Demonstration of cathepsins B, H and L in xenografts of normal and Duchenne-muscular-dystrophy muscles transplanted into nude mice.
The activities and contents of the lysosomal cysteine proteinases cathepsins B, H and L were examined in xenografts of biopsied muscles transplanted from age-matched normal subjects and Duchenne-muscular-dystrophy (DMD) patients into nude mice. The activity of cathepsin B increased 9-fold and that of B-plus-L increased 24-fold in the first week after transplantation in normal muscle xenografts. By the third week, the activity of cathepsin B increased a total of 20-fold and B-plus-L increased to 36-fold the original level. The activity levels of cathepsin B, B-plus-L, H and D, and acid phosphatase in normal and DMD xenografts were not significantly different when compared 2 weeks after transplantation. However, the protein content of cathepsin B in DMD muscle xenografts was more than 3-fold that of normal xenografts at 2 weeks. The profile of cathepsin H activity in normal muscle xenografts was different than those of cathepsins B and B-plus-L. In the first week, the cathepsin H diminished sharply to about one-third of the biopsied muscle level and then, by 3 weeks after transplantation, it had increased slightly to about half the original level. The amount of endogenous cysteine-proteinase inhibitor changed in parallel with the activity of cathepsins B and B-plus-L. Cathepsins B and H, but not cathepsin L, were found immunohistochemically in regenerating muscle fibres of normal and DMD xenografts 2 weeks after transplantation. Staining of cathepsin B in DMD xenografts was slightly stronger than that in normal subjects. There was no immunostaining in degenerating or necrotic muscle fibres 2 weeks after transplantation. Western-blot analysis revealed that the cathepsin B band at 29 kDa was increased in normal xenografts 2 and 3 weeks after transplantation. Also, 2 weeks after transplantation the staining intensity of this band was slightly stronger in DMD xenografts than in normal xenografts. These results suggest that cathepsin B participates in the regeneration of transplanted muscle, both normal and DMD, and in the DMD muscle fibre-wasting processes, during regeneration.
Takeda
A
A
Department of Clinical Pathology, Showa University Fujigaoka Hospital, Showa University School of Medicine, Yokohama, Japan.
Jimi
T
T
Wakayama
Y
Y
Misugi
N
N
Miyake
S
S
Kumagai
T
T
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002403:Cathepsins / Q000276:immunology / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009132:Muscles / Q000201:enzymology*; D009136:Muscular Dystrophies / Q000201:enzymology*; D013997:Time Factors; D014183:Transplantation, Heterologous
D000135:Acid Phosphatase; D002403:Cathepsins