|Budget Amount *help
¥13,200,000 (Direct Cost : ¥13,200,000)
Fiscal Year 1999 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1998 : ¥12,200,000 (Direct Cost : ¥12,200,000)
We have cloned a new member of the zinc finger transcription factor, G23/Gli5 from incisor pulp RNA by RT-PCR using degenerate primers. The five zinc finger domain encoded by mouse G23 has almost 65% amino acid sequence homology with Gli1, Gli2 and Gli3. Northern blot analysis revealed G23/Gli5 is expressed in dental pulp, kidney and testis. In situ hybridization of sections and while mount embryos demonstrated G23/Gli5 is first detected diffusely in forelimb and hindlimb bud at 10.0 days post coitus (dpc). At 10.5 dpc, it is expressed in the branchial arches, limb bud, craniofacial border, and ventral part of the tail. Later, it is expressed in whisker follicle, intervertebral disc, kidney, and testis. In tooth germ, G23/Gli5 is expressed in dental papillae at bell stage, suggesting that it might function as a repressor during odontoblast differentiation.
We made targeted disruption of G23/Gli5. The second exon, 850bp from 5'-untranslated region to 3rd zinc finger DNA binding domain, containing the start codon, ATG was replaced by LacZ polyA and the lox-neo-polyA cassette. Homologous recombination was confirmed by Southern blot and by PCR. The homozygotes were fully viable and did not seem to have any conspicuous phenotype. The complementary expression patterns of G23/Gli5 and Gli1 family members suggest the redundant function of G23/Gli5 and Gli1 members. We are now analyzing the double homozygotes to find the function of G23/Gli5 during tooth development.