Aquaporins in complex tissues. I. Developmental patterns in respiratory and glandular tissues of rat.
Developmental expression of aquaporin water transport proteins is not well understood in respiratory tract or secretory glands; here we define aquaporin protein ontogeny in rat. Expression of aquaporin-3 (AQP3), AQP4, and AQP5 proteins occurs within 2 wk after birth, whereas AQP1 first appears before birth. In most tissues, aquaporin protein expression increases progressively, although transient high-level expression is noted in distal lung (AQP4 at postnatal day +2) and trachea (AQP5 at postnatal day +21 and AQP3 at postnatal day +42). In mature animals, AQP5 is abundant in distal lung and salivary glands, AQP3 and AQP4 are present in trachea, and AQP1 is present in all of these tissues except salivary glands. Surprisingly, all four aquaporin proteins are highly abundant in nasopharynx. Unlike AQP1, corticosteroids did not induce expression of AQP3, AQP4, or AQP5 in lung. Our results seemingly implicate aquaporins in proximal airway humidification, glandular secretion, and perinatal clearance of fluid from distal airways. However, the studies underscore a need for detailed immunohistochemical characterizations and definitive functional studies.
King
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LS
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA.
Nielsen
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S
Agre
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D000305:Adrenal Cortex Hormones / Q000494:pharmacology; D000375:Aging / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D051398:Aquaporin 1; D051400:Aquaporin 3; D051401:Aquaporin 4; D051402:Aquaporin 5; D020346:Aquaporins; D001623:Betamethasone / Q000494:pharmacology; D005314:Embryonic and Fetal Development; D005123:Eye / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D007473:Ion Channels / Q000096:biosynthesis*; D008168:Lung / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010446:Peptide Fragments; D051381:Rats; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000196:embryology / Q000254:growth & development; D012469:Salivary Glands / Q000196:embryology / Q000254:growth & development / Q000502:physiology*
D000305:Adrenal Cortex Hormones; D000906:Antibodies; C496022:Aqp1 protein, rat; C496029:Aqp3 protein, rat; C496032:Aqp4 protein, rat; C496040:Aqp5 protein, rat; D051401:Aquaporin 4; D051402:Aquaporin 5; D020346:Aquaporins; D007473:Ion Channels; D008565:Membrane Proteins; D010446:Peptide Fragments; D051398:Aquaporin 1; D051400:Aquaporin 3; D001623:Betamethasone