Immunocytochemistry of nuclear domains and Emery-Dreifuss muscular dystrophy pathophysiology

The present review summarizes recent cytochemical findings on the functional organization of the nuclear domains, with a particular emphasis on the relation between nuclear envelope- associated proteins and chromatin. Mutations in two nuclear envelope-associated proteins, emerin and lamin A/C cause the Emery-Dreifuss muscular dystrophy; the cellular pathology associated with the disease and the functional role of emerin and lamin A/C in muscle cells are not well established. On the other hand, a large body of evidence indicates that nuclear envelope-associated proteins are involved in tissue-specific gene regulation. Moreover, chromatin remodeling complexes trigger gene expression by utilizing the nuclear matrix-associated actin, which is known to interact with both emerin and lamin A/C. It is thus conceivable that altered expression of these nuclear envelope-associated proteins can account for an impairment of gene expression mainly during cell differentiation as suggested by recent experimental findings on the involvement of emerin in myogenesis. The possibility that Emery-Deifuss muscular dystrophy pathogenesis could involve alteration of the signaling pathway is considered.