当前位置： SCI文献检索 > EUROPEAN JOURNAL OF CELL BIOLOGY期刊下所有文献 > Expression and immunolocalization of the aquaporin-8 water channel in rat gastrointestinal tract.

Expression and immunolocalization of the aquaporin-8 water channel in rat gastrointestinal tract.

Abstract：

:A remarkable amount, of water is transported in the gastrointestinal (GI) organs to fulfil the secretory and absorptive functions of the GI tract. However, the molecular basis of water movement in the GI epithelial barriers is still poorly known. Important clues about the mechanisms by which water is transported in the GI tract were provided by the recent identification of multiple aquaporin water channels expressed in GI tissues. Here we define the mRNA and protein expression and the cellular and subcellular distribution of aquaporin-8 (AQP8) in the rat GI tract. By semi-quantitative RT-PCR the AQP8 mRNA was detected in duodenum, proximal jejunum, proximal colon, rectum, pancreas and liver and, to a lesser extent, in stomach and distal colon. Immunohistochemistry using affinity-purified antibodies revealed AQP8 staining in the absorptive epithelial cells of duodenum, proximal jejunum, proximal colon and rectum where labeling was largely intracellular and confined to the subapical cytoplasm. Confirming previous results, AQP8 staining was seen at the apical pole of pancreatic acinar cells. Interestingly, both light and immunoelectron microscopy analyses showed AQP8 reactivity in liver where labeling was associated to hepatocyte intracellular vesicles and over the plasma membrane delimiting the bile canaliculi. A complex pattern was observed by immunoblotting with total membranes of the above GI organs incubated with affinity-purified anti-AQP8 antibodies which revealed multiple bands with molecular masses ranging between 28 and 45 kDa. This immunoblotting pattern was not modified after deglycosylation with N-glycosidase F except the 34-kDa band of liver that, as already reported, was partially down-shifted to 28 kDa. No bands were detected after preadsorption of the anti-AQP8 antibodies with the immunizing peptide. The cellular and subcellular distribution of AQP8 suggest physiological roles for this aquaporin in the absorption of water in the intestine and the secretion of bile and pancreatic juice in liver and pancreas, respectively. The large intracellular expression of AQP8 may indicate its recycling between the cytoplasmic compartment and the plasma membrane. The cytoplasmic localization observed may also relate to the involvement of AQP8 in processes of intracellular osmoregulation.

journal_name

Eur J Cell Biol

journal_title

European journal of cell biology

authors

Calamita G,Mazzone A,Bizzoca A,Cavalier A,Cassano G,Thomas D,Svelto M

doi

10.1078/0171-9335-00210

subject

Has Abstract

pub_date

2001-11-01 00:00:00

pages

711-9

issue

eissn

0171-9335

issn

1618-1298

pii

S0171-9335(04)70188-0

journal_volume

pub_type

杂志文章

在线工具

Expression and immunolocalization of the aquaporin-8 water channel in rat gastrointestinal tract.