Testosterone (T) supplementation increases muscle mass and decreases fat mass in a variety of clinical trials using healthy young men, hypogonadal men, and in older men with low serum T levels. However, the molecular mechanisms by which T regulates body composition are not well known. We identified that T increases muscle mass and decreases fat mass in mesenchymal multipotent cells via androgen receptor (AR)-mediated pathway and activates AR/beta-catenin/TCF-4 pathway in preadipocyte cells to inhibit adipogenesis that was associated with up-regulation of follistatin (Fst). We hypothesize that T activates AR/beta-catenin/TCF-4 pathway both in vitro and in vivo to activate Fst, which regulates body composition by inhibiting Mst/TGF-beta signaling. We will employ two validated in vitro models of adult, mesenchymal stem cells to test whether T and DHT activate Fst via activation of AR/beta-catenin/TCF-4 pathway to regulate cell differention, and inhibition of beta-catenin by SiRNA abolishes these effects. We will determine the interaction between AR, beta-catenin, and TCF-4 by immunoprecipitation and their nuclear translocation by immunofluorescence and cell fractionation. TCF-4 transcriptional activation in response to androgen will be measured by using TCF-4 luciferase reporter assay. We will determine whether these androgens inhibit TGF-beta/Mst signaling in vitro through up-regulation of Fst. We will test whether T and DHT inhibit Mst bioactivity, Smad2/3 phosphorylation and activate Smad7 in vitro and inhibition of Fst levels either by Fst SiRNA or use of anti-Fst antibody blocks the effects of these androgens on myogenic differentiation. We will investigate whether castration-induced effects on body composition in C57/BL6J mice are accompanied by parallel decrease in Fst levels and supplementation of T or recombinant follistatin in these castrated mice significantly block castration-induced effects on fat-free mass and overall body composition. These studies will provide novel insights into the mechanisms of androgen action and have direct relevance to the application of either Fst alone or in combination of low doses of T for the treatment of HIV and aging-associated muscle loss as high supraphysiological doses of T are associated with its pleotropic effects including increased risk of prostate cancer by elevating prostate-specific antigen.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Enhancement Award (SC1)
Project #
5SC1AG033407-03
Application #
7892286
Study Section
Special Emphasis Panel (ZGM1-MBRS-0 (NP))
Program Officer
Williams, John
Project Start
2008-08-01
Project End
2012-07-31
Budget Start
2010-08-01
Budget End
2011-07-31
Support Year
3
Fiscal Year
2010
Total Cost
$282,000
Indirect Cost
Name
Charles R. Drew University of Medicine & Science
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
785877408
City
Los Angeles
State
CA
Country
United States
Zip Code
90059
Pervin, Shehla; Singh, Vineeta; Tucker, Alexandria et al. (2017) Modulation of transforming growth factor-?/follistatin signaling and white adipose browning: therapeutic implications for obesity related disorders. Horm Mol Biol Clin Investig 31:
Braga, Melissa; Reddy, Srinivasa T; Vergnes, Laurent et al. (2014) Follistatin promotes adipocyte differentiation, browning, and energy metabolism. J Lipid Res 55:375-84
Jasuja, Ravi; Costello, James C; Singh, Rajan et al. (2014) Combined administration of testosterone plus an ornithine decarboxylase inhibitor as a selective prostate-sparing anabolic therapy. Aging Cell 13:303-10
Braga, Melissa; Pervin, Shehla; Norris, Keith et al. (2013) Inhibition of in vitro and in vivo brown fat differentiation program by myostatin. Obesity (Silver Spring) 21:1180-8
Singh, Rajan; Avliyakulov, Nuraly K; Braga, Melissa et al. (2013) Proteomic identification of mitochondrial targets of arginase in human breast cancer. PLoS One 8:e79242
Pervin, Shehla; Hewison, Martin; Braga, Melissa et al. (2013) Down-regulation of vitamin D receptor in mammospheres: implications for vitamin D resistance in breast cancer and potential for combination therapy. PLoS One 8:e53287
Pervin, S; Tran, L; Urman, R et al. (2013) Oxidative stress specifically downregulates survivin to promote breast tumour formation. Br J Cancer 108:848-58
Braga, Melissa; Bhasin, Shalender; Jasuja, Ravi et al. (2012) Testosterone inhibits transforming growth factor-? signaling during myogenic differentiation and proliferation of mouse satellite cells: potential role of follistatin in mediating testosterone action. Mol Cell Endocrinol 350:39-52
Pervin, S; Tran, A; Tran, L et al. (2011) Reduced association of anti-apoptotic protein Mcl-1 with E3 ligase Mule increases the stability of Mcl-1 in breast cancer cells. Br J Cancer 105:428-37
Kumar, Raj; Zakharov, Mikhail N; Khan, Shagufta H et al. (2011) The dynamic structure of the estrogen receptor. J Amino Acids 2011:812540

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