5; CaCl2, 2; GSK458 nmr MgSO4, 1; NaH2PO4, 1.25; NaHCO3 26; and glucose, 20; bubbled with 95% O2 and 5% CO2. Bicuculline (10 μm) or picrotoxin (100 μm) was always added to block inhibitory synaptic transmission. The signals of membrane currents were filtered at 3 kHz and digitized at 20 kHz for recording evoked climbing fiber-mediated excitatory postsynaptic currents (CF-EPSCs) or at 10 kHz for recording postsynaptic AMPA receptor-mediated currents. On-line

data acquisition and off-line data analysis were performed using PULSE software (HEKA, Lambrecht/Pfalz, Germany). Climbing fibers were stimulated via the stimulation pipette placed in the granule cell layer. Stimuli (duration, 0.1 ms; amplitude, 0–90 V) were applied at 0.2 Hz. In the experiment for the I–V relationships of the postsynaptic AMPA receptor-mediated currents, spermine (100 μm) was added to the intracellular solution and cyclothiazide (100 μm) and tetrodotoxin (0.5 μm) were added to the external solution. All experiments were carried out at 31°C. To investigate the roles of TARP γ-2 and γ-7 in synaptic expression and function

of cerebellar AMPA receptors, we generated mice deficient in γ-2 or γ-7 on the C57BL/6N background (Fig. 1A–E). A previous study reported that, when backcrossed to the C57BL/6J background, mice carrying GDC-0449 mouse the stg mutation died before weaning (Letts et al., 2003). However, our γ-2-KO mice were viable after weaning and exhibited essentially the same phenotype as the original stg mouse, including ataxic gait and head-lifting behavior. In addition, γ-2-KO mice were small in size with 73% of the body weight of their WT littermates at 8–10 weeks of age, similarly Phosphatidylethanolamine N-methyltransferase to original stg mice. On the other hand, γ-7-KO mice were viable, fertile and indistinguishable from their WT littermates. Then we crossed the two mouse lines to obtain γ-2/γ-7 double-KO (DKO) mice, which had approximately 70% of the body weight of their WT littermates. DKO mice showed much more severe ataxia than γ-2-KO mice did, as they could not walk straight and displayed frequent tumbling

and rolling as appreciated from footprint patterns (Fig. 1F). The distribution of γ-2 and γ-7 at the protein level was examined in the cerebellar cortex by producing specific antibodies. The specificity was verified by the lack of immunoreacted bands in the corresponding KO cerebella (Fig. 1E). We further noted that cerebellar content of γ-7 was reduced in γ-2-KO cerebellum, while that of γ-2 was not altered in γ-7-KO cerebellum (Fig. 1E). By immunohistochemistry, γ-2 and γ-7 were distributed at the highest levels in the cerebellum (Fig. 2A and E), the specificity of which was verified by blank immunostaining in the corresponding KO brains (Fig. 2B and F). Within the cerebellum, γ-2 was detected as clustered staining in the granular layer (i.e., synaptic glomeruli) and as punctate staining in the molecular layer (Fig. 2C and D).