A miRNA signature in leukocytes from sporadic amyotrophic lateral sclerosis Bruna De Felice a, ⁎, Marco Guida b , Maurizio Guida c , Cinzia Coppola d, e , Giovanna De Mieri a , Roberto Cotrufo d, e a Department of Life Sciences, University of Naples II, Via Vivaldi 43, 81100 Caserta, Italy b Department of Biological Sciences, University of Naples “FedericoII”, Via Mezzocannone 16, 80134 Napoli, Italy c Department of Medicine, University of Salerno, Italy d First Division of Neurology, Department of Clinical and Experimental Medicine “F. Magrassi and A. Lanzara” of the Second University of Naples (SUN), Naples, Italy e Regional Interuniversity Center for Research in Neuroscience (CIRN) Naples, Italy abstract article info Article history: Accepted 30 July 2012 Available online 8 August 2012 Keywords: microRNAs sALS Leukocytes Microarray Amyotrophic lateral sclerosis (ALS) is a progressive and seriously disabling adult-onset neurological disease. Accumulating evidence indicates that various miRNAs, expressed in a spatially and temporally controlled man- ner in the brain, play a key role in neuronal development. In addition, misregulation of microRNAs contributes to some mental disorders and neurodegeneration diseases. Here, we analyzed the expression profiles of 911 human miRNAs using microarray technology in leukocytes, the most readily available human tissue cells, obtained from 8 patients affected by sporadic amyotrophic lateral sclerosis (sALS) and 12 healthy controls. An independent group of 14 sALS patients and 14 controls was used for validation by TaqMan real-time polymerase chain reaction assay. We identified 8 miRNAs that were significantly up- or downregulated in sALS patients as compared to healthy controls. The significant variations in miRNAs profiles detected in leukocytes have been related to miRNAs predominantly expressed in the nervous system. One of these miRNAs, miR-338-3p, has previously been shown to be de-regulated in ALS brains. This study, for the first time, detected specific microRNAs disease-related changes at an earlier stage of sALS. We suggest that miRNAs profiles found in the peripheral blood leukocytes from sALS patients can be relevant to understand the pathogenesis of sALS and/or used as biomarkers of the disease. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Amyotrophic lateral sclerosis (ALS), the main form of the motor neu- ron disease, is characterized by progressive degeneration of cortico- spinal tract, brain stem motor nuclei and spinal anterior horn neurons, leading to paralysis and death typically 3–5 years after symptoms begin. ALS can be inherited as an autosomal dominant trait in a subset of individuals who make up 5% to 10% of the total population of those affected. Therefore, more than 90% of ALS patients are sporadic, not showing any familial trait. In addition, 20% to 30% of familial ALS (fALS) cases are associated with a mutation in SOD1 while in sporadic ALS (sALS), causative or critical genes situated upstream of the disease pathway, have not been identified. In the search for genetic risk factors, monogenic association studies (MASs) found mutations in genes encoding TDP-43 (TARDBP) (Schymick et al., 2007). By whole-genome expression profiling, de- regulated genes have been identified in the motor cortex of post- mortem sALS patients. Contrary to expectations for a tissue under oxidative stress, nuclear-encoded mitochondrial and glycolytic genes are uniformly down-regulated, with a possible role in the death of ALS motoneurons (Lederer et al., 2007). In transgenic mice expressing a mutant form of superoxide dismutase (SOD1), in which glycine-93 is replaced with alanine (G93A-SOD1), as seen in a subset of human familial ALS patients, up-regulation of miR- 206 coincided with the onset of neurological symptoms (Williams et al., 2009). The pathogenesis of sporadic ALS is largely unknown, but there is emerging evidence that several distinct molecular mechanisms may play a role including oxidative stress, glutamate excitotoxicity, protein misfolding, apoptosis, inflammation, dysfunction of axonal transport, and mitochondrial dysfunction (Pantelidou et al., 2007). The identification of molecular pathways related to sALS remains an important challenge. Drawbacks of previous studies include limited sample size, the use of monogenic animal models, or human tissue from autopsy at the very end stage of motor neuron degeneration. Since access to spinal cord tissue is ethically unacceptable in life, changes in gene expression profiles have been investigated in blood cells of sALS patients (Saris et al., 2009); a differential gene expression profile was Gene 508 (2012) 35–40 Abbreviations: miRNA, microRNA; ALS, Amyotrophic lateral sclerosis; sALS, Sporadic Amyotrophic lateral sclerosis; rRNA, Ribosomal ribonucleic acid; mRNA, messenger ribonucleic acid; SLC1A2, solute carrier family 1 member 2. ⁎ Corresponding author. Tel.: +39 0823 274543; fax: +39 0823 274571. E-mail address: bruna.defelice@unina2.it (B. De Felice). 0378-1119/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gene.2012.07.058 Contents lists available at SciVerse ScienceDirect Gene journal homepage: www.elsevier.com/locate/gene