Spotlight

State of the art laboratories

Research in to the basic, epidemiological, preventive, clinical and translational aspects of leukemia and other hematologic malignancies

Patients, Scientists, Doctors; working together to cure leukemia

Research centred on patients

Caring research

News

2017 August 21

Link between defects in DNA replication and loss of heterochromatin.

Tanya Vavouri from Institut de Recerca contra la Leucèmia Josep Carreras (IJC) and Institut de Recerca Germans Trias i Pujol (IGTP) and Eduard Casas from IGTP, working together with Ben Lehner and his team from the Centre for Genomic Regulation (CRG) in Barcelona, Spain, have discovered that a fault in the process that copies DNA between cell divisions can cause genes that are normally silent to become active, not only in the same animals when they become adults, but also in their offspring for five generations. The findings were published on the 16th of August in the journal Science Advances.
 
For the correct function of cells and ultimately the health of the organism, it is important to keep certain genes active and others silenced. Inside cells, there are DNA-protein complexes called heterochromatin that prevent genes from becoming activated when they should not be. Initially, the researchers noticed that a gene artificially inserted into the genome of the model organism C. elegans and normally silenced by being packaged into heterochromatin was activated in animals that carried mutations in proteins involved in copying of DNA. Vavouri, Lehner and their team members found that this was caused by loss of heterochromatin and that other genes also silenced by heterochromatin were activated too. Unexpectedly, the transgene was inappropriately activated for five generations in animals that did not carry the mutation in the DNA replication machinery but had ancestors that did. 
 
Abnormal DNA replication occurs in tumors in humans. This means that problems with DNA replication may not only contribute to cancer formation by promoting new mutations but also by de-silencing certain genes.
 
This publication follows up from the work recently reported in the journal Science, by the same authors, which showed that environmental change can have an impact on gene activity in worms for 14 generations.
 
References: 
 
A. Klosin, K. Reis, C. Hidalgo-Carcedo, E. Casas, T. Vavouri, B. Lehner, Impaired DNA replication derepresses chromatin and generates a transgenerational inherited epigenetic memory. Science Advances. 3, e1701143 (2017).
 
A. Klosin, E. Casas, C. Hidalgo-Carceldo, T. Vavouri, B. Lehner, Transgenerational transmission of environmental information in C. elegans. Science. 356(6335):320-323. (2017).

 

Recent publications

Torres-Ruiz R, Martinez-Lage M, Martin MC, Garcia A, Bueno C, Castaño J, Ramirez JC, Menendez P, Cigudosa JC, Rodriguez-Perales S

Efficient Recreation of t(11;22) EWSR1-FLI1(+) in Human Stem Cells Using CRISPR/Cas9.

Stem Cell Reports 9 May 2017, 8 (5) 1408-1420.
Efficient methodologies for recreating cancer-associated chromosome translocations are in high demand as tools for investigating how such events initiate cancer. The CRISPR/Cas9 system has been used to reconstruct the genetics of these complex rearrangements at native loci while maintaining the architecture and regulatory elements. However, the CRISPR system remains inefficient in human stem cells. Here, we compared three strategies aimed at enhancing the efficiency of the CRISPR-mediated t(11;22) translocation in human stem cells, including mesenchymal and induced pluripotent stem cells: (1) using end-joining DNA processing factors involved in repair mechanisms, or (2) ssODNs to guide the ligation of the double-strand break ends generated by CRISPR/Cas9; and (3) all-in-one plasmid or ribonucleoprotein complex-based approaches. We report that the generation of targeted t(11;22) is significantly increased by using a combination of ribonucleoprotein complexes and ssODNs. The CRISPR/Cas9-mediated generation of targeted t(11;22) in human stem cells opens up new avenues in modeling Ewing sarcoma.
More information
Romero-Moya D, Santos-Ocaña C, Castaño J, Garrabou G, Rodríguez-Gómez JA, Ruiz-Bonilla V, Bueno C, González-Rodriguez P, Giorgetti A, Perdiguero E, Prieto C, Moren-Nuñez C, Fernández-Ayala DJ, Cascajo MV, Velasco I, Canals JM, Montero R, Yubero D, Jou C, López-Barneo J, Cardellach F, Muñoz-Cánoves P, Artuch R, Navas P, Menéndez P

Genetic rescue of Mitochondrial and Skeletal Muscle Impairment in an IPSCs Model of Coenzyme Q10 Deficiency.

Stem Cells 4 May 2017, . Epub 4 May 2017
Coenzyme Q10 (CoQ10 ) plays a crucial role in mitochondria as an electron carrier within the mitochondrial respiratory chain (MRC), and is an essential antioxidant. Mutations in genes responsible for CoQ10 biosynthesis (COQ genes) cause primary CoQ10 deficiency, a rare and heterogeneous mitochondrial disorder with no clear genotype-phenotype association, mainly affecting tissues with high-energy demand including brain and skeletal muscle (SkM). Here, we report a 4-year old girl diagnosed with minor mental retardation and lethal rhabdomyolysis harboring a heterozygous mutation (c.483G>C (E161D)) in COQ4. The patient's fibroblasts showed a decrease in [CoQ10 ], CoQ10 biosynthesis, MRC activity affecting complexes I/II+III, and respiration defects. Bona fide induced pluripotent stem cell (iPSCs) lines carrying the COQ4 mutation (CQ4-iPSCs) were generated, characterized and genetically edited using the CRISPR-Cas9 system (CQ4(ed) -iPSCs). Extensive differentiation and metabolic assays of control-iPSCs, CQ4-iPSCs and CQ4(ed) -iPSCs demonstrated a genotype association, reproducing the disease phenotype. The COQ4 mutation in iPSC was associated with CoQ10 deficiency, metabolic dysfunction, and respiration defects. iPSC differentiation into SkM was compromised, and the resulting SkM also displayed respiration defects. Remarkably, iPSC differentiation in dopaminergic or motor neurons was unaffected. This study offers an unprecedented iPSC model recapitulating CoQ10 deficiency-associated functional and metabolic phenotypes caused by COQ4 mutation. This article is protected by copyright. All rights reserved.
More information
Pesarrodona M, Crosas E, Cubarsi R, Sánchez-Chardi A, Saccardo P, Unzueta U, Rueda F, Sanchez-García L, Serna N, Mangues R, Ferrer-Miralles N, Vázquez E, Villaverde A

Intrinsic functional and architectonic heterogeneity of tumor-targeted protein nanoparticles.

Nanoscale 2 May 2017, . Epub 2 May 2017
Self-assembling proteins are gaining attention as building blocks for application-tailored nanoscale materials. This is mostly due to the biocompatibility, biodegradability, and functional versatility of peptide chains. Such a potential for adaptability is particularly high in the case of recombinant proteins, which are produced in living cells and are suitable for genetic engineering. However, how the cell factory itself and the particular protein folding machinery influence the architecture and function of the final material is still poorly explored. In this study we have used diverse analytical approaches, including small-angle X-ray scattering (SAXS) and field emission scanning electron microscopy (FESEM) to determine the fine architecture and geometry of recombinant, tumor-targeted protein nanoparticles of interest as drug carriers, constructed on a GFP-based modular scheme. A set of related oligomers were produced in alternative Escherichia coli strains with variant protein folding networks. This resulted in highly regular populations of morphometric types, ranging from 2.4 to 28 nm and from spherical- to rod-shaped materials. These differential geometric species, whose relative proportions were determined by the features of the producing strain, were found associated with particular fluorescence emission, cell penetrability and receptor specificity profiles. Then, nanoparticles with optimal properties could be analytically identified and further isolated from producing cells for use. The cell's protein folding machinery greatly modulates the final geometry reached by the constructs, which in turn defines the key parameters and biological performance of the material.
More information
Sanchez R, Ayala R, Alonso RA, Martínez MP, Ribera J, García O, Sanchez-Pina J, Mercadal S, Montesinos P, Martino R, Barba P, González-Campos J, Barrios M, Lavilla E, Gil C, Bernal T, Escoda L, Abella E, Amigo ML, Moreno MJ, Bravo P, Guàrdia R, Hernández-Rivas JM, García-Guiñón A, Piernas S, Ribera JM, Martínez-López J

Clinical characteristics of patients with central nervous system relapse in BCR-ABL1-positive acute lymphoblastic leukemia: the importance of characterizing ABL1 mutations in cerebrospinal fluid.

Ann. Hematol. 27 Apr 2017, . Epub 27 Apr 2017
We investigated the frequency, predictors, and evolution of acute lymphoblastic leukemia (ALL) in patients with CNS relapse and introduced a novel method for studying BCR-ABL1 protein variants in cDNA from bone marrow (BM) and cerebrospinal fluid (CSF) blast cells. A total of 128 patients were analyzed in two PETHEMA clinical trials. All achieved complete remission after imatinib treatment. Of these, 30 (23%) experienced a relapse after achieving complete remission, and 13 (10%) had an isolated CNS relapse or combined CNS and BM relapses. We compared the characteristics of patients with and without CNS relapse and further analyzed CSF and BM samples from two of the 13 patients with CNS relapse. In both patients, classical sequencing analysis of the kinase domain of BCR-ABL1 from the cDNA of CSF blasts revealed the pathogenic variant p.L387M. We also performed ultra-deep next-generation sequencing (NGS) in three samples from one of the relapsed patients. We did not find the mutation in the BM sample, but we did find it in CSF blasts with 45% of reads at the time of relapse. These data demonstrate the feasibility of detecting BCR-ABL1 mutations in CSF blasts by NGS and highlight the importance of monitoring clonal evolution over time.
More information
Sorigue M, Juncà J, Orna E, Romanic N, Sarrate E, Castellvi J, Soler M, Rodríguez-Hernandez I, Feliu E, Ruiz S

Retinal vein occlusion and paroxysmal nocturnal hemoglobinuria.

J. Thromb. Thrombolysis 26 Apr 2017, . Epub 26 Apr 2017
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disorder associated with increased risk for thrombosis and reduced life expectancy. Retinal vein occlusion (RVO) is a frequent cause of vision loss but its relationship with PNH has not been studied systematically. Patients followed up for RVO in our ophthalmology department were screened for the presence of a PNH clone in peripheral blood by means of flow cytometry. The presence of other well-documented risk factors for RVO was also analyzed. In a series of 110 patients (54 males, median age of 67) we found no evidence of PNH. Most patients (97/110) had cardiovascular risk factors and/or hyperhomocysteinemia (67/110). Inherited thrombophilias were rare (three confirmed cases). Therefore, PNH does not appear to play a role in the development of RVO. However, this finding does not necessarily apply to young patients and/or those with no conventional risk factors for RVO, due to the low number of patients in these subgroups in our population.
More information

Events