Fine mapping of the neurally expressed gene SOX14 to human 3q23, relative to three congenital diseases

Members of the Sox gene family encode transcription factors that have diverse and important functions during development. We have recently described the cloning of chick and mouse Sox14 and the expression of these genes in a population of ventral interneurons in the embryonic spinal cord. We report here the cloning and sequencing of the human orthologue of Sox14. Human SOX14 shows remarkable sequence conservation compared with orthologues from other vertebrate species and probably mirrors the expression of these genes in the developing brain and spinal cord. Using radiation hybrid mapping and fluorescence in situ hybridisation, we have localised SOX14 close to the sequence tagged site D3S1576 on human chromosome 3q23. Three congenital disorders have been localised to this region: blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), Charcot-Marie-Tooth neuropathy type IIB (CMT2B) and Mobius syndrome type 2 (MBS2). We have found that SOX14 is unlikely to be involved in any of these disorders because of the position of SOX14 proximal to a BPES breakpoint and the lack of SOX14 coding region alterations in BPES, CMT2B and MBS2 patients.

The HMG box transcription factor gene Sox14 marks a novel subset of ventral interneurons and is regulated by sonic hedgehog

Cell-type diversity along the dorsoventral axis of the developing neural tube is influenced by factors secreted by groups of cells at the dorsal and ventral midline. Upon reception of these signals, precursor cells express specific sets of transcription factors which, in turn, play critical roles in cell-type specification. Here we report the cloning and characterization of Sox14, a novel and highly conserved member of the Sry-related Sox transcription factor gene family, in mouse and chick. Sox14 expression is restricted to a limited population of neurons in the developing brain and spinal cord of both species. Sox14 marks a subset of interneurons at a defined dorsoventral position adjacent to ventral motor neurons in the spinal cord. In vivo grafting of chick notochord tissue to ectopic positions adjacent to the developing spinal cord altered the expression domain of Sox14. Furthermore, expression of Sox14 in spinal cord explants was found to be regulated by Sonic hedgehog in a dose-dependent manner. These data implicate a novel class of transcription factors in dorsoventral cell-type specification in the spinal cord.

Molecular control of cell type diversity in the developing spinal cord

1. During embryonic development, a diverse array of neurons and glia are generated at specific positions along the dorsoventral and rostro-caudal axes of the spinal cord from a common pool of precursor cells. 2. This cell type diversity can be distinguished by the spatially and temporally coordinated expression of several transcription factors that are also linked to cell type specification at a very early stage of spinal cord development. 3. Recent studies have started to uncover that the generation of cell type diversity in the developing spinal cord. Moreover, distinct cell types in the spinal cord appear to be determined by the spatially and temporally coordinated expression of transcription factors. 4. The expression of these factors also appears to be controlled by gradients of factors expressed by ventral and dorsal midline cells, namely Sonic hedgehog and members of the transforming growth factor-beta family. 5. Changes in the competence of precursor cells and local cell interactions may also play important roles in cell type specification within the developing spinal cord.

Expression of the Sox11 gene in mouse embryos suggests roles in neuronal maturation and epithelio-mesenchymal induction

Sry, the mammalian Y-linked testis determining gene, is a member of a family of genes known as Sox genes, which encode transcription factors related by a DNA-binding motif termed the HMG box. Sox genes are known to have diverse roles in vertebrate differentiation and development. We report here the cloning and characterisation of one of these genes, Sox11, in mice. In addition to an N-terminal HMG box domain, the deduced SOX11 protein contains a number of highly conserved C-terminal motifs, which may function in transcriptional regulation. Expression of Sox11 in mouse embryos was prominent in the periventricular cells of the central nervous system, suggesting a role in neuronal maturation. Expression was also observed in a wide range of tissues involved in epithelial-mesenchymal interactions, suggesting an additional role in tissue modelling during development.

Effect of chemotherapy on tear drop poikilocytes and other peripheral blood findings in myelofibrosis

A leukoerythroblastic blood picture and tear drop shaped red cells are two characteristic features of myelofibrosis (MF). Following our earlier observation of an increase in the hemoglobin level with chemotherapy, we have now reviewed the pre- and post-treatment peripheral blood smears from 14 patients with MF to assess the effect of treatment on the above mentioned peripheral blood features. Our results suggest that these features are reversible with effective chemotherapy.