AKI after conditional and kidney-specific knockdown of stanniocalcin-1.
Stanniocalcin-1 is an intracrine protein; it binds to the cell surface, is internalized to the mitochondria, and diminishes superoxide generation through induction of uncoupling proteins. In vitro, stanniocalcin-1 inhibits macrophages and preserves endothelial barrier function, and transgenic overexpression of stanniocalcin-1 in mice protects against ischemia-reperfusion kidney injury. We sought to determine the kidney phenotype after kidney endothelium-specific expression of stanniocalcin-1 small hairpin RNA (shRNA). We generated transgenic mice that express stanniocalcin-1 shRNA or scrambled shRNA upon removal of a floxed reporter (phosphoglycerate kinase-driven enhanced green fluorescent protein) and used ultrasound microbubbles to deliver tyrosine kinase receptor-2 promoter-driven Cre to the kidney to permit kidney endothelium-specific shRNA expression. Stanniocalcin-1 mRNA and protein were expressed throughout the kidney in wild-type mice. Delivery of tyrosine kinase receptor-2 promoter-driven Cre to stanniocalcin-1 shRNA transgenic kidneys diminished the expression of stanniocalcin-1 mRNA and protein throughout the kidneys. Stanniocalcin-1 mRNA and protein expression did not change in similarly treated scrambled shRNA transgenic kidneys, and we observed no Cre protein expression in cultured and tyrosine kinase receptor-2 promoter-driven Cre-transfected proximal tubule cells, suggesting that knockdown of stanniocalcin-1 in epithelial cells in vivo may result from stanniocalcin-1 shRNA transfer from endothelial cells to epithelial cells. Kidney-specific knockdown of stanniocalcin-1 led to severe proximal tubule injury characterized by vacuolization, decreased uncoupling of protein-2 expression, greater generation of superoxide, activation of the unfolded protein response, initiation of autophagy, cell apoptosis, and kidney failure. Our observations suggest that stanniocalcin-1 is critical for tubular epithelial survival under physiologic conditions.
Department of Medicine/Division of Nephrology.
Luping
L
Huang
Department of Medicine/Division of Nephrology.
Tatiana
T
Belousova
Department of Medicine/Division of Nephrology.
Jenny Szu-Chin
JS
Pan
Department of Medicine/Division of Nephrology.
Jie
J
Du
Department of Medicine/Division of Nephrology.
Huiming
H
Ju
Department of Medicine/Division of Nephrology.
Lianghao
L
Lu
Department of Molecular Physiology and Biophysics, and.
Pumin
P
Zhang
Kidney Pathology Laboratory, The Methodist Hospital/Weill Cornell University, Houston, Texas.
Luan D
LD
Truong
Department of Pediatrics/Nutrition, Baylor College of Medicine, Houston, Texas; and.
Alli
A
Nuotio-Antar
Department of Medicine/Division of Nephrology, sheikh@bcm.tmc.edu.
David
D
Sheikh-Hamad
D058186:Acute Kidney Injury / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D005260:Female; D055785:Gene Knockdown Techniques; D005838:Genotype; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000502:physiology*; D008297:Male; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D013481:Superoxides / Q000378:metabolism; D056811:Unfolded Protein Response
D006023:Glycoproteins; D013481:Superoxides; C051795:teleocalcin