Aberrant glycosylation and localization of polycystin-1 cause polycystic kidney in an AQP11 knockout model.
We previously reported that disruption of the aquaporin-11 (AQP11) gene in mice resulted in cystogenesis in the kidney. In this study, we aimed to clarify the mechanism of cystogenesis in AQP11(-/-) mice. To enable the analyses of AQP11 at the protein level in vivo, AQP11 BAC transgenic mice (Tg(AQP11)) that express 3×HA-tagged AQP11 protein were generated. This AQP11 localized to the endoplasmic reticulum (ER) of proximal tubule cells in Tg(AQP11) mice and rescued renal cystogenesis in AQP11(-/-) mice. Therefore, we hypothesized that the absence of AQP11 in the ER could result in impaired quality control and aberrant trafficking of polycystin-1 (PC-1) and polycystin-2 (PC-2). Compared with kidneys of wild-type mice, AQP11(-/-) kidneys exhibited increased protein expression levels of PC-1 and decreased protein expression levels of PC-2. Moreover, PC-1 isolated from AQP11(-/-) mice displayed an altered electrophoretic mobility caused by impaired N-glycosylation processing, and density gradient centrifugation of kidney homogenate and in vivo protein biotinylation revealed impaired membrane trafficking of PC-1 in these mice. Finally, we showed that the Pkd1(+/-) background increased the severity of cystogenesis in AQP11(-/-) mouse kidneys, indicating that PC-1 is involved in the mechanism of cystogenesis in AQP11(-/-) mice. Additionally, the primary cilia of proximal tubules were elongated in AQP11(-/-) mice. Taken together, these data show that impaired glycosylation processing and aberrant membrane trafficking of PC-1 in AQP11(-/-) mice could be a key mechanism of cystogenesis in AQP11(-/-) mice.
Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan;
Yuichi
Y
Inoue
Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; esohara.kid@tmd.ac.jp.
Eisei
E
Sohara
Division of Molecular Genetics, Clinical Research Center, Chiba-East National Hospital, Chiba, Japan;
Katsuki
K
Kobayashi
Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan;
Motoko
M
Chiga
Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan;
Tatemitsu
T
Rai
Department of Medical Physiology, Meiji Pharmaceutical University, Tokyo, Japan;
Kenichi
K
Ishibashi
Department of Urology, Juntendo University School of Medicine, Tokyo, Japan; and.
Shigeo
S
Horie
Renal Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Xuefeng
X
Su
Renal Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Jing
J
Zhou
Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan;
Sei
S
Sasaki
Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan;
Shinichi
S
Uchida
D000818:Animals; D020346:Aquaporins / Q000235:genetics*; D019921:Biotinylation; D004195:Disease Models, Animal; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005838:Genotype; D006031:Glycosylation; D015151:Immunoblotting; D007668:Kidney / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D007690:Polycystic Kidney Diseases / Q000235:genetics*; D013347:Subcellular Fractions / Q000378:metabolism; D050396:TRPP Cation Channels / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes
D020346:Aquaporins; D050396:TRPP Cation Channels; C503878:Aqp11 protein, mouse