Abstract: SA-PO978
CDK9-Cyclin T1 Complex Mediates Medial Calcification Through the Induction of CHOP
Session Information
- Hypertension and CVD: Mechanisms - II
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Hypertension and CVD
- 1403 Hypertension and CVD: Mechanisms
Authors
- Shiozaki, Yuji, University of Colorado Denver, Aurora, Colorado, United States
- Kohno, Shohei, University of Colorado Denver, Aurora, Colorado, United States
- Keenan, Audrey L., University of Colorado AMC, Aurora, Colorado, United States
- Miyazaki-anzai, Shinobu, University of Colorado-Denver, Aurora, Colorado, United States
- Miyazaki, Makoto, University of Colorado-Denver, Aurora, Colorado, United States
Background
Our recent studies indicate that activation of the Activating transcription factor 4 (ATF4) pathway through the ER stress response induced by saturated fatty acids (SFAs) plays a causative role in vascular calcification in chronic kidney disease (CKD). we 1) studied a pro-apoptotic CHOP transcription factor that contributes to CKD-dependent medial calcification and 2) identified a novel regulator of ER stress-mediated CHOP expression
Methods
1) To study the smooth muscle cells (SMC)-specific role of CHOP in regulating medial calcification, we generated SMC-specific CHOP conditional transgenic mice and analyzed aortic region of control and SMC-specific CHOP TG mice under CKD (5/6 nephrectomy). 2) To explore a signaling pathway that blocks SFA-induced CHOP expression, we screened a kinase inhibitor library containing >140 compounds by treating human vascular smooth muscle cells with a saturated fatty acid.
Results
SMC-specific CHOP transgenic mice developed severe vascular apoptosis and medial calcification under CKD. Protein kinase inhibitor library screening identified 16 compounds, including 7 cyclin-dependent kinase (CDK) inhibitors, that significantly suppressed the induction of CHOP through ER stress. In addition, selective inhibitors against CDK9 and CDK9-specific inhibition through a gene-editing technique blocked SFA-mediated induction of CHOP, while other CDK isoform inhibitors did not affect CHOP expression. Knockout of cyclin T1 inhibited SFA-mediated induction of CHOP and mineralization, whereas deletion of cyclin T2 and cyclin K promoted CHOP expression levels and mineralization. The CDK9-cyclin T1 complex directly phosphorylated and activated ATF4.
Conclusion
These results demonstrate that 1) the CDK9-cyclin T1 and CDK9-cyclin T2/K complexes have opposing roles in CHOP expression and vascular calcification and 2) the CDK9-cyclin T1 complex mediates vascular calcification due to CHOP induction through phosphorylation-mediated ATF4 activation.
Funding
- NIDDK Support