Abstract: TH-PO580

Pkd1-Deficient Mice Show Increased Susceptibility to Induction of Endoplasmic Reticulum Stress Following Mild Renal Ischemia/Reperfusion

Session Information

Category: Genetic Diseases of the Kidney

  • 801 Cystic Kidney Diseases

Authors

  • Amaral, Andressa G., University of São Paulo, Sao Paulo, Brazil
  • Pires, Andre F., Sirio Libanes Hospital, Sao Paulo, Brazil
  • Watanabe, Elieser H., University of São Paulo, Sao Paulo, Brazil
  • Onuchic, Luiz F., University of São Paulo, Sao Paulo, Brazil
Background

Pkd1 haploinsufficiency has been shown to increase susceptibility to renal ischemia-reperfusion (IR) in mice. IR is a classical cause of endoplasmic reticulum stress (RS) and RS can aggravate renal injury induced by IR. Inactivation of Xbp1, in turn, has been proposed to amplify the cystic phenotype of Sec63flox/flox:Ksp-Cre mice by decreasing polycystin-1 activity. To investigate the effect of mild renal IR on RS in Pkd1 deficiency, we analyzed RS and inflammation markers in Pkd1+/- (HT) and Pkd1+/+ (WT) mice submitted to mild renal IR.

Methods

HT and WT male mice were submitted to 32-min bilateral renal IR or sham intervention (SI). Serum urea nitrogen (SUN) was measured 24h prior to and 48h after these procedures. Kidneys were harvested 48h post-IR or SI to evaluate IL1β, IL6, IL10, MCP1, TNFα and RANTES by multiplex assay; GRP78 and XBP1s by western blot; Hif1α, Hspa5 and Ddit3 by real time RT-PCR; and Xbp1s/Xbp1u transcript ratio by end-point RT-PCR.

Results

SUN did not differ between WT and HT mice after IR and SI. Hif1α expression did not significantly increase following renal IR in mice with either genotype, indicating that the induced insult was mild. The levels of IL1β, IL6, IL10, MCP1, TNFα and RANTES did not differ between HT and WT kidneys in response to IR and SI. Renal expression of XBP1s protein was higher in HT than WT animals after IR [0.67 (0.55-0.72) vs 0.48 (0.34-0.53), p<0.01)] while HT kidneys presented lower Xbp1s/Xbp1u than WT following this insult [6.59 (5.85-7.05) vs 10.29 (9.48-12.18); p<0.001). Notably, renal IR decreased this ratio in HT mice [vs 9.00 (8.24-9.14), p<0.01] whereas slightly increased it in WT animals [vs 8.22 (6.48-9.54), p<0.05]. No differences in Hspa5 gene and GRP78 protein expression were detected between kidneys of both genotypes in response to IR and SI. Ddit3 gene expression, in addition, did not differ between HT and WT kidneys after IR and SI.

Conclusion

Our findings support that Pkd1 haploinsufficiency increases the level of RS following mild renal IR in mice, by favoring the activation of the IRE1α-XBP1 branch of UPR. Our data suggest that this effect may possibly modulate polycystin-1 functional activity and attenuate renal injury in mild IR, potentially limiting the increased susceptibility associated with Pkd1 haploinsufficiency.

Funding

  • Government Support - Non-U.S.