ALPHA-SYNUCLEIN DEFICIENCY IN THE C57BL/6JOlaHsd STRAIN DOES NOT MODIFY DISEASE PROGRESSION IN THE ME7-MODEL OF PRION DISEASE A. A. ASUNI, a,b * K. HILTON, a,b Z. SISKOVA, a,b K. LUNNON, a,b R. REYNOLDS, a,b V. H. PERRY a,b AND V. O’CONNOR b a CNS Inflammation Group, University of Southampton, UK SO16 7PX b School of Biological Sciences, University of Southampton, UK SO16 7PX Abstract—We previously detailed how intrahippocampal in- oculation of C57BL/6J mice with murine modified scrapie (ME7) leads to chronic neurodegeneration (Cunningham C, Deacon R, Wells H, Boche D, Waters S, Diniz CP, Scott H, Rawlins JN, Perry VH (2003) Eur J Neurosci 17:2147–2155.). Our characterization of the ME7-model is based on inocula- tion of this murine modified scrapie agent into C57BL/6J mice from Harlan laboratories. This agent in the C57BL/6J host generates a disease that spans a 24-week time course. The hippocampal pathology shows progressive misfolded prion (PrP Sc ) deposition, astrogliosis and leads to behavioural dys- function underpinned by the early synaptic loss that pre- cedes neuronal death. The Harlan C57BL/6J, although widely used as a wild type mouse, are a sub-strain harbouring a spontaneous deletion of -synuclein with the full description C57BL/6JOlaHsd. Recently -synuclein has been shown to ameliorate the synaptic loss in a mouse model lacking the synaptic chaperone CSP-. This opens a potential confound of the ME7-model, particularly with respect to the signature synaptic loss that underpin the physiological and behav- ioural dysfunction. To investigate if this strain-selective loss of a candidate disease modifier impacts on signature ME7 pathology, we compared cohorts of C57BL/6JOlaHsd (- synuclein negative) with the founder strain from Charles Riv- ers (C57BL/6JCrl, -synuclein positive). There were subtle changes in behaviour when comparing control animals from the two sub-strains indicating potentially significant conse- quences for studies assuming neurobiogical identity of both strains. However, there was no evidence that the absence of -synuclein modifies disease. Indeed, accumulation of PrP Sc , synaptic loss and the behavioural dysfunction associated with the ME7-agent was the same in both genetic back- grounds. Our data suggest that -synuclein deficiency does not contribute to the compartment specific processes that give rise to prion disease mediated synaptotoxicity and neurodegeneration. © 2010 IBRO. Published by Elsevier Ltd. All rights reserved. Key words: C57BL/6JCrl, C57BL/6JOlaHsd, neurodegenera- tion, synaptopathy, spontaneous-deletion. Intracerebral microinjection of murine modified scrapie (ME7) prion agent into the dorsal hippocampus of C57BL/6 mice is an established model of progressive hippocampal degeneration. Neuroanatomical, electrophysiological, and biochemical studies have shown that disease progression involves synaptic dysfunction typified by selective loss of CA1 stratum radiatum synapses. This loss correlates with electrophysiological and hippocampal based behavioural dysfunction at 12 weeks, a time that precedes overt clinical symptoms in this disease (Scott et al., 1994; Jeffrey et al., 2000a; Cunningham et al., 2003; Chiti et al., 2006). The neuropathology is characterized by activated microglia, marked astrogliosis, vacuolation, spongiform degenera- tion, and neuronal loss (Cunningham et al., 2003). Preced- ing this neuronal loss, a post-translational modification of the plasma membrane localized cellular prion protein (PrP c ) leads to accumulation of the conformationally al- tered isoform, PrP Sc (Williams et al., 1994, 1997; Prusiner, 1996; Herms et al., 1999; Jeffrey et al., 2000b; Morris et al., 2006). The generation of misfolded and extracellular accumula- tion of PrP Sc involves a complex cascade of protein and subcellular interactions (Sarnataro et al., 2004; Kovacs and Budka, 2008). The focus of synapses as a target of PrP associated protein misfolding coincides with the emergence of sub-compartment processes in modulating disease pro- gression in a number of proteinopathies (Gylys et al., 2004; Fuhrmann et al., 2007; Fein et al., 2008). Indeed, prion dis- ease and in particular the inoculation of the ME7-agent into the hippocampus of C57BL/6J mice has provided some of the best evidence for a compartment selective degeneration in which synaptic loss might be uncoupled from a preceding neuronal loss (Scott et al., 1994; Jeffrey et al., 2000a; Cun- ningham et al., 2003; Chiti et al., 2006). The mechanistic details of synaptic degeneration are poorly understood but a number of proteins which are misfolded and directly implicated in disease have also emerged as modulators of degenerative pathways. Among these is the identification through genetic interaction stud- ies two presynaptic proteins -synuclein and cysteine- string protein-alpha (CSP) (Chandra et al., 2005), that appear to contribute to molecular interactions which act against loss of the presynaptic compartment. Interestingly, the CSP paradigm is among the only genetic ablations in which the kind of compartment specific degeneration re- ported to occur in prion disease has been documented. Synucleins are a protein family with wide neuronal expression associated with selective localization to synap- tic terminals (Nakajo et al., 1993; Totterdell et al., 2004; *Corresponding author. Tel: 0044-023-80594187. E-mail address: asuni@mac.com (A. A. Asuni). Abbreviations: CSP, cysteine-string protein; GAPDH, Glyceraldehyde- 3-phosphate dehydrogenase; GFAP, glial fibrillary acidic protein; ME7, murine modified scrapie; NBH, brain homogenate prepared from nor- mal brains; PCR, polymerase chain reaction; PrP c , cellular prion protein. Neuroscience 165 (2010) 662– 674 0306-4522/10 $ - see front matter © 2010 IBRO. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.neuroscience.2009.10.047 662