RESUMO
The generation of cortical projection neurons relies on the coordination of radial migration with branching. Here, we report that the multisubunit histone acetyltransferase Elongator complex, which contributes to transcript elongation, also regulates the maturation of projection neurons. Indeed, silencing of its scaffold (Elp1) or catalytic subunit (Elp3) cell-autonomously delays the migration and impairs the branching of projection neurons. Strikingly, neurons defective in Elongator show reduced levels of acetylated alpha-tubulin. Reduction of alpha-tubulin acetylation via expression of a nonacetylatable alpha-tubulin mutant leads to comparable defects in cortical neurons and suggests that alpha-tubulin is a target of Elp3. This is further supported by the demonstration that Elp3 promotes acetylation and counteracts HDAC6-mediated deacetylation of this substrate in vitro. Our results uncover alpha-tubulin as a target of the Elongator complex and suggest that a tight regulation of its acetylation underlies the maturation of cortical projection neurons.
Assuntos
Movimento Celular , Córtex Cerebral/citologia , Histona Acetiltransferases/metabolismo , Neurônios/citologia , Tubulina (Proteína)/metabolismo , Acetilação , Animais , Linhagem Celular , Células Cultivadas , Embrião de Mamíferos/citologia , Embrião de Mamíferos/metabolismo , Feminino , Humanos , Camundongos , Complexos Multienzimáticos/metabolismo , NeurogêneseRESUMO
The Elongator complex is composed of 6 subunits (Elp1-Elp6) and promotes RNAPII transcript elongation through histone acetylation in the nucleus as well as tRNA modification in the cytoplasm. This acetyltransferase complex directly or indirectly regulates numerous biological processes ranging from exocytosis and resistance to heat shock in yeast to cell migration and neuronal differentiation in higher eukaryotes. The identity of human ELP1 through ELP4 has been reported but human ELP5 and ELP6 have remained uncharacterized. Here, we report that DERP6 (ELP5) and C3ORF75 (ELP6) encode these subunits of human Elongator. We further investigated the importance and function of these two subunits by a combination of biochemical analysis and cellular assays. Our results show that DERP6/ELP5 is required for the integrity of Elongator and directly connects ELP3 to ELP4. Importantly, the migration and tumorigenicity of melanoma-derived cells are significantly decreased upon Elongator depletion through ELP1 or ELP3. Strikingly, DERP6/ELP5 and C3ORF75/ELP6-depleted melanoma cells have similar defects, further supporting the idea that DERP6/ELP5 and C3ORF75/ELP6 are essential for Elongator function. Together, our data identify DERP6/ELP5 and C3ORF75/ELP6 as key players for migration, invasion and tumorigenicity of melanoma cells, as integral subunits of Elongator.
Assuntos
Proteínas de Transporte/metabolismo , Movimento Celular , Melanoma/metabolismo , Complexos Multiproteicos/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas/metabolismo , Proteínas de Transporte/genética , Linhagem Celular Tumoral , Deleção de Genes , Células HEK293 , Histona Acetiltransferases , Humanos , Melanoma/genética , Melanoma/patologia , Complexos Multiproteicos/genética , Invasividade Neoplásica , Proteínas de Neoplasias/genética , Proteínas/genética , RNA Polimerase II/genética , RNA Polimerase II/metabolismoRESUMO
Lysine acetylation is a post-translational modification that critically regulates gene transcription by targeting histones as well as a variety of transcription factors in the nucleus. More recent reports have also demonstrated that numerous proteins located outside the nucleus are also acetylated and that this modification has profound consequences on their functions. This review describes the latest findings on the substrates acetylated outside the nucleus and on the acetylases and deacetylates that catalyse these modifications. Protein acetylation is emerging as a major mechanism by which key proteins are regulated in many physiological processes such as migration, metabolism and aging as well as in pathological circumstances such as cancer and neurodegenerative disorders.
Assuntos
Lisina/metabolismo , Proteínas/metabolismo , Acetilação , Animais , Humanos , Processamento de Proteína Pós-TraducionalAssuntos
Proteínas de Transporte/fisiologia , Córtex Cerebral/citologia , Disautonomia Familiar/genética , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/fisiologia , Acetilação , Animais , Proteínas de Transporte/genética , Movimento Celular , Disautonomia Familiar/fisiopatologia , Histona Acetiltransferases/fisiologia , Histonas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Complexos Multiproteicos , Neurogênese/genética , Processamento de Proteína Pós-Traducional , Transporte Proteico , RNA Mensageiro/biossíntese , Transdução de Sinais , Fatores de Elongação da Transcrição , Tubulina (Proteína)/metabolismoRESUMO
Elongator, a multi-subunit complex assembled by the IkappaB kinase-associated protein (IKAP)/hELP1 scaffold protein is involved in transcriptional elongation in the nucleus as well as in tRNA modifications in the cytoplasm. However, the biological processes regulated by Elongator in human cells only start to be elucidated. Here we demonstrate that IKAP/hELP1 depleted colon cancer-derived cells show enhanced basal expression of some but not all pro-apoptotic p53-dependent genes such as BAX. Moreover, Elongator deficiency causes increased basal and daunomycin-induced expression of the pro-survival serum- and glucocorticoid-induced protein kinase (SGK) gene through a p53-dependent pathway. Thus, our data collectively demonstrate that Elongator deficiency triggers the activation of p53-dependent genes harbouring opposite functions with respect to apoptosis.