A novel crosstalk mechanism between nuclear receptor-mediated and growth factor/Ras-mediated pathways through PNRC-Grb2 interaction.
It has been demonstrated that proline-rich nuclear receptor coregulatory protein (PNRC) is a nuclear receptor coactivator that interacts with nuclear receptors through an SH3-binding motif located in its C-terminus. In the present report, a physical interaction between PNRC and Grb2 (an adapter protein involved in growth factor/Ras-mediated pathways) has been demonstrated using the GST pull-down assay, the yeast two-hybrid assay, as well as by coimmunoprecipitation. Cotransfection and fluorescence imaging have also confirmed the colocalization of PNRC and Grb2 in mammalian cells. Transient transfection experiments have demonstrated that, by interacting with each other, Grb2 decreases the coactivator activity of PNRC for nuclear receptors, and that PNRC suppresses Grb2-mediated Ras/MAP-kinase activation. Furthermore, it was discovered that HeLa cells overexpressing PNRC grew more slowly when compared to matched controls. Additionally, using a RT-PCR analysis of mRNA on six pairs of cancer/noncancer tissues, PNRC expression was found to be significantly lower in breast cancer tissue than in noncancer tissue. Based on these findings, we believe that PNRC and Grb2, by interacting with each other, can suppress nuclear receptor-mediated regulation and growth factor-mediated regulation in human breast tissue. This is a newly identified crosstalk mechanism for modulating these two important types of regulatory pathways.
Zhou
Dujin
D
Department of Surgical Research, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.
Chen
Bin
B
Ye
Jing-Jing
JJ
Chen
Shiuan
S
D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D015153:Blotting, Western; D002455:Cell Division; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D051380:GRB2 Adaptor Protein; D005982:Glutathione Transferase / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D020935:MAP Kinase Signaling System; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D015398:Signal Transduction; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D006133:Growth Substances; D009687:Nuclear Proteins; C096395:PNRC1 protein, human; D011506:Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014157:Transcription Factors; D005982:Glutathione Transferase