study builds a structural framework for understanding of NleB-catalyzed arginine GlcNAcylation of host death domain.
Assuntos
Escherichia coli Enteropatogênica/genética , Proteínas de Escherichia coli/química , Interações Hospedeiro-Patógeno/genética , Conformação Proteica , Fatores de Virulência/química , Animais , Apoptose/genética , Arginina/química , Arginina/genética , Coenzima A Ligases/química , Coenzima A Ligases/genética , Cristalografia por Raios X , Domínio de Morte/genética , Escherichia coli Enteropatogênica/patogenicidade , Proteínas de Escherichia coli/genética , Guanidina/química , Humanos , Manganês/química , Camundongos , Mutagênese , Proteína de Domínio de Morte Associada a Receptor de TNF/química , Proteína de Domínio de Morte Associada a Receptor de TNF/genética , Fatores de Virulência/genéticaRESUMO
The post-translational modification of key residues at the C-terminal domain of RNA polymerase II (RNAP2-CTD) coordinates transcription, splicing, and RNA processing by modulating its capacity to act as a landing platform for a variety of protein complexes. Here, we identify a new modification at the CTD, the deimination of arginine and its conversion to citrulline by peptidyl arginine deiminase 2 (PADI2), an enzyme that has been associated with several diseases, including cancer. We show that, among PADI family members, only PADI2 citrullinates R1810 (Cit1810) at repeat 31 of the CTD. Depletion of PADI2 or loss of R1810 results in accumulation of RNAP2 at transcription start sites, reduced gene expression, and inhibition of cell proliferation. Cit1810 is needed for interaction with the P-TEFb (positive transcription elongation factor b) kinase complex and for its recruitment to chromatin. In this way, CTD-Cit1810 favors RNAP2 pause release and efficient transcription in breast cancer cells.
Assuntos
Neoplasias da Mama/enzimologia , Processamento de Proteína Pós-Traducional , RNA Polimerase II/metabolismo , Transcrição Gênica , Arginina , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Proliferação de Células , Citrulinação , Feminino , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Células MCF-7 , Fator B de Elongação Transcricional Positiva/genética , Fator B de Elongação Transcricional Positiva/metabolismo , Regiões Promotoras Genéticas , Ligação Proteica , Domínios Proteicos , Proteína-Arginina Desiminase do Tipo 2 , Desiminases de Arginina em Proteínas/genética , Desiminases de Arginina em Proteínas/metabolismo , RNA Polimerase II/química , RNA Polimerase II/genética , Transdução de SinaisRESUMO
Fibrillar centers (FCs) and dense fibrillar components (DFCs) are essential morphologically distinct sub-regions of mammalian cell nucleoli for rDNA transcription and pre-rRNA processing. Here, we report that a human nucleolus consists of several dozen FC/DFC units, each containing 2-3 transcriptionally active rDNAs at the FC/DFC border. Pre-rRNA processing factors, such as fibrillarin (FBL), form 18-24 clusters that further assemble into the DFC surrounding the FC. Mechanistically, the 5' end of nascent 47S pre-rRNA binds co-transcriptionally to the RNA-binding domain of FBL. FBL diffuses to the DFC, where local self-association via its glycine- and arginine-rich (GAR) domain forms phase-separated clusters to immobilize FBL-interacting pre-rRNA, thus promoting directional traffic of nascent pre-rRNA while facilitating pre-rRNA processing and DFC formation. These results unveil FC/DFC ultrastructures in nucleoli and suggest a conceptual framework for considering nascent RNA sorting using multivalent interactions of their binding proteins.
Assuntos
Nucléolo Celular/metabolismo , Precursores de RNA/metabolismo , Processamento Pós-Transcricional do RNA , RNA Ribossômico/metabolismo , Transporte Ativo do Núcleo Celular , Antígenos Nucleares/genética , Antígenos Nucleares/metabolismo , Nucléolo Celular/genética , Nucléolo Celular/ultraestrutura , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Feminino , Células HEK293 , Células HeLa , Humanos , Conformação de Ácido Nucleico , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Precursores de RNA/genética , Precursores de RNA/ultraestrutura , RNA Ribossômico/genética , RNA Ribossômico/ultraestruturaRESUMO
All forms of life are presumed to synthesize arginine from citrulline via a two-step pathway consisting of argininosuccinate synthetase and argininosuccinate lyase using citrulline, adenosine 5'-triphosphate (ATP), and aspartate as substrates. Conversion of arginine to citrulline predominantly proceeds via hydrolysis. Here, from the hyperthermophilic archaeon Thermococcus kodakarensis, we identified an enzyme which we designate "arginine synthetase". In arginine synthesis, the enzyme converts citrulline, ATP, and free ammonia to arginine, adenosine 5'-diphosphate (ADP), and phosphate. In the reverse direction, arginine synthetase conserves the energy of arginine deimination and generates ATP from ADP and phosphate while releasing ammonia. The equilibrium constant of this reaction at pH 7.0 is [Cit][ATP][NH3]/[Arg][ADP][Pi] = 10.1 ± 0.7 at 80 °C, corresponding to a ΔG°' of -6.8 ± 0.2 kJ mol-1. Growth of the gene disruption strain was compared to the host strain in medium composed of amino acids. The results suggested that arginine synthetase is necessary in providing ornithine, the precursor for proline biosynthesis, as well as in generating ATP. Growth in medium supplemented with citrulline indicated that arginine synthetase can function in the direction of arginine synthesis. The enzyme is widespread in nature, including bacteria and eukaryotes, and catalyzes a long-overlooked energy-conserving reaction in microbial amino acid metabolism. Along with ornithine transcarbamoylase and carbamate kinase, the pathway identified here is designated the arginine synthetase pathway.
Assuntos
Arginina , Ligases , Arginina/metabolismo , Citrulina/metabolismo , Amônia , Ornitina/genética , Trifosfato de Adenosina/metabolismo , Fosfatos , Adenosina , CatáliseRESUMO
Arginine vasopressin (AVP) neurons of the hypothalamic paraventricular region (AVPPVN) mediate sex-biased social behaviors across most species, including mammals. In mice, neural sex differences are thought to be established during a critical window around birth ( embryonic (E) day 18 to postnatal (P) day 2) whereby circulating testosterone from the fetal testis is converted to estrogen in sex-dimorphic brain regions. Here, we found that AVPPVN neurons are sexually dimorphic by E15.5, prior to this critical window, and that gestational bisphenol A (BPA) exposure permanently masculinized female AVPPVN neuronal numbers, projections, and electrophysiological properties, causing them to display male-like phenotypes into adulthood. Moreover, we showed that nearly twice as many neurons that became AVP+ by P0 were born at E11 in males and BPA-exposed females compared to control females, suggesting that AVPPVN neuronal masculinization occurs between E11 and P0. We further narrowed this sensitive period to around the timing of neurogenesis by demonstrating that exogenous estrogen exposure from E14.5 to E15.5 masculinized female AVPPVN neuronal numbers, whereas a pan-estrogen receptor antagonist exposed from E13.5 to E15.5 blocked masculinization of males. Finally, we showed that restricting BPA exposure to E7.5-E15.5 caused adult females to display increased social dominance over control females, consistent with an acquisition of male-like behaviors. Our study reveals an E11.5 to E15.5 window of estrogen sensitivity impacting AVPPVN sex differentiation, which is impacted by prenatal BPA exposure.