Kidney Week

Abstract: FR-PO205

Transcriptomic Profiling of Tight Junction Dysfunction in CKD

Session Information

• Vascular Biology and Dysfunction
  November 03, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Hypertension

• 1103 Vascular Biology and Dysfunction

Authors

• Xu, Jen, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States

Jen Xu,

• Lim, Kenneth, Massachusetts General Hospital, Boston, Massachusetts, United States

Kenneth Lim,

• Ho, Li-lun, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States

Li-lun Ho,

• Hiemstra, Thomas F., University of Cambridge, Cambridge, United Kingdom

Thomas F. Hiemstra,

• Lu, Tzongshi, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States

Tzongshi Lu,

Background

Tight junctions (TJ) are specialized membrane domains that play multiple functions in endothelium and epithelium to maintain cellular homeostasis. TJ dysfunction is an important pathogenic process in the development of uremic-related cardiovascular disease (CVD), cerebral small-vessel diseases (CSVD) and cystogenesis in polycystic kidney disease. The goal of the present study was to elucidate the transcriptomic profile of TJ dysfunction in CKD.

Methods

We performed transcriptome analysis by RNA sequencing in: 1) primary human aortic endothelial cells (HAECs) and human brain microvascular endothelial cells (HBMECs) that were treated in calcification medium (CM: 5mM β-glycerolphosphate+5mM CaCl₂) in time-course experiments (0-48 hours), in vitro; 2) human kidney proximal tubule epithelial cells (HK-2) treated with H₂O₂, in vitro and 3) human arteries, ex vivo from healthy and CKD patients; Gene selections were performed by the combinations of fold-changes on log 2 ratio, and p value < 0.05.

Results

In primary cells treated with CM: we found that heat-shock protein 70 (HSP70) co-chaperone , BAG1 (Bcl2 Associated Athanogene 1) was significantly increased at 6 hours prior to upregulation of antiapoptotic gene, Bcl2 at 12 hours in HAECs but not in HBMECs. DNAJB6 (HSP40) and HSPA5 (HSP70 member5) was significantly increased at 24 and 12 hours respectively in HAECs. The major transmembrane TJ protein-Occludin was upregulated at 6 hours and peaked at 24 hours (HAECs) and 48 hours (HBMECs) under CM treatment respectively, but cytoplasma TJ-ZO1 displayed similar patterns in HAECs only. Inflammation sensitive TJ, Claudin-5 increased at 1 hour followed by upregulation of downstream ZO-1 at 6 hours. In addition, ZO1, occludin and Claudin-5 were downregulated after H₂O₂ treated but preserved by HSP70 induction in HK2 cells. In human CKD arteries, we found that claudin-5 was down-regulated (Fold changes, FC, 2.16) while ZO-1 was upregulated (FC=2.17). Bcl2 (FC=4.52) and HSPA5 (FC=3.85) was preserved in healthy arteries alone with activated BAG1 (FC=7.44).

Conclusion

Complex differential gene regulation involving apoptosis, TJ dysfunction and upregulation of the HSP stress response occur in endothelial and epithelial cells in renal failure. Our findings may serve to inform the rational development of therapeutic strategies for arterial and epithelial cells dysfunction in CKD.

Funding

• Private Foundation Support