Proliferative and protective effects of SurR9-C84A on differentiated neural cells Sara Baratchi a , Rupinder K. Kanwar a , Chun Hei Antonio Cheung b , Jagat R. Kanwar a, ⁎ a Institute of Biotechnology (BioDeakin), Institute for Technology Research and Innovation (ITRI), Deakin University, Australia b Department of Molecular Medicine and Pathology, Faculty of Medicine and Health Science, The University of Auckland, New Zealand abstract article info Article history: Received 14 April 2010 Received in revised form 31 May 2010 Accepted 29 June 2010 Keywords: SurR9-C84A Neuroprotection Neuroproliferation Neurodegenerative disease Targeting survivin has the ability to inhibit apoptosis and regulate mitosis for the protection of neuronal cells, and it offers several advantages for neuronal repair and protection. We found that the BIR motif mutant of survivin (SurR9-C84A) can bind to microtubules and regulate their stability, induce cell division, increase proliferation and activate the expression of cell cycle and neuronal markers in differentiated SK-N-SH and HCN-2 neurons. We further showed the protective effects of SurR9-C84A against post differentiation retinoic acid induced neurotoxicity. These abilities of SurR9-C84A offer a great potential for future neuronal repair therapy. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved. 1. Introduction The limited capacity of neuronal cells for proliferation and repair is the main cause of disability among patients suffering from neurode- generative disorders (Yang et al., 2001). The efficient generation and proliferation of neuronal cells is the focus of intense investigation in neuronal repair therapy (Lindvall et al., 2004). Various studies have been conducted to study targeting inhibitors of apoptosis (IAPs) to identify appropriate treatments for cancers and neurodegenerative diseases (Blancas and Moran, 2007; Kanwar et al., 2010; Kells and Connor, 2008; Liste et al., 2007; Shen et al., 2009; Xu et al., 1999). Although the role of survivin in early brain development has been studied (Jiang et al., 2005), no further efforts have been made to evaluate its potential role in neuroproliferation and protection. Among the different IAPs, survivin is a unique family member due to its dual effects on the inhibition of apoptosis and cell division (Altieri, 2008). During cell division, survivin has an intriguing function in the chromosomal passenger complex (CPC), which consists of survivin, aurora B kinase, INCEPT and borealin. Survivin dimerises with borealin and translocates to the central spindle during anaphase (Ruchaud et al., 2007). The presence of an intact baculovirus IAP repeat (BIR) motif in the structure of survivin is necessary for its involvement in the CPC, although the lack of a BIR motif does not inhibit proper localisation of the CPC to the central spindle. The survivin present at the CPC guides aurora B kinase to its substrate by phosphorylation at threonine 117 (Wheatley et al., 2004). Survivin also attaches to microtubules, improving their stability (Altieri, 2006), and enhances the correct alignment of chromosomes on mitotic spindles (Makrantoni and Stark, 2009). The inhibitory role of survivin during apoptosis occurs via its dimerisation with hepatitis B X- interacting protein (HBXIP) and its co-factor XIAP. This complex attaches to procaspase 9 and inhibits apoptosis through mitochon- drial and cytochrome C pathways (Marusawa et al., 2003). These abilities make it an ideal target for neuroprotection and proliferation. Survivin is highly expressed during the G2/M phase, but poorly expressed during the G0/G1 and S phases of the cell cycle (Altieri, 2005). Overexpression of survivin in inflammatory tissues (Tumes et al., 2009), traumatic brain injuries (Johnson et al., 2005; Ozisik et al., 2006) and cancers (Kanwar et al., 2001; Shi et al., 2007) has been reported previously. Different mutant forms of survivin have been studied so far, primarily for structural analysis, although a few have been studied for the purpose of cancer therapy, including survivin-T34A (2009), survivin-C84A (2006), survivin-T34A-C84A (2008) and survivin- D53A (2006) (Yan et al., 2006). Among these mutants, the BIR motif mutant has the unique ability to localise to the microtubule organising centre during interphase, indistinguishable from wild type survivin (Li et al., 1998), and does not interfere with any aspects of chromosome separation or cell cleavage during mitosis (Skoufias et al., 2000). Whereas the role of the T34A mutant, which cannot be phosphorylated, on different cell lines has been studied and the involved pathways have been characterised (Grossman et al., 1999; Islam et al., 2000; Kanwar et al., 2001, 2004b, 2010; Khan et al., 2009; Shankar et al., 2001), the neuroprotective effects of SurR9-C84A have not yet been investigated. SurR9-C84A is a BIR motif mutant of survivin in which the BIR domain structure is disturbed. Taking advantage of the above features, we report here for the first time the role of SurR9-C84A in the proliferation of differentiated Journal of Neuroimmunology 227 (2010) 120–132 ⁎ Corresponding author. Tel.: +61 3 52271148; fax: +61 3 52273402. E-mail address: jagat.kanwar@deakin.edu.au (J.R. Kanwar). 0165-5728/$ – see front matter. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.jneuroim.2010.06.024 Contents lists available at ScienceDirect Journal of Neuroimmunology journal homepage: www.elsevier.com/locate/jneuroim