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1.
Mol Cancer Res ; 19(10): 1712-1726, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34183451

RESUMO

Controlling cell proliferation is critical for organism development, tissue homeostasis, disease, and regeneration. IQGAP3 has been shown to be required for proper cell proliferation and migration, and is associated to a number of cancers. Moreover, its expression is inversely correlated with the overall survival rate in the majority of cancers. Here, we show that IQGAP3 expression is elevated in cervical cancer and that in these cancers IQGAP3 high expression is correlated with an increased lethality. Furthermore, we demonstrate that IQGAP3 is a target of YAP, a regulator of cell cycle gene expression. IQGAP3 knockdown resulted in an increased percentage of HeLa cells in S phase, delayed progression through mitosis, and caused multipolar spindle formation and consequentially aneuploidy. Protein-protein interaction studies revealed that IQGAP3 interacts with MMS19, which is known in Drosophila to permit, by competitive binding to Xpd, Cdk7 to be fully active as a Cdk-activating kinase (CAK). Notably, IQGAP3 knockdown caused decreased MMS19 protein levels and XPD knockdown partially rescued the reduced proliferation rate upon IQGAP3 knockdown. This suggests that IQGAP3 modulates the cell cycle via the MMS19/XPD/CAK axis. Thus, in addition to governing proliferation and migration, IQGAP3 is a critical regulator of mitotic progression and genome stability. IMPLICATIONS: Our data indicate that, while IQGAP3 inhibition might be initially effective in decreasing cancer cell proliferation, this approach harbors the risk to promote aneuploidy and, therefore, the formation of more aggressive cancers.


Assuntos
Proteínas de Ciclo Celular/genética , Ciclo Celular/genética , Proteínas Ativadoras de GTPase/genética , Instabilidade Genômica/genética , Fatores de Transcrição/genética , Animais , Linhagem Celular , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Drosophila/genética , Células HCT116 , Células HEK293 , Células HeLa , Humanos , Mitose/genética , Mapas de Interação de Proteínas/genética , Transdução de Sinais/genética
2.
Blood ; 137(5): 646-660, 2021 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-33538798

RESUMO

Richter's transformation (RT) is an aggressive lymphoma that occurs upon progression from chronic lymphocytic leukemia (CLL). Transformation has been associated with genetic aberrations in the CLL phase involving TP53, CDKN2A, MYC, and NOTCH1; however, a significant proportion of RT cases lack CLL phase-associated events. Here, we report that high levels of AKT phosphorylation occur both in high-risk CLL patients harboring TP53 and NOTCH1 mutations as well as in patients with RT. Genetic overactivation of Akt in the murine Eµ-TCL1 CLL mouse model resulted in CLL transformation to RT with significantly reduced survival and an aggressive lymphoma phenotype. In the absence of recurrent mutations, we identified a profile of genomic aberrations intermediate between CLL and diffuse large B-cell lymphoma. Multiomics assessment by phosphoproteomic/proteomic and single-cell transcriptomic profiles of this Akt-induced murine RT revealed an S100 protein-defined subcluster of highly aggressive lymphoma cells that developed from CLL cells, through activation of Notch via Notch ligand expressed by T cells. Constitutively active Notch1 similarly induced RT of murine CLL. We identify Akt activation as an initiator of CLL transformation toward aggressive lymphoma by inducing Notch signaling between RT cells and microenvironmental T cells.


Assuntos
Leucemia Linfocítica Crônica de Células B/patologia , Linfoma Difuso de Grandes Células B/patologia , Proteínas de Neoplasias/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Receptor Notch1/fisiologia , Animais , Evolução Clonal , Progressão da Doença , Ativação Enzimática , Regulação Neoplásica da Expressão Gênica , Genes p53 , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/fisiopatologia , Linfócitos do Interstício Tumoral/imunologia , Linfoma Difuso de Grandes Células B/genética , Linfoma Difuso de Grandes Células B/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Fenótipo , Fosfoproteínas/fisiologia , Proteínas Proto-Oncogênicas c-akt/genética , Receptores de Antígenos de Linfócitos B/imunologia , Transdução de Sinais/fisiologia , Transcriptoma , Microambiente Tumoral , Proteína Supressora de Tumor p53/fisiologia , Regulação para Cima
3.
FEBS J ; 288(9): 2911-2929, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33112492

RESUMO

Cysteine prenylation is a post-translational modification that is used by nature to control crucial biological functions of proteins, such as membrane trafficking, signal transduction, and apoptosis. It mainly occurs in eukaryotic proteins at a C-terminal CaaX box and is mediated by prenyltransferases. Since the discovery of prenylated proteins, various tools have been developed to study the mechanisms of prenyltransferases, as well as to visualize and to identify prenylated proteins. Herein, we introduce cell-permeable peptides bearing a C-terminal CaaX motif based on Ras sequences. We demonstrate that intracellular accumulation of those peptides in different cells is controlled by the presence of their CaaX motif and that they specifically interact with intracellular prenyltransferases. As proof of concept, we further highlight their utilization to alter downstream signaling of Ras proteins, particularly of K-Ras-4B, in pancreatic cancer cells. Application of this strategy holds great promise to better understand and regulate post-translational cysteine prenylation.


Assuntos
Alquil e Aril Transferases/genética , Neoplasias/genética , Prenilação/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Sequência de Aminoácidos/genética , Cisteína/genética , Regulação Neoplásica da Expressão Gênica/genética , Células HeLa , Humanos , Células MCF-7 , Neoplasias/patologia , Peptídeos/genética , Peptídeos/farmacologia , Processamento de Proteína Pós-Traducional/genética , Transdução de Sinais/efeitos dos fármacos
4.
Nucleic Acids Res ; 48(15): 8626-8644, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32621609

RESUMO

The exon junction complex (EJC) is an essential constituent and regulator of spliced messenger ribonucleoprotein particles (mRNPs) in metazoans. As a core component of the EJC, CASC3 was described to be pivotal for EJC-dependent nuclear and cytoplasmic processes. However, recent evidence suggests that CASC3 functions differently from other EJC core proteins. Here, we have established human CASC3 knockout cell lines to elucidate the cellular role of CASC3. In the knockout cells, overall EJC composition and EJC-dependent splicing are unchanged. A transcriptome-wide analysis reveals that hundreds of mRNA isoforms targeted by nonsense-mediated decay (NMD) are upregulated. Mechanistically, recruiting CASC3 to reporter mRNAs by direct tethering or via binding to the EJC stimulates mRNA decay and endonucleolytic cleavage at the termination codon. Building on existing EJC-NMD models, we propose that CASC3 equips the EJC with the persisting ability to communicate with the NMD machinery in the cytoplasm. Collectively, our results characterize CASC3 as a peripheral EJC protein that tailors the transcriptome by promoting the degradation of EJC-dependent NMD substrates.


Assuntos
Proteínas de Neoplasias/genética , Degradação do RNAm Mediada por Códon sem Sentido/genética , Splicing de RNA/genética , Proteínas de Ligação a RNA/genética , Transcriptoma/genética , Sequência de Aminoácidos/genética , Núcleo Celular/genética , Éxons/genética , Técnicas de Inativação de Genes , Humanos , RNA Mensageiro/genética , Ribonucleoproteínas/genética
5.
Nat Commun ; 11(1): 1747, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32269263

RESUMO

Receptor interacting protein kinase 1 (RIPK1) regulates cell death and inflammatory responses downstream of TNFR1 and other receptors, and has been implicated in the pathogenesis of inflammatory and degenerative diseases. RIPK1 kinase activity induces apoptosis and necroptosis, however the mechanisms and phosphorylation events regulating RIPK1-dependent cell death signaling remain poorly understood. Here we show that RIPK1 autophosphorylation at serine 166 plays a critical role for the activation of RIPK1 kinase-dependent apoptosis and necroptosis. Moreover, we show that S166 phosphorylation is required for RIPK1 kinase-dependent pathogenesis of inflammatory pathologies in vivo in four relevant mouse models. Mechanistically, we provide evidence that trans autophosphorylation at S166 modulates RIPK1 kinase activation but is not by itself sufficient to induce cell death. These results show that S166 autophosphorylation licenses RIPK1 kinase activity to induce downstream cell death signaling and inflammation, suggesting that S166 phosphorylation can serve as a reliable biomarker for RIPK1 kinase-dependent pathologies.


Assuntos
Apoptose , Inflamação/metabolismo , Inflamação/patologia , Fosfosserina/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Alanina Transaminase/metabolismo , Animais , Células da Medula Óssea/citologia , Colite/patologia , Genótipo , Hepatite/patologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Mutação/genética , Neoplasias/patologia , Fosforilação , Sepse/patologia , Pele/patologia , Fator de Necrose Tumoral alfa
6.
EMBO J ; 39(9): e102731, 2020 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-32149416

RESUMO

Mitochondria house anabolic and catabolic processes that must be balanced and adjusted to meet cellular demands. The RNA-binding protein CLUH (clustered mitochondria homolog) binds mRNAs of nuclear-encoded mitochondrial proteins and is highly expressed in the liver, where it regulates metabolic plasticity. Here, we show that in primary hepatocytes, CLUH coalesces in specific ribonucleoprotein particles that define the translational fate of target mRNAs, such as Pcx, Hadha, and Hmgcs2, to match nutrient availability. Moreover, CLUH granules play signaling roles, by recruiting mTOR kinase and the RNA-binding proteins G3BP1 and G3BP2. Upon starvation, CLUH regulates translation of Hmgcs2, involved in ketogenesis, inhibits mTORC1 activation and mitochondrial anabolic pathways, and promotes mitochondrial turnover, thus allowing efficient reprograming of metabolic function. In the absence of CLUH, a mitophagy block causes mitochondrial clustering that is rescued by rapamycin treatment or depletion of G3BP1 and G3BP2. Our data demonstrate that metabolic adaptation of liver mitochondria to nutrient availability depends on a compartmentalized CLUH-dependent post-transcriptional mechanism that controls both mTORC1 and G3BP signaling and ensures survival.


Assuntos
Mitocôndrias Hepáticas/fisiologia , Proteínas Mitocondriais/genética , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais , Animais , Células COS , Chlorocebus aethiops , Grânulos Citoplasmáticos/genética , Grânulos Citoplasmáticos/metabolismo , Regulação da Expressão Gênica , Células HeLa , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos , Mitofagia , Proteínas de Ligação a RNA/genética
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