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Abstract: TH-PO869

Knockout of Heterogeneous Nuclear Ribonucleoprotein F (hnRNP F) in Podocytes Aggravates Podocyte Loss in Streptozotocin-Induced Diabetic Mice Through Alternative Splicing of Insulin Receptor Gene

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Lo, Chao-Sheng, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada
  • Chenier, Isabelle, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada
  • Filep, Janos G., Maisonneuve-Rosemont Hosp., Montreal, Quebec, Canada
  • Ingelfinger, Julie R., The New England Journal of Medicine, Boston, Massachusetts, United States
  • Zhang, Shao-Ling, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada
  • Chan, John S.D., CRCHUM, Universite de Montreal, Montreal, Quebec, Canada
Background

Insulin receptor (INSR) signaling is important for podocyte integrity. The INSR gene encodes two isoforms via alternative splicing: INSR-A (excluding exon 11) and INSR-B (including exon 11). In pancreatic beta cells, INSR-A renders beta cells vulnerable to programmed cell death, whereas INSR-B is protective. In the present study, we investigated whether deletion of heterogeneous nuclear ribonuclear protein F (hnRNP F) in podocytes would aggravate podocyte injury in streptozotocin (STZ)-induced diabetic mice through modulating the alternative splicing of INSR isoforms.

Methods

Podocyte-specific hnRNP F knockout (KO) mice were generated by crossbreeding podocin (Pod)-Cre mice with floxed hnRNP F mice. Diabetes was induced in male 12-week old Pod-hnRNP F KO mice and control littermates with streptozotocin (STZ) (i.p., 50 mg/kg/day) for five consecutive days. Mice were euthanized 8 weeks after the STZ injections. Urinary ACR was assessed at 4 and 8 weeks after STZ-administration. Kidneys were processed for histology. Podocyte numbers were counted by p57 staining. Mouse renal cortex, isolated glomeruli and primary cultured podocytes were subjected to RT-PCR to assess INSR-A and INSR-B mRNA expression. Podocytes from control littermates and Pod-hnRNP F KO mice cultured in normal and high glucose media were also studied.

Results

INSR-A and INSR-B mRNA were equally expressed in the glomeruli of non-diabetic WT mice. STZ-induced diabetes aggravated kidney injury and podocyte loss in Pod-hnRNP F KO mice as compared with diabetic control littermates. Diabetic Pod-hnRNP F KO mice exhibited lower INSR-B/A mRNA ratio in isolated glomeruli and primary cultured podocytes as compared to diabetic control mice. In vitro, in high glucose media, more cultured podocytes from Pod-hnRNP F KO were detached as compared to those from control littermates.

Conclusion

Deficiency of hnRNP F in podocytes aggravates podocyte loss and kidney injury in STZ-diabetic mice through modulation of the alternative splicing of INSR mRNA resulting in lower INSR-B/A mRNA ratio.

Funding

  • Government Support - Non-U.S.