Target genes of neuron-restrictive silencer factor are abnormally up-regulated in human myotilinopathy

Abstract

Myotilinopathy is a subgroup of myofibrillar myop athies caused by mutations in the myotilin gene in which there is aggregation of abnormal cytoskeletal proteins and ubiquitin. We report here on the ac cumulation of neuron-related proteins such as ubiq uitin carboxy-terminal hydrolase L1 (UCHL1), syn aptosomal-associated protein 25, synaptophysin, and α-internexin in aberrant protein aggregates in myotilinopathy. We have determined that the neuron restrictive silencer factor (NRSF)/RE1 silencing tran scription factor (BJEST), a transcription factor ex pressed in non-neuronal tissues repressing the expression of several neuronal genes, is reduced in myotilinopathies. Moreover, NRSF transfection re duces UCHL1, synaptosomal-associated protein 25, synaptophysin, and α-internexin mRNA levels in DMS53 cells, whereas short interferring NRSF trans fection increases UCHL1 and synaptophysin mRNA levels in U87-MG cells. Chromatin immunoprecipita tion assays have shown that NRSF interacts with the UCHL1 promoter in U87-MG and HeLa cells. In silico analysis of the UCHL1 gene promoter sequence using the MatInspector software has predicted three poten tial neuron-restrictive silencer elements (NRSEs): NRSE1 located in the complementary DNA chain and NRSE2 and NRSE3 in intron 1, in the coding and complementary chains, respectively. Together, these findings show, for the first time, abnormal regulation of NRSF/REST as a mechanism associated with the aberrant expression of selected neuron-related proteins, which in turn accumulate in abnormal pro tein aggregates, in myotilinopathy. Copyright © American Society for Investigative Pathology.