Transient expression of osteopontin mRNA and protein in amoeboid microglia in developing rat brain.
To investigate a potential role of osteopontin (OPN) in developing rat brain, the expression of OPN mRNA and protein in the developing rat brain relative to the distribution of brain macrophages was investigated using in situ hybridization and immunohistochemistry, and the phagocytic capability of OPN-expressing cells was accessed using rhodamine isothiocyanate (RhIc) as a tracer. OPN-expressing cells appeared from embryonic day 16. During the first week of postnatal life, OPN-labeled cells increased markedly, and peaked around P7, then declined and had completely disappeared by the end of the second postnatal week. The spatiotemporal distribution pattern of OPN mRNA closely matched that of OPN protein. Their morphology and localization were compared with those of cells expressing the established microglial marker OX-42 in adjacent sections, and double-labeling studies demonstrated that OPN was localized to the amoeboid microglia which stain with the lectin GSI-B4, another marker for microglia. Furthermore, OPN-labeled cells were confirmed to be active phagocytes emitting RhIc fluorescence indicating that the tracer into the brain tissues was engulfed by phagocytosis. Therefore, these results provide the first evidence that OPN is transiently expressed in active brain macrophages in the embryonic and early postnatal brain, and suggest that OPN may contribute to the migration and phagocytic function of brain macrophages in the developing brain.
Choi
Jeong-Sun
JS
Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, 137-701 Seoul, Korea.
Cha
Jung-Ho
JH
Park
Hyun-Jung
HJ
Chung
Jin-Woong
JW
Chun
Myung-Hoon
MH
Lee
Mun-Yong
MY
D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D051926:Basigin; D001798:Blood Proteins; D001921:Brain / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D005260:Female; D005333:Fetus; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D007150:Immunohistochemistry; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D017628:Microglia / Q000166:cytology / Q000378:metabolism*; D053495:Osteopontin; D010587:Phagocytosis / Q000235:genetics; D037121:Plant Lectins; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012235:Rhodamines; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism*
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D001798:Blood Proteins; C102624:Bsg protein, Gallus gallus; C079432:Bsg protein, rat; C045475:Griffonia simplicifolia lectins; D008562:Membrane Glycoproteins; D037121:Plant Lectins; D012333:RNA, Messenger; D012235:Rhodamines; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; D053495:Osteopontin; D051926:Basigin; C027755:rhodamine isothiocyanate