Neural and orofacial defects in Folp1 knockout mice [corrected].
BACKGROUND
Folic acid is essential for the development of the nervous system and other associated structures. Mice deficient in the folic acid-binding protein one (Folbp1) gene display multiple developmental abnormalities, including neural and craniofacial defects. To better understand potential interactions between Folbp1 gene and selected genes involved in neural and craniofacial morphogenesis, we evaluated the expression patterns of a panel of crucial differentiation markers (Pax-3, En-2, Hox-a1, Shh, Bmp-4, Wnt-1, and Pax-1).


METHODS
Folbp1 mice were supplemented with low dosages of folinic add to rescue nullizygotes from dying in utero before gestational day 10. The gene marker analyses were carried out by in situ hybridization.


RESULTS
In nullizygote embryos with open cranial neural tube defects, the downregulation of Pax-3 and En-2 in the impaired midbrain, along with an observed upregulation of the ventralizing marker Shh in the expanded floor plate, suggested an important regulatory interaction among these three genes. Moreover, the nullizygotes also exhibit craniofacial abnormalities, such as cleft lip and palate. Pax-3 signals in the impaired medial nasal primordia were significantly increased, whereas Pax-1 showed no expression in the undeveloped lateral nasal processes. Although Shh was downregulated, Bmp-4 was strongly expressed in the medial and lateral nasal processes, highlighting the antagonistic activities of these molecules.


CONCLUSIONS
Impairment of Folbp1 gene function adversely impacts the expression of several critical signaling molecules. Mis-expression of these molecules, perhaps mediated by Shh, may potentially contribute to the observed failure of neural tube closure and the development of craniofacial defects in the mutant mice.
Tang
Louisa S
LS
Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, Texas 77030-3303, USA.
Finnell
Richard H
RH
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D019465:Craniofacial Abnormalities / Q000235:genetics*; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000097:blood; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005819:Genetic Markers; D005838:Genotype; D006710:Homocysteine / Q000097:blood; D006720:Homozygote; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009436:Neural Tube Defects / Q000235:genetics*; D011956:Receptors, Cell Surface
D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D005819:Genetic Markers; D011956:Receptors, Cell Surface; D006710:Homocysteine; D005492:Folic Acid