RESUMEN
N6-methyladenosine (m6A), the most abundant internal modifier of mRNAs installed by the methyltransferase 13 (METTL3) at the (G/A)(m6A)C motif, plays a critical role in the regulation of gene expression. METTL3 is essential for embryonic development, and its dysregulation is linked to various diseases. However, the role of METTL3 in liver biology is largely unknown. In this study, METTL3 function was unraveled in mice depleted of Mettl3 in neonatal livers (Mettl3fl/fl; Alb-Cre). Liver-specific Mettl3 knockout (M3LKO) mice exhibited global decrease in m6A on polyadenylated RNAs and pathologic features associated with nonalcoholic fatty liver disease (eg, hepatocyte ballooning, ductular reaction, microsteatosis, pleomorphic nuclei, DNA damage, foci of altered hepatocytes, focal lobular and portal inflammation, and elevated serum alanine transaminase/alkaline phosphatase levels). Mettl3-depleted hepatocytes were highly proliferative, with decreased numbers of binucleate hepatocytes and increased nuclear polyploidy. M3LKO livers were characterized by reduced m6A and expression of several key metabolic transcripts regulated by circadian rhythm and decreased nuclear protein levels of the core clock transcription factors BMAL1 and CLOCK. A significant decrease in total Bmal1 and Clock mRNAs but an increase in their nuclear levels were observed in M3LKO livers, suggesting impaired nuclear export. Consistent with the phenotype, methylated (m6A) RNA immunoprecipitation coupled with sequencing and RNA sequencing revealed transcriptome-wide loss of m6A markers and alterations in abundance of mRNAs involved in metabolism in M3LKO. Collectively, METTL3 and m6A modifications are critical regulators of liver homeostasis and function.
Asunto(s)
Ritmo Circadiano/genética , Regulación de la Expresión Génica , Hepatocitos/metabolismo , Homeostasis , Hígado/metabolismo , Metiltransferasas/metabolismo , Ploidias , Factores de Transcripción ARNTL/metabolismo , Animales , Animales Recién Nacidos , Secuencia de Bases , Proteínas CLOCK/genética , Proteínas CLOCK/metabolismo , Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , Metilación de ADN/genética , Eliminación de Gen , Perfilación de la Expresión Génica , Hígado/patología , Ratones Noqueados , Poliadenilación , Poliploidía , Proteínas Tirosina Quinasas/metabolismo , Transcriptoma/genéticaRESUMEN
Epithelial growth factor-like 7 (EGFL7) is a protein that is secreted by endothelial cells and plays an important role in angiogenesis. Although EGFL7 is aberrantly overexpressed in solid tumors, its role in leukemia has not been evaluated. Here, we report that levels of both EGFL7 mRNA and EGFL7 protein are increased in blasts of patients with acute myeloid leukemia (AML) compared with normal bone marrow cells. High EGFL7 mRNA expression associates with lower complete remission rates, and shorter event-free and overall survival in older (age ≥60 y) and younger (age <60 y) patients with cytogenetically normal AML. We further show that AML blasts secrete EGFL7 protein and that higher levels of EGFL7 protein are found in the sera from AML patients than in sera from healthy controls. Treatment of patient AML blasts with recombinant EGFL7 in vitro leads to increases in leukemic blast cell growth and levels of phosphorylated AKT. EGFL7 blockade with an anti-EGFL7 antibody reduced the growth potential and viability of AML cells. Our findings demonstrate that increased EGFL7 expression and secretion is an autocrine mechanism supporting growth of leukemic blasts in patients with AML.
Asunto(s)
Factores de Crecimiento Endotelial/genética , Factores de Crecimiento Endotelial/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Proteínas Angiogénicas/antagonistas & inhibidores , Proteínas Angiogénicas/genética , Proteínas Angiogénicas/metabolismo , Animales , Anticuerpos Bloqueadores/farmacología , Proteínas de Unión al Calcio , Estudios de Casos y Controles , Línea Celular Tumoral , Proliferación Celular , Supervivencia sin Enfermedad , Familia de Proteínas EGF , Factores de Crecimiento Endotelial/antagonistas & inhibidores , Femenino , Humanos , Leucemia Mieloide Aguda/terapia , Masculino , Ratones , MicroARNs/genética , MicroARNs/metabolismo , Persona de Mediana Edad , Pronóstico , Proteínas/metabolismo , Proteínas/farmacología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacología , Factores de Riesgo , Regulación hacia Arriba , Adulto JovenAsunto(s)
Agammaglobulinemia Tirosina Quinasa/genética , Resistencia a Antineoplásicos/genética , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Leucemia Linfocítica Crónica de Células B/genética , Mutación , Fosfolipasa C gamma/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Adenina/análogos & derivados , Adenina/uso terapéutico , Anciano , Antineoplásicos/uso terapéutico , Compuestos Bicíclicos Heterocíclicos con Puentes/uso terapéutico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Terapia Molecular Dirigida , Piperidinas/uso terapéutico , Sulfonamidas/uso terapéuticoRESUMEN
Richter's Transformation (RT) is a poorly understood and fatal progression of chronic lymphocytic leukemia (CLL) manifesting histologically as diffuse large B-cell lymphoma. Protein arginine methyltransferase 5 (PRMT5) is implicated in lymphomagenesis, but its role in CLL or RT progression is unknown. We demonstrate herein that tumors uniformly overexpress PRMT5 in patients with progression to RT. Furthermore, mice with B-specific overexpression of hPRMT5 develop a B-lymphoid expansion with increased risk of death, and Eµ-PRMT5/TCL1 double transgenic mice develop a highly aggressive disease with transformation that histologically resembles RT; where large-scale transcriptional profiling identifies oncogenic pathways mediating PRMT5-driven disease progression. Lastly, we report the development of a SAM-competitive PRMT5 inhibitor, PRT382, with exclusive selectivity and optimal in vitro and in vivo activity compared to available PRMT5 inhibitors. Taken together, the discovery that PRMT5 drives oncogenic pathways promoting RT provides a compelling rationale for clinical investigation of PRMT5 inhibitors such as PRT382 in aggressive CLL/RT cases.