Developmental changes in carnitine octanoyltransferase gene expression in intestine and liver of suckling rats

Carnitine octanoyltransferase (COT), which facilitates the transport of sho rtened fatty acyl-CoAs from peroxisomes to mitochondria, is expressed in th e intestinal mucosa of suckling rats; its mRNA levels increase rapidly afte r birth, remain steady until day 15, and decrease until weaning, when basal , adult values are established, which remain unchanged thereafter. The proc ess seems to be controlled at the transcriptional level since the developme ntal pattern of mRNA coincides with that of pre-mRNA values. Dam's milk may influence the intestinal expression of GOT, since mRNA levels at birth are low and increase after the first lactation. Moreover, mRNA levels decrease in rats weaned on day 18 or 21, COT is also expressed in the liver of suck ling rats. Hepatic COT mRNA is maximal at day 3, remains constant until day 9, and decreases thereafter; this pattern is also similar to that of pre-m RNA values. The profile of expression of COT in intestine and liver strongl y resembles that of mitochondrial 3-hydroxy 3-methylglutaryl-coenzyme A syn thase and carnitine palmitoyltransferase I, suggesting that analogous trans cription factors modulate ketogenesis and mitochondrial and peroxisomal fat ty acid oxidation. (C) 2001 Academic Press.