Biomedical subjects

Magali Irla

Publications and source records attributed to Magali Irla.

4 recordsLinked to original sources

PubMed2006

Dynamic distribution of Spatial during mouse spermatogenesis and its interaction with the kinesin KIF17b.

The Spatial gene is expressed in highly polarized cell types, such as epithelial cells in the thymus, neurons in the brain and germ cells in the testis. In this study, we report the characterization and distribution of Spatial proteins during mouse spermatogenesis. Besides Spatial-epsilon and -delta, we show that the newly described short isoform Spatial-beta is expressed specifically in round spermatids. Using indirect immunofluorescence, we detected Spatial in the cytosol of the early round spermatid. By the end stages of round spermatids, Spatial is concentrated at the opposite face of the acrosome near the nascent flagellum and in the manchette during the elongation process. Finally in mature sperm, Spatial persists in the principal piece of the tail. Moreover, we found that Spatial colocalizes with KIF17b, a testis-specific isoform of the brain kinesin-2 motor KIF17. This colocalization is restricted to the manchette and the principal piece of the sperm tail. Further, coimmunoprecipitation experiments of native proteins from testis lysates confirmed Spatial-KIF17b association through the long Spatial-epsilon isoform. Together, these findings imply a function of Spatial in spermatid differentiation as a new cargo of kinesin KIF17b, in a microtubule-dependent mechanism specific to the manchette and the principal piece of the sperm tail.

Animals↗

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↗

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↗