The Genes, Proteins, and the Cell Biological Processes Underlying Emery-Dreifuss Muscular Dystrophy

Abstract

Emery-Dreifuss Muscular Dystrophy (EDMD) is a type of muscular dystrophy characterized by contractures, or shortening of muscles or joints in the elbows and Achilles tendons, muscle wasting and weakness as well as cardiomyopathy. There are two main forms of inherited EDMD, X-linked recessive and autosomal dominant. There is also a rarer form of autosomal recessive inheritance with only a few cases ever reported. The X-linked form of EDMD is caused by mutation of the STA gene that encodes the protein emerin, while the autosomal dominant form is caused by a missense mutation on the LMNA gene, which encodes lamin A/C proteins. Both emerin and lamin A/C are nuclear envelope proteins that interact with other proteins to create a connective network that attaches the nuclear lamina to the cytoskeleton. These nuclear envelope proteins interact via accessory proteins to chromatin and also thereby stimulate gene expression. The exact mechanism of how mutations in these genes lead to muscular dystrophy is not well understood. The “structural hypothesis,” states that the absence of these envelope proteins result in a weakened cell and would eventually end in nuclear disruption. The “gene regulatory hypothesis” states that emerin and lamin may be transcription factors whose absence results in tissue-specific effects. This review will addresses these hypotheses, describes what is known about the cell and molecular biology underlying EDMD and considers recent as advances in therapeutics.