Gonadotropin-releasing hormone (GnRH) was first isolated in mammals and shown to be the primary regulator of the reproductive system. After this initial discovery, GnRH has been shown to be part of a larger family of similar peptides found in the brain and other tissues. To date, over 20 family members have been identified in vertebrate and invertebrates, and they have been shown to have diverse functions. As with most peptides, GnRH is regulated at the synthesis level (gene expression and translation) and at secretion. In addition, GnRH is processed by a zinc metalloendopeptidase EC 3.4.24.15 (EP24.15) that cleaves the hormone at the covalent bond between the 5th and 6th residue of the decapeptide (Tyr5-Gly6) to form a subproduct, GnRH-(1-5). This subproduct of GnRH, GnRH-(1-5) is bioactive and has been shown to regulate gene expression and facilitate reproductive behavior in brain and other tissues. Dr. Wu?s laboratory recently identified an orphan G-protein coupled receptor (GPR) that binds to GnRH-(1-5) with high affinity and this receptor is likely to be the mediator of GnRH-(1-5) activities. To that end, this project will use two physiological approaches and an anatomical approach to test this hypothesis. These studies will identify a ligand and a function for an orphan receptor. The collective data will underscore the importance of peptide processing in regulating neurobiological processes that is beyond the attributes of the parent peptide ? an evolutionary influence to increase diversity. The results of this study and the identification of a novel receptor may also resolve many present quandaries in the current utilization of the parent peptide. Broader Impact: The project will include a significant training component in which a postdoctoral fellow, 1-2 graduate students and at least 6 college students and high school students will receive training in neuroendocrine techniques. Each student will be involved in one specific aim supervised by a senior member of the laboratory. The high school student will participate in lab meetings, they will conduct some of the experiments and present at high school?s science fair, ultimately submitting their work to local and national science fairs and competitions.
Annual Project Report for Award 1052288 Research Activities During this funding period, we completed the characterization of the receptors to GnRH-(1-5). GnRH-(1-5) binds to GPR101 and GPR173 where they are mediated by Galpha13 and beta-arrestin 2, respectively. 4 papers were submitted and published during this period. The following summary of the progress is summarized below: GnRH-(1-5) binds to GPR173 and influences neuronal migration (Endocrinology 154:783-795, 2013) GnRH-(1-5) action on GPR173 is mediated by beta-arrestin 2 (Endocrinology 154: 4726-4736, 2013) Both GnRH-(1-5) and GPR173 is highly conserved across mammalian species that is localized in various regions of the brain important to reproduction (Frontiers in Endocrinology 4:1-10, 2013) GnRH-(1-5) binds to GPR101 and hyperphosphorylates the EGFR via the release of EGF (Molecular Endocrinology 28:80-98, 2014) Current studies are focused on identifying the signaling pathway mediating GPR173 activation (2014 Endocrine Society abstracts submitted) Educational Activities During the funding period, the PI was involved in several broader outreaches. These include training students in the laboratory and forming a new outreach for the university. Training Dr. Eleane Beadle, a military pediatric neonatal fellow joined our laboratory for her fellowship research. The title of her thesis is "Developmental Expression of GPR101 in the Hypothalamus – its importance in puberty". Dr. Beadle completed her thesis requirements in the laboratory and is currently in the process of submitting her work to a peer-reviewed journal. Dr. Beadle (Major, US Army) is a board certified neonatal pediatric physician currently stationed at Tripler Army Medical Center. Darwin Omar Larco was a graduate student in the laboratory and completed his PhD in May 2013. During this funding period, Dr. Larco stayed in the laboratory as a postdoctoral fellow to complete his work. Joseph Groberg is a college student from Brigham Young University. Mr. Groberg worked on establishing more tools for the studies including screening antibodies to the GPRs by western blots and basic cloning. Maya Sorini is a high school student from the Holton Arms School. She was involved with analyzing the matrix metalloproteinase mediating GnRH-(1-5) action via the G-protein coupled receptor. Outreach During this funding period, the PI started a formal summer research program for the University, the USU Research Training Program (USURTP: www.usuhs.mil/rtp). The program focused on local high school students who competitively applied for 1 of 12 positions. As part of the program, the students have to attend weekly brown bag seminars and workshops on science careers and scientific method/communication. At the end of the 12 week internship, the students prepare and present their work in a poster format. The posters were ranked and the top 3 received an award. In addition, to the creation of this program, the PI took on a senior role and mentored 3 junior faculty in administering this program. The long term goal of the USURTP is to expand to 25 students with special outreaches to the under-represented groups in science. In addition, the PI will continue to recruit and train junior faculty to take on the leadership of USURTP.
