title: Expression of epidermal fatty acid binding protein (E-FABP) in septoclasts in the growth plate cartilage of mice.
abstract: n-3 Polyunsaturated fatty acids play a role in regulating the growth of the long bones. Fatty acid-binding proteins (FABPs) bind and transport hydrophobic long-chain fatty acids intracellularly, and epidermal-type FABP (E-FABP) has an affinity for n-3 fatty acids. This study aimed to clarify the localization of E-FABP in the growth plate of the mouse tibia. At the chondro-osseous junction (COJ) of the growth plate, E-FABP-immunoreactivity was exclusively localized in mononuclear, spindle-shaped cells with several long processes. These E-FABP-immunoreactive cells were identified as being septoclasts, i.e., cells that resorb uncalcified transverse septa. The processes of these immunoreactive septoclasts terminated between the longitudinal and transverse septa. E-FABP-immunoreactivity was found in the entire cytoplasm and on the mitochondrial outer membrane. In ontogeny, immunoreactive septoclasts were observed immediately after emergence of the primary ossifying center and were distributed not only at the COJ but also in the metaphysis near the COJ. The number of septoclasts increased at the postnatal age of 1 week (P1w)-P2w, and thereafter gradually decreased; and the cells became concentrated at the COJ after P3w-P4w. The immunoreactivity for peroxisome proliferator-activated receptor (PPAR)β/δ was detected in these E-FABP-immunoreactive septoclasts. The present results suggest that fatty acids, preferably n-3 ones, are intracellularly transported by E-FABP to various targets, including mitochondria and nucleus, in which PPARβ/δ may play functional roles in the transcriptional regulation of genes involved in the endochondral ossification.
authors.affiliation: Division of Anatomy, Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama, 3500283, Japan, y-bando@dent.meikai.ac.jp.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Bando
authors.forename: Miyuki
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Koji
authors.initials: K
authors.lastname: Sakiyama
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Inoue
authors.forename: Shota
authors.initials: S
authors.lastname: Takizawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Owada
authors.forename: Shoichi
authors.initials: S
authors.lastname: Iseki
authors.forename: Hisatake
authors.initials: H
authors.lastname: Kondo
authors.forename: Osamu
authors.initials: O
authors.lastname: Amano
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006132:Growth Plate / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D051336:Mitochondrial Membranes / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D047494:PPAR delta / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013977:Tibia / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors
chemical_list: C082667:Fabp5 protein, mouse; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D047494:PPAR delta; D047495:PPAR gamma