Phosphatidylserine colocalizes with epichromatin in interphase nuclei and mitotic chromosomes

Abstract

Cycling eukaryotic cells rapidly re-establish the nuclear envelope and internal architecture following mitosis. Studies with a specific anti-nucleosome antibody recently demonstrated that the surface (“epichromatin”) of interphase and mitotic chromatin possesses a unique and conserved conformation, suggesting a role in postmitotic nuclear reformation. Here we present evidence showing that the anionic glycerophospholipid phosphatidylserine is specifically located in epichromatin throughout the cell cycle and is associated with nucleosome core histones. This suggests that chromatin bound phosphatidylserine may function as a nucleation site for the binding of ER and re-establishment of the nuclear envelope.

Keywords: :

• Chromatin
• confocal and deconvolution microscopy
• glycerophospholipid
• nuclear architecture

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

A.L.O. and D.E.O. were Visiting Scientists at the German Cancer Research Center (DKFZ, Heidelberg) in the laboratories of Peter Lichter and Harald Herrmann, and at MMCRI in the laboratory of I.P. I.P. was supported by grant HL35627 from NIH and a grant from the Maine Cancer Foundation, and institutional support from Maine Medical Center. C.P.H.V. was supported by NIH grant HL083151 and institutional support from the Maine Medical Center. Y.M. was supported by the DFG. This project was supported by the Protein, Nucleic Acid and Cell Imaging Core facility (I.P. and C.P.H.V.) of grant number P30RR030927/P30GM103392, Phase III COBRE in Vascular Biology (R. Friesel, P.I.), a grant supported by the National Center for Research Resources and the National Institute of General Medical Sciences. The authors thank M. Monestier (Temple University) for the gift of antibodies and helpful comments, and to L. Schermelleh (University of Oxford) and H. Leonhardt (Ludwig Maximilians University Munich) for generous assistance with 3-D SIM. K. Palczewski and D. Mustafi (Case Western Reserve University) generously provided an aliquot of mAb 4B6. Thanks are also extended to M. Cremer (LMU, Munich), M. Hergt (DKFZ) and A. Kirov (MMCRI).