APP(DeltaNL695) expression in murine tissue downregulates CNBP expression.

The cellular nucleic acid binding protein (CNBP) is a ubiquitously expressed protein involved in regulation of transcription and translation. CNBP, and its encoding gene ZNF9, have been shown to be involved in type 2 myotonic dystrophy. Both Alzheimer's disease (AD) and sporadic inclusion body myositis (sIBM) are age-related degenerative diseases associated with the accumulation of beta-amyloid. Overexpression of amyloid precursor protein (APP) in mice has been used to generate models of both diseases. We show here that overexpression of APP in skeletal muscle from a mouse model of sIBM reduces the expression of CNBP significantly. We examined CNBP expression in a brain-specific APP-overexpressing strain, and a whole body APP knock-in strain, and found that there was a reduction in CNBP expression in tissue expressing APP(Swe). We conclude that expression of APP(Swe) in murine tissue induces a decrease in CNBP expression. This effect does not appear to be due to alterations in CNBP transcription. APP(Swe) expression may provide a tool for the study of CNBP regulation and clues to the roles of both proteins in disease.