The expression of acetyl coenzyme A carboxylase is related to megakaryocyte maturation

We have previously demonstrated that de novo fatty acid synthesis predominantly occurs in later phases of megakaryocyte maturation. Therefore we have investigated the expression of fatty acid synthase (FAS) and acetyl coenzyme A carboxylase (ACC), key enzymes for fatty acid synthesis in megakaryocytes at different phases of maturation. Immature and mature megakaryocytes were isolated. Guinea pig-specific FAS and ACC cDNA probes were prepared by reverse transcriptase reaction-polymerase chain reaction (RT-PCR). The probes were used to assess the expression of mRNA for ACC and FAS by Northern blotting. The hybrids were quantitated by densitometry. Endogenous megakaryocyte ACC was quantitated by virtue of its biotin content by Western blotting with streptavidin and enhanced chemiluminescence (ECL). The ratio of ACC mRNA between mature and immature megakaryocytes was 2.43 +/- 0.86, and the ratio of FAS mRNA was 0.50 +/- 0.13 (mean +/- SD, n = 4). The ratio of endogenous ACC in mature and immature megakaryocytes was 1.96 +/- 0.62 (n = 6). The study showed that the FAS mRNA was expressed in all phases of megakaryocyte maturation. However, both mRNA for ACC and endogenous ACC were demonstrated primarily in mature megakaryocytes. Thus de novo fatty acid synthesis in megakaryocytes may depend on the expression of ACC in mature cells. The expression of ACC occurs during the terminal phases of megakaryocyte maturation and may be a marker of megakaryocyte maturity.