A monoclonal antibody against insect CALNUC recognizes the prooncoprotein EWS specifically in mammalian cells. Immunohistochemical and biochemical studies of the antigen in rat tissues
J. Kawano et al., A monoclonal antibody against insect CALNUC recognizes the prooncoprotein EWS specifically in mammalian cells. Immunohistochemical and biochemical studies of the antigen in rat tissues, HISTOCHEM C, 115(5), 2001, pp. 421-428
A monoclonal antibody against insect CALNUC was shown to recognize an 85-kD
a nuclear protein specifically in mammalian cells. Amino acid sequencing of
the protein purified from rat liver revealed it to be EWS, a prooncoprotei
n for Ewing sarcomas and related tumors. Using the antibody, distribution o
f EWS was studied in rat tissues fixed with 4% paraformaldehyde by immunohi
stochemical methods. On thaw-fixed cryosections or those of perfusion-fixed
tissues, almost all cell nuclei showed the specific staining. In immersion
-fixed tissues, the staining unexpectedly disappeared in particular tissues
(kidney cortex, liver, etc.), although it was recovered by autoclaving the
cryosections. Western blotting also demonstrated the ubiquitous expression
of EWS in the tissues. In extracts from the liver, the 85-kDa band rapidly
disappeared in a Ca2+-dependent manner, but never in the testis. The antig
en was very labile in kidney homogenates even without Ca2+. Biochemical stu
dies with digoxigenin-labeled EWS showed that the Ca2+-dependent disappeara
nce was associated with upward mobility shifts of EWS. These suggested that
EWS was ubiquitously expressed in rat tissues, and that the antigen was ma
sked in particular tissues during the immersion fixation.