Changes in sialylation in homozygous Sp2H mouse mutant embryos.
BACKGROUND
The splotch (Sp(2H)), Pax-3 mutant mice are characterized by neurulation defects, neural crest deficiencies, and altered somitogenesis. A link connecting all morphological abnormalities in the Pax-3 homozygous embryos is the composition of extracellular matrix and misexpression of cell adhesion molecules. The neural cell adhesion molecule (NCAM) is one of the Pax-3 target genes. Its adhesive properties depend on the attached polysialic acid (PSA). We have studied whether NCAM sialylation has been affected in the Pax-3 mutant embryos.


METHODS
Genotyping of embryos was determined using polymerase chain reaction. The periodate-resorcinol method was used for quantitative determination of sialic acid. Immunoblotting was used to detect sialylated NCAM isoforms and sialic acids on the blot. This antibody was also used to detect PSA-NCAM spatial expression.


RESULTS
Quantitative determination of sialic acid at days 10.5-13.5 showed decreased sialic acid content in Sp(2H) homozygotes. The results of both techniques used in evaluating the expression of PSA-NCAM isoforms in our study indicate that the 180-kDa isoform is decreased in homozygous Splotch (Sp(2H)) embryos. Immunohistochemistry showed decreased staining in the neural tube, ganglion VIII, (day 13.5), frontal lobe, olfactory bulb, and neuroblastic retinal cells (day 18.5).


CONCLUSIONS
PSA-NCAM is present in Sp(2H) embryos of all genotypes, starting on developmental day 9.5. Sialylation of the 180-kDa NCAM isoform begins to decrease on day 12.5 in Sp(2H) homozygotes. Reduced NCAM sialylation could contribute to the decreased migration of cells in the sensory organs.
Glogarová
Katerina
K
Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Videnská 1083, 142 20 Prague 4, Czech Republic.
Buckiová
Daniela
D
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics*; D004622:Embryo, Mammalian / Q000378:metabolism*; D005260:Female; D006720:Homozygote; D008297:Male; D051379:Mice; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors / Q000235:genetics*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D019006:Neural Cell Adhesion Molecules; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; C068686:Pax3 protein, mouse; D019158:N-Acetylneuraminic Acid