1 Scientific RepoRts | 7:41221 | DOI: 10.1038/srep41221 www.nature.com/scientificreports Phosphorylated Histone 3 at Serine 10 Identifes Activated Spinal Neurons and Contributes to the Development of Tissue Injury- Associated Pain Jose Vicente Torres-Pérez 1 , Péter Sántha 2 , Angelika Varga 3 , peter Szucs 3,4 , Joao Sousa- Valente 1 , Botond Gaal 4 , Miklós Sivadó 3,4 , Anna P Andreou 1 , Sara Beattie 1 , Bence Nagy 5 , Klara Matesz 4 , J. Simon C. Arthur 6 , Gábor Jancsó 2 & Istvan Nagy 1 Transcriptional changes in superfcial spinal dorsal horn neurons (SSDHN) are essential in the development and maintenance of prolonged pain. Epigenetic mechanisms including post-translational modifcations in histones are pivotal in regulating transcription. Here, we report that phosphorylation of serine 10 (S10) in histone 3 (H3) specifcally occurs in a group of rat SSDHN following the activation of nociceptive primary sensory neurons by burn injury, capsaicin application or sustained electrical activation of nociceptive primary sensory nerve fbres. In contrast, brief thermal or mechanical nociceptive stimuli, which fail to induce tissue injury or infammation, do not produce the same efect. Blocking N-methyl-D-aspartate receptors or activation of extracellular signal-regulated kinases 1 and 2, or blocking or deleting the mitogen- and stress-activated kinases 1 and 2 (MSK1/2), which phosphorylate S10 in H3, inhibit up-regulation in phosphorylated S10 in H3 (p-S10H3) as well as fos transcription, a down-stream efect of p-S10H3. Deleting MSK1/2 also inhibits the development of carrageenan-induced infammatory heat hyperalgesia in mice. We propose that p-S10H3 is a novel marker for nociceptive processing in SSDHN with high relevance to transcriptional changes and the development of prolonged pain. Prolonged pain presents a major unmet clinical need because the currently available analgesics, due to their low efcacy, ofen provide unsatisfactory pain relief 1 . Attempts to translate promising candidate molecules into clinically useful efective analgesics have repeatedly failed in the last three decades. Terefore, in order to identify targets for the development of novel analgesics to improve the relief of prolonged pain, alternative approaches to elucidate fundamental mechanisms must be employed. Te development of prolonged pain depends on long-term increase in the efcacy of nociceptive signal trans- duction, which includes activity-dependent increase in the excitability and activity (sensitisation) of, and altered synaptic strength between, neurons involved in nociceptive processing 2,3 . Although sensitisation occurs at all levels of the pain-processing pathways 4 , this process is particularly important in the superfcial spinal dorsal horn, because neuronal circuitries in that area form the “gateway” of nociceptive information towards supraspinal cen- tres where the pain experience manifests 5 . Sensitisation including that of spinal cord neurons (spinal sensitisation) involves activity-dependent post-translational changes in membrane molecules and changes in gene transcription which respectively occur 1 nociception Group, Section of Anaesthetics, Pain Medicine and intensive care, Department of Surgery and cancer, Imperial College London, London, SW10 9NH, United Kingdom. 2 Department of Physiology, University of Szeged, Szeged, H-6720, Hungary. 3 MTA-DE-NAP B-Pain Control Research Group, University of Debrecen, Debrecen, H- 4012, Hungary. 4 Department of Anatomy, Histology and Embryology, University of Debrecen, Debrecen, H-4012, Hungary. 5 The Ipswich Hospital, Ipswich, IP4 5PD, United Kingdom. 6 Division of cell Signalling and immunology, College of Life Sciences, Sir James Black Centre, University of Dundee, Dundee DD1 5EH, United Kingdom. Correspondence and requests for materials should be addressed to I.N. (email: i.nagy@imperial.ac.uk) Received: 09 June 2016 Accepted: 16 December 2016 Published: 25 January 2017 OPEN