Importance of forkhead transcription factor Fkhl18 for development of testicular vasculature.
Forkhead transcription factors are characterized by a winged helix DNA binding domain, and the members of this family are classified into 20 subclasses by phylogenetic analyses. Fkhl18 is structurally unique, and is classified into FoxS subfamily. We found Fkhl18 expression in periendothelial cells of the developing mouse fetal testis. In an attempt to clarify its function, we generated mice with Fkhl18 gene disruption. Although KO mice developed normally and were fertile in both sexes, we frequently noticed unusual blood accumulation in the fetal testis. Electron microscopic analysis demonstrated frequent gaps, measuring 100-400 nm, in endothelial cells of blood vessels. These gaps probably represented ectopic apoptosis of testicular periendothelial cells, identified by caspase-3 expression, in KO fetuses. No apoptosis of endothelial cells was noted. Fkhl18 suppressed the transcriptional activity of FoxO3a and FoxO4. Considering that Fas ligand gene expression is activated by Foxs, the elevated activity of Foxs in the absence of Fkhl18 probably explains the marked apoptosis of periendothelial cells in Fkhl18 KO mice.
Sato
Yuko
Y
Division of Sex Differentiation, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Japan.
Baba
Takashi
T
Zubair
Mohamad
M
Miyabayashi
Kanako
K
Toyama
Yoshiro
Y
Maekawa
Mamiko
M
Owaki
Akiko
A
Mizusaki
Hirofumi
H
Sawamura
Tatsuya
T
Toshimori
Kiyotaka
K
Morohashi
Ken-Ichirou
K
Katoh-Fukui
Yuko
Y
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001808:Blood Vessels / Q000002:abnormalities / Q000196:embryology / Q000378:metabolism; D004622:Embryo, Mammalian; D004730:Endothelium, Vascular / Q000378:metabolism; D053222:Fas Ligand Protein / Q000235:genetics; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000098:blood supply / Q000196:embryology* / Q000378:metabolism; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D053222:Fas Ligand Protein; D051858:Forkhead Transcription Factors; C502463:Foxs1 protein, mouse; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors