Biomedical subjects

Marie-Claude Gaillard

Publications and source records attributed to Marie-Claude Gaillard.

4 recordsLinked to original sources

PubMed2006

Involvement of mitochondrial complex II defects in neuronal death produced by N-terminus fragment of mutated huntingtin.

Alterations of mitochondrial function may play a central role in neuronal death in Huntington's disease (HD). However, the molecular mechanisms underlying such functional deficits of mitochondria are not elucidated yet. We herein showed that the expression of two important constituents of mitochondrial complex II, the 30-kDa iron-sulfur (Ip) subunit and the 70-kDa FAD (Fp) subunit, was preferentially decreased in the striatum of HD patients compared with controls. We also examined several mitochondrial proteins in striatal neurons that were infected with lentiviral vectors coding for the N-terminus part of huntingtin (Htt) with either a pathological (Htt171-82Q) or physiological (Htt171-19Q) polyglutamine tract. Compared with Htt171-19Q, expression of Htt171-82Q preferentially decreased the levels of Ip and Fp subunits and affected the dehydrogenase activity of the complex. The Htt171-82Q-induced preferential loss of complex II was not associated with a decrease in mRNA levels, suggesting the involvement of a posttranscriptional mechanism. Importantly, the overexpression of either Ip or Fp subunit restored complex II levels and blocked mitochondrial dysfunction and striatal cell death induced by Htt171-82Q in striatal neurons. The present results strongly suggest that complex II defects in HD may be instrumental in striatal cell death.

Apoptosis↗

PubMed2005

Progressive and selective striatal degeneration in primary neuronal cultures using lentiviral vector coding for a mutant huntingtin fragment.

A lentiviral vector expressing a mutant huntingtin protein (htt171-82Q) was used to generate a chronic model of Huntington's disease (HD) in rat primary striatal cultures. In this model, the majority of neurons expressed the transgene so that Western blot analysis and flow cytometry measurement could complement immunohistological evaluation. Mutant huntingtin produced a slowly progressing pathology characterized after 1 month by the appearance of neuritic aggregates followed by intranuclear inclusions, morphological anomalies of neurites, loss of neurofilament 160, increased expression in stress response protein Hsp70, and later loss of neuronal markers such as NeuN and MAP-2. At 2 months post-infection, a significant increase in TUNEL-positive cells confirmed actual striatal cell loss. Interestingly, cortical cultures infected with the same vector showed no sign of neuronal dysfunction despite accumulation of numerous inclusions. We finally examined whether the trophic factors CNTF and BDNF that were found neuroprotective in acute HD models could prevent striatal degeneration in a chronic model. Results demonstrated that both agents were neuroprotective without modifying inclusion formation. The present study demonstrates that viral vectors coding for mutant htt provides an advantageous system for histological and biochemical analysis of HD pathogenesis in primary striatal cultures.

Animals↗

PubMed2003

A panoramic view of gene expression in the human kidney.

To gain a molecular understanding of kidney functions, we established a high-resolution map of gene expression patterns in the human kidney. The glomerulus and seven different nephron segments were isolated by microdissection from fresh tissue specimens, and their transcriptome was characterized by using the serial analysis of gene expression (SAGE) method. More than 400,000 mRNA SAGE tags were sequenced, making it possible to detect in each structure transcripts present at 18 copies per cell with a 95% confidence level. Expression of genes responsible for nephron transport and permeability properties was evidenced through transcripts for 119 solute carriers, 84 channels, 43 ion-transport ATPases, and 12 claudins. Searching for differences between the transcriptomes, we found 998 transcripts greatly varying in abundance from one nephron portion to another. Clustering analysis of these transcripts evidenced different extents of similarity between the nephron portions. Approximately 75% of the differentially distributed transcripts corresponded to cDNAs of known or unknown function that are accurately mapped in the human genome. This systematic large-scale analysis of individual structures of a complex human tissue reveals sets of genes underlying the function of well-defined nephron portions. It also provides quantitative expression data for a variety of genes mutated in hereditary diseases and helps in sorting candidate genes for renal diseases that affect specific portions of the human nephron.

Cluster Analysis↗

PubMed2003

Quantitative assessment of transcriptome differences between brain territories.

Transcriptome analysis of mammalian brain structures is a potentially powerful approach in addressing the diversity of cerebral functions. Here, we used a microassay for serial analysis of gene expression (SAGE) to generate quantitative mRNA expression profiles of normal adult mouse striatum, nucleus accumbens, and somatosensory cortex. Comparison of these profiles revealed 135 transcripts heterogeneously distributed in the brain. Among them, a majority (78), although matching a registered sequence, are novel regional markers. To improve the anatomical resolution of our analysis, we performed in situ hybridization and observed unique expression patterns in discrete brain regions for a number of candidates. We assessed the distribution of the new markers in peripheral tissues using quantitative RT-PCR, Northern hybridization, and published SAGE data. In most cases, expression was higher in the brain than in peripheral tissues. Because the markers were selected according to their expression level, without reference to prior knowledge, our studies provide an unbiased, comprehensive molecular signature for various mammalian brain structures that can be used to investigate their plasticity under a variety of circumstances.

Animals↗