057 Localization of lysosomal and cytoplasmic proteases in pelage of neonatal rats

K. Morioka1, K. Sato-Kusubata1, S. Kawashima1, T. Ueno2, E. Kominami2, H, Sakuraba1, S. Ihara3 Tokyo Metropolian Organization for Medical Research, The Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan1, Dept. Biochemistry, Juntendo University School of Medicine, Tokyo, Japan2, Dept. Biological Science, Faculty of Life and Environmental Science, Shimane University, Shimane, Japan3

The major cause of the extinction of organelles during differentiation of erythroid cells was found to be ascribable to the digestion in autolysosomesa. Epidermal keratinocytes and hair follicle cells share the fate with the erythrocytes with respect to the loss of organelles during the course of differentiationb. Immunohistochemical analyses demonstrated that cathepsins (B, D, L), lamp-1 and µ-calpain co-localize at the areas rich in the cells on the way of keratinization, such as s.granulosum, s.spinosum, keratinizing Henle’s layer, and lower part of hair shaft etc., suggesting a coordinated contribution of lysosomal and cytoplasmic proteolytic systems to the differentiation of epidermal and hair follicle cells through overall decomposition of intracellular structural components except keratin fibers. aAutophagy of organelles in embryonic erythroid cells: its role in maturation. H. Takano-Ohmuro et al., Eur.J.Cell Biol. 79, 759-764(2000). bExtinction of organelles in differentiating epidermis. K. Morioka et al., Acta Histochem. Cytochem. 32, 465-476(1999).