Regulation of Differentially Released Transmitter

Saint Louis University, Saint Louis MO

Investigators

Abstract

INTELLECTUAL MERIT: All organisms' ability to successfully live and function within their own habitat depends on cell-to-cell communication that is necessary for the most basic reflexes to the highest order thought processes. This cellular communication by neurons occurs by specialized signals that rapidly allow a chemical transmitter to be released from one neuronal cell and have an effect on an adjacent neuronal cell. It is not understood how these signals can be modulated to cause more or less chemical transmitter to be released, or to release one type of chemical transmitter preferentially over another. Previous work has established that two chemical transmitters, neuropeptide Y (NPY) and catecholamines (CAs), that are packaged into the same small vesicles undergo differential release. That is, NPY requires a longer stimulation duration and/or a higher frequency of stimulation than required to release CAs from the same vesicles. How this differential regulation of chemical transmitter release occurs is not known. The aims of this research will test the hypothesis that different members of a family of proteins, called synaptotagmins (syt), sense and control calcium-dependent release of the chemical transmitters from the vesicles. This project will utilize a combination of electrophysiology, molecular biology and biochemistry techniques in a model secretory cell system to study how these proteins may regulate release of NPY compared to the CAs. The objectives of this study are 1) to determine what types of stimuli are required for differential release, 2) to determine whether a Ca2+-dependent , or 3) a Ca2+-independent syt protein regulates differential release of chemical transmitter. Intellectually, this project will establish whether one protein that functions to sense Ca2+ and trigger secretion of transmitter can also preferentially determine the release of one particular transmitter over another. BROADER IMPACT: These results will have broad application to understanding how one type of vesicle can preferentially release transmitter from the same population of vesicles, a basic mechanism that underlies neuronal communication. Results from this project will provide the basis for future research directions to understand how transmitter is regulated in release not only from secretory cells and neurons, but also from brain tissues. Education initiatives will involve students at all levels. The PI will continue to a) participate in an outreach science program for middle school inner city girls, b) participate in a highly competitive high school student research program (STARS), c) involve undergraduate students in research from simple lab techniques to Honors research theses, and d) train graduate students pursuing their PhDs to enter the academic arena. Students at all levels will be introduced to the disciplines of biophysics, molecular biology and chemistry as a combined approach to research. Current efforts to recruit female and minority researchers will be continued and expanded. All generated cell lines will be freely distributed to other researchers. To disseminate findings from this project, students will continue to present results at national conferences, and publish their work in peer-reviewed journals. As an outreach program for high school and undergraduate students, as well as a tool for all researchers to use, the students will provide lay descriptions of their projects and their scientific protocols on the laboratory's website. This research program will provide a platform for integrating research with education for students, scientists, and the lay community.