Immunohistochemical localization of calbindin D28k during root formation of rat molar teeth

Abstract

The present study was undertaken to examine the localization of calbindin D28k (CB)-like immunoreactivity (-LI) during the root formation of the rat molar. In the adult rat, CB-LI was detected in some of the cells of the epithelial rest of Malassez at the bifurcational region and in certain cells between the root dentin and cementum at the apical region. These cells had indented nuclei and many tonofilaments, and cementocytes lacked CB-LI. Moreover, CB-LI was observed in the periodontal fibroblasts in the alveolar half of the apical region. During root formation, the cells in the Hertwig's epithelial root sheath (HERS) lacked CB-LI, but most fragmented cells along the root surface began to express CB-LI when HERS was disrupted. Preodontoblasts and odontoblasts at the apical portion of the root also showed CB-LI. After the formation of cellular cementum, the CB-immunoreactive (-IR) cells were entrapped between the root dentin and cementum in the apical portion of the root. The number of CB-IR cells at the root surface decreased gradually, while that between the root dentin and cementum increased. The fibroblasts in the periodontal ligament began to express CB-LI after commencement of the occlusion, and the number and the staining intensity of CB-IR fibroblasts increased gradually with the passage of time. The present results suggest that CB may play an important role in the survival of the epithelial cells, in the cellular responses of periodontal fibroblasts against mechanical forces caused by the occlusion, and in the initial mineralization by the odontoblasts through the regulation of intracellular Ca(2+) concentration.

The Ca2+-binding protein calretinin is selectively enriched in a subpopulation of the epithelial rests of Malassez

“…In contrast to our results in the adult rat ERM, calbindin D28k has been detected not only in the ERM during root formation, but also in the ERM of the adult rat (Onishi et al 1999) and adult mouse (Onishi et al 2003) molar PDLs. This discrepancy can be explained on the basis of the use of different antibodies against calretinin and calbindin D28k in our and in earlier studies.…”

“…Therefore, in earlier studies, cross-reactivity of antisera has been described between calbindin D28k and calretinin (Rogers 1987;Schwaller et al 1993;Schwaller 2009). Adult ERM, which have previously been described as containing calbindin D28k (Onishi et al 1999(Onishi et al , 2003 possibly also contains calretinin. The rabbit polyclonal (Schwaller et al 1993) and mouse monoclonal (Zimmermann and Schwaller 2002) anti-calretinin antibodies that we have used in our study react specifically with calretinin and do not cross-react with calbindin D28k.…”

“…These findings indicate that the regulation of Ca 2+ by the various calcium-binding proteins is important for the proliferation and differentiation of ameloblasts and odontoblasts during tooth development. Calbindin D28k in the ERM has been detected during root formation and in the adult rat (Onishi et al 1999) and mouse (Onishi et al 2003) molars. However, the regulation of [Ca 2+ ] i by the Ca 2+ -binding proteins parvalbumin and calretinin in the ERM of the adult PDL is unknown.…”

Role of Hertwig's epithelial root sheath cells in tooth root development

“…The expression of keratin by HERS in vivo has been demonstrated by several investigators (Alatli et al, 1996;Kaneko et al, 1999;Onishi et al, 1999), and as expected, HERS in vitro express keratin. Unexpected was the simultaneous expression of vimentin mRNA, although coexpression of vimentin and keratin has been reported for other epithelial cell lines maintained in culture (Zuk et al, 1989).…”

The epithelial cell rests of Malassez – a role in periodontal regeneration?

“…Other proteins expressed by the ERM include cell-surface molecules, such as calbindin D28 (which are vitamin Ddependent calcium-binding proteins) and epidermal growth factor receptor, growth factors such as epidermal growth factor and bone morphogenetic proteins 2 and 4, various cytokines, including interleukin-1a, interleukin-6, interleukin-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF), b defensin (BD-1) and prostaglandins E and F (58)(59)(60)(61)(62)(63)(64).…”