Acid ceramidase (ASAH1) represses steroidogenic factor 1-dependent gene transcription in H295R human adrenocortical cells by binding to the receptor

Mol Cell Biol. 2012 Nov;32(21):4419-31. doi: 10.1128/MCB.00378-12. Epub 2012 Aug 27.

Abstract

Adrenocorticotropin (ACTH) signaling increases glucocorticoid production by promoting the interaction of transcription factors and coactivator proteins with the promoter of steroidogenic genes. The nuclear receptor steroidogenic factor 1 (SF-1) is essential for steroidogenic gene transcription. Sphingosine (SPH) is a ligand for SF-1. Moreover, suppression of expression of acid ceramidase (ASAH1), an enzyme that produces SPH, increases the transcription of multiple steroidogenic genes. Given that SF-1 is a nuclear protein, we sought to define the molecular mechanisms by which ASAH1 regulates SF-1 function. We show that ASAH1 is localized in the nuclei of H295R adrenocortical cells and that cyclic AMP (cAMP) signaling promotes nuclear sphingolipid metabolism in an ASAH1-dependent manner. ASAH1 suppresses SF-1 activity by directly interacting with the receptor. Chromatin immunoprecipitation (ChIP) assays revealed that ASAH1 is recruited to the promoter of various SF-1 target genes and that ASAH1 and SF-1 colocalize on the same promoter region of the CYP17A1 and steroidogenic acute regulatory protein (StAR) genes. Taken together, these results demonstrate that ASAH1 is a novel coregulatory protein that represses SF-1 function by directly binding to the receptor on SF-1 target gene promoters and identify a key role for nuclear lipid metabolism in regulating gene transcription.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Ceramidase / metabolism*
  • Adrenal Cortex / cytology
  • Adrenal Cortex / enzymology
  • Adrenal Cortex / metabolism*
  • Adrenocorticotropic Hormone / metabolism
  • Animals
  • Cell Line
  • Cell Nucleus / metabolism
  • Chromatin Immunoprecipitation
  • Cyclic AMP / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Haplorhini
  • Humans
  • Lipid Metabolism*
  • Mice
  • Phosphoproteins / genetics
  • Promoter Regions, Genetic
  • RNA Interference
  • RNA, Small Interfering
  • Regulatory Sequences, Nucleic Acid
  • Signal Transduction / genetics
  • Sphingolipids / metabolism
  • Sphingosine / metabolism
  • Steroid 17-alpha-Hydroxylase / genetics
  • Steroidogenic Factor 1 / genetics
  • Steroidogenic Factor 1 / metabolism*
  • Transcription, Genetic*

Substances

  • DNA-Binding Proteins
  • NR5A1 protein, human
  • Phosphoproteins
  • RNA, Small Interfering
  • Sphingolipids
  • Steroidogenic Factor 1
  • steroidogenic acute regulatory protein
  • Adrenocorticotropic Hormone
  • Cyclic AMP
  • CYP17A1 protein, human
  • Steroid 17-alpha-Hydroxylase
  • ASAH1 protein, human
  • Acid Ceramidase
  • Sphingosine