PROJECT III (Kl: KAISER) G protein-coupled receptors (GPCRs) are the largest family of transmembrane proteins in vertebrates and are the molecular targets for nearly half of the therapeutic drugs that are prescribed worldwide. The approximately 1,000 members of the GPCR family exhibit a conserved 7-transmembrane domain topology and mediate physiological responses to diverse ligands, such as hormones, neurotransmitters and sensory stimuli. The role of three ligand/receptor pairs, (1) KISS1/KISS1R;(2) PROK2/PROKR2;and (3) TAC3/TACR3, have been implicated in the neuroendocrine regulation of reproduction and have been identified as underlying reproductive disorders. However, there remains much to be learned about the domains of these receptors important to cell surface expression, ligand binding, and activation of cellular signaling pathways relevant to the function of these receptors in the control of GnRH release. The human mutations will serve as tools to learn about the biology of these GPCRs and their ligands, with implications for structure-function relationships of GPCRs. In our first aim we will build on our previous studies of mutations in KISS1 and KISS1R to further define the cellular mechanisms by which KISS1/KISS1R regulate GnRH. In the second aim, our studies will identify proteins (chaperones) that modulate intracellular trafficking of GPCRs involved in the neuroendocrine regulation of reproduction. These studies will focus initially on PROKR2 as a model, and our findings will be extended to studies of KISS1R and TACR3 to determine their general applicability. Finally, we propose to leverage human mutations to elucidate new features of GPCR structure-function relationships, focusing on poorly understood GPCR domains, recently identified and insufficiently studied receptors, and interactions between receptors.

Public Health Relevance

This project aims to gain a better understanding of the mechanisms by which gene mutations affect receptor function. This will enable a better understanding of reproductive disorders and may help develop new diagnostic tools and treatments.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Specialized Center--Cooperative Agreements (U54)
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Special Emphasis Panel (ZHD1-DSR-L)
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Massachusetts General Hospital
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Sidhoum, Valerie F; Chan, Yee-Ming; Lippincott, Margaret F et al. (2014) Reversal and relapse of hypogonadotropic hypogonadism: resilience and fragility of the reproductive neuroendocrine system. J Clin Endocrinol Metab 99:861-70
Martin, Cecilia; Navarro, VĂ­ctor M; Simavli, Serap et al. (2014) Leptin-responsive GABAergic neurons regulate fertility through pathways that result in reduced kisspeptinergic tone. J Neurosci 34:6047-56
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Salian-Mehta, S; Xu, M; Knox, A J et al. (2014) Functional consequences of AXL sequence variants in hypogonadotropic hypogonadism. J Clin Endocrinol Metab 99:1452-60
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Macedo, Delanie B; Abreu, Ana Paula; Reis, Ana Claudia S et al. (2014) Central precocious puberty that appears to be sporadic caused by paternally inherited mutations in the imprinted gene makorin ring finger 3. J Clin Endocrinol Metab 99:E1097-103
Beneduzzi, Daiane; Trarbach, Ericka B; Min, Le et al. (2014) Role of gonadotropin-releasing hormone receptor mutations in patients with a wide spectrum of pubertal delay. Fertil Steril 102:838-846.e2

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