Specificity protein 7 is not essential for tooth morphogenesis. (August 2014)

• Record Type: Journal Article
• Authors: Clarke, John C.; Bae, Ji-Myung; Adhami, Mitra; Rashid, Harunur; Chen, Haiyan; Napierala, Dobrawa; Gutierrez, Soraya E.; Sinha, Krishna; Crombrugghe, Benoit de; Javed, Amjad
• Is Part Of: Connective tissue research. Volume 55:Number 1(2014:Feb.)
• Page Start: 88
• Page End: 91
• Publication Date: 2014-08
• Subjects: Connective tissues -- Periodicals; 616.770072
• DOI: 10.3109/03008207.2014.923874
• Languages: English
• ISSNs: 0300-8207

Abstract

<abstract> <title>Abstract</title> <p>Tooth formation is a multifaceted process involving numerous interactions between oral epithelium and neural crest derived ecto-mesenchyme from morphogenesis to cyto-differentiation. The precise molecular regulator that drives the cyto-differentiation and dynamic cross-talk between the two cell types has yet to be fully understood. Runx2 along with its downstream target Sp7 are essential transcription factors for development of the mineralizing cell types. Global knockout of the <italic>Runx2</italic> gene results in an arrest of tooth morphogenesis at the late bud stage. Like <italic>Runx2, Sp7</italic>-null mutants exhibit peri-natal lethality and are completely devoid of alveolar bone. However, the role of Sp7 in tooth development remains elusive. Here, we report the effects of <italic>Sp7</italic> deletion on tooth formation. Surprisingly, tooth morphogenesis progresses normally until the mid bell stage in <italic>Sp7</italic>-homozygous mutants. Incisors and multi-cusped first and second molars were noted in both littermates. Thus, formation of alveolar bone is not a prerequisite for tooth morphogenesis. Tooth organs of <italic>Sp7</italic>-null however, were significantly smaller in size when compared to WT. Differentiation of both ameloblasts and odontoblasts was disrupted in <italic>Sp7</italic>-null mice. Only premature and disorganized ameloblasts and odontoblasts were noted in mutant mice. These data indicate that Sp7 is not required for tooth morphogenesis but is obligatory for the functional maturation of both ameloblasts and odontoblasts.</p> </abstract>