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Regulation of alpha1G T-type calcium channel gene (CACNA1G) expression during neuronal differentiation

Gabriel E Bertolesi1, Christine A B Jollimore, Chanjuan Shi

  • 1Laboratory for Retina and Optic Nerve Research, Dalhousie University, Halifax, Nova Scotia, B3H 4H7, Canada.

The European Journal of Neuroscience
|May 20, 2003
PubMed

Insights

Down-regulation of T-type calcium channels in Y79 retinoblastoma cells is linked to cell differentiation. Transcriptional regulation via two promoters (A and B) of the CACNA1G gene controls Cav3.1 calcium channel expression during this process.

Area of Science:

  • Molecular Biology
  • Neuroscience
  • Cell Biology

Background:

  • Y79 retinoblastoma cells exhibit decreased T-type calcium channel activity and mRNA upon differentiation.
  • Understanding the transcriptional regulation of calcium channel genes is crucial for cell differentiation studies.

Purpose of the Study:

  • To investigate the transcriptional regulation of the Cav3.1 calcium channel gene (CACNA1G) in differentiating Y79 retinoblastoma cells.
  • To identify the mechanisms controlling the down-regulation of T-type calcium channel expression during Y79 cell differentiation.

Main Methods:

  • Genomic DNA cloning and sequencing to identify putative promoters.
  • Reverse transcriptase-polymerase chain reaction (RT-PCR) and 5' rapid amplification of cDNA ends-polymerase chain reaction (5' RACE-PCR) to analyze transcripts.
  • Functional promoter analyses, including identification of enhancer and repressor elements.

Main Results:

  • Two distinct transcripts with different 5' untranslated regions were identified, originating from different transcription start sites.
  • Promoter A was favored in undifferentiated Y79 cells, while promoter B was favored in differentiated cells.
  • Both promoters were found to be active, with enhancer and repressor sequences influencing their activity, suggesting promoter A down-regulation mediates reduced alpha1G mRNA.

Conclusions:

  • Differential promoter activity (A and B) and regulatory elements control CACNA1G gene expression during Y79 cell differentiation.
  • Down-regulation of alpha1G mRNA in differentiated Y79 cells is primarily mediated by decreased activity of promoter A, potentially with promoter B repression.
  • Reduced T-type calcium channel expression is a key signaling event for Y79 cell phenotypic maturation and the expression of other ion channel subtypes.

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