Opa1 overexpression ameliorates the phenotype of two mitochondrial disease mouse models

SummaryIncreased levels of the mitochondria-shaping protein Opa1 improve respiratory chain efficiency and protect from tissue damage, suggesting that it could be an attractive target to counteract mitochondrial dysfunction. Here we show that Opa1 overexpression ameliorates two mouse models of defective mitochondrial bioenergetics. The offspring from crosses of a constitutive knockout for the structural complex I component Ndufs4 (Ndufs4−/−), and of a muscle-specific conditional knockout for the complex IV assembly factor Cox15 (Cox15sm/sm), with Opa1 transgenic (Opa1tg) mice showed improved motor skills and respiratory chain activities compared to the naive, non-Opa1-overexpressing, models. While the amelioration was modest in Ndufs4−/−::Opa1tg mice, correction of cristae ultrastructure and mitochondrial respiration, improvement of motor performance and prolongation of lifespan were remarkable in Cox15sm/sm::Opa1tg mice. Mechanistically, respiratory chain supercomplexes were increased in Cox15sm/sm::Opa1tg mice, and residual monomeric complex IV was stabilized. In conclusion, cristae shape amelioration by controlled Opa1 overexpression improves two mouse models of mitochondrial disease

The circulating microRNome demonstrates distinct lymphocyte subset-dependent signatures

Upon activation, lymphocytes release vesicles containing microRNAs (miRNAs). However, little is known as to whether this release results in modulation of circulating miRNAs (the miRNome) in the serum. The present work aims to identify lymphocyte subset-specific signatures of miRNAs within the serum circulating miRNome. We therefore assessed serum miRNA expression profiles in wild type mice; in mice lacking either CD4(+) T cells, CD8(+) T cells, invariant Natural Killer T (iNKT) cells or B cells; and, as a control, in mice in which Dicer has been ablated in T lymphocytes. We found that specific serum miRNAs are differentially modulated when different lymphocyte subsets are lacking. In particular, the serum level of miR-181b-5p, previously demonstrated to be fundamental for the development of iNKT cells, is specifically reduced in mice in which iNKT cells are absent. Interestingly, our results indicate a direct link between the biological role of a single miRNA in lymphocyte development and its serum level, and prove that even a population composed of relatively few cells in vivo, such as iNKT lymphocytes, has a measurable effect on the serum circulating miRNome

The circulating microRNome demonstrates distinct lymphocyte subset-dependent signatures

Upon activation, lymphocytes release vesicles containing microRNAs (miRNAs). However, little is known as to whether this release results in modulation of circulating miRNAs (the miRNome) in the serum. The present work aims to identify lymphocyte subset-specific signatures of miRNAs within the serum circulating miRNome. We therefore assessed serum miRNA expression profiles in wild-type mice; in mice lacking either CD4+ T cells, CD8+ T cells, invariant natural killer T (iNKT) cells, or B cells; and, as a control, in mice in which Dicer has been ablated in T lymphocytes. We found that specific serum miRNAs are differentially modulated when different lymphocyte subsets are lacking. In particular, the serum level of miR-181b-5p, previously demonstrated to be fundamental for the development of iNKT cells, is specifically reduced in mice in which iNKT cells are absent. Interestingly, our results indicate a direct link between the biological role of a single miRNA in lymphocyte development and its serum level, and prove that even a population composed of relatively few cells in vivo, such as iNKT lymphocytes, has a measurable effect on the serum circulating miRNome

Integration of genomic and gene expression data of childhood ALL without known aberrations identifies subgroups with specific genetic hallmarks.

Pediatric acute lymphoblastic leukemia (ALL) comprises genetically distinct subtypes. However, 25% of cases still lack defined genetic hallmarks. To identify genomic aberrancies in childhood ALL patients nonclassifiable by conventional methods, we performed a single nucleotide polymorphisms (SNP) array-based genomic analysis of leukemic cells from 29 cases. The vast majority of cases analyzed (19/24, 79%) showed genomic abnormalities; at least one of them affected either genes involved in cell cycle regulation or in B-cell development. The most relevant abnormalities were CDKN2A/9p21 deletions (7/24, 29%), ETV6 (TEL)/12p13 deletions (3/24, 12%), and intrachromosomal amplifications of chromosome 21 (iAMP21) (3/24, 12%). To identify variation in expression of genes directly or indirectly affected by recurrent genomic alterations, we integrated genomic and gene expression data generated by microarray analyses of the same samples. SMAD1 emerged as a down-regulated gene in CDKN2A homozygous deleted cases compared with nondeleted. The JAG1 gene, encoding the Jagged 1 ligand of the Notch receptor, was among a list of differentially expressed (up-regulated) genes in ETV6-deleted cases. Our findings demonstrate that integration of genomic analysis and gene expression profiling can identify genetic lesions undetected by routine methods and potential novel pathways involved in B-progenitor ALL pathogenesis

Pretransplant HLA mistyping in diagnostic samples of acute myeloid leukemia patients due to acquired uniparental disomy

Although acquired uniparental disomy (aUPD) has been reported in relapse acute myeloid leukemia (AML), pretransplant aUPD involving chromosome 6 is poorly documented. Such events could be of interest because loss of heterozygosity (LOH) resulting from aUPD in leukemic cells may lead to erroneous results if HLA typing for hematopoietic stem cell donor searches is performed on blood samples drawn during blastic crisis. We report here six AML patients whose HLA typing was performed on DNA extracted from peripheral blood obtained at diagnosis. We observed LOH involving the entire HLA region (three patients), HLA-A, B, C (two patients) and HLA-A only (one patient). An array-comparative genomic hybridization showed that copy number was neutral for all loci, thus revealing partial aUPD of chromosome 6p21. When HLA typing was performed on remission blood samples both haplotypes were detected. A 3-4% LOH incidence was estimated in AML patients with high blast counts. Based on DNA mixing experiments, we determined by PCR sequence-specific oligonucleotide hybridization on microbeads arrays a detection threshold for HLA-A, B, DRB1 heterozygosity in blood samples with <80% blasts. Because aUPD may be partial, any homozygous HLA result should be confirmed by a second typing performed on buccal swabs or on blood samples from the patient in remission

Intracellular modulation, extracellular disposal and serum increase of MiR-150 mark lymphocyte activation

Activated lymphocytes release nano-sized vesicles (exosomes) containing microRNAs that can be monitored in the bloodstream. We asked whether elicitation of immune responses is followed by release of lymphocyte-specific microRNAs. We found that, upon activation in vitro, human and mouse lymphocytes down-modulate intracellular miR-150 and accumulate it in exosomes. In vivo, miR-150 levels increased significantly in serum of humans immunized with flu vaccines and in mice immunized with ovalbumin, and this increase correlated with elevation of antibody titers. Immunization of immune-deficient mice, lacking MHCII, resulted neither in antibody production nor in elevation of circulating miR-150. This study provides proof of concept that serum microRNAs can be detected, with minimally invasive procedure, as biomarkers of vaccination and more in general of adaptive immune responses. Furthermore, the prompt reduction of intracellular level of miR-150, a key regulator of mRNAs critical for lymphocyte differentiation and functions, linked to its release in the external milieu suggests that the selective extracellular disposal of microRNAs can be a rapid way to regulate gene expression during lymphocyte activation

Intracellular Modulation, Extracellular Disposal and Serum Increase of MiR-150 Mark Lymphocyte Activation

Activated lymphocytes release nano-sized vesicles (exosomes) containing microRNAs that can be monitored in the bloodstream. We asked whether elicitation of immune responses is followed by release of lymphocyte-specific microRNAs. We found that, upon activation in vitro, human and mouse lymphocytes down-modulate intracellular miR-150 and accumulate it in exosomes. In vivo, miR-150 levels increased significantly in serum of humans immunized with flu vaccines and in mice immunized with ovalbumin, and this increase correlated with elevation of antibody titers. Immunization of immune-deficient mice, lacking MHCII, resulted neither in antibody production nor in elevation of circulating miR-150. This study provides proof of concept that serum microRNAs can be detected, with minimally invasive procedure, as biomarkers of vaccination and more in general of adaptive immune responses. Furthermore, the prompt reduction of intracellular level of miR-150, a key regulator of mRNAs critical for lymphocyte differentiation and functions, linked to its release in the external milieu suggests that the selective extracellular disposal of microRNAs can be a rapid way to regulate gene expression during lymphocyte activation. © 2013 de Candia et al