title: The Role of Foxo3 in Leydig Cells.
abstract: OBJECTIVE
  Foxo3 in female reproduction has been reported to regulate proliferation of granulose cells that form follicles. There are no reports so far that discuss on the role of Foxo3 in males. This study was designed to outline the role of Foxo3 in the testes.
  
  
  METHODS
  Testes from mice at birth to postpartum week (PPW) 5 were isolated and examined for the expression of Foxo3 using immunostaining. To elucidate role of Foxo3 in Leydig cells, R2C cells were treated with luteinizing hormone (LH) and the phosphorylation of Foxo3. Testosterone and steroidogenic acute regulatory (StAR) protein levels were measured after constitutive active [triple mutant (TM)] human FOXO3 adenovirus was transduced and StAR promoter assay was performed.
  
  
  RESULTS
  Foxo3 expression in the testicles started from birth and lasted until PPW 3. After PPW 3, most Foxo3 expression occurred in the nuclei of Leydig cells; however, at PPW 5, Foxo3 was expressed in both the nucleus and cytoplasm. When R2C cells were treated with luteinizing hormone, Foxo3 phosphorylation levels by AKT increased. After blocking the PI3K pathway, LH-induced phosphorylated Foxo3 levels decreased, indicating that LH signaling regulates Foxo3 localization. When active FOXO3-TM adenovirus was introduced into a Leydig tumor cell line, the concentrations of testosterone and StAR protein decreased. When FOXO3 and a StAR promoter vector were co-transfected into HEK293 cells for a reporter assay, FOXO3 inhibited the StAR promoter.
  
  
  CONCLUSIONS
  FOXO3 affects testosterone synthesis by inhibiting the formation of StAR protein. LH hormone, meanwhile, influences Foxo3 localization, mediating its function.
authors.affiliation: Endocrinology, Institute of Endocrine Research, Brain Korea 21 PLUS Project for Medical Science and Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Young Suk
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Endocrinology, Institute of Endocrine Research, Brain Korea 21 PLUS Project for Medical Science and Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Joo Eun
authors.initials: JE
authors.lastname: Song
authors.affiliation: Endocrinology, Institute of Endocrine Research, Brain Korea 21 PLUS Project for Medical Science and Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Byung Soo
authors.initials: BS
authors.lastname: Kong
authors.affiliation: Department of Internal Medicine, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Hong
authors.affiliation: Endocrinology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Novelli
authors.affiliation: Endocrinology, Institute of Endocrine Research, Brain Korea 21 PLUS Project for Medical Science and Yonsei University College of Medicine, Seoul, Korea. EJLEE423@yuhs.ac.
authors.forename: Eun Jig
authors.initials: EJ
authors.lastname: Lee
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D016922:Cellular Senescence / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007985:Leydig Cells / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction / Q000187:drug effects; D013739:Testosterone / Q000097:blood / Q000378:metabolism*; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C474033:FoxO3 protein, mouse; D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D013739:Testosterone; D007986:Luteinizing Hormone; D019869:Phosphatidylinositol 3-Kinases
keywords: Foxo3; Leydig cell; StAR; testosterone