BRCA1/BARD1 inhibition of mRNA 3' processing involves targeted degradation of RNA polymerase II.
Mammalian cells exhibit a complex response to DNA damage. The tumor suppressor BRCA1 and associated protein BARD1 are thought to play an important role in this response, and our previous work demonstrated that this includes transient inhibition of the pre-mRNA 3' processing machinery. Here we provide evidence that this inhibition involves proteasomal degradation of a component necessary for processing, RNA polymerase II (RNAP II). We further show that RNAP IIO, the elongating form of the enzyme, is a specific in vitro target of the BRCA1/BARD1 ubiquitin ligase activity. Significantly, siRNA-mediated knockdown of BRCA1 and BARD1 resulted in stabilization of RNAP II after DNA damage. In addition, inhibition of 3' cleavage induced by DNA damage was reverted in extracts of BRCA1-, BARD1-, or BRCA1/BARD1-depleted cells. We also describe corresponding changes in the nuclear localization and/or accumulation of these factors following DNA damage. Our results support a model in which a BRCA1/BARD1-containing complex functions to initiate degradation of stalled RNAP IIO, inhibiting the coupled transcription-RNA processing machinery and facilitating repair.
Kleiman
Frida E
FE
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Wu-Baer
Foon
F
Fonseca
Danae
D
Kaneko
Syuzo
S
Baer
Richard
R
Manley
James L
JL
D024509:3' Flanking Region / Q000502:physiology; D000818:Animals; D019313:BRCA1 Protein / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D011485:Protein Binding / Q000502:physiology; D026721:RNA 3' End Processing / Q000502:physiology*; D012319:RNA Polymerase II / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D014452:Ubiquitins / Q000378:metabolism
D019313:BRCA1 Protein; D012322:RNA Precursors; D025521:Tumor Suppressor Proteins; D014452:Ubiquitins; C102449:BARD1 protein, human; D044767:Ubiquitin-Protein Ligases; D012319:RNA Polymerase II