Estudio del papel de E2F1/E2F2 en la transición epitelio-mesénquima (EMT): caracterización del fenotipo celular asociado y del mecanismo molecular subyacente.

197 p.En este trabajo hemos puesto de manifiesto que los E2F activadores (E2F1/E2F2) juegan un papel relevante en la regulación del proceso de transición epitelio-mesénquima (EMT) en células de cáncer colorrectal, una función no descrita hasta la fecha para estos factores de transcripción.Hemos demostrado que E2F1/E2F2 actúan como inhibidores del proceso de EMT en líneas celulares de cáncer de colon. La depleción de estos factores conduce a la desestructuración de la monocapa epitelial dando lugar a células con morfología mesenquimal. La adquisición de esta morfología viene acompañada de la deslocalización de la proteína E-cadherina de la membrana plasmática y una pérdida en la capacidad de adhesión intercelular. Además, mostramos que las células de cáncer de colon knockdown para E2F1/2 adquieren capacidad migratoria e invasiva.Mediante un análisis transcriptómico hemos puesto de manifiesto la implicación de E2F1/E2F2 en la regulación de genes relacionados con la motilidad y la adhesión celular en las células HCT116. El enriquecimiento en motivos de unión E2F en el promotor de estos genes sugiere que podrían estar directamente regulados por E2F1/2. Notablemente, hemos demostrado que E2F1/2 regulan de manera negativa la expresión de SLUG, factor de transcripción promotor de EMT, en células de cáncer de colon, y que SLUG actúa como mediador del fenotipo EMT ocasionado por la ausencia de E2F1/2

Golgi Oncoprotein GOLPH3 Gene Expression is Regulated by Functional E2F and CREB/ATF Promoter Elements

The Golgi organelle duplicates its protein and lipid content to segregate evenly between two daughter cells after mitosis. However, how Golgi biogenesis is regulated during interphase remains largely unknown. Here we show that messenger RNA (mRNA) expression of GOLPH3 and GOLGA2, two genes encoding Golgi proteins, is induced specifically in G1 phase, suggesting a link between cell cycle regulation and Golgi growth. We have examined the role of E2F transcription factors, critical regulators of G1 to S progression of the cell cycle, in the expression of Golgi proteins during interphase. We show that promoter activity for GOLPH3, a Golgi protein that is also oncogenic, is induced by E2F1-3 and repressed by E2F7. Mutation of the E2F motifs present in the GOLPH3 promoter region abrogates E2F1-mediated induction of a GOLPH3 luciferase reporter construct. Furthermore, we identify a critical CREB/ATF element in the GOLPH3 promoter that is required for its steady state and ATF2-induced expression. Interestingly, depletion of GOLPH3 with small interfering RNA (siRNA) delays the G1 to S transition in synchronized U2OS cells. Taken together, our results reveal a link between cell cycle regulation and Golgi function, and suggest that E2F-mediated regulation of Golgi genes is required for the timely progression of the cell cycle.This work was supported by grants from the Spanish Ministry (SAF2015-67562-R, co-financed by Feder funds, and SAF2014-57791-REDC) and the Basque Government (IT634-13) to AMZ. B.P.-G. is recipient of a Spanish Ministry FPI fellowship for graduate studies; J.V.R. was recipient of a UPV/EHU fellowship for graduate studies; G.M. was recipient of a Spanish Ministry FPU fellowship for graduate studies

Golgi Oncoprotein GOLPH3 Gene Expression is Regulated by Functional E2F and CREB/ATF Promoter Elements

The Golgi organelle duplicates its protein and lipid content to segregate evenly between two daughter cells after mitosis. However, how Golgi biogenesis is regulated during interphase remains largely unknown. Here we show that messenger RNA (mRNA) expression of GOLPH3 and GOLGA2, two genes encoding Golgi proteins, is induced specifically in G1 phase, suggesting a link between cell cycle regulation and Golgi growth. We have examined the role of E2F transcription factors, critical regulators of G1 to S progression of the cell cycle, in the expression of Golgi proteins during interphase. We show that promoter activity for GOLPH3, a Golgi protein that is also oncogenic, is induced by E2F1-3 and repressed by E2F7. Mutation of the E2F motifs present in the GOLPH3 promoter region abrogates E2F1-mediated induction of a GOLPH3 luciferase reporter construct. Furthermore, we identify a critical CREB/ATF element in the GOLPH3 promoter that is required for its steady state and ATF2-induced expression. Interestingly, depletion of GOLPH3 with small interfering RNA (siRNA) delays the G1 to S transition in synchronized U2OS cells. Taken together, our results reveal a link between cell cycle regulation and Golgi function, and suggest that E2F-mediated regulation of Golgi genes is required for the timely progression of the cell cycle.This work was supported by grants from the Spanish Ministry (SAF2015-67562-R, co-financed by Feder funds, and SAF2014-57791-REDC) and the Basque Government (IT634-13) to AMZ. B.P.-G. is recipient of a Spanish Ministry FPI fellowship for graduate studies; J.V.R. was recipient of a UPV/EHU fellowship for graduate studies; G.M. was recipient of a Spanish Ministry FPU fellowship for graduate studies

Targeting CAG repeat RNAs reduces Huntington's disease phenotype independently of huntingtin levels.

Huntington's disease (HD) is a polyglutamine disorder caused by a CAG expansion in the Huntingtin (HTT) gene exon 1. This expansion encodes a mutant protein whose abnormal function is traditionally associated with HD pathogenesis; however, recent evidence has also linked HD pathogenesis to RNA stable hairpins formed by the mutant HTT expansion. Here, we have shown that a locked nucleic acid-modified antisense oligonucleotide complementary to the CAG repeat (LNA-CTG) preferentially binds to mutant HTT without affecting HTT mRNA or protein levels. LNA-CTGs produced rapid and sustained improvement of motor deficits in an R6/2 mouse HD model that was paralleled by persistent binding of LNA-CTG to the expanded HTT exon 1 transgene. Motor improvement was accompanied by a pronounced recovery in the levels of several striatal neuronal markers severely impaired in R6/2 mice. Furthermore, in R6/2 mice, LNA-CTG blocked several pathogenic mechanisms caused by expanded CAG RNA, including small RNA toxicity and decreased Rn45s expression levels. These results suggest that LNA-CTGs promote neuroprotection by blocking the detrimental activity of CAG repeats within HTT mRNA. The present data emphasize the relevance of expanded CAG RNA to HD pathogenesis, indicate that inhibition of HTT expression is not required to reverse motor deficits, and further suggest a therapeutic potential for LNA-CTG in polyglutamine disorders.This work was supported by the Spanish government through the Plan Nacional de I+D+I and cofunded by grants from the Instituto de Salud Carlos III (ISCIII) – Subdirección General de Evaluación and the Fondo Europeo de Desarrollo Regional (FEDER) (project PI11/02036, to EM, and PI13/01250, to EPN); the Spanish Ministerio de Economía y Competitividad (MINECO) (SAF2008-00357 and SAF2013-49108-R, to XE, and SAF2014-60551-R: iRPaD, to EM); and the Generalitat de Catalunya, Departament Economia i Coneixement, Secretaria Universitats i Recerca (AGAUR 2014 SGR-1138, to XE)