Wj. Lukiw et al., RUN-ON GENE-TRANSCRIPTION IN HUMAN NEOCORTICAL NUCLEI - INHIBITION BYNANOMOLAR ALUMINUM AND IMPLICATIONS FOR NEURODEGENERATIVE DISEASE, Journal of molecular neuroscience, 11(1), 1998, pp. 67-78
The incorporation of [alpha-P-32]-uridine triphosphate into DNA transc
ription products was examined in short post-mortem interval (PMI) huma
n brain neocortical nuclei (n, 22; PMI, 0.5-24 h) using run-on gene tr
anscription. Reverse Northern dot-blot hybridization of newly synthesi
zed RNA against either total cDNA or Alu repetitive DNA indicated that
human brain neocortical nuclei of up to 4-h PMI were efficient in inc
orporating radiolabel into new transcription products, after which the
re was a graded decline in de novo RNA biosynthetic capacity. To test
the effects of 0-3000 nM concentrations of ambient aluminum on RNA pol
ymerase I (RNAP I) and RNA polymerase II (RNAP II) transcription, dot
blots containing 0.5, 1.0, 2.0, and 5.0 mu g of DNA for (1) the human-
specific Alu repetitive element (2) the neurofilament light (NFL) chai
n, and (3) glial fibrillary acidic protein (GFAP) were Northern hybrid
ized against newly synthesized radiolabeled total RNA. These DNAs repr
esent heterogeneous nuclear RNA (hnRNA), neuronal-, and glial-specific
markers, respectively. We report here a dose-dependent repression in
the biosynthetic capabilities of brain RNAP II in the range of 50-100
nM aluminum, deficits similar to those previously described using a ra
bbit neocortical nuclei transcription system and at concentrations tha
t have been reported in Alzheimer's disease (AD) euchromatin. Transcri
ption from RNAP II and the neuron-specific NFL gene in the presence of
aluminum was found to be particularly affected. These findings suppor
t the hypothesis that brain gene transcription in the presence of trac
e amounts of ambient aluminum impairs mammalian brain DNA to adequatel
y read out genetic information.