RESUMEN
Human thermogenic adipose tissue mitigates metabolic disease, raising much interest in understanding its development and function. Here, we show that human thermogenic adipocytes specifically express a primate-specific long non-coding RNA, LINC00473 which is highly correlated with UCP1 expression and decreased in obesity and type-2 diabetes. LINC00473 is detected in progenitor cells, and increases upon differentiation and in response to cAMP. In contrast to other known adipocyte LincRNAs, LINC00473 shuttles out of the nucleus, colocalizes and can be crosslinked to mitochondrial and lipid droplet proteins. Up- or down- regulation of LINC00473 results in reciprocal alterations in lipolysis, respiration and transcription of genes associated with mitochondrial oxidative metabolism. Depletion of PLIN1 results in impaired cAMP-responsive LINC00473 expression and lipolysis, indicating bidirectional interactions between PLIN1, LINC00473 and mitochondrial oxidative functions. Thus, we suggest that LINC00473 is a key regulator of human thermogenic adipocyte function, and reveals a role for a LincRNA in inter-organelle communication and human energy metabolism.
Asunto(s)
Adipocitos/fisiología , ARN Largo no Codificante/genética , ARN Largo no Codificante/fisiología , Termogénesis/genética , Termogénesis/fisiología , Adulto , Anciano , Anciano de 80 o más Años , Comunicación Celular/genética , Comunicación Celular/fisiología , Núcleo Celular/metabolismo , Células Cultivadas , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Metabolismo Energético/genética , Metabolismo Energético/fisiología , Ácidos Grasos no Esterificados/metabolismo , Femenino , Regulación de la Expresión Génica , Humanos , Gotas Lipídicas , Masculino , Persona de Mediana Edad , Obesidad/genética , Obesidad/metabolismo , Consumo de Oxígeno/genética , Consumo de Oxígeno/fisiología , Perilipina-1/deficiencia , Perilipina-1/genética , Proteína Desacopladora 1/biosíntesis , Proteína Desacopladora 1/genética , Adulto JovenRESUMEN
Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic disorders. MDS is frequently associated with deletions on chromosome 5q as well as aberrant DNA methylation patterns including hypermethylation of key tumor suppressors. We have previously shown that hypermethylation and silencing of the non-coding RNA VTRNA2-1 are correlated with poor outcomes in acute myeloid leukemia patients. In this study, we find that VTRNA1-2 and VTRNA1-3, both located on chromosome 5q, can be regulated and silenced by promoter DNA methylation, and that the hypomethylating agent 5-aza-2-deoxycytidine causes reactivation these genes. In normal hematopoiesis, we find that vault RNAs (vtRNAs) show differential methylation between various hematopoietic cell populations, indicating that allele-specific methylation events may occur during hematopoiesis. In addition, we show that VTRNA1-3 promoter hypermethylation is frequent in lower risk MDS patients and is associated with a decreased overall survival.
RESUMEN
Deletions of chromosome 5q are associated with poor outcomes in acute myeloid leukemia (AML) suggesting the presence of tumor suppressor(s) at the locus. However, definitive identification of putative tumor suppressor genes remains controversial. Here we show that a 106-nucleotide noncoding RNA vault RNA2-1 (vtRNA2-1), previously misannotated as miR886, could potentially play a role in the biology and prognosis of AML. vtRNA2-1 is transcribed by polymerase III and is monoallelically methylated in 75% of healthy individuals whereas the remaining 25% of the population have biallelic hypomethylation. AML patients without methylation of VTRNA2-1 have a considerably better outcome than those with monoallelic or biallelic methylation (n = 101, P = .001). We show that methylation is inversely correlated with vtRNA2-1 expression, and that 5-azanucleosides induce vtRNA2-1 and down-regulate the phosphorylated RNA-dependent protein kinase (pPKR), whose activity has been shown to be modulated by vtRNA2-1. Because pPKR promotes cell survival in AML, the data are consistent with vtRNA2-1 being a tumor suppressor in AML. This is the first study to show that vtRNA2-1 might play a significant role in AML, that it is either mono- or biallelically expressed in the blood cells of healthy individuals, and that its methylation state predicts outcome in AML.
