Expression of beta-amyloid precursor protein in the developing human spinal cord.
Human fetal spinal cords and other non-neural tissues from cases with gestational age from 6 to 21 weeks were examined with a panel of antibodies to different domains of beta-amyloid precursor proteins (beta-APPs). In the early developmental stages, the beta-APPs were expressed in three distinct layers, i.e., primitive neuroepithelial cell layer, mantle layer and marginal layer. beta-APP immunoreactivity was most prominent in cell bodies of putative neuroblasts located in the outer ventral part of the mantle layer. beta-APP expression diminished as the spinal cord matured and a weak residual immunoreactivity was detected exclusively in a subset of the anterior horn cells by 21 weeks gestational age. Throughout the gestational ages examined, no convincing beta/A4 immunostaining was seen in any of the spinal cord regions. Outside the spinal cord, beta-APP immunostaining was consistently present in (1) cell bodies and proximal nerves of immature neurons of dorsal root ganglia and in (2) myotubules, although these cells were devoid of beta/A4 immunoreactivity. Western blot analysis of fetal spinal cord revealed immunoreactive bands with apparent molecular weight between 100 and 140 kDa in the membrane-associated fraction, while soluble proteins with a molecular mass centered on 115 kDa were detected in the cytosolic fraction. Our results indicate that: (1) one or more isoforms of full length beta-APPs are expressed at very early gestational ages in the developing human spinal cord; (2) the normal metabolism of beta-APPs does not result in accumulations of beta/A4 fragments.
Arai
H
H
Department of Neurology, Motojima General Hospital, Gunma, Japan.
Higuchi
S
S
Matsushita
S
S
Yuzuriha
T
T
Trojanowski
J Q
JQ
Lee
V M
VM
D016564:Amyloid beta-Protein Precursor / Q000032:analysis*; D015153:Blotting, Western; D005314:Embryonic and Fetal Development / Q000502:physiology; D006801:Humans; D007124:Immunoenzyme Techniques; D009419:Nerve Tissue Proteins / Q000032:analysis*; D013116:Spinal Cord / Q000737:chemistry* / Q000196:embryology
D016564:Amyloid beta-Protein Precursor; D009419:Nerve Tissue Proteins