d JOURNAL OF NEUROCHEMISTRY | 2008 | 105 | 1384–1393 doi: 10.1111/j.1471-4159.2008.05335.x
Regulation of dendritic spine morphology by an NMDA receptor-associated Rho GTPase-activating protein, p250GAP
Takanobu Nakazawa,* Toshihiko Kuriu, Tohru Tezuka,*,1 Hisashi Umemori,*,à Shigeo Okabe§,¶ and Tadashi Yamamoto*
*Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan Department of Neurophysiology, Faculty of Pharmaceutical Sciences at Kagawa, Tokushima Bunri University, Sanuki, Kagawa, Japan àMolecular & Behavioral Neuroscience Institute and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA §Department of Cellular Neurobiology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan ¶Solution Oriented Research for Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
Abstract RhoA. Furthermore, p250GAP is involved in NMDA receptor- The NMDA receptor regulates spine morphological plasticity mediated RhoA activation. In response to NMDA receptor by modulating Rho GTPases. However, the molecular activation, exogenously expressed green fluorescent protein mechanisms for NMDA receptor-mediated regulation of Rho (GFP)-tagged p250GAP was redistributed. Thus, these data GTPases remain elusive. In this study, we show that suggest that p250GAP plays an important role in NMDA p250GAP, an NMDA receptor-associated RhoGAP, regulates receptor-mediated regulation of RhoA activity leading to spine spine morphogenesis by modulating RhoA activity. Knock- morphological plasticity. down of p250GAP increased spine width and elevated the Keywords: dendritic spine, NMDA receptor, p250GAP, endogenous RhoA activity in primary hippocampal neurons. RhoA, spine morphogenesis. The increased spine width by p250GAP knock-down was J. Neurochem. (2008) 105, 1384–1393. suppressed by the expression of a dominant-negative form of
Dendritic spines are specialized protrusions that receive the The N-methyl-D-aspartate subtype of ionotropic glutamate majority of excitatory synaptic input in the CNS. Spines are receptor (NMDA receptor) plays a critical role in the activity- highly plastic, changing their shape and size in response to dependent morphological plasticity of spines (Kennedy et al. synaptic activity (Bonhoeffer and Yuste 2002; Kennedy et al. 2005; Matus 2005; Segal 2005). Given that the morpholog- 2005; Matus 2005; Segal 2005; Tada and Sheng 2006). ical plasticity of spines depends on reorganization of actin Long-term potentiation is associated with an increase in spine number or spine size (Matsuzaki et al. 2004; Nagerl et al. 2004; Okamoto et al. 2004), while long-term depres- Received November 26, 2007; revised manuscript received February 22, sion results in shrinkage or retraction of spines in the 2008; accepted February 29, 2008. forebrain (Nagerl et al. 2004; Okamoto et al. 2004; Zhou Address correspondence and reprint requests to Tadashi Yamamoto, Division of Oncology, Department of Cancer Biology, Institute of et al. 2004). Drugs that inhibit spine motility interfere with Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, long-term potentiation (Fischer et al. 1998). These findings Japan. E-mail: [email protected] argue that synaptic activity-regulated morphological plastic- 1The present address of Tohru Tezuka is the Medical Top Track Program, ity of spines plays an important role in the functional Medical Research Institute, Tokyo Medical and Dental University, 1-5- plasticity of synaptic transmission that underlies learning and 45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan. Abbreviations used: 4-AP, 4-aminopyridine; APV, 2-amino-5-phos- memory formation (Fischer et al. 1998; Matsuzaki et al. phonovaleric acid; DIV, days in vitro; GAP, GTPase-activating protein; 2004; Nagerl et al. 2004; Okamoto et al. 2004; Zhou et al. GEF, guanine-nucleotide exchange factor; GFP, green fluorescent 2004). protein; LTP, long-term potentiation; TTX, tetrodotoxin.