Biomedical subjects

Geneviève Victorero

Publications and source records attributed to Geneviève Victorero.

6 recordsLinked to original sources

PubMed2004

A general survey of thymocyte differentiation by transcriptional analysis of knockout mouse models.

The thymus is the primary site of T cell lymphopoiesis. To undergo proper differentiation, developing T cells follow a well-ordered genetic program that strictly depends on the heterogeneous and highly specialized thymic microenvironment. In this study, we used microarray technology to extensively describe transcriptional events regulating alphabeta T cell fate. To get an integrated view of these processes, both whole thymi from genetically engineered mice together with purified thymocytes were analyzed. Using mice exhibiting various transcriptional perturbations and developmental blockades, we performed a transcriptional microdissection of the organ. Multiple signatures covering both cortical and medullary stroma as well as various thymocyte maturation intermediates were clearly defined. Beyond the definition of histological and functional signatures (proliferation, rearrangement), we provide the first evidence that such an approach may also highlight the complex cross-talk events that occur between maturing T cells and stroma. Our data constitute a useful integrated resource describing the main gene networks set up during thymocyte development and a first step toward a more systematic transcriptional analysis of genetically modified mice.

Animals↗

PubMed2004

Genomic organization and the tissue distribution of alternatively spliced isoforms of the mouse Spatial gene.

BACKGROUND: The stromal component of the thymic microenvironment is critical for T lymphocyte generation. Thymocyte differentiation involves a cascade of coordinated stromal genes controlling thymocyte survival, lineage commitment and selection. The "Stromal Protein Associated with Thymii And Lymph-node" (Spatial) gene encodes a putative transcription factor which may be involved in T-cell development. In the testis, the Spatial gene is also expressed by round spermatids during spermatogenesis. RESULTS: The Spatial gene maps to the B3-B4 region of murine chromosome 10 corresponding to the human syntenic region 10q22.1. The mouse Spatial genomic DNA is organised into 10 exons and is alternatively spliced to generate two short isoforms (Spatial-alpha and -gamma) and two other long isoforms (Spatial-delta and -epsilon) comprising 5 additional exons on the 3' site. Here, we report the cloning of a new short isoform, Spatial-beta, which differs from other isoforms by an additional alternative exon of 69 bases. This new exon encodes an interesting proline-rich signature that could confer to the 34 kDa Spatial-beta protein a particular function. By quantitative TaqMan RT-PCR, we have shown that the short isoforms are highly expressed in the thymus while the long isoforms are highly expressed in the testis. We further examined the inter-species conservation of Spatial between several mammals and identified that the protein which is rich in proline and positive amino acids, is highly conserved. CONCLUSIONS: The Spatial gene generates at least five alternative spliced variants: three short isoforms (Spatial-alpha, -beta and -gamma) highly expressed in the thymus and two long isoforms (Spatial-delta and -epsilon) highly expressed in the testis. These alternative spliced variants could have a tissue specific function.

Alternative Splicing↗

PubMed2004

Gene expression profiling of colon cancer by DNA microarrays and correlation with histoclinical parameters.

Different diagnostic and prognostic groups of colorectal carcinoma (CRC) have been defined. However, accurate diagnosis and prediction of survival are sometimes difficult. Gene expression profiling might improve these classifications and bring new insights into underlying molecular mechanisms. We profiled 50 cancerous and noncancerous colon tissues using DNA microarrrays consisting of approximately 8000 spotted human cDNA. Global hierarchical clustering was to some extent able to distinguish clinically relevant subgroups, normal versus cancer tissues and metastatic versus nonmetastatic tumours. Supervised analyses improved these segregations by identifying sets of genes that discriminated between normal and tumour tissues, tumours associated or not with lymph node invasion or genetic instability, and tumours from the right or left colon. A similar approach identified a gene set that divided patients with significantly different 5-year survival (100% in one group and 40% in the other group; P=0.005). Discriminator genes were associated with various cellular processes. An immunohistochemical study on 382 tumour and normal samples deposited onto a tissue microarray subsequently validated the upregulation of NM23 in CRC and a downregulation in poor prognosis tumours. These results suggest that microarrays may provide means to improve the classification of CRC, provide new potential targets against carcinogenesis and new diagnostic and/or prognostic markers and therapeutic targets.

Colon↗

PubMed2004

Large scale gene expression analysis of CBA/J mouse strain fetal thymus using cDNA-array hybridizations.

The CBA/J inbred mouse strain constitutes an interesting in vivo model-system for studies on molecular genetics of thymus ontogeny. Using RT-PCR method we have found previously that several immune system related genes as interleukins and MHC are differentially expressed. During this period the onset of T-cell receptor beta rearrangements also occur. To know which other genes are modulated during the ontogeny of the thymus, the mRNA expression levels of fetal thymus (15 and 16 days gestation) of CBA/J mouse strain were measured by hybridization with a set of four macroarrays containing a panel of 6,144 IMAGE cDNA clones from MTB thymus library. We found 145 differentially expressed sequences; 44 were up- and 101 down-regulated in the thymus at 15-16 days gestation. Among these sequences, only 20 are identified as genes whose functions are known and 125 are still unknown. Our data demonstrated that, despite intense research on maturation of the immune system focusing on the activity of several well-characterized genes, the large scale expression profile during thymus ontogeny is still an open matter. The use of cDNA-array technology is an affordable method to identify new genes that may play a role in this phenomenon.

Animals↗

PubMed2003

Spatial, a new nuclear factor tightly regulated during mouse spermatogenesis.

In order to clarify general mechanisms of T cell development, we used array technology to identify genes differentially expressed between wild type and mutant mice thymuses. This quantitative differential screening leads to the isolation of Spatial, a putative transcription factor, expressed at high level in thymic cortical stromal cells. We report here, by RT-PCR on 48 distinct tissues that Spatial is also highly expressed in testis. Interestingly, the testicular expression is developmentally regulated, since it only appears in adult mice around 7-8 weeks of age. Analysis of purified testicular cell types show that Spatial expression is restricted to haploid round spermatids during spermiogenesis and the expression sites were further localized by in situ hybridization to step 2-10 spermatids. Thus, this recently described nuclear factor constitutes a new marker of the round spermatid stage that may play a key role in the control of male germ cell development.

Animals↗

PubMed2003

Gene expression profiling during thymus ontogeny and its association with TCRVbeta8.1-Dbeta2.1 rearrangements of inbred mouse strains.

The V(D)J recombination of TCRalpha and beta in early developing T-cells is a highly modulated phenomenon initiated and completed by recombinase complex (RAG-1 and RAG-2), and regulated by other gene products such as interleukins. To further evaluate the association of several other gene products with the evolution of TCRVbeta8.1 V(D)J rearrangements in vivo, the mRNA expression levels of seven interleukins, three cytokines, receptors TCRVbeta8.1 and IL-2Rbeta, MHC-I/MHC-II, RAG-1/ RAG-2 and retroviral superantigen MMTV(SW) were measured by RT-PCR during the fetal development of the thymus of three inbred mouse strains (Balb-c, C57B1/6 and CBA/J). Clustering using the Tree View software, was used to organize these genes based on similarity of expression patterns. Each strain displayed a different expression profile during thymus ontogeny. During the late developmental stage the most evident association was the kinetics of MMTV(SW) retrovirus, IL-2Rbeta and IL-7 overexpression with reduction of TCRVbeta8.1-D1beta2.1 rearrangement in the thymus of CBA/J mice. These data suggest a susceptibility of this strain to expression of MMTV(SW) upon reduction of the rearranged TCRVbeta8.1-Dbeta2.1 segment in developing thymocytes, with parallel IL-7 overexpression.

Animals↗