title: Expression and immunolocalization of aquaporins HC-1, -2, and -3 in Cope's gray treefrog, Hyla chrysoscelis.
abstract: We have previously identified two aquaporins (HC-1, HC-2) and a glyceroporin (HC-3), homologs, respectively, of mammalian AQP1, AQP2, and AQP3, from the freeze-tolerant treefrog Hyla chrysoscelis. The objective of the present study was to investigate by Western blotting and immunohistofluorescence the expression and localization of these proteins in warm-acclimated, hydrated treefrogs. We hypothesized that patterns of protein expression would reflect unique osmoregulatory roles for the three aquaporins. Western blots revealed a spectrum of protein bands from 28 kDa to 65+ kDa; treatment with N-glycosidase suggested that this reflected variable glycosidation of the aquaporins. HC-1 was expressed in all organs, including dermis of skin, sinusoids and septa of liver, Bowman's capsule of kidney, intestinal lacteal vessels, and perimysium and vasculature of muscle. HC-3 expression was also widespread, but with different localization, including epidermis and dermis of skin, renal collecting ducts, and colonic villous epithelium. HC-2 expression was limited to osmoregulatory organs (renal collecting ducts and epidermis). In many ways, the expression of these proteins paralleled their mammalian homologs. For example, HC-2 and HC-3 expression in collecting ducts appeared similar to the mammalian pattern (the former more apical, the latter more basal). However, some aspects of localization (e.g. HC-1 in Bowman's capsule) were unique, and the ubiquity of HC-3 expression may relate to its facilitation of glycerol transport in this animal that possesses glycerol-dependent freeze tolerance.
authors.affiliation: Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA.
authors.forename: Ram Naresh
authors.initials: RN
authors.lastname: Pandey
authors.forename: Sushmita
authors.initials: S
authors.lastname: Yaganti
authors.forename: Stephanie
authors.initials: S
authors.lastname: Coffey
authors.forename: James
authors.initials: J
authors.lastname: Frisbie
authors.forename: Khadijeh
authors.initials: K
authors.lastname: Alnajjar
authors.forename: David
authors.initials: D
authors.lastname: Goldstein
mesh_terms: D000818:Animals; D001001:Anura / Q000276:immunology / Q000378:metabolism*; D020346:Aquaporins / Q000032:analysis* / Q000096:biosynthesis* / Q000276:immunology; D015153:Blotting, Western; D007150:Immunohistochemistry
chemical_list: D020346:Aquaporins