Molecular and Genetic Analysis of Drosophila Proteasomes

Syracuse University, Syracuse NY

Investigators

Abstract

Regulated protein degradation is important for normal cell function, playing a key role in such diverse processes as growth control, metabolic regulation, embryonic development, and cell cycle progression. Targeted protein breakdown is also important for protecting cells against the potentially deadly effect of accumulated damaged or malformed polypeptides. Thus, an understanding of how cells selectively identify unwanted proteins and target them for destruction has fundamental importance for the study of development, cellular metabolism, and cell fate determination. An essential component of this pathway is the proteasome, a large, multi-subunit complex that acts as the proteolytic "machine" that removes abnormal polypeptides and short-lived regulatory proteins from cells. Recent work, using the tools of biochemistry and cell biology, has revealed much about the physical and biochemical properties of proteasomes, but many aspects of their biological function remain unclear. As an approach toward learning more about their role during development, a genetic and molecular study of Drosophila proteasomes is being undertaken. This project is focused on two major questions: (1) what is the role of the ubiquitin-proteasome pathway in specific developmental processes, and (2) are there structurally distinct cell-type specific proteasomes that have specialized functions? To address the first question, a mutational approach is being pursued. A number of dominant proteasome mutants have been isolated, and are being used to disrupt proteasome function in vivo, so that their effects on specific biological processes can be examined. For the second question, a reverse genetics approach is being used. Several proteasome subunit genes that are expressed exclusively in male germ cells have been isolated by molecular cloning methods. A combination of molecular, cell biological, and genetic approaches are being used to investigate the importance of proteasome-mediated protein degradation in spermatogenesis, and to address the functional role of a "sperm-specific" proteasome in this process.