Effects of arsenic on the topology and solubility of promyelocytic leukemia (PML)-nuclear bodies

Promyelocytic leukemia (PML) proteins are involved in the pathogenesis of acute promyelocytic leukemia (APL). Trivalent arsenic (As3+) is known to cure APL by binding to cysteine residues of PML and enhance the degradation of PML-retinoic acid receptor a (RAR alpha), a t (15;17) gene translocation product in APL cells, and restore PML-nuclear bodies (NBs). The size, number, and shape of PML-NBs vary among cell types and during cell division. However, topological changes of PML-NBs in As3+- exposed cells have not been well-documented. We report that As3+- induced solubility shift underlies rapid SUMOylation of PML and late agglomeration of PML-NBs. Most PML-NBs were toroidal and granular dot-like in GFPPML-transduced CHO-K1 and HEK293 cells, respectively. Exposure to As3+ and antimony (Sb3+) greatly reduced the solubility of PML and enhanced SUMOylation within 2 h in the absence of changes in the number and size of PML-NBs. However, the prolonged exposure to As3+ and Sb3+ resulted in agglomeration of PML-NBs. Exposure to bismuth (Bi3+), another Group 15 element, did not induce any of these changes. ML792, a SUMO activation inhibitor, reduced the number of PML-NBs and increased the size of the NBs, but had little effect on the As3+- induced solubility change of PML. These results warrant the importance of As3+- or Sb3+- induced solubility shift of PML for the regulation intranuclear dynamics of PML-NBs.

Automated summary

Promyelocytic leukemia (PML) proteins play a role in the development of acute promyelocytic leukemia (APL) and can be affected by trivalent arsenic (As3+). The exposure to As3+ can lead to changes in PML-NBs, including solubility shift, SUMOylation, and late agglomeration. Understanding these changes is important for the regulation of intranuclear dynamics of PML-NBs.