Recombinant Human Centromere Protein B (CENP-B) [His]

The oncogenic transcription factor forkhead box Ml (FoxMl) is overexpressed in a number of different carcinomas, whereas its expression is turned off in terminally differentiated cells. For this reason, FoxMl is an attractive target for therapeutic intervention in cancer treatment. As a first step toward realizing this goal, in this study, using a high-throughput, cell-based assay system, we screened for and isolated the antibiotic thiazole compound Siomycin A as an inhibitor of FoxMl. Interestingly, we observed that Siomycin A was able to down-regulate the transcriptional activity as well as the protein and mRNA abundance of FoxMl. Consequently, we found that the downstream target genes of FoxMl, such as Cdc25B, Sarvivin, and CENPB, were repressed. Also, we observed that consistent with earlier reports of FoxMl inhibition, Siomycin A was able to reduce anchorage-independent growth of cells in soft agar. Furthermore, we found that Siomycin A was able to induce apoptosis selectively in transformed but not normal cells of the same origin. Taken together, our data suggest that FoxMl inhibitor Siomycin A could represent a useful starting point for the development of anticancer therapeutics.

Background: Anticentromere autoantibodies have been reported to be associated with scleroderma and serve as a marker in different rheumatic diseases in humans. Major centromere autoantigens described so far include constitutive kinetochore proteins such as CENPA, CENPB, CENPC and CENPH and facultative proteins such as CENPE. CENPF and INCENP. We examined the inner kinetochore component CENPI as a new putative centromere autoantigen in scleroderma patients. Methods: To test for the presence of CENPI centromere autoantibodies, 72 sera from patients with systemic lupus erythematosus and systemic sclerosis were assayed by immunofluorescence and further tested by immunoblots with an Nt-CENPI recombinant protein. Results: 8 out of 31 (25.8%) patients diagnosed of scleroderma or Undifferentiated Connective Tissue Disease (UCTD) produced anti-CENPI autoantibodies. Epitopes were demonstrated to be located mainly but not exclusively in the N-terminal domain of the human CENPI protein. Five of the 8 (62.5%) CENPI positive sera also had other autoantibodies related to primary biliary cirrhosis. Further, two patients (25%) with anti-CENPI autoantibodies had concurrent diagnosis of primary biliary cirrhosis. Conclusions: This study demonstrates that CENPI, a centromere protein that localizes to the inner kinetochore structure, is a human autoantigen. The significance of anti-CENPI autoantibodies could be relevant in scleroderma patients as a marker for concurrent autoimmune liver disease. (C) 2011 Elsevier B.V. All rights reserved.