G. Poznanovic et al., PROPERTIES OF NUCLEAR MATRIX PROTEINS THAT BIND THE 5'-FLANKING REGION OF THE HAPTOGLOBIN GENE ARE CHANGED DURING THE ACUTE-PHASE RESPONSE, Cell biology international, 20(11), 1996, pp. 751-762
It was previously shown that during the acute-phase response-induced e
levated transcription of the rat haptoglobin gene, protein p55 and the
lamins mediate the increased binding of restriction fragment II (-541
/-146) via a 38 bp adenine tract lying 147 bp upstream from the haptog
lobin gene cis element (-165/-56), to scaffold type II-like nuclear ma
trices. Here we show that the fragment II binding pattern to greater t
han or equal to 40 kDa proteins of nuclear matrices analogous to type
I scaffolds is more complex. Fragment II bound conspicuously to a 40 a
nd less so to p55, a 60 kDa protein and the lamins of control matrices
. During increased gene transcription, it bound prominently to p55, th
e lamins, and less so to 45 and 52 kDa proteins. This was accompanied
by the tenacious binding of the DNA to isolated nuclear matrices in vi
tro and post-translational modifications of certain matrix proteins. T
he lamins and p55 demonstrated a greater N-acetylglucosamine/sialic ac
id content and p55 an increased in vitro phosphorylation by a nuclear
matrix-associated cyclic-nucleotide-independent kinase, The acute-phas
e response also caused an increased partitioning of p55 with the nucle
ar matrix. It was concluded that, as a result of a molecular remodelli
ng of the nuclear matrix at the point of contact with chromatin, the n
ature of its association with region II DNA changed during elevated ha
ptoglobin gene expression. (C) 1996 Academic Press Limited