Congenital
spina bifida aperta is a common congenital malformation in children and has an incidence of 1‰ to 5‰ in China. However, we currently lack specific
biomarkers for screening or prenatal diagnosis and there is no method to entirely cure or prevent such defects. In this study, we used two-dimensional gel electrophoresis (2-DE)/mass spectrometry (MS) to characterize differentially expressed
proteins in amniotic-fluid samples (AFSs) of embryonic day (E) 17.5 rat fetuses with
spina bifida aperta induced by
retinoic acid (RA). We identified five
proteins differentially expressed in AFSs of
spina bifida aperta, including three upregulated
proteins (
transferrin,
alpha-1 antiproteinase and
signal recognition particle receptor, B subunit [SRPRB] 55 kDa), two downregulated
proteins (
apolipoprotein A IV [APO A4] and Srprb 77 kDa). Specifically, we found 11 alpha-1
fetoprotein (AFP) fragments that were downregulated and 35 AFP fragments that were upregulated in AFSs from embryos with
spina bifida aperta. Of the downregulated AFP fragments, 72.7% (8/11) were confined to the AFP N-terminus (
amino acids [aas] 25-440) and 77.1% (27/35) of upregulated AFP fragments were confined to the AFP C-terminus (aas 340-596). We also confirmed APO A4 and AFP by immunoblot analysis. This is the first comparative proteomic study of AFSs from rat fetuses with
spina bifida aperta. We demonstrate proteomic alterations in the AFS of
spina bifida aperta, which may provide new insights in
neural tube defects and contribute to the prenatal screening.