Expression of type II Na-P(i) cotransporter in alveolar type II cells.
Type II Na-P(i) cotransporters (type IIa and type IIb) represent apically located Na-P(i) cotransporters in epithelia of proximal tubules (type IIa) and small intestine (type IIb). Here we provide evidence that the type IIb (but not the type IIa) Na-P(i) cotransporter is also expressed in the lung. With the use of immunohistochemistry, location of the type IIb protein was found exclusively in the apical membrane of type II cells of the alveolar epithelium. Such a location of the type IIb cotransporter suggests an involvement in the reuptake of phosphate necessary for the synthesis of surfactant. A possible regulation of the abundance of the type IIb cotransporter in the lung was studied after adaptation of mice to a low-P(i) diet. After a chronic adaptation to a low-P(i) diet, no changes in the type IIb protein and the type IIb transcript were observed. These results exclude dietary intake of phosphate as a regulatory factor of the type IIb Na-P(i) cotransporter in alveolar type II cells.
Traebert
M
M
Institute of Anatomy, University of Zurich, CH-8057 Zurich, Switzerland.
Hattenhauer
O
O
Murer
H
H
Kaissling
B
B
Biber
J
J
D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000032:analysis* / Q000235:genetics*; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000502:physiology; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D008871:Microvilli / Q000737:chemistry / Q000648:ultrastructure; D010710:Phosphates / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000737:chemistry* / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050608:Sodium-Phosphate Cotransporter Proteins; D050610:Sodium-Phosphate Cotransporter Proteins, Type II; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb; D027981:Symporters
D002352:Carrier Proteins; D010710:Phosphates; D012333:RNA, Messenger; C493555:Slc34a1 protein, mouse; C493558:Slc34a2 protein, mouse; D050608:Sodium-Phosphate Cotransporter Proteins; D050610:Sodium-Phosphate Cotransporter Proteins, Type II; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb; D027981:Symporters