Long-chain acyl-CoA esters and acyl-CoA binding protein are present in thenucleus of rat liver cells

A detailed analysis of the subcellular distribution of acyl-CoA esters in r at liver revealed that significant amounts of long-chain acyl-CoA esters ar e present in highly purified nuclei. No contamination of microsomal or mito chondrial marker enzymes was detectable in the nuclear fraction. C16:1 and C18:3-CoA esters were the most abundant species, and thus, the composition of acyl-CoA esters in the nuclear fraction deviates notably from the overal l composition of acyl-CoA esters in the cell. After intravenous administrat ion of the non-beta-oxidizable [C-14]tetradecylthioacetic acid (TTA), the T TA-CoA ester could be recovered from the nuclear fraction. Acyl-CoA esters bind with high affinity to the ubiquitously eh-pressed acyl-CoA binding pro tein (ACBP), and several lines of evidence suggest that ACBP functions as a pool former and transporter of acyl-CoA esters in the cytoplasm. By using immunohistochemistry, immunofluorescence microscopy, and immunoelectron mic roscopy we demonstrate that ACBP localizes to the nucleus as web as the cyl oplasm of rat liver cell and rat hepatoma cells, suggesting that ACBP may a lso be involved in regulation of acyl-CoA-dependent processes in the nucleu s.