Molecular cloning of rat leukemia inhibitory factor receptor α-chain gene and its expression during pregnancy

Leukemia inhibitory factor (LIF) is a secreted glycoprotein and a pluripotent growth factor that acts on diverse cell systems. LIF transmits its effects via binding to transmembrane receptors, of which both high- and low-affinity forms have been identified. In this study, we analyzed the structure and expression of rat LIF receptor α-chain (rLIFR α) cDNA. A full-length clone of the cDNA encoding the membrane-bound form of rLIFR α protein was prepared by a combination of LA-PCR and 5' RACE using DNA reverse-transcribed from total RNA isolated from the livers of day-12 and day-14 pregnant rats as templates. The nucleotide sequence of a full-length clone was determined and further confirmed by analysis of shorter DNA fragment prepared by PCR using pfu polymerase. The gene for rLIFR α encodes a 1093 amine acid residue protein. The rLIFR α protein shows a high degree of similarity to mouse and human LIF receptor α-chain protein (89% and 76% amino acid sequence identifies, respectively). Only one molecular species of mRNA for the rLIFR α gene was detected in the liver and placenta. rLIFR α was expressed in liver of both non-pregnant and pregnant rats. The level of mRNA for the rLIFR α gene in placenta was maximum on day 16 of pregnancy.