BIM and NOXA are mitochondrial effectors of TAF6δ-driven apoptosis

Cell Death Dis. 2018 Jan 22;9(2):70. doi: 10.1038/s41419-017-0115-3.

Abstract

TAF6δ is a pro-apoptotic splice variant of the RNA polymerase II general transcription factor, TAF6, that can dictate life vs. death decisions in animal cells. TAF6δ stands out from classical pro-apoptotic proteins because it is encoded by a gene that is essential at the cellular level, and because it functions as a component of the basal transcription machinery. TAF6δ has been shown to modulate the transcriptome landscape, but it is not known if changes in gene expression trigger apoptosis nor which TAF6δ-regulated genes contribute to cell death. Here we used microarrays to interrogate the genome-wide impact of TAF6δ on transcriptome dynamics at temporal resolution. The results revealed changes in pro-apoptotic BH3-only mitochondrial genes that correlate tightly with the onset of cell death. These results prompted us to test and validate a role for the mitochondrial pathway by showing that TAF6δ expression causes cytochrome c release into the cytoplasm. To further dissect the mechanism by which TAF6δ drives apoptosis, we pinpointed BIM and NOXA as candidate effectors. siRNA experiments showed that both BIM and NOXA contribute to TAF6δ-dependent cell death. Our results identify mitochondrial effectors of TAF6δ-driven apoptosis, thereby providing the first of mechanistic framework underlying the atypical TAF6δ apoptotic pathway's capacity to intersect with the classically defined apoptotic machinery to trigger cell death.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis* / drug effects
  • Bcl-2-Like Protein 11 / metabolism*
  • Cell Line, Tumor
  • Cisplatin / pharmacology
  • Cytochromes c / metabolism
  • Gene Ontology
  • Humans
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • TATA-Binding Protein Associated Factors / metabolism*
  • TNF-Related Apoptosis-Inducing Ligand / pharmacology
  • Time Factors
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / genetics
  • Transcriptome / genetics
  • bcl-X Protein / metabolism

Substances

  • Bcl-2-Like Protein 11
  • PMAIP1 protein, human
  • Proto-Oncogene Proteins c-bcl-2
  • TAF6 protein, human
  • TATA-Binding Protein Associated Factors
  • TNF-Related Apoptosis-Inducing Ligand
  • bcl-X Protein
  • Cytochromes c
  • Cisplatin