ORIGINAL PAPER Intermediate filaments are important for astrocyte response to oxidative stress induced by oxygen–glucose deprivation and reperfusion Yolanda de Pablo • Michael Nilsson • Marcela Pekna • Milos Pekny Accepted: 29 May 2013 / Published online: 12 June 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract As a response to central nervous system injury, astrocytes become reactive. Two cellular hallmarks of reac- tive gliosis are hypertrophy of astrocyte processes and upregulation of intermediate filament (nanofilament) proteins glial fibrillary acidic protein (GFAP), vimentin, nestin, and synemin. Astrocytes in mice devoid of GFAP and vimentin (GFAP -/- Vim -/- ) do not form cytoplasmic intermediate filaments. GFAP -/- Vim -/- mice develop larger infarcts after ischemic stroke (Li et al. in J Cereb Blood Flow Metab 28(3):468–481, 2008). Here, we attempted to analyze the underlying mechanisms using oxygen–glucose deprivation (OGD), an in vitro ischemia model, examining a potential link between astrocyte intermediate filaments and reactive oxygen species (ROS). We observed a reorganization of the intermediate filament network in astrocytes exposed to OGD. ROS accumulation was higher in GFAP -/- Vim -/- than wild- type astrocytes when exposed to OGD followed by reperfu- sion or when exposed to hydrogen peroxide. These results indicate that the elimination of ROS is impaired in the absence of the intermediate filament system. Compared to wild-type astrocytes, GFAP -/- Vim -/- astrocytes exposed to OGD and reperfusion exhibited increased cell death and conferred lower degree of protection to cocultured neurons. We conclude that the astrocyte intermediate filament system is important for the cell response to oxidative stress induced by OGD followed by reperfusion. Keywords Astrocytes Á Intermediate filaments Á Nanofilaments Á Stroke Á Oxidative stress Á Oxygen–glucose deprivation Introduction In diseases such as neurotrauma and stroke, astrocytes become reactive. This phenomenon is known as reactive gliosis and is accompanied by an altered expression of many genes (Pekny et al. 2013; Sofroniew and Vinters 2010). The hallmarks of reactive gliosis are hypertrophy of astrocyte processes, upregulation of cytoplasmic interme- diate filament (nanofilament) proteins glial fibrillary acidic protein (GFAP), vimentin, nestin, and synemin, increased cell proliferation, and release of molecules modulating inflammation and post-traumatic remodeling (Jing et al. 2007; Parpura et al. 2012; Pekny and Nilsson 2005; So- froniew 2009; Wilhelmsson et al. 2006). Astrocyte intermediate filaments are highly dynamic structures involved in cell signaling and migration. They also act as a signaling platform that controls cell responses to various types of stress, both in health and in disease (Eriksson et al. 2009; Pallari and Eriksson 2006; Pekny and Lane 2007). We have generated and utilized animal models in which the role of reactive astrocytes in physiological or Y. de Pablo Á M. Nilsson Á M. Pekna Á M. Pekny Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 9A, Gothenburg 413 90, Sweden Y. de Pablo (&) Á M. Pekny (&) Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Box 440, Gothenburg 405 30, Sweden e-mail: yolanda.depablo@neuro.gu.se M. Pekny e-mail: milos.pekny@neuro.gu.se M. Nilsson Hunter Medical Research Institute, Newcastle, Australia 123 Histochem Cell Biol (2013) 140:81–91 DOI 10.1007/s00418-013-1110-0