Ds. Straus et al., PROTEIN RESTRICTION SPECIFICALLY DECREASES THE ABUNDANCE OF SERUM-ALBUMIN AND TRANSTHYRETIN NUCLEAR TRANSCRIPTS IN RAT-LIVER, The Journal of nutrition, 124(7), 1994, pp. 1041-1051
The expression of the genes for serum albumin and several other plasma
proteins is decreased in animals consuming inadequate amounts of diet
ary protein. To define the specificity of this phenomenon, we examined
the effect of dietary protein restriction on the abundance of the mRN
A for nine genes in rat liver. The results of this and previous studie
s indicate that genes in liver can be divided into two classes based o
n their response to protein restriction. Group I genes (albumin, trans
thyretin, carbamyl phosphate synthetase-I, class I alcohol dehydrogena
se, insulin-like growth factor-I) exhibit decreased expression in resp
onse to protein restriction. In contrast, the expression of group II g
enes (hypoxanthine-guanine phosphoribosyl transferase, ubiquitin, H-fe
rritin, insulin like growth factor binding proteins-1, -2 and -4) is e
ither unchanged or increased in response to protein restriction. To in
vestigate the molecular mechanism(s) leading to the decreased level of
albumin and transthyretin mRNA in protein-restricted animals, the eff
ect of protein restriction on the abundance of albumin and transthyret
in nuclear transcripts was examined. The results demonstrated that pro
tein restriction specifically decreased the abundance of albumin and t
ransthyretin nuclear transcripts, indicating that the reduction in mRN
A levels is caused at least partly by a decrease in gene transcription
.