Mass spectroscopy identifies the splicing-associated proteins, PSF, hnRNP H3, hnRNP A2/B1, and TLS/FUS as interacting partners of the ZNF198 protein associated with rearrangement in myeloproliferative disease.

ZNF198 is fused with FGFR1 in an atypical myeloproliferative disease that results in constitutive activation of the kinase domain and mislocalization to the cytoplasm. We have used immunoprecipitation of a GFP-tagged ZNF198 combined with MALDI-TOF mass spectroscopy to identify interacting proteins. P splicing factor (PSF) was identified as one of the proteins and this interaction was confirmed by Western blotting. Other proteins identified were the spliceosomal components hnRNP A2/B1, hnRNP H3, and TLS/FUS. PSF is also known to interact with PTB, another member of the hnRNP family of proteins, and we further demonstrated that PTB interacts with ZNF198. The interaction between TLS/FUS and ZNF198 was confirmed using Western blot analysis. In 293 cells expressing the ZNF198/FGFR1 fusion protein, neither PSF nor PTB binds to the fusion protein, possibly because of their differential localization in the cell.