Expression of a carboxy-terminal region of the beta-amyloid precursor protein in a heterogeneous culture of neuroblastoma cells: evidence for altered processing and selective neurotoxicity.
Six independent clonal isolates from a morphologically heterogeneous human neuroblastoma cell line stably expressed several products of the human amyloid precursor protein (APP) from an introduced DNA construct; the "substrate-adherent" phenotype (fibroblast-like cells) predominated in all 6; these displayed immunoreactivity of vimentin, but little to no reactivity of neuron-specific enolase. A stably transfected isolate which did not show any expression from the identical construct (presumably because of a position effect) exhibited the predominantly neuronal phenotype of the parental cells (neuron-specific enolase positive). These results suggest selective neurotoxicity of the expressed products. Two of the 6 stably expressing cell lines showed a decrease of native mRNA for APP to levels that were 1/4-1/3 that of the parental cells and a decrease of their growth rates to half that of the parental cells; these decreased growth rates were improved by conditioned medium from the parental cell line. Western blot analysis revealed at least four distinct fragments of the COOH-terminus of APP in the isolate which expressed protein and mRNA in greatest abundance, suggesting that overexpression of APP in a human neural cell line leads to aberrant cleavage of APP.
Fukuchi
K
K
Department of Pathology, University of Washington, Seattle 98195.
Kamino
K
K
Deeb
S S
SS
Furlong
C E
CE
Sundstrom
J A
JA
Smith
A C
AC
Martin
G M
GM
D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000737:chemistry; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D017077:Culture Media, Conditioned; D005819:Genetic Markers / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000737:chemistry; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D012333:RNA, Messenger / Q000096:biosynthesis; D014162:Transfection / Q000235:genetics; D014407:Tumor Cells, Cultured
D016564:Amyloid beta-Protein Precursor; D017077:Culture Media, Conditioned; D005819:Genetic Markers; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger