Research Interests
Living organisms have a defined set of genes, whose number ranges from about 4,000 in E. coli to over 20,000 in humans. These genes, however, are not necessarily expressed or utilized constantly; rather, living organisms express only those genes that are necessary for the conditions under which they live. Thus, many biological phenomena such as development, differentiation and cell cycle can be defined by where and when certain sets of genes become expressed.
In fact, by altering the gene expression pattern of a cell, we can change the identity or properties of the cell. It is now possible to create pluripotent stem cells (iPS cells) from differentiated somatic cells. By studying gene regulation, we can understand the molecular basis of iPS cell induction and find clues for new treatments for cancer, lifestyle diseases, allergic disorder, and other diseases that afflict us. Also, these understandings may be of great use for medical application of ES cells and iPS cells.
Gene expression includes several steps such as transcription, posttranscriptional processing, RNA export, translation, and RNA degradation. Although all the steps are subject to regulation, transcription is the first step—and therefore most regulated—step of gene expression and plays a central role in regulating gene expression.
In eukaryotes such as human, DNA is packaged into a structure termed chromatin, and its structural alterations play important roles in regulating transcription. Histones, which are the main structural component of chromatin, undergo posttranscriptional modifications including acetylation, methylation, phosphorylation and ubiquitination. These modifications combine to create “histone codes” to define chromatin structure and function, permitting histones to regulate transcription as well as to compact DNA.
In our lab, we employ biochemical as well as molecular biological methods to unravel mechanisms that underlie the complex regulations of gene expression, iPS cell induction, and cell differentiation. Our current research interests are summarized as below.