Human lung enolase: cloning and sequencing of cDNA and its inducibility with dexamethasone

Corticosteroids used orally and intravenously lead to lung diseases and vascular disorder. To investigate whether enolase levels are also changed by treatment with synthetic steroid dexamethasone (as alteration in the enolase levels have been correlated with lung cancer) we performed the following studies. A cDNA library was prepared from poly(A) mRNA extracted from human lung fibroblast cells. cDNA clone HLE1 containing 1.7 kb insert coding for enolase was isolated. Its identity was confirmed by (a) translation of the hybrid selected mRNA and (b) nucleotide sequence analysis of the insert and comparison with known enolase sequences from other species. The lung enolase is coded by a polypeptide of 458 amino acid residues (mr = 49.5 kD). Nucleotide sequencing and derived amino acid sequence data suggest that the cloned enolase is non-neuronal isoform of enolase (NNE). In lung fibroblast cells, dexamethasone caused remarkable increase in the abundance of the enolase mRNA, which was concentration and time dependent. The induction by dexamethasone required de novo RNA synthesis but not de novo protein synthesis.