Dr. Yoshimura's research interests include the study of tumorigenesis by murine retroviruses, and porcine retroviruses and their potential pathogenesis in xenotransplantation. To elucidate the mechanism by which murine retroviruses cause T cell tumors, her laboratory has focused on the regulation of transcription of cellular oncogenes by retroviral sequences. She has identified binding sites for transcription factors in the long terminal repeat region of the virus that regulate transcription in a T cell-specific manner. Some of these sites have been shown to be important for tumorigenesis by these viruses. Her research includes studies of the ability of oncogenic murine retroviruses to induce apoptosis of thymic lymphocytes. The methodology involved in her laboratory includes DNA footprinting, gel mobility shift assays, site-directed mutagenesis, transfection of mammalian cells, reporter gene assays, flow cytometry, and assays for apoptosis. Questions her laboratory is currently pursuing include the 1). Identification of proteins that bind to transcriptional regulatory sites; 2). Isolation of these proteins and cloning of the genes that encode them; 3). Determination of how these proteins interact with promoter sequences to regulate transcription; 4). Identification of the cell type in the thymus that is involved in tumorigenesis and apoptosis.

Her work with porcine retroviruses includes the identification of viruses which are able to infect human cells and tissues. Questions that are currently being pursued in this area of research include: 1). Whether various pig tissues and organs either already in use or being considered for human transplantation express retroviruses; 2). Which human tissues and organs are infectable by these retroviruses; 3). How can viral replication in human tissues be prevented.