Identification of early-responsive genes correlated to valproic acid-induced neural tube defects in mice.
BACKGROUND
Valproic acid (VPA) causes the failure of neural tube closure in newborn mice. However, the molecular mechanism of its teratogenesis is unknown. This study was conducted to investigate the genomewide effects of VPA disruption of normal neural tube development in mice.


METHODS
Microarray analysis was performed on the head part of NMRI mouse embryos treated for 1 hr with VPA on gestational day (GD) 8. Subsequently, we attempted to isolate genes that changed in correlation with the teratogenic action of VPA by employing reduced teratogenic VPA analogs, valpromide (VPD) and valnoctamide (VCD), in a real-time PCR study.


RESULTS
Microarray results demonstrated that during neurulation, many genes, some of whose functions are known and some unknown, were either increased or decreased after VPA injection. Some genes were affected by VPD or VCD in the same way as VPA, but others were not changed by the analogs. In this way, our system identified 11 increased and 20 decreased genes. Annotation analysis revealed that the increased genes included gadd45b, ier5, per1, phfl3, pou3f1, and sox4, and the decreased genes included ccne2, ccnl, gas5, egr2, sirt1, and zfp105.


CONCLUSIONS
These findings demonstrate that expression changes in genes having roles in the cell cycle and apoptosis pathways of neural tube cells were strongly expected to relate to the teratogenic, but not antiepileptic, activity of VPA. Our approach has allowed the expansion of the catalog of molecules immediately affected by VPA in the developing neural tube.
Okada
Akinobu
A
Drug Safety Research Laboratories, Astellas Pharma Inc., 2-1-6 Kashima, Yodogawa-ku, Osaka 532-8514, Japan.
Kushima
Kiyoshi
K
Aoki
Yoshinobu
Y
Bialer
Meir
M
Fujiwara
Michio
M
D000014:Abnormalities, Drug-Induced / Q000235:genetics*; D000577:Amides / Q000633:toxicity; D000818:Animals; D004622:Embryo, Mammalian / Q000187:drug effects; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D017874:Immediate-Early Proteins / Q000235:genetics; D051379:Mice; D009436:Neural Tube Defects / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D014635:Valproic Acid / Q000031:analogs & derivatives* / Q000633:toxicity*
D000577:Amides; C518820:IEX-1 protein, mouse; D017874:Immediate-Early Proteins; C045179:valnoctamide; D014635:Valproic Acid; C004651:dipropylacetamide