Ionizing irradiation in patients is proposed to cause thrombus formation. An increase
in von Willebrand factor secretion in response to irradiation is a major contributing
factor to thrombus formation. We have previously reported that the increased VWF secretion
in response to irradiation is mediated at the transcriptional level. The VWF core
promoter fragment (sequences –90 to +22) was shown to contain the necessary cis-acting
element(s) to mediate the irradiation response of the VWF gene. Here we report that
a CCAAT element in the VWF promoter is the cis-acting element necessary for irradiation
induction and that the NFY transcription factor interacts with this element. These
analyses demonstrate that inhibition of NFY’s interaction with the CCAAT element abolishes
the irradiation induction of the VWF promoter. These results provide a novel role
for NFY and add this factor to the small list of irradiation-responsive transcription
factors. Coimmunoprecipitation experiments demonstrated that NFY is associated with
the histone acetylase P/CAF in vivo and that irradiation resulted in an increased association of NFY with coactivator
P/CAF. We propose that irradiation induction of the VWF promoter involves a mechanism
resulting in increased recruitment of the coactivator P/CAF to the promoter via the
NFY transcription factor.
Keywords
NFY - von Willebrand factor - irradiation - promoter