1. ¹Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
2. ²Chromatin Transcription and Regulation Laboratory, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
3. ³ARC Centre of Excellence for Biotechnology and Development, Clayton, Victoria, Australia

Correspondence: David A Jans, Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia. E-mail: david.jans@med.monash.edu.au

Received 16 August 2006; Accepted 29 November 2006; Published online 27 February 2007.

Abstract

Gene delivery into the nucleus of eukaryotic cells is inefficient, largely because of the significant barriers within the target cell of the plasma membrane and nuclear envelope. Recently, a group of basic proteins, including the HIV-1 Tat protein and the four core histones, have been shown to enter cells through a novel energy- and receptor-independent manner. Here, we show that engineered histone H2B proteins are able to mediate the efficient delivery of either green fluorescent protein or DNA into HeLa cells through the process of "Histone-Mediated Transduction" (HMT), with further enhancement achieved by utilizing a dimer of histones H2B and H2A. Subsequent nuclear delivery was accelerated approximately two-fold by the addition of an optimized nuclear localization signal to histone H2B, thereby increasing the affinity of interaction with components of the cellular nuclear import machinery, resulting in increased expression of a reporter gene. Further, we demonstrate that the domains responsible for this histone transduction are located in the N-terminal tail and globular regions of histone H2B. HMT represents a new, efficient, and technically non-demanding means to deliver DNA to the nucleus of intact cells, including embryonic stem cells, which has important applications in gene therapy and cancer therapeutics.