Gonadotropes synthesize and secrete heterodimeric glycoproteins luteinizing hormone (LH) and follicle stimulating hormone (FSH) that are critical for reproductive function. The genes encoding the common alpha subunit (Cga) and the hormone-specific beta subunits (Lhb and Fshb) are coordinately regulated by hypothalamic gonadotropin-releasing hormone, steroids and gonadal peptides, inhibin and activin. Although a wealth of knowledge has accumulated on transcriptional control of gonadotropin beta subunits, post- transcriptional mechanisms of these genes are unknown. Recently, micro RNAs (miRNAs) produced by Dicer, an RNA endonuclease III, have emerged as key regulators of gene expression, mRNA stability and protein synthesis. Knowledge on miRNAs that regulate gonadotrope and consequently reproductive function is lacking. Our long-term research goal is to elucidate the in vivo mechanisms that regulate gonadotropin synthesis and secretion. The central hypothesis is that Dicer is a key factor in miRNA biogenesis in gonadotropes and plays essential roles in gonadotropin synthesis and consequently reproductive function.
In Specific Aim 1, we will conditionally delete Dicer exclusively in gonadotropes by cre-lox technology and analyze gonadotropin synthesis and secretion. Additionally, we will use novel mouse strains, in which gonadotropes are labeled with GFP on a normal or activin receptor-II (Acvr2) null genetic background. Pure populations of gonadotropes will be isolated from these mice by cell sorting based on GFP fluorescence and miRNAs regulated by Acvr2 identified.
In Specific Aim 2, reproductive phenotypes secondary to changes in gonadotropins as a result of Dicer deletion in gonadotropes will be determined. These studies should provide new knowledge on Dicer - dependent miRNAs in gonadotropes and identify novel post-transcriptional mechanisms for gonadotropin secretion. Delineation of mechanisms of gonadotropin secretion is fundamental to physiology of reproduction and offers long-term clinical benefits of diagnosing and treating gonadotropin-dependent fertility/infertility disorders.

Public Health Relevance

Our studies should provide new knowledge on how Dicer that produces small RNAs called micro RNAs regulates synthesis and secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from pituitary gland. Delineation of mechanisms of FSH and LH secretion is fundamental to physiology of reproduction and offers clinical benefits of diagnosing and treating FSH-dependent fertility/infertility disorders. Some of these include hyperstimulation syndromes, amenorrhea and testicular defects.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Small Research Grants (R03)
Project #
1R03HD069751-01A1
Application #
8301917
Study Section
Pediatrics Subcommittee (CHHD)
Program Officer
Lamar, Charisee A
Project Start
2012-04-16
Project End
2014-03-31
Budget Start
2012-04-16
Budget End
2013-03-31
Support Year
1
Fiscal Year
2012
Total Cost
$75,500
Indirect Cost
$25,500
Name
University of Kansas
Department
Physiology
Type
Schools of Medicine
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
Wang, Huizhen; Larson, Melissa; Jablonka-Shariff, Albina et al. (2014) Redirecting intracellular trafficking and the secretion pattern of FSH dramatically enhances ovarian function in mice. Proc Natl Acad Sci U S A 111:5735-40