Fluorescent characterization of amyloid deposits in the kidneys of mdx mice

Abstract

An amyloidosis is a group of diseases that occurs when amyloid proteins are deposited in tissues and organs. In this study, we demonstrated, at the first time, the presence of amyloid deposits in the kidneys of dystrophin-deficient mdx mice, which are widely used as an experimental model of Duchenne muscular dystrophy. We examined cases of renal amyloidosis in aged mdx mice using traditional methods for amyloid detection (Congo red and Thioflavin T), as well as a new fluorescent dye, disodium salt of 2,7-(1-amino-4-sulfo- 2-naphthylazo) fluorene (DSNAF). Using these different fluorescent dyes, we confirmed the amyloid structure of protein deposits in kidneys of aged mdx mice. Additionally, we found that fixation method has profound effects on downstream staining procedures, and demonstrated that the application of specific fixative, zinc-ethanolformaldehyde, instead of traditional neutral-buffered formalin allows reducing the background fluorescence. Also we illustrated the usefulness of novel fluorescent dye DSNAF for detection of amyloid deposits in mouse tissues. Taken together, our results indicate the association of amyloid formation with Duchenne muscular dystrophy and provides new opportunities for studying naturally occurring amyloidosis development in tissues also.