Our laboratory has proposed 10 years ago that there is a common endocrine control of bone mass, appetite and reproduction. We have in the last decade embarked in a two-pronged approach to verify this hypothesis. In the first aspect of our work we showed that the adipocyte - derived hormone leptin regulates bone mass via a central relay. In the second aspect of this work we then showed that the osteoblast-derived hormone osteocalcin favors glucose handling by the body and enhances energy homeostasis. Taken together, these two aspects of our work cover the first arm of our hypothesis namely that there is a common control of bone and energy metabolisms. More recently we came across another phenotype in the Osteocalcin-deficient mice that may allow us to establish an endocrine link between bone remodeling and reproduction. Indeed, Osteocalcin-deficient male mice are subfertile, have significantly smaller testes, decreased sperm counts and display a 60 to 80% decrease in circulating testosterone levels compared to wildtype littermates. These and additional preliminary data presented in this application suggest the hypothesis that osteocalcin may regulate not only energy metabolism but also reproduction. To further test this hypothesis we propose to use a combination of molecular, genetic and morphologic approaches.
Our specific aims are: - To perform a thorough molecular and morphological characterization of the fertility phenotype of male Osteocalcin-deficient mice - To determine genetically and pharmacologically whether it is the carboxylated or the uncarboxylated form of osteocalcin that regulates spermatogenesis - To demonstrate genetically that it is through its osteoblast expression that osteocalcin favors sperm production and testosterone synthesis. - To use genetic epistasis to demonstrate that a putative osteocalcin receptor expressed on Leydig cells mediates osteocalcin function on sperm production and testosterone synthesis.

Public Health Relevance

Osteocalcin-deficient male mice are subfertile, have decreased sperm counts and circulating testosterone levels compared to wildtype littermates suggesting that osteocalcin may regulate not only energy metabolism but also reproduction. To further test this hypothesis we propose to define the molecular bases of this phenotype and test which form of osteocalcin is involved in this novel function. We also intend to define which osteocalcin-producing cell type and whether a putative osteocalcin receptor is mediating osteocalcin regulation of male reproduction.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD065439-19
Application #
8305054
Study Section
Integrative and Clinical Endocrinology and Reproduction Study Section (ICER)
Program Officer
Moss, Stuart B
Project Start
1995-09-01
Project End
2015-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
19
Fiscal Year
2012
Total Cost
$346,371
Indirect Cost
$118,796
Name
Columbia University (N.Y.)
Department
Genetics
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Karsenty, Gerard (2014) Broadening the role of osteocalcin in Leydig cells. Endocrinology 155:4115-6
Wei, Jianwen; Hanna, Timothy; Suda, Nina et al. (2014) Osteocalcin promotes ?-cell proliferation during development and adulthood through Gprc6a. Diabetes 63:1021-31
Karsenty, Gerard; Oury, Franck (2014) Regulation of male fertility by the bone-derived hormone osteocalcin. Mol Cell Endocrinol 382:521-526
Nohara, Kazunari; Liu, Suhuan; Meyers, Matthew S et al. (2013) Developmental androgen excess disrupts reproduction and energy homeostasis in adult male mice. J Endocrinol 219:259-68
Oury, Franck; Ferron, Mathieu; Huizhen, Wang et al. (2013) Osteocalcin regulates murine and human fertility through a pancreas-bone-testis axis. J Clin Invest 123:2421-33
Karsenty, GĂ©rard; Ferron, Mathieu (2012) The contribution of bone to whole-organism physiology. Nature 481:314-20
Karsenty, Gerard; Oury, Franck (2012) Biology without walls: the novel endocrinology of bone. Annu Rev Physiol 74:87-105
Karsenty, G (2011) Regulation of male fertility by bone. Cold Spring Harb Symp Quant Biol 76:279-83
Oury, Franck; Sumara, Grzegorz; Sumara, Olga et al. (2011) Endocrine regulation of male fertility by the skeleton. Cell 144:796-809