5-Lipoxygenase in mouse cerebellar Purkinje cells.

It has been suggested that the enzymatic pathway of 5-lipoxygenase (5-LOX) influences brain functioning and pathobiology. The mRNAs for both the enzyme 5-LOX and its activating protein FLAP have been found in the cerebellum. In this work, we investigated the cellular expression of 5-LOX in the adult mouse cerebellar cortex. We used the in situ mRNA hybridization assay, immunocytochemistry, laser capture microdissection, and our previously developed method for assaying the DNA methylation status of a putative mouse 5-LOX promoter. Since both 5-LOX mRNA in situ hybridization signal and FLAP immunoreactivity co-localize with calbindin 28 kD immunoreactivity (a Purkinje cell marker) but not with S-100β immunoreactivity (a Bergmann glia marker), the suggestion is that the 5-LOX pathway is expressed in cerebellar Purkinje cells. We found that methylation in the sites targeted by methylation-sensitive restriction endonucleases AciI and HinP1I but not BstUI and HpaII was greater in DNA samples obtained from a high-5-LOX-expressing cerebellar region (Purkinje cells) versus a low-5-LOX-expressing region (the molecular cell layer), suggesting a possible epigenetic contribution to the cell-specific 5-LOX expression in the cerebellum. We propose that Purkinje cell-localized 5-LOX and FLAP expression may be involved in the cerebellar synthesis of leukotrienes and/or could influence the Dicer-mediated microRNA formation and processes of neuroplasticity.