RESUMEN
AML cells are arranged in a hierarchy with stem/progenitor cells giving rise to more differentiated bulk cells. Despite the importance of stem/progenitors in the pathogenesis of AML, the determinants of the AML stem/progenitor state are not fully understood. Through a comparison of genes that are significant for growth and viability of AML cells by way of a CRISPR screen, with genes that are differentially expressed in leukemia stem cells (LSC), we identified importin 11 (IPO11) as a novel target in AML. Importin 11 (IPO11) is a member of the importin ß family of proteins that mediate transport of proteins across the nuclear membrane. In AML, knockdown of IPO11 decreased growth, reduced engraftment potential of LSC, and induced differentiation. Mechanistically, we identified the transcription factors BZW1 and BZW2 as novel cargo of IPO11. We further show that BZW1/2 mediate a transcriptional signature that promotes stemness and survival of LSC. Thus, we demonstrate for the first time how specific cytoplasmic-nuclear regulation supports stem-like transcriptional signature in relapsed AML.
Asunto(s)
Leucemia Mieloide Aguda , beta Carioferinas , Transporte Activo de Núcleo Celular , Proteínas de Ciclo Celular/metabolismo , Proteínas de Unión al ADN/metabolismo , Humanos , Leucemia Mieloide Aguda/patología , Células Madre Neoplásicas/patología , Células Madre/metabolismo , beta Carioferinas/genética , beta Carioferinas/metabolismoRESUMEN
Myoblast fusion is essential for muscle development and regeneration. Yet, it remains poorly understood how mononucleated myoblasts fuse with preexisting fibers. We demonstrate that ERK1/2 inhibition (ERKi) induces robust differentiation and fusion of primary mouse myoblasts through a linear pathway involving RXR, ryanodine receptors, and calcium-dependent activation of CaMKII in nascent myotubes. CaMKII activation results in myotube growth via fusion with mononucleated myoblasts at a fusogenic synapse. Mechanistically, CaMKII interacts with and regulates MYMK and Rac1, and CaMKIIδ/γ knockout mice exhibit smaller regenerated myofibers following injury. In addition, the expression of a dominant negative CaMKII inhibits the formation of large multinucleated myotubes. Finally, we demonstrate the evolutionary conservation of the pathway in chicken myoblasts. We conclude that ERK1/2 represses a signaling cascade leading to CaMKII-mediated fusion of myoblasts to myotubes, providing an attractive target for the cultivated meat industry and regenerative medicine.
Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Fibras Musculares Esqueléticas/citología , Mioblastos/citología , Actinas/metabolismo , Animales , Calcio/metabolismo , Diferenciación Celular/efectos de los fármacos , Fusión Celular , Proliferación Celular/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Ratones Endogámicos C57BL , Modelos Biológicos , Fibras Musculares Esqueléticas/efectos de los fármacos , Fibras Musculares Esqueléticas/metabolismo , Proteínas Musculares/metabolismo , Mioblastos/efectos de los fármacos , Mioblastos/metabolismo , Unión Proteica , Inhibidores de Proteínas Quinasas/farmacología , Receptores de Ácido Retinoico/metabolismo , Transducción de Señal , Proteína de Unión al GTP rac1/metabolismoRESUMEN
Endosomes are compositionally dynamic organelles that regulate signaling, nutrient status and organelle quality by specifying whether material entering the cells will be shuttled back to the cell surface or degraded by the lysosome. Recently, membrane contact sites (MCSs) between the endoplasmic reticulum (ER) and endosomes have emerged as important players in endosomal protein sorting, dynamics and motility. Here, we show that PDZD8, a Synaptotagmin-like Mitochondrial lipid-binding Proteins (SMP) domain-containing ER transmembrane protein, utilizes distinct domains to interact with Rab7-GTP and the ER transmembrane protein Protrudin and together these components localize to an ER-late endosome MCS. At these ER-late endosome MCSs, mitochondria are also recruited to form a three-way contact. Thus, our data indicate that PDZD8 is a shared component of two distinct MCSs and suggest a role for SMP-mediated lipid transport in the regulation of endosome function.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Retículo Endoplásmico/metabolismo , Endosomas/metabolismo , Mitocondrias/metabolismo , Transporte Biológico , Línea Celular , Humanos , Proteínas de la Membrana/metabolismo , Proteínas Mitocondriales/metabolismo , Transporte de Proteínas , Proteínas de Transporte Vesicular/metabolismo , Proteínas de Unión al GTP rab/metabolismo , Proteínas de Unión a GTP rab7RESUMEN
Segev et al. introduce fusogens - the proteins that coordinate, execute and control membrane fusion - and discuss their various physiological functions.
Asunto(s)
Fusión de Membrana/fisiología , Proteínas de la Membrana/fisiología , Animales , Fusión Celular , Membrana Celular/metabolismo , Membrana Celular/fisiología , Humanos , Fusión de Membrana/genética , Proteínas de la Membrana/metabolismo , Fosfolípidos/fisiologíaRESUMEN
Genome duplication in eukaryotes created paralog pairs of ribosomal proteins (RPs) that show high sequence similarity/identity. However, individual paralogs can confer vastly different effects upon cellular processes, e.g., specific yeast paralogs regulate actin organization, bud site selection, and mRNA localization, although how specificity is conferred is unknown. Changes in the RP composition of ribosomes might allow for specialized translation of different subsets of mRNAs, yet it is unclear whether specialized ribosomes exist and if paralog specificity controls translation. Using translatome analyses, we show that the translation of mitochondrial proteins is highly down-regulated in yeast lacking RP paralogs required for normal mitochondrial function (e.g., RPL1b). Although RPL1a and RPL1b encode identical proteins, Rpl1b-containing ribosomes confer more efficient translation of respiration-related proteins. Thus, ribosomes varying in RP composition may confer specialized functions, and RP paralog specificity defines a novel means of translational control.