Advances in Bioscience and Biotechnology, 2014, 5, 546-556 Published Online May 2014 in SciRes. http://www.scirp.org/journal/abb http://dx.doi.org/10.4236/abb.2014.56064 How to cite this paper: Reddy, D., Bhattacharya, S. and Gupta, S. (2014) Histone Chaperones: Functions beyond Nucleo- some Deposition. Advances in Bioscience and Biotechnology, 5, 546-556. http://dx.doi.org/10.4236/abb.2014.56064 Histone Chaperones: Functions beyond Nucleosome Deposition Divya Reddy, Saikat Bhattacharya, Sanjay Gupta * Epigenetics and Chromatin Biology Group, Gupta Lab., Cancer Research Institute, Advanced Centre for Treatment, Research and Education in Cancer, Tata Memorial Centre, Navi Mumbai, India Email: dvelga@actrec.gov.in , sbhattacharya@actrec.gov.in , * sgupta@actrec.gov.in Received 4 April 2014; revised 5 May 2014; accepted 15 May 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Histones, the structural unit of chromatin, must be assembled/dissembled to preserve or change chromatin organization in accordance to cellular needs. Initially, function of histone chaperones was thought to be only “histone carriers/vehicles”, but now with accumulating evidences they are known to be the key actors of histone metabolism. With this outburst of knowledge, histone cha- perones are now placed at the center of gene regulation, having roles to play in DNA replication, repair and transcription. This review will focus on the current knowledge we have about the role of histone chaperones in regulating cellular processes and their relation to disease. In addition, we discuss the potential of histone chaperones as a therapeutic target. Keywords Histones, Chromatin, Cancer, Therapeutic Target 1. Introduction If the DNA of all the cells of a human body is joined end to end, it can cover the distance from the sun to the Pluto and back. It was always a matter of interest to understand how the DNA of a cell which is over a meter long is packaged inside the nucleus only about 10 microns in diameter. Later, it was found that basic proteins called “histones” play a major role in packaging of DNA, in a very orderly fashion so that it can be unwound quickly when required in specific foci, and then wound back without getting into a tangle. During compaction, at first ~147 bp of DNA is wrapped around histone octamer comprising 2 each of histones H2A, H2B, H3, H4, thus giving rise to nucleosome core particle (NCP)—a basic unit of chromatin [1]. This conformation achieved is also known as “beads on a string structure” or 10-nm chromatin fibre. The nucleosome assembly occurs in an * Corresponding author.