PKD1 protein is involved in reactive oxygen species-mediated mitochondrial depolarization in cooperation with protein kinase Cδ (PKCδ).

In this study, we used gene targeting in mice to identify the in vivo functions of PKD1. In addition to phenotypically characterizing the resulting knock-out animals, we also used mouse embryonic fibroblasts to investigate the associated signaling pathways in detail. This study is the first to use genetic deletion to reveal that PKD1 is a key regulator involved in determining the threshold of mitochondrial depolarization that leads to the production of reactive oxygen species. In addition, we also provide clear evidence that PKCδ is upstream of PKD1 in this process and acts as the activating kinase of PKD1. Therefore, our in vivo data indicate that PKD1 functions not only in the context of aging but also during nutrient deprivation, which occurs during specific phases of tumor growth.