Another part of the covalent binding to lipids resistant to mild acid media might also be attributed to the formation of ethyl esters of fatty acids. It is known that
liver microsomes and cytosol contain enzyme systems
able to esterify free fatty acids or transesterify other esters
to ethyl esters
. Whether nuclear preparations from
mammary tissue have similar ability remains to be established. Irrespectively of the present lack of knowledge
about the structure of the reaction products formed, it is
not unexpected to envisage that the alteration of nuclear
membranes by their reaction with either acetaldehyde or
1-hydroxyethyl or resulting from ester formation with
ethanol, might lead to profound alterations in liver nuclear functions. It is well established that ethanol also strikingly alters other liver membranes and their fluidity. It
is known that nuclear lipids may be part of an intracellular signaling system modulating protein kinase C, an enzyme involved in phosphorylation of nuclear proteins.
The covalent binding to nuclear phospholipids deserves
special interest since they have a known ability to regulate
gene function, nucleosome structure, RNA synthesis and
activation of DNA polymerase alpha
. Past studies
from the laboratory reported correlations between alterations in nuclear lipids resulting from a free radical attack
and the different response of the rat strains employed to
the carcinogenic effects of CCl4