Altered distribution of aquaporin 5 and its C-terminal binding protein in the lacrimal glands of a mouse model for Sjögren's syndrome.
OBJECTIVE
To investigate the distribution and expression of aquaporin 5 (AQP5) and its C-terminal binding protein in the apical membrane of the lacrimal glands (LGs) in a mouse model for Sjogren's syndrome (SS).


METHODS
The LGs of NOD mice (mouse model for SS) and ICR mice (normal control) were homogenized and delivered into the affinity columns bound to synthetic AQP5 C-terminal peptide. The eluates were analyzed by electrophoresis and liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS) techniques.


RESULTS
AQP5 from the NOD mice exhibited the capacity to bind a 21-kDa protein that was lacking in the ICR mice. Instead, ICR mouse expressed a 17-kDa AQP5 binding protein that was absent in LGs of SS. LC-MS/MS analysis revealed these respective proteins to be major urinary protein 4 (MUP4) and prolactin-inducible protein (PIP). The treatment of ICR mice with antisense PIP oligonucleotides decreased immunostaining of AQP5 in the apical membrane.


CONCLUSIONS
These observations suggest that the binding of PIP to the C-terminal portion of AQP5 may cause AQP5 to be transported to the apical membrane of LGs. Correction of the aberrant binding of PIP to the AQP5 C-terminus could normalize AQP5 trafficking to the apical membrane, leading to a treatment for patients with SS.
Ohashi
Yoshiki
Y
Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. yoshiki.ohashi@santen.co.jp
Tsuzaka
Kensei
K
Takeuchi
Tsutomu
T
Sasaki
Yasumasa
Y
Tsubota
Kazuo
K
D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000818:Animals; D051402:Aquaporin 5 / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D002853:Chromatography, Liquid; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D004591:Electrophoresis, Polyacrylamide Gel; D019084:Fluorescent Antibody Technique, Indirect; D007765:Lacrimal Apparatus / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D016688:Mice, Inbred NOD; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D012859:Sjogren's Syndrome / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
C496038:Aqp5 protein, mouse; D051402:Aquaporin 5; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D016376:Oligonucleotides, Antisense; D011506:Proteins; C035737:major urinary proteins; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein