Research Associate St. Boniface Hospital Albrechtsen Research Centre Winnipeg, Manitoba, Canada
Mohammad Sabbir (St. Boniface Hospital Albrechtsen Research Centre)| Carla Taylor (St. Boniface Hospital Albrechtsen Research Centre, St. Boniface Hospital Albrechtsen Research Centre)| Peter Zahradka (University of Manitoba, University of Manitoba)
The arachidonate 12-lipoxygenase (ALOX12) gene encodes an enzyme that acts on polyunsaturated fatty acid substrates and generates bioactive lipid mediators regulating a variety of biological processes associated with various disease pathologies. The human genome assembly (version GRCh38/hg38) revealed that the ALOX12 gene is overlapped by a previously uncharacterized antisense long non-coding RNA (lncRNA) designated as ALOX12-antisense 1 (ALOX12-AS1) indicating a possibility of antisense-sense regulation of the coding ALOX12. Furthermore, based on expressed sequence tag (EST) mapping, the Ensemble database revealed the existence of multiple transcriptional isoforms of ALOX12-AS1. Nine transcripts successively numbered as 201-209 are supported by at least one EST. Therefore, the objective of this study was to characterize human tissue and cell-type-specific expression as well as intracellular localization of ALOX12-AS1 lncRNA isoforms. Reverse transcription polymerase chain reaction and northern blotting-based studies revealed that ALOX12-AS1-201 and -202 are the dominant transcripts expressed in a variety of adult primary human tissues including adipose, artery, bone marrow, cerebellum, cortex, intestine, liver, smooth muscle, and skin tissues. Furthermore, RNA fluorescence in situ hybridization using primary adult human tissues as well as five transformed human cell lines (A431: skin epithelial, EA.hy926: endothelial, THP-1: monocytic, HEK293: embryonic kidney-derived, and HepG2: hepatoma-derived) revealed cell-type-specific expression and intracellular localization of the lncRNA. ALOX12-AS1-201 and -202 isoforms were differentially localized in the cytosol, nucleoplasm, as well as nucleoli, and the subcellular distribution exhibited variation depending on the cell-type and cell division state. The tissue and cell-type-specificity of ALOX12-AS1 lncRNA isoforms indicate that the isoforms might be involved in cell-type-specific regulation of ALOX12. This has been further reinforced by the overlapping nature of specific antisense-sense sequence elements involving both genes. Future studies are warranted to unravel the details of potential antisense-sense regulatory mechanism which is beyond the scope of the present study. Overall, this study provided a starting point to unravel a lncRNA-mediated regulation of ALOX12 that may underlie the generation of potent bioactive lipid mediators associated with disease pathogenesis.