title: Protein modifications regulate the role of 14-3-3γ adaptor protein in cAMP-induced steroidogenesis in MA-10 Leydig cells.
abstract: The 14-3-3 protein family comprises adaptors and scaffolds that regulate intracellular signaling pathways. The 14-3-3γ isoform is a negative regulator of steroidogenesis that is hormonally induced and transiently functions at the initiation of steroidogenesis by delaying maximal steroidogenesis in MA-10 mouse tumor Leydig cells. Treatment of MA-10 cells with the cAMP analog 8-bromo-cAMP (8-Br-cAMP), which stimulates steroidogenesis, triggers the interaction of 14-3-3γ with the steroidogenic acute regulatory protein (STAR) in the cytosol, limiting STAR activity to basal levels. Over time, this interaction ceases, allowing for a 2-fold induction in STAR activity and maximal increase in the rate of steroid formation. The 14-3-3γ/STAR pattern of interaction was found to be opposite that of the 14-3-3γ homodimerization pattern. Phosphorylation and acetylation of 14-3-3γ showed similar patterns to homodimerization and STAR binding, respectively. 14-3-3γ Ser(58) phosphorylation and 14-3-3γ Lys(49) acetylation were blocked using trans-activator of HIV transcription factor 1 peptides coupled to 14-3-3γ sequences containing Ser(58) or Lys(49). Blocking either one of these modifications further induced 8-Br-cAMP-induced steroidogenesis while reducing lipid storage, suggesting that the stored cholesterol is used for steroid formation. Taken together, these results indicate that Ser(58) phosphorylation and Lys(49) acetylation of 14-3-3γ occur in a coordinated time-dependent manner to regulate 14-3-3γ homodimerization. 14-3-3γ Ser(58) phosphorylation is required for STAR interactions under control conditions, and 14-3-3γ Lys(49) acetylation is important for the cAMP-dependent induction of these interactions.
authors.affiliation: Research Institute of the McGill University Health Centre and the Department of Medicine and McGill University, Montreal, Quebec H3G 1A4, Canada.
authors.forename: Yasaman
authors.initials: Y
authors.lastname: Aghazadeh
authors.affiliation: Protein Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Ye
authors.affiliation: Protein Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702.
authors.forename: Josip
authors.initials: J
authors.lastname: Blonder
authors.affiliation: Research Institute of the McGill University Health Centre and the Department of Medicine and McGill University, Montreal, Quebec H3G 1A4, Canada; Departments of Pharmacology and Therapeutics and McGill University, Montreal, Quebec H3G 1A4, Canada; Departments of Biochemistry, McGill University, Montreal, Quebec H3G 1A4, Canada and. Electronic address: vassilios.papadopoulos@mcgill.ca.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Papadopoulos
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000096:biosynthesis*; D000242:Cyclic AMP / Q000502:physiology*; D007985:Leydig Cells / Q000378:metabolism*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D055503:Protein Multimerization; D011499:Protein Processing, Post-Translational; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D048948:14-3-3 Proteins; D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D002784:Cholesterol; D000242:Cyclic AMP
keywords: Adaptor Protein; Mitochondria; Post-translational Modification (PTM); Steroidogenesis; Testis
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