title: Prolonged Starvation Causes Up-Regulation of AQP1 in Adipose Tissue Capillaries of AQP7 Knock-Out Mice.
abstract: Aquaporins (AQPs) are membrane proteins involved in the regulation of cellular transport and the balance of water and glycerol and cell volume in the white adipose tissue (WAT). In our previous study, we found the co-expression of the AQP1 water channel and AQP7 in the mouse WAT. In our present study, we aimed to find out whether prolonged starvation influences the AQP1 expression of AQP7 knock-out mice (AQP7 KO) in the WAT. To resolve this hypothesis, immunoperoxidase, immunoblot and immunogold microscopy were used. AQP1 expression was found with the use of immunohistochemistry and was confirmed by immunogold microscopy in the vessels of mouse WAT of all studied groups. Semi-quantitative immunoblot and quantitative immunogold microscopy showed a significant increase (by 2.5- to 3-fold) in the abundance of AQP1 protein expression in WAT in the 72 h starved AQP7 KO mice as compared to AQP7+/+ (p < 0.05) and AQP7-/- (p < 0.01) controls, respectively. In conclusion, the AQP1 water channel located in the vessels of WAT is up-regulated in response to prolonged starvation in the WAT of AQP7 KO mice. The present data suggest that an interaction of different AQP isoforms is required for maintaining proper water homeostasis within the mice WAT.
authors.affiliation: Department of Animal Physiology, University of Warmia and Mazury in Olsztyn, Olsztyn 10-752, Poland. skowron@uwm.edu.pl.
authors.forename: Mariusz T
authors.initials: MT
authors.lastname: Skowronski
authors.affiliation: Department of Human Physiology, University of Warmia and Mazury in Olsztyn, Olsztyn 10-752, Poland. agnieszka.skowronska@uwm.edu.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Skowronska
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg 9220, Denmark. aleksandra_rojek@yahoo.com.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Rojek
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg 9220, Denmark. mko@hst.aau.dk.
authors.forename: Michal K
authors.initials: MK
authors.lastname: Oklinski
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg 9220, Denmark. sn@hst.aau.dk.
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D051398:Aquaporin 1 / Q000378:metabolism*; D020346:Aquaporins / Q000502:physiology*; D002196:Capillaries / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D013217:Starvation / Q000503:physiopathology*; D015854:Up-Regulation
chemical_list: C496021:Aqp1 protein, mouse; C491927:Aqp7 protein, mouse; D020346:Aquaporins; D051398:Aquaporin 1; D005990:Glycerol
keywords: AQP1; AQP7 knock-out mice; fasting; immunoelectron microscopy; immunolocalization; protein expression