Identification of variants of 5‐lipoxygenase mRNA in human B lymphocytic cell lines

Abstract

5-lipoxygenase (5-LO) catalyzes the initial reactions leading to the conversion of arachidonic acid into a number of biologically important mediators of inflammation. We seek to better understand the control of the biosynthesis of 5-LO products which is linked to inflammatory diseases such as asthma and atherosclerosis. In this study we used the human acute lymphocytic leukemia and Burkitt lymphoma cell lines REH and Raji, respectively, to investigate whether alternative variants of 5-LO mRNA are produced. Using reverse-transcription of extracted mRNA coupled with PCR, followed by molecular cloning and sequencing experiments, we have identified 4 different variants of 5-LO mRNA in these cell lines including the full length mRNA containing all 14 exons with the expected splicing sites. Amongst the alternative isoforms, one resulting from the exclusion of exon 13 was identified in both cell lines and was present in approximately 30% of the generated clones. This exclusion of exon 13 does not induce a reading frame shift but would result in a translation product missing 57 amino acids near the carboxyl terminal. Experiments are underway to determine whether the translation products of these variant isoforms are expressed and have an impact on the capacity of cells to synthesize 5-LO products. (Supported by the Canadian Institutes of Health Research and the Canada Research Chairs Program)