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Iroquois 1 (Irx1) Marks the Stratum Intermedium and Periodontal Complex Cells
Author(s) -
RomeroBustillos Miguel,
Yu Wenjie,
Eliason Steve,
Amendt Brad A.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.902.10
Subject(s) - cementoblast , cementum , endodermis , periodontal fiber , biology , microbiology and biotechnology , dentistry , medicine , dentin
Iroquois 1 (Irx1) is a homobox transcription factor that was identified in craniofacial tissues through RNA‐sequencing and bioinformatics analyses. Irx1 is expressed in specific dental tissues during development and adult stages. Irx1 is present in the outer enamel epithelium and the stratum intermedium at prenatal stages. The expression of Irx1 is maintained until tooth eruption and at this stage it appears to play a role in root formation. Heterozygous Irx1 knockout mice show Irx1 expression in the Hertwig Epithelial Root Sheath and in the outer enamel epithelium at post‐natal stage p12 in molars. Epithelial rests of Malassez and isolated cells in the inter‐radicular cementum are positive for Irx1 expression. The presence of Irx1 is nonexistent in late stages on the root surface. Differences in Irx1 levels can be found in cultured cementoblast and periodontal ligament cells. Cementoblasts have a higher level of Irx1 than periodontal ligament cells. These findings were confirmed by real‐time PCR and protein levels. Under mineralization conditions cementoblasts show a reduction in the level of Irx1 expression. The presence of Irx1 during tooth development is indicative of the implication of this novel transcription factor in tooth formation. Moreover, the positive expression of Irx1 in cementoblasts under non‐mineralization conditions and its reduction of expression under‐mineralization conditions may suggest it regulates genes involved in root formation and possibly the origin progenitor cells of the cementum. Support or Funding Information Miguel Romero‐Bustillos would like to acknowledge the support received from the NIH under the R90 DE024296‐03 grant.