THE PRESENCE OF FAC1 PROTEIN IN HIRANO BODIES

We have previously reported that the FAC1 protein is contained in hipp ocampal structures that resemble Hirano bodies, Hirano bodies are cyto plasmic inclusions containing actin filaments that are numerous in the hippocampus of many Alzheimer's disease patients. FAC1 is a developme ntally regulated protein that is localized to the cytoplasm of neurons during development and is predominately a nuclear protein in adult br ain. In hippocampal sections from non-demented adults, Alzheimer's dis ease, and dementia with Lewy bodies patients, Hirano bodies were immun olabelled with antibodies to the FAC1 protein. Confocal laser microsco py demonstrated the presence of actin in FAC1 labelled Hirano bodies, and ultrastructural analysis confirmed the presence of a lattice struc ture within FAC1 labelled Hirano bodies. Numerous FAC1 immunoreactive swollen dendrites were also present in the hippocampus of Alzheimer's disease and dementia with Lewy bodies patients. Within any one case th e total number of FAC1 positive swollen dendrites correlated with the total number of Hirano bodies, suggesting an association between the t wo structures. Thus, FAC1 protein is contained in Hirano bodies and sw ollen dendrites in the hippocampus of patients with Alzheimer's diseas e and dementia with Lewy bodies.