| First Author | Buckle VJ | Year | 1997 |
| Journal | Mouse Genome | Volume | 95 |
| Issue | 3 | Pages | 695-697 |
| Mgi Jnum | J:43281 | Mgi Id | MGI:1097461 |
| Citation | Buckle VJ, et al. (1997) Mapping of the mouse homeobox gene Cdx2 to G2-G3 of Chromosome 5. Mouse Genome 95(3):695-697 |
| abstractText | Full text of Mouse Genome contribution: MAPPING OF THE MOUSE HOMEOBOX GENE Cdx2 to G2-G3 OF CHROMOSOME 5. Veronica J. Buckle^, Helen P.Wilmore+ and Vasanta Subramanian+* ^MRC Molecular Haematology Unit, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford and +School of Biology and Biochemistry, South Building, University of Bath, Bath BA2 7AY * author to whom correspondence should be addressed. Introduction The mouse caudal (Cdx) type homeobox genes are a group of transcription factors which are the mammalian homologues of the Drosophila gene Caudal (1). The expression of the Caudal protein is regulated by the binding of the Bicoid gene product to the 3'UTR of Caudal RNA which leads to its translational repression in the anterior of the early Drosophila embryo (2). To date, three members of the Caudal type homeobox genes have been identified in the mouse, Cdx1, Cdx2 and Cdx4. Their expression is regulated spatially and temporally during development and in the adult (3, 4, 5, 6, 7 and 8). More recently, by gene targeting Cdxl, has been shown to play a key role in specifying axial skeletal identities and to activate Hox genes in the mesoderm (5) and Cdx2 has been shown to be involved in skeletal defects as well as in the genesis of some intestinal tumours (9). The mammalian Caudal type homeobox genes are not clustered like the Hox genes. Cdxl has been mapped to mouse chromosome 18 (3) and Cdx 4 (10) to the X-chromosome. The human homologue of the mouse Cdx2 (CDX3) has been mapped by FISH to human chromosome 13q 12.3 along with LMX1(11). Chawengsaksophak and Beck (12) report the localization of Cdx2 to mouse chromosome 5 using inter specific backcrosses. Here we report an independent and precise mapping of the mouse Cdx2 gene to G2-G3 of mouse chromosome 5 using FISH. Materials and Methods The mouse Cdx2 genomic clone was isolated from a 129 genomic library in lambda Dash II (provided by Paul Martin and Agnes Begue, Institut Pasteur) by screening with the mouse Cdx2 cDNA. The identity of the clones was confirmed by hybridisation, mapping and sequencing. ChromosomaI localisation was carried out by FISH as described by Buckle and Rack (13). Lambda phage DNA from clones P4C3-2 and P4C3-3 containing the 14 kb of Cdx2 genomic sequence was pooled and labelled with biotin -11 -dUTP by nick translation and hybridised in situ to mouse metaphase chromosome preparations prepared from Iipo-polysaccharide stimulated mouse spleen cells. The hybridization mixture (11 ul) containing 200 ng of labelled phage DNA and 5 ug of unlabelled total mouse DNA as competitor was denatured and allowed to anneal at 37 degrees C for 15 min prior to hybridisation. Hybridisation was carried out at 42 degrees C overnight. After stringent washes, hybridisation sites were detected with successive layers of Texas red conjugated avidin (5 ug/ml) and biotinylated anti-avidin (5 ug/ml), both from Vector laboratories. Slides were mounted in Vectashield (Vector laboratories) containing 1ug/ml 4', 6-diamidino-2-phenylindole (DAPI). Results were analysed and images captured using a cooled CCD imaging system (PSI Chester, UK). Flourescent probe images were overlaid onto enhanced G-bands obtained from DAPI images using Macprobe version 3.3 software (PSI, Chester, UK). Results and discussion Hybridisation of the Cdx2 probe (lambda P4 C2-2 and P4 C3-3) to mouse metaphase chromosomes resulted in specific labelling of only the distal end of chromosome 5. On each of the twenty metaphase plates that were examined, hybridisation signal was observed on chromosome 5. The signals were highly specific on 5 G2-G3 on all the four chromatids. This indicates that the mouse Cdx2 gene is located on chromosome 5 G2-G3 (Fig 1). This also is in keeping with the localisation of the human homologue of this gene which maps to the syntenic human 13q12.3 region. Fig 1 (Legend) FISH localisation of biotin labelled lambda Dash P4C2-2 and P4C3-3 (genomic clones of mouse Cdx2) to mouse metaphase chromosomes from lipopolysaccharide stimulated peripheral blood lymphocytes. The hybridising chromosome 5 homologues are indicated by arrows. Specific labelling was at the distal end of chr 5 - 5G2-G3. Acknowledgements We would like to thank the Wellcome Trust and the MRC, UK for financial support. References: 1. Macdonald, P.M. and Struhl, G. Nature 324, 537-545 (1986). 2. Dubnau, J and Struhl, G. Nature 379, 694-699 (1996). 3. Duprey, P., Chowdhury, K., Dressler, G.R., Balling, R., Simon, D., Guenet, J-L. and Gruss, P. Genes Dev. 2, 1647-1654 (1988). 4. Meyer, B. and Gruss, P. Development 117, 191-203 (1993). 5, Subramanian,V., Meyer, B.I., and Gruss, P. Cell 83, 641-653 (1995). 6. James, R. and Kazenwadel, J. J.Biol. Chem. 266, 3246-3251 (1991). 7. Beck, F. , Erler, T., Russell. A. and James, R. Dev. Dyn. 204, 219-227 (1995). 8. Gamer, L. W. and Wright, C.V.E. Mech. Dev. 43, 71-81 (1993). 9. Chawengsaksophak, K., James, R., Hammond, V.E., Kontgen, F. and Beck, F. Nature 386, 84-87 (1997). 10. Horn, J.M. and Ashworth, A. Hum. Mol. Genet. 4, 1041-1047 (1995). 11. German, M.S., Wang, J., Fernald, A.A., Espinosa, R., Le Beau, M. M. and Bell, G.I. Genomics 24, 403-404 (1994). 12. Chawengsaksophak, K and Beck, F. Genomics 34, 271-272 (1996). 13. Buckle, V.J. and Rack, K.A. In Human Genetic Disease Analysis, ed K.E. Davies, IRL Press pg 59-82 (1993). |
