hsp70 chaperones and type i prmts are sequestered at intranuclear inclusions caused by polyalanine expansions in pabpn1hsp70陪伴和i型prmts隔离在pabpn1 polyalanine扩张造成的核内包涵体.pdfVIP

Hsp70 Chaperones and Type I PRMTs Are Sequestered at Intranuclear Inclusions Caused by Polyalanine Expansions in PABPN1 ˜ 1¤ 2 2 2 1 Joao Paulo Tavanez , Rocio Bengoechea , Maria T. Berciano , Miguel Lafarga , Maria Carmo-Fonseca , Francisco J. Enguita1* 1 Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal, 2 Department of Anatomy and Cell Biology, and ‘‘Centro de ´ ´ Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)’’, University of Cantabria, Santander, Spain Abstract Genomic instability at loci with tandem arrays of simple repeats is the cause for many neurological, neurodegenerative and neuromuscular diseases. When located in coding regions, disease-associated expansions of trinucleotide repeats are translated into homopolymeric amino acid stretches of glutamine or alanine. Polyalanine expansions in the poly(A)-binding protein nuclear 1 (PABPN1) gene causes oculopharyngeal muscular dystrophy (OPMD). To gain novel insight into the molecular pathophysiology of OPMD, we studied the interaction of cellular proteins with normal and expanded PABPN1. Pull-down assays show that heat shock proteins including Hsp70, and type I arginine methyl transferases (PRMT1 and PRMT3) associate preferentially with expanded PABPN1. Immunofluorescence microscopy further reveals accumulation of these proteins at intranuclear inclusions in muscle from OPMD patients. Recombinant PABPN1 with expanded polyalanine stretches binds Hsp70 with higher affinity, and data from molecular simulations suggest that expansions of the PABPN1 polyalanine tract result in transition