Transient Expression of Heat Shock Protein (Hsp) 25 in the Dental Pulp and Enamel Organ during Odontogenesis in the Rat Incisor.

Abstract

The expression of heat shock protein (Hsp) 25 during odontogenesis in the dental pulp and enamel organ of rat incisors was investigated by immunocytochemistry and confocal microscopy. In the process of dentin formation, immature odontoblasts first exhibited Hsp 25-immunoreactivity, and increased in immunointensity with the advance of their differentiation. In the dental pulp, in contrast, intense immunoreaction in the mesenchymal cells became weak or negative in parallel with the progress of cell differentiation. The immunoreaction for Hsp 25 in the enamel organ revealed a characteristic stage-related alteration during amelogenesis. In secretory ameloblasts, the immunoreaction for Hsp 25 was found throughout their cell bodies, intense reactivity being located near the proximal and distal terminal webs. At the maturation stage, ruffle-ended ameloblasts (RA) consistently showed Hsp 25-immunoreactivity throughout the cell bodies, whereas smooth-ended ameloblasts (SA) lacking a ruffled border were weak in immunoreaction at the distal cytoplasm. Other cellular elements of the enamel organ were negative. The subcellular localization of Hsp 25-immunoreactivity in this study appeared essentially identical to that of actin filaments as demonstrated by confocal microscopy using rhodamine-labeled phalloidin. These immunocytochemical data suggest that the Hsp 25 molecule is involved in reinforcement of the cell layer following cell movement during odontogenesis and in the formation and maintenance of the ruffled border of RA.

Pulpal regeneration after cavity preparation, with special reference to close spatio‐relationships between odontoblasts and immunocompetent cells

“…Our previous observations showed constant and intense Hsp 25-immunoreaction in the differentiated odontoblasts in the incisor pulp and the coronal pulp of the molar. Moreover, the odontoblasts in the root and floor pulp of the molar were initially weak or negative, but increased in Hsp 25-immunointensity during the later stages of development (Ohshima et al, 2000a(Ohshima et al, , 2002. These findings indicate the possibility that Hsp 25-immunoreaction is a useful marker for distinguishing between undifferentiated and differentiated odontoblasts, as Hsp 25 has been reported to accumulate in the early phase of differentiation concomitantly with a decreased rate of cellular proliferation (Mehlen et al, 1997).…”

“…In addition to stressful and normal conditions, the transient expression of Hsp 25 has been shown during cellular development and differentiation (Arrigo and Préville, 1999). Our recent studies have demonstrated a stage-specific expression pattern of Hsp 25-immunoreactivity in the odontoblasts under normal (Ohshima et al, 2000a(Ohshima et al, , 2002 and experimental conditions (Ohshima et al, 2001a,b), suggesting that this protein is a useful marker for the differentiation of odontoblasts during the pulpal healing process.…”

“…These immunostained sections did not contain any specific immunoreaction. Further characterization of the primary antibodies has been reported elsewhere (Ohshima et al, 2000a;Plumier et al, 1997).…”

Cell dynamics in the pulpal healing process following cavity preparation in rat molars

“…Our protocol for HSP-25-immunohistochemistry has been shown in previous reports (Ohshima et al 2000;Nakakura-Ohshima et al 2003;Kawagishi et al 2006). The immunostained sections were stained with 0.03% methylene blue.…”

“…In addition to stressful and normal conditions, the transient expression of HSP-25 has been reported in various cells during development and cell diVerentiation (Arrigo and Préville 1999). With respect to tooth development, the odontoblast-lineage cells show a stage-speciWc expression pattern of HSP-25-immunoreactivity (IR) during dentinogenesis (Ohshima et al 2000(Ohshima et al , 2002: Wrst, pulpal mesenchymal cells show weak HSP-25-IR and subsequently odontoblasts consistently express intense HSP-25-IR. In addition, newly diVerentiated odontoblast-like cells also express intense HSP-25-IR under pathological conditions such as cavity preparation, tooth replantation, and laser irradiation using experimental animal models (Ohshima et al 2001a(Ohshima et al , 2001bNakakura-Ohshima et al 2003;Suzuki et al 2004;Tate et al 2006;Tsukamoto-Tanaka et al 2006;Kawagishi et al 2006), suggesting that this protein is a useful marker for the diVerentiation of odontoblastlike cells during the pulpal healing process after exogenous harmful injuries.…”