Lysyl oxidase‐variant 2 (LOX‐v2) colocalizes with promyelocytic leukemia‐nuclear bodies in the nucleus

Lysyl oxidase‐variant 2 (LOX‐v2) is a novel variant of LOX that functions as an amine oxidase for the formation of collagen and elastin fibrils in the extracellular matrix (ECM). LOX‐v2 lacks the N‐terminal prepropeptide region of LOX but contains the C‐terminal domains required for amine oxidase activity. To study the cellular localization of LOX‐v2, we generated a recombinant construct of LOX‐v2 with an epitope tag at the C‐terminus and then transfected the recombinant construct into HEK293 cells. Upon ectopic expression, LOX‐v2 showed much higher expression in the nucleus than in the cytoplasm. In coimmunofluorescence staining with subnuclear structures, LOX‐v2 colocalized with the promyelocytic leukemia‐nuclear bodies (PML‐NBs). Further, the ectopic expression of LOX‐v2 increased global SUMOylation in the nucleus. PML‐NBs have been implicated in various cellular activities, including transcriptional regulation, DNA repair, cell cycle control, anti‐viral response, and apoptosis. Our findings strongly indicate that LOX‐v2 may be subject to different cellular processing from what LOX undergoes, playing a distinct functional role in the PML‐NBs, beyond the cross‐linking of the structural proteins.