BRIEF REPORT |
Correspondence to: Thomas G.H. Diekwisch, Director, Allan G. Brodie Laboratory for Craniofacial Genetics, University of Illinois at Chicago College of Dentistry (M/C 841), 801 South Paulina, Chicago, IL 60612. E-mail: tomdkw@uic.edu
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Summary |
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cp27 is a novel gene involved in early vertebrate development that features a distinct protein localization pattern in developing tooth organs. During initial tooth development, CP27 was detected at the epithelialmesenchymal interface of dental lamina stage tooth organs. At later stages of tooth development, CP27 was localized in the stellate reticulum, the oral mucosa mesenchyme, and alveolar bone. The significant changes in the highly restricted distribution pattern suggest that CP27 might be involved at several different levels during tooth development. (J Histochem Cytochem 50:583586, 2002)
Key Words: tooth development, CP27, BCNT, mouse embryo, dental lamina, stellate reticulum, oral mucosa, odontoblasts, dental follicle, alveolar bone, bone formation, craniofacial development, organogenesis
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Introduction |
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THE EXTRACELLULAR MATRIX (ECM) is an intercellular protein network that exerts profound control over cells. The ECM collaborates with cell surface receptors to regulate gene expression associated with cell growth, differentiation, and survival (gt11 library and mapped to the human chromosome region 16q22.2-22.3 close to a region associated with several craniofacial syndromes (
To reveal the localization pattern of CP27 during tooth development, we prepared tissues from mice at stages E11, E13, E15, E19, and 3 days postnatal, according to Baylor College of Dentistry animal care guidelines. For paraffin immunohistochemistry, tissues were fixed in formalin, dehydrated, and embedded in paraffin as previously described (
At the beginning of tooth development, CP27 IHC delineated a distinct and highly confined localization pattern. During the dental lamina stage (E11) CP27 was localized in the basement membrane of the dental lamina and in mesenchymal cells adjacent to the dental lamina (Fig 1A and Fig 1B). In the mesenchymal cells, CP27-related epitopes were localized either extracellularly or in the periphery of the cytoplasm, but not in the epithelium. During the bud stage (E13), CP27 was localized in the basal lamina of the oral epithelium. At this stage (E13), CP27 was also localized in a 100-nm-diameter half dome-shaped area of mesenchymal cells surrounding the developing tooth buds (Fig 1C and Fig 1D). In contrast, the condensed dental mesenchyme and the dental follicle did not demonstrate any CP27 immunoreactivity. The immunopositive areas in the mesenchyme were restricted to extracellular matrices and the mesenchymal stroma. In the bell stage (E15) and all of the following stages until 3 days postnatal, CP27 was present in the stellate reticulum, in the oral mucosa and, to a lesser degree, in the dental pulp (Fig 1E1H). Methodological controls were negative (data not shown). Same-sized control peptide antibodies against amelogenin sequence did not react with the stellate reticulum, the alveolar bone, the oral mucosa, and the dental lamina basement membrane (data not shown). Outside of the developing tooth organ, CP27 was localized in the periphery of developing organs, including periosteum, perichondrium, and pericardium (data not shown).
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In the present study we documented a tightly restricted temporospatial localization pattern for CP27 during tooth development. CP27 was highly condensed in significant areas during tooth formation, including the epithelialmesenchymal interface of dental lamina stage tooth organs, the dental papilla, the alveolar bone, the stellate reticulum, and the oral mucosa mesenchyme. A series of control reactions including controls with similar-sized peptide antibodies against sequence fragments from other genes established the specificity of the CP27 antibody.
CP27 featured a highly distinct localization pattern in the epithelialmesenchymal interface of dental lamina stage tooth organs. The basement membrane of the dental lamina epithelium in dental lamina stage tooth organs is a site of pivotal importance for the onset of tooth development. This basement membrane is the primary site for epithelialmesenchymal interaction signal transduction. It transmits signals from the neural crest-derived dental mesenchyme to the oral epithelium and reciprocal signals from the tooth-forming epithelium towards the dental mesenchyme. Indirectly, these signals provide evidence for the significance of the dental lamina epithelium basement membrane as a potential site of epithelialmesenchymal information exchange. The distinct localization of CP27 in the basement membrane of the early developing tooth organ suggests that CP27 might play an important role during the epithelialmesenchymal interactions at the onset of tooth development.
Our results further revealed that CP27 is a constitutive element of the stellate reticulum ECM of cap and bell stage tooth organs. The stellate reticulum is a population of star-shaped cells between the dental sac and the developing tooth crown that has remarkably large intercellular spaces (
Our finding of a distinct localization of CP27 in the stellate reticulum of developing teeth is consistent with other findings from our group reporting the collapse of the stellate reticulum and subsequent inhibition of tooth crown formation after inhibition of CP27 function (
There were distinct differences between the microscopic CP27 mRNA localization as reported earlier (
The significant changes in the highly restricted CP27 localization pattern suggest that CP27 might be involved in tooth formation at several different levels during development. Our immunolocalization studies have localized CP27 in the ECM of the dental lamina basement membrane and of the stellate reticulum. Our findings are consistent with CP27 function studies that establish CP27 as an essential gene product for normal tooth crown formation (
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Acknowledgments |
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Support for these studies by NIH grant DE13095 to T.G.H.D. is gratefully acknowledged.
Received for publication September 6, 2001; accepted December 14, 2001.
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