Molecular biological approaches to aging in Japan: an overview

Progress in molecular biological investigations of aging in Japan is overviewed. Emphasis is put on studies which, in the author's opinion, appear to have considerable relevance to a definition of aging, i.e. functional decline of cells and tissues with advancing age. (1) Changes in the nuclear DNA, most significantly in methylation, and deletions of mitochondrial DNA have been shown to occur with age. (2) Various aspects of protein metabolism have been investigated, i.e. the fidelity of translation, accumulation of altered enzymes, oxidative damage, and half-lives and degradation of proteins. (3) Japanese researchers have made significant contributions to the understanding of the chemical structure and the mechanisms of generation of paired helical filaments in Alzheimer's disease. Also, studies on beta-amyloid peptide are noteworthy. (4) Murine models of aging were developed and molecular biological investigations on them are progressing. Nematodes and fruit flies are also used as models.(5) Changes in gene expression with age have attracted considerable interest.