RESUMEN
In mammals, the transcription factor SRY, encoded by the Y chromosome, is normally responsible for triggering the indifferent gonads to develop as testes rather than ovaries. However, testis differentiation can occur in its absence. Here we demonstrate in the mouse that a single factor, the forkhead transcriptional regulator FOXL2, is required to prevent transdifferentiation of an adult ovary to a testis. Inducible deletion of Foxl2 in adult ovarian follicles leads to immediate upregulation of testis-specific genes including the critical SRY target gene Sox9. Concordantly, reprogramming of granulosa and theca cell lineages into Sertoli-like and Leydig-like cell lineages occurs with testosterone levels comparable to those of normal XY male littermates. Our results show that maintenance of the ovarian phenotype is an active process throughout life. They might also have important medical implications for the understanding and treatment of some disorders of sexual development in children and premature menopause in women.
Asunto(s)
Transdiferenciación Celular , Factores de Transcripción Forkhead/metabolismo , Ovario/metabolismo , Testículo/metabolismo , Animales , Femenino , Proteína Forkhead Box L2 , Factores de Transcripción Forkhead/genética , Eliminación de Gen , Células de la Granulosa/citología , Masculino , Ratones , Oocitos/metabolismo , Ovario/citología , Células de Sertoli/citología , Testículo/citologíaRESUMEN
Aspartate is crucial for nucleotide synthesis, ammonia detoxification, and maintaining redox balance via the malate-aspartate-shuttle (MAS). To disentangle these multiple roles of aspartate metabolism, tools are required that measure aspartate concentrations in real time and in live cells. We introduce AspSnFR, a genetically encoded green fluorescent biosensor for intracellular aspartate, engineered through displaying and screening biosensor libraries on mammalian cells. In live cells, AspSnFR is able to precisely and quantitatively measure cytosolic aspartate concentrations and dissect its production from glutamine. Combining high-content imaging of AspSnFR with pharmacological perturbations exposes differences in metabolic vulnerabilities of aspartate levels based on nutrient availability. Further, AspSnFR facilitates tracking of aspartate export from mitochondria through SLC25A12, the MAS' key transporter. We show that SLC25A12 is a rapidly responding and direct route to couple Ca2+ signaling with mitochondrial aspartate export. This establishes SLC25A12 as a crucial link between cellular signaling, mitochondrial respiration, and metabolism.
Asunto(s)
Ácido Aspártico , Técnicas Biosensibles , Ácido Aspártico/metabolismo , Humanos , Mitocondrias/metabolismo , Células HEK293 , Células HeLa , Proteínas Fluorescentes Verdes/metabolismo , Proteínas Fluorescentes Verdes/genéticaRESUMEN
Acute myeloid leukemia (AML) is an aggressive disease for which only few targeted therapies are available. Using high-throughput RNA interference (RNAi) screening in AML cell lines, we identified LIM kinase 1 (LIMK1) as a potential novel target for AML treatment. High LIMK1 expression was significantly correlated with shorter survival of AML patients and coincided with FLT3 mutations, KMT2A rearrangements, and elevated HOX gene expression. RNAi- and CRISPR-Cas9-mediated suppression as well as pharmacologic inhibition of LIMK1 and its close homolog LIMK2 reduced colony formation and decreased proliferation due to slowed cell-cycle progression of KMT2A-rearranged AML cell lines and patient-derived xenograft (PDX) samples. This was accompanied by morphologic changes indicative of myeloid differentiation. Transcriptome analysis showed upregulation of several tumor suppressor genes as well as downregulation of HOXA9 targets and mitosis-associated genes in response to LIMK1 suppression, providing a potential mechanistic basis for the anti-leukemic phenotype. Finally, we observed a reciprocal regulation between LIM kinases (LIMK) and CDK6, a kinase known to be involved in the differentiation block of KMT2A-rearranged AML, and addition of the CDK6 inhibitor palbociclib further enhanced the anti-proliferative effect of LIMK inhibition. Together, these data suggest that LIMK are promising targets for AML therapy.
Asunto(s)
Leucemia Mieloide Aguda/genética , Quinasas Lim/genética , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Quinasa 6 Dependiente de la Ciclina/genética , Perfilación de la Expresión Génica/métodos , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Regulación Leucémica de la Expresión Génica/genética , Genes Homeobox/genética , Células HL-60 , Humanos , Leucemia Mieloide Aguda/tratamiento farmacológico , Mutación/genética , Piperazinas/farmacología , Piridinas/farmacología , Células U937RESUMEN
How metabolism is rewired during embryonic development is still largely unknown, as it remains a major technical challenge to resolve metabolic activities or metabolite levels with spatiotemporal resolution. Here, we investigated metabolic changes during development of organogenesis-stage mouse embryos, focusing on the presomitic mesoderm (PSM). We measured glycolytic labeling kinetics from 13C-glucose tracing experiments and detected elevated glycolysis in the posterior, more undifferentiated PSM. We found evidence that the spatial metabolic differences are functionally relevant during PSM development. To enable real-time quantification of a glycolytic metabolite with spatiotemporal resolution, we generated a pyruvate FRET-sensor reporter mouse line. We revealed dynamic changes in cytosolic pyruvate levels as cells transit toward a more anterior PSM state. Combined, our approach identifies a gradient of glycolytic activity across the PSM, and we provide evidence that these spatiotemporal metabolic changes are intrinsically linked to PSM development and differentiation.