BiP/Kar2 is a universally conserved molecular chaperone based in the endoplasmic reticulum that performs a variety of functions in the cell including protein folding of both newly synthesized and denatured protein ?clients? and targeted degradation of terminally misfolded proteins. In yeast, Kar2 function is regulated by co-chaperones such as Sec63, Jem1 and Scj1. While Scj1 and Jem1 appear to have some redundant functions, previous studies have demonstrated phenotypic differences between cells lacking Scj1 or Jem1. The specific roles of Jem1 and Scj1 in activating Kar2 and their particular client portfolio remains undetermined. All organisms require correct and accurate replication of DNA to grow and proliferate. Misregulation of DNA replication can result in either cell death or cancer. Our recent studies have uncovered a role for Scj1 and Kar2 in regulating genome integrity. While ER chaperone function and genome integrity are fundamental cellular processes, no connection between them has previously been established. Our recent studies suggest that this ER chaperone-genome integrity connection may be conserved in mammalian cells as loss of ERdj1 (co-chaperone of mammalian Kar2, BiP) sensitizes cells to DNA replication inhibitors such as triapine and hydroxyurea. Any strategy that lowers the rate of DNA replication in cells may form the basis of novel anticancer therapies. In this proposal, we expect to gain further mechanistic insight into how ER chaperones and co- chaperones control DNA replication. We propose to use both molecular biology and state-of-the-art mass spectrometric techniques in and yeast and cancer cells to achieve the aims of the objectives in our proposal. The scope of this work has broad implications for a variety of diseases associated with DNA replication and ER molecular chaperone function, including many types of cancer, viral infection and malaria. !
This study will allow us to understand how the ER-located chaperone proteins Kar2 and Scj1 (and their human equivalents BiP and ERdj1) regulate the DNA replication process. This will allow the development of new drugs that inhibit DNA replication. The scope of this work has broad implications for a variety of diseases associated with both DNA replication, including many types of cancer.
