Differential Expression of PGC-1α and Metabolic Sensors Suggest Age-Dependent Induction of Mitochondrial Biogenesis in Friedreich Ataxia Fibroblasts

11 pages, 6 figures. PMID:21687738[PubMed] PMCID: PMC3110204BACKGROUND: Friedreich's ataxia (FRDA) is a mitochondrial rare disease, which molecular origin is associated with defect in the expression of frataxin. The pathological consequences are degeneration of nervous system structures and cardiomyopathy with necrosis and fibrosis, among others. PRINCIPAL FINDINGS: Using FRDA fibroblasts we have characterized the oxidative stress status and mitochondrial biogenesis. We observed deficiency of MnSOD, increased ROS levels and low levels of ATP. Expression of PGC-1α and mtTFA was increased and the active form of the upstream signals p38 MAPK and AMPK in fibroblasts from two patients. Interestingly, the expression of energetic factors correlated with the natural history of disease of the patients, the age when skin biopsy was performed and the size of the GAA expanded alleles. Furthermore, idebenone inhibit mitochondriogenic responses in FRDA cells. CONCLUSIONS: The induction of mitochondrial biogenesis in FRDA may be a consequence of the mitochondrial impairment associated with disease evolution. The increase of ROS and the involvement of the oxidative phosphorylation may be an early event in the cell pathophysiology of frataxin deficiency, whereas increase of mitochondriogenic response might be a later phenomenon associated to the individual age and natural history of the disease, being more evident as the patient age increases and disease evolves. This is a possible explanation of heart disease in FRDA.This work was supported by grants SAF2008-01338, SAF2006-01047 and SAF2009-07063 from the Ministerio de Ciencia e Innovación and financial support from the CIBERER (Biomedical Network Research Center for Rare Diseases). A.G. thanks the Conselleria de Educación of the Generalitat Valenciana for the financial support by grants GVPRE/2008/154. A.B.-A. is the recipient of a JAE-CSIC predoctoral fellowship. The CIBERER is an initiative of the Instituto de Salud Carlos III and INGENIO 2010.Peer reviewe

Limitations in a frataxin knockdown cell model for Friedreich ataxia in a high-throughput drug screen

<p>Abstract</p> <p>Background</p> <p>Pharmacological high-throughput screening (HTS) represents a powerful strategy for drug discovery in genetic diseases, particularly when the full spectrum of pathological dysfunctions remains unclear, such as in Friedreich ataxia (FRDA). FRDA, the most common recessive ataxia, results from a generalized deficiency of mitochondrial and cytosolic iron-sulfur cluster (ISC) proteins activity, due to a partial loss of frataxin function, a mitochondrial protein proposed to function as an iron-chaperone for ISC biosynthesis. In the absence of measurable catalytic function for frataxin, a cell-based assay is required for HTS assay.</p> <p>Methods</p> <p>Using a targeted ribozyme strategy in murine fibroblasts, we have developed a cellular model with strongly reduced levels of frataxin. We have used this model to screen the Prestwick Chemical Library, a collection of one thousand off-patent drugs, for potential molecules for FRDA.</p> <p>Results</p> <p>The frataxin deficient cell lines exhibit a proliferation defect, associated with an ISC enzyme deficit. Using the growth defect as end-point criteria, we screened the Prestwick Chemical Library. However no molecule presented a significant and reproducible effect on the proliferation rate of frataxin deficient cells. Moreover over numerous passages, the antisense ribozyme fibroblast cell lines revealed an increase in frataxin residual level associated with the normalization of ISC enzyme activities. However, the ribozyme cell lines and FRDA patient cells presented an increase in Mthfd2 transcript, a mitochondrial enzyme that was previously shown to be upregulated at very early stages of the pathogenesis in the cardiac mouse model.</p> <p>Conclusion</p> <p>Although no active hit has been identified, the present study demonstrates the feasibility of using a cell-based approach to HTS for FRDA. Furthermore, it highlights the difficulty in the development of a stable frataxin-deficient cell model, an essential condition for productive HTS in the future.</p

O uso de procedimentos de estruturação de rotina em indivíduos com anóxia cerebral: relato de caso Procedures to improve daily activities performance in individuals with cerebral anoxia: case report

OBJETIVO: Apresentar um estudo de caso de reabilitação com procedimentos de estruturação de rotina para realização das atividades de vida diária (AVDs). PACIENTE: Quadro de anóxia cerebral, com déficit de memória verbal e visual, desorientação temporal, abulia e bradipsiquismo. MÉTODO: Estruturação de horários fixos na rotina diária; exposição a um calendário 3 vezes ao dia; caminhadas diárias; monitorização do familiar na execução de tarefas de auto cuidado, fornecendo auxílio mediante comandos verbais curtos e pistas específicas. RESULTADOS: Foram observados aumento da iniciativa, maior autonomia nas AVDs, diminuição do período de latência para qualquer resposta, melhora da atenção, orientação temporal e bradipsiquismo. CONCLUSÕES: Estratégias de controle do comportamento trazem ganhos e limitações para pacientes e familiares. Embora obriguem a adaptação a uma rotina pouco flexível, promovem o aprendizado através da automatização de procedimentos que se valem de mecanismos de memória implícita preservados. Estes recursos podem elevar o grau de autonomia do paciente em casa.<br>OBJECTIVE: To present a rehabilitation case study; procedures to improve the performance on daily activities were used by the caregiver. PATIENT: Cerebral anoxia due to cardiac arrest. He presented memory deficits for both visual and verbal material, temporal disorientation, abulia, psychomotor slowing and bradypsychism. METHODS: daily activities were developed in fixed hours; calendar was presented 3 times a day ; daily walks were performed; self-care activities were performed by the patient with short verbal commands and cues from the caregiver. RESULTS: We observed improvement on initiative and autonomy for daily activities, attention, temporal orientation and bradypsychism. There was also reduction on response time. CONCLUSIONS: Behavioral control strategies result on improvement for patients and their family although limit their routine. Behavioral control strategy promotes learning through the preserved implicit memory mechanism and results on enhancement at patient's autonomy at home

Modelling habitat requirements of bullhead (Cottus gobio) in Alpine streams

In the context of water resources planning and management, the prediction of fish distribution related to habitat characteristics is fundamental for the definition of environmental flows and habitat restoration measures. In particular, threatened and endemic fish species should be the targets of biodiversity safeguard and wildlife conservation actions. The recently developed meso-scale habitat model (MesoHABSIM) can provide solutions in this sense by using multivariate statistical techniques to predict fish species distribution and to define habitat suitability criteria. In this research, Random Forests (RF) and Logistic Regressions (LR) models were used to predict the distribution of bullhead (Cottus gobio) as a function of habitat conditions. In ten reference streams of the Alps (NW Italy), 95 mesohabitats were sampled for hydro-morphologic and biological parameters, and RF and LR were used to distinguish between absence/presence and presence/abundance of fish. The obtained models were compared on the basis of their performances (model accuracy, sensitivity, specificity, Cohen's kappa and area under ROC curve). Results indicate that RF outperformed LR, for both absence/presence (RF: 84 % accuracy, k = 0.58 and AUC = 0.88; LR: 78 % accuracy, k = 0.54 and AUC = 0.85) and presence/abundance models (RF: 79 % accuracy, k = 0.57 and AUC = 0.87; LR: 69 % accuracy, k = 0.43 and AUC = 0.81). The most important variables, selected in each model, are discussed and compared to the available literature. Lastly, results from models' application in regulated sites are presented to show the possible use of RF in predicting habitat availability for fish in Alpine stream