Gene expression is the process of decoding the information stored in DNA to produce functional proteins or RNA. This process occurs in multiple steps. First, the DNA sequence is transcribed into RNA. The RNA may then be spliced to remove non-coding intron sequences, and transported to specific regions of the cell, before it is translated into protein. Finally, the RNA is degraded into nucleotides to terminate its expression. Each of these stages can be independently regulated, but they can also be linked by markers that reveal the history of an RNA molecule. One such marker is the exon-junction complex (EJC), a set of four core proteins that bind to RNA molecules during splicing and identify them as having been spliced. The presence of a bound EJC can alter RNA stability, localization and translation. This project is based on the discovery of a novel function for EJC subunits in the splicing process itself. The MAP kinase protein is an important mediator of many developmental signaling pathways that regulate cell survival, proliferation and differentiation. However, the cell faces challenges in expressing the MAP kinase gene, which is located in a repressive chromatin region and has very large introns that must be spliced out to produce the protein-coding transcript. Three subunits of the EJC (Mago, Y14 and eIF4AIII) are specifically required to splice MAP kinase as well as RNAs transcribed from other genes that have similar features. In contrast, the fourth subunit, Btz, has no effect on MAP kinase, but is required for the normal expression of a neuronal RNA-binding protein, Elav. This project will take a genome-wide approach to identify all the genes that are regulated by each subunit of the EJC and to determine the common features of each group. This analysis is likely to reveal new molecular functions for the complex as a whole and for its individual subunits. In addition, the project will investigate two potentially new biological functions for subunits of the EJC. One set of experiments will test whether Btz affects synapse formation by controlling the ability of Elav to regulate alternative splicing. Another set will test whether Mago and Y14 allow normal egg production by generating small RNAs used as a defense mechanism against mobile genetic elements. The results will give us a deeper understanding of the connection between splicing and other modes of RNA-based regulation.
Broader impacts: The results of these studies will be published in scientific journals and presented at scientific meetings, and will also reach a broad audience through the Treisman lab web site. The project will provide advanced training to individuals at the graduate and postgraduate levels, and undergraduate students and high school students, including under-represented minorities, are also expected to participate during the summers. In addition, a former colleague and collaborator, Dr. Helen Sink, is now a science teacher at PS 7, a middle school in Harlem. The PI will provide Dr. Sink materials and equipment for scientific activities at PS 7 and will host interested students from Dr. Sink?s classes in the laboratory at NYU to carry out small projects related to the research. These outreach activities will increase awareness of scientific research among minority students at an early stage of their education.
