Low prevalence of autoantibodies to CENP-H, -I, -K, -L, -M, -N, -T and -U in a Japanese cohort of anti-centromere positive samples

Abstract

Objective: The constituents of the centromere region, centromere protein (CENP)-A, -B, and -C, are mainly targeted by anticentromere antibodies (ACA). Many other proteins also assemble around CENP-A nucleosomes in interphase nuclei to form the interphase centromere complex (ICEN). CENP-H, -I, -K, -L, -M, -N, -T, and -U have been reported as the constitutive components of ICEN. In this study, we examined the reactivities of ACA to the 8 CENPs for the purpose of investigating their autoantigenicity.

Methods: Sera from 95 patients with ACA were tested by western blotting (WB) and enzyme-linked immunosorbent assay (ELISA) with the recombinant C-terminal of CENP-B (Ct-CENP-B). Next, the sera were examined for autoantibodies against the 8 CENPs by WB with each recombinant protein. Furthermore, the coiled-coil motifs and granzyme B (GB) cleavage for various CENPs were analyzed with computer tools.

Results: Out of 95 ACA-positive sera, 85 and 93 sera were positive for anti-Ct-CENP-B antibodies in WB and in ELISA, respectively. In WB using the 8 CENPs, no sera reacted to any other 7 CENPs, except 1 serum, which reacted weakly to CENP-T. We were unable to find any obvious relationships between the autoantigenicity of CENPs and coiled-coil-forming probabilities or potential substrates for GB.

Conclusion: This study demonstrates that ACA rarely target the 8 CENPs, in contrast to CENP-B. Protein structures might not contribute in a major way to the autoantigenicity of CENPs.

Keywords::

• Autoantibody
• centromere
• systemic sclerosis

Acknowledgments

We thank Dr Masashi Ikeno of the Institute for Comprehensive Medical Science, Fujita Health University, Dr Kinya Yoda of Nagoya University; and Dr Todokoro at RIKEN for their generous provision of CENP cDNAs.

Declaration of interest

This work was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (to Y.M., K.S., and M.A.) and a grant from the Ministry of Health, Labour and Welfare of Japan (to Y.M.). The authors declared no conflict of interest.