EXPRESSION OF CYP2E1 IN HUMAN LUNG AND KIDNEY DURING DEVELOPMENT AND IN FULL-TERM PLACENTA - A DIFFERENTIAL METHYLATION OF THE GENE IS INVOLVED IN THE REGULATION PROCESS

Methylation of dinucleotide CG residues located in the 5' end of the C YP2E1 gene has been demonstrated to play a role in the control of gene expression in the human developing liver. This study was undertaken t o examine the CYP2E1 RNA content of human lung, kidney and full-term p lacenta and to determine whether the expression of CYP2E1 was controll ed by its methylation status in these tissues. CYP2E1 was expressed at a very low lever in the lung and kidney at whatever age, and at a var iable level in full-term placentas. The restriction profile of genomic DNA was identical in lung and kidney and corresponded to a heavy meth ylation of HpaII/MspI sites located within the promoter, the first exo n and first intron of the CYP2E1 gene. A different pattern of methylat ion was obtained in full-term placentas, indicating that CpG residues located in the 5' end of the gene were predominantly but not fully dem ethylated. However, the variable level of CYP2E1 RNA in full-term plac entas suggests the involvement of other elements in the regulation pro cess of CYP2E1 in this tissue.