A peptidylic inhibitor for neutralizing r(GGGGCC)exp-associated neurodegeneration in C9ORF72-associated amyotrophic lateral sclerosis and frontotemporal dementia

Abstract "One-drug, two diseases" is a rare and economical therapeutic strategy that is highly desirable in the pharmaceutical industry. We previously reported a 21-amino acid peptide named beta-structured inhibitor for neurodegenerative diseases (BIND) that can effectively inhibit expanded CAG trinucleotide toxicity in polyglutamine (polyQ) diseases. Here we report that BIND, also effectively inhibits GGGGCC repeat-mediated neurodegeneration in vitro and in vivo . When fused with a cell-penetrating peptide derived from the trans-activator of transcription (TAT) protein of the human immunodeficiency virus, TAT-BIND reduces cell death, formation of GGGGCC RNA foci and levels of poly-GR/GA/GP dipeptide proteins in cell models of C9ORF72 -associated amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD). We showed that TAT-BIND disrupts the interaction between GGGGCC RNA and nucleolin protein, restores ribosomal RNA maturation, and inhibits mislocalization of nucleolin and B23, which eventually suppresses nucleolar stress in C9ALS/FTD. In a Drosophila model of C9ALS/FTD, TAT-BIND suppresses retinal degeneration, rescues climbing ability and extends the lifespan of flies. In contrast, TAT-BIND has no effect on UAS-poly-glycine-arginine (poly-GR) 100 -expressing flies which generates only poly-GR protein toxicity, indicating BIND ameliorates toxicity in C9ALS/FTD models via a r (GGGGCC) exp -dependent inhibitory mechanism. Our findings demonstrated that, apart from being a potential therapeutic for polyQ diseases, BIND is also a potent peptidylic inhibitor that suppresses expanded GGGGCC RNA-mediated neurodegeneration, highlighting its potential application in C9ALS/FTD treatment.