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author:("loukkos, keio")
1.  Dact1-3 mRNAs exhibit distinct expression domains during tooth development 
Gene expression patterns : GEP  2010;10(2-3):140-143.
Wnt signaling is essential for tooth formation. Dact proteins modulate Wnt signaling by binding to the intracellular protein Dishevelled (Dvl). Comparison of all known mouse Dact genes, Dact1-3, from the morphological initiation of mandibular first molar development after the onset of the root formation using sectional in situ hybridization showed distinct, complementary and overlapping expression patterns for the studied genes. While Dact2 expression was restricted to the dental epithelium including the enamel knot signaling centers and tooth specific preameloblasts, Dact1 and Dact3 showed developmentally regulated expression in the dental mesenchyme. Both mRNAs were first detected in the presumptive dental mesenchyme. After being downregulated from the condensed dental mesenchyme of the bud stage tooth germ, Dact1 was upregulated in the dental follicle masenchyme at the cap stage and subsequently also in the dental papilla at the bell stage where the expression persisted to the postnatal stages. In contrast, Dact3 transcripts persisted throughout the dental mesenchymal tissue components including the tooth-specific cells, preodontoblasts before transcripts were largely downregulated from the tooth germ postnatally. Collectively these results suggest that Dact1 and -3 may contribute to early tooth formation by modulation of Wnt signaling pathways in the mesenchyme, including preodontoblasts, whereas Dact2 may play important signal-modulating roles in the adjacent epithelial cells including the enamel knot signaling centers and preameloblasts. Future loss-of-function studies will help elucidate whether any of these functions are redundant, particularly for Dact1 and Dact3.
PMCID: PMC2849867  PMID: 20170752
2.  The Histidine Triad Protein Hint Is Not Required for Murine Development or Cdk7 Function 
Molecular and Cellular Biology  2003;23(11):3929-3935.
The histidine triad (HIT) protein Hint has been found to associate with mammalian Cdk7, as well as to interact both physically and genetically with the budding yeast Cdk7 homologue Kin28. To study the function of Hint and to explore its possible role in modulating Cdk7 activity in vivo, we have characterized the expression pattern of murine Hint and generated Hint-deficient (Hint−/−) mice. Hint was widely expressed during mouse development, with pronounced expression in several neuronal ganglia, epithelia, hearts, and testes from embryonic day 15 onward. Despite this widespread expression, disruption of Hint did not impair murine development. Moreover, Hint-deficient mice had a normal life span and were apparently healthy. Histological examination of tissues with high Hint expression in wild-type animals did not show signs of abnormal pathology in Hint−/− mice. Functional redundancy within the HIT family was addressed by crossing Hint−/− mice with mice lacking the related HIT protein, Fhit, and by assaying the expression levels of the HIT protein gene family members Hint2 and Hint3 in Hint+/+ and Hint−/− tissues. Finally, Cdk7 kinase activity and cell cycle kinetics were found to be comparable in wild-type and Hint−/− mouse embryonic fibroblasts, suggesting that Hint may not be a key regulator of Cdk7 activity.
PMCID: PMC155213  PMID: 12748294

Results 1-2 (2)