Immunocytochemical study of cathepsin l and rat salivary cystatin-3 in rat osteoclasts treated with e-64 in vivo

Ryoji Moroi, Takayoshi Yamaza, Toshihiro Nishiura, Yukio Nishimura, Yoshihiro Terada, Kimio Abe, Masaru Himeno, Teruo Tanaka

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17 Citations (Scopus)


The localization of cathepsin L and rat salivary cystatin-3 (RSC-3) in rat osteoclasts (rat femoral and alveolar bones) treated with or without E- 64 (control) was examined immunocytochemically. In osteoclasts pretreated with E-64, immunoreactivity for cathepsin L was very weak extracellularly compared to that in the control osteoclasts. However, it was strong intracellularly. The localization of RSC-3 was unclear in the control osteoclasts, while in E-64 treated osteoclasts, both the clear zone and ruffled border areas showed a very strong immunoreaction. At the electron- microscopic level, in normal osteoclasts, numerous immunoreaction products for cathepsin L were found extracellularly in the bone matrix under the ruffled border, while few intracellular products were observed. In contrast, in the E-64-treated osteoclasts, only a few immunoreaction products were found extracellularly, while intracellularly cathepsin L was found in numerous endosome-lysosomal vacuoles. In the immunoreaction for RSC-3, the cytoplasm of the ruffled border was positive, and the tips of the RSC-3- positive ruffled border appeared to enter deeply into the bone matrix. Intracellularly, the granular reaction products of RSC-3 were found in the vacuoles (probably autophagolysosomes). Thus, in E-64-treated osteoclasts, inhibition of the extracellular release of cathepsin L was demonstrated. In addition, intralysosomal accumulation of RSC-3 and deep penetration of the RSC-3-positive ruffled border into the hone matrix were found. These findings suggest that RSC-3 is associated with the inhibition of cathepsin L in both the lysosomes (in the osteoclasts) and bone matrix.

Original languageEnglish
Pages (from-to)305-315
Number of pages11
JournalArchives of Oral Biology
Issue number4
Publication statusPublished - Apr 1997

All Science Journal Classification (ASJC) codes

  • Otorhinolaryngology
  • General Dentistry
  • Cell Biology


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