Midkine expression is associated with postnatal development of the lungs.
A heparin-binding growth factor, midkine, is the product of a retinoic acid-responsive gene. Since retinol plays critical roles in lung development and treatment of bronchopulmonary dysplasia, and midkine has been implicated in the maturation of lung explants and in cytoprotection, we herein examined midkine expression during postnatal development of the lungs and hyperoxic lung injury. Midkine protein transiently increased to a maximum level at around 4 days postnatal. Immunohistochemistry revealed that the amounts of midkine increased in resident alveolar cells, but not in smooth muscle cells or the large airway epithelium. If neonatal mice were exposed to >95% oxygen, lung development was impaired and midkine expression was suppressed. In contrast, when adult mouse lungs as well as in vitro cultured lung adenocarcinoma cells were exposed to hyperoxia, midkine expression was not affected. Furthermore, a pronounced induction of midkine by retinoic acid was observed in neonatal lungs. The results indicate that midkine expression is associated with postnatal lung development, but not necessarily with hyperoxic cell damage.
Department of Biochemistry, Nagoya University School of Medicine, Japan.
Onrai
O
Matsuura
Kenji
K
Kadomatsu
Yoshifumi
Y
Takei
Kenji
K
Uchimura
Shunji
S
Mimura
Kazuyoshi
K
Watanabe
Takashi
T
Muramatsu
D000818:Animals; D000831:Animals, Newborn; D000970:Antineoplastic Agents / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D018496:Hyperoxia / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D000078792:Midkine; D010100:Oxygen / Q000494:pharmacology; D011247:Pregnancy; D011650:Pulmonary Alveoli / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D000970:Antineoplastic Agents; D002352:Carrier Proteins; D016207:Cytokines; D000078792:Midkine; D014212:Tretinoin; D010100:Oxygen