Immunoreactivity to ubiquitin-protein conjugates is present early in the disease process in the brains of scrapie-infected mice.
Brains from mice infected with either the 87V or the ME7 strains of mouse-passaged sheep scrapie were taken at stages during the disease process and immunostained to show the localization of ubiquitin-protein conjugates. In both models, conjugates were seen as fine, dot-like structures; as coarser, granular lesions within or adjacent to neurones; and in areas surrounding plaques. The dot-like structures were visible at 28 days post-ME7 infection and at 55 days in 87V-infected mice. In both models, the extent of immunoreactive changes increased as the disease progressed and terminal infection was as described earlier by us (Lowe et al., J. Pathol 1990; 162: 61-66). The patterns of development of these features were distinctive in two ways: progression from region to region was observable and the density of the pathological lesions grew exponentially as the clinical symptoms appeared. The earliest pathological dot-like structures corresponded temporally with the earliest detection of PrPSC by Western blotting, and immunogold electron microscopic investigation of the dot-like lesions indicated that they were the multi-vesicular, lysosome-related, dense bodies that we have described previously in terminal disease (Laszlo et al., J Pathol 1992; 166: 333-341). Until now, ubiquitin-protein conjugates were seen mainly in inclusion bodies associated with the terminal stages of a range of human degenerative diseases. This study establishes that ubiquitin-protein conjugates accumulate in lysosome-related bodies very early and appear to be intimately related to the pathological processes in the animal disorders that we have studied.
Lowe
J
J
Department of Pathology, University of Nottingham Medical School, Queen's Medical Centre, U.K.
Fergusson
J
J
Kenward
N
N
Laszlo
L
L
Landon
M
M
Farquhar
C
C
Brown
J
J
Hope
J
J
Mayer
R J
RJ
D000818:Animals; D001921:Brain / Q000473:pathology; D001923:Brain Chemistry; D051379:Mice; D008815:Mice, Inbred Strains; D011506:Proteins / Q000032:analysis* / Q000276:immunology; D012608:Scrapie / Q000378:metabolism* / Q000473:pathology; D014452:Ubiquitins / Q000032:analysis* / Q000276:immunology
D011506:Proteins; D014452:Ubiquitins