ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: FR-PO201

Coupling of Transient Receptor Potential Canonical Channel (TRPC6) and Phosphodiesterase 1 (PDE1) Activity in Diabetic Nephropathy

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Dey, Asim Bikash, Eli Lilly and Company, Indianapolis, Indiana, United States
  • Li, Fang, Eli Lilly and Company, Indianapolis, Indiana, United States
  • Kowala, Mark, Eli Lilly and Company, Indianapolis, Indiana, United States
  • Atkinson, Simon J., Indiana University - Purdue University Indianapolis, Indianapolis, Indiana, United States
  • Rekhter, Mark D., Integral Health, Carmel, Indiana, United States
Background

Diabetic Nephropathy (DN) is a major complication of diabetes and the incomplete understanding of its molecular mechanisms is highlighted by the limited treatments options. Our investigation focused on the link between TRPC6 and the calcium activated PDE1. Three isoforms of PDE1 are differentially expressed in vascular smooth muscle cells, renal tubular epithelial cells, podocytes, and mesangial cells. While TRPC6 renal expression is associated with DN and inhibition of PDE1 causes vasodilation, their interaction in the context of DN has not been studied. We hypothesized that the diabetic milieu stimulates TRPC6-mediated calcium flux which in turn activates PDE1and propagates kidney injury.

Methods

To investigate the role of PDE1 and TRPC6 mediated calcium flux and apoptosis, cultured primary human mesangial cells or isolated rat glomeruli were treated with TRPC6 agonist HYP9 with or without a pan-PDE1 inhibitor. Apoptosis was measured using high throughput imaging platform using caspase 3/7 as a marker. The role of PDE1 in hypertension and DN was evaluated in telemeterized spontaneously hypertensive rats (SHR) and in hypertensive type 2 diabetic (db/db) mice over expressing the renin gene.

Results

TRPC6 mediated calcium flux induced apoptosis in human mesangial cells and isolated rat glomeruli, which was attenuated by bothTRPC6 and PDE1 inhibitor thereby suggesting a functional coupling between TRPC6 (as a source of calcium) and PDE1 activation. Renal cell protection with PDE1 inhibition was tested in mouse model of DN, featuring a combination of diabetes, nephron loss and arterial hypertension. In this model a novel PDE1 inhibitor caused a significant reduction of albuminuria up to 69% after 6 weeks of treatment compared to vehicle. This was accompanied by a significant reduction in serum creatinine and several urine biomarkers of inflammation and injury. Histopathological analysis revealed substantial improvement in glomerular sclerosis, interstitial fibrosis and reduction in mesangial matrix compared to vehicle. Gene expression analysis of the kidney revealed changes the gene clusters associated with innate immunity and fibrosis.

Conclusion

The results demonstrates that TRPC6 mediated calcium flux is linked to the activation of PDE1 and its inhibition leads to renoprotective effects in DN.

Funding

  • Commercial Support