ATRA inhibits ceramide kinase transcription in a human neuroblastoma cell line, SH-SY5Y cells: the role of COUP-TFI

J Neurochem. 2010 Jan;112(2):511-20. doi: 10.1111/j.1471-4159.2009.06486.x. Epub 2009 Nov 7.

Abstract

Ceramide is the central lipid in the sphingolipid metabolism. Ceramide kinase (CERK) and its product, ceramide 1-phosphate, have been implicated in various cellular functions. However, the regulatory mechanism of CERK gene expression remains to be determined. Here, we examined CERK mRNA level during all-trans retinoic acid (ATRA)-induced differentiation of a human neuroblastoma cell line, SH-SY5Y. ATRA reduced CERK mRNA and protein levels. Over-expression and small interfering RNA (siRNA) of CERK revealed that CERK is inhibitory against ATRA-induced neuronal differentiation and cell growth arrest. ATRA inhibited the transcriptional activity of 5'-promoter of CERK. Truncation and mutation study suggests that ATRA-responsible region was mainly located in the tandem retinoic acid responsive elements (RARE) between -40 bp and the first exon. The electrophoresis mobility shift assay revealed that ATRA produced two retarded bands, which were erased by antibody against chicken ovalbumin upstream promoter transcription factor I (COUP-TFI), RARalpha, and RXRalpha, respectively. DNA pull-down assay confirmed increased binding of these transcription factors to RARE. Transient expression of RAR, RXR, and COUP-TFI and siRNA transfection of these genes revealed that COUP-TFI inhibited CERK mRNA. Furthermore, chromatin immunoprecipitation assay showed the recruitment of co-repressors as well as three transcription factors. These results suggest that COUP-TFI was the ATRA-responsive suppressive transcription factor of CERK gene transcription.

MeSH terms

  • Binding Sites / drug effects
  • COUP Transcription Factor I / genetics
  • COUP Transcription Factor I / metabolism*
  • Cell Death / drug effects
  • Cell Proliferation / drug effects
  • Electrophoretic Mobility Shift Assay / methods
  • Exons / drug effects
  • Exons / physiology
  • Humans
  • Immunoprecipitation / methods
  • Molecular Sequence Data
  • Neurites / drug effects
  • Neuroblastoma
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Promoter Regions, Genetic / drug effects
  • RNA, Small Interfering / pharmacology
  • Receptors, Retinoic Acid / metabolism
  • Retinoic Acid Receptor alpha
  • Retinoid X Receptors / metabolism
  • Transcriptional Activation / drug effects*
  • Transfection / methods
  • Tretinoin / pharmacology*

Substances

  • COUP Transcription Factor I
  • RARA protein, human
  • RNA, Small Interfering
  • Receptors, Retinoic Acid
  • Retinoic Acid Receptor alpha
  • Retinoid X Receptors
  • Tretinoin
  • Phosphotransferases (Alcohol Group Acceptor)
  • ceramide kinase