Neurogranin (Ng) is a brain-specific, postsynaptically located protein kinase C (PKC) substrate, highly expressed in the cortex, hippocampus, striatum, and amygdala. This protein is a Ca2-sensitive calmodulin (CaM)-binding protein whose CaM-binding affinity is modulated by phosphorylation and oxidation. To investigate the role of Ng in neural function, a strain of Ng knockout mouse (KO) was generated. Previously we reported (Pak, J. H., Huang, F. L., Li, J., Balschun, D., Reymann, K. G., Chiang, C., Westphal, H., and Huang, K. -P. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 11232- 11237) that these KO mice displayed no obvious neuroanatomical abnormality, but exhibited deficits in learning and memory and activation of Ca2/CaM-dependent protein kinase II. In this report, we analyzed several downstream phosphorylation targets in phorbol 12-myristate 13-acetate-and forskolin-treated hippocampal slices from wild type (WT) and KO mice. Phorbol 12-myristate 13-acetate caused phosphorylation of Ng in WT mice and promoted the translocation of PKC from the cytosolic to the particulate fractions of both the WT and KO mice, albeit to a lesser extent in the latter. Phosphorylation of downstream targets, including mitogenactivated protein kinases, 90-kDa ribosomal S6 kinase, and the cAMP response element binding protein (CREB) was significantly attenuated in KO mice. Stimulation of hippocampal slices with forskolin also caused greater stimulation of protein kinase A (PKA) in the WT as compared with those of the KO mice. Again, phosphorylation of the downstream targets of PKA was attenuated in the KO mice. These results suggest that Ng plays a pivotal role in regulating both PKC-and PKA-mediated signaling pathways, and that the deficits in learning and memory of spatial tasks detected in the KO mice may be the result of defects in the signaling pathways leading to the phosphorylation of CREB.

Neurogranin (Ng) is a brain-specific, postsynaptically located protein kinase C (PKC) substrate, highly expressed in the cortex, hippocampus, striatum, and amygdala. This protein is a Ca2-sensitive calmodulin (CaM)-binding protein whose CaM-binding affinity is modulated by phosphorylation and oxidation. To investigate the role of Ng in neural function, a strain of Ng knockout mouse (KO) was generated. Previously we reported (Pak, J. H., Huang, F. L., Li, J., Balschun, D., Reymann, K. G., Chiang, C., Westphal, H., and Huang, K. -P. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 11232- 11237) that these KO mice displayed no obvious neuroanatomical abnormality, but exhibited deficits in learning and memory and activation of Ca2/CaM-dependent protein kinase II. In this report, we analyzed several downstream phosphorylation targets in phorbol 12-myristate 13-acetate-and forskolin-treated hippocampal slices from wild type (WT) and KO mice. Phorbol 12-myristate 13-acetate caused phosphorylation of Ng in WT mice and promoted the translocation of PKC from the cytosolic to the particulate fractions of both the WT and KO mice, albeit to a lesser extent in the latter. Phosphorylation of downstream targets, including mitogenactivated protein kinases, 90-kDa ribosomal S6 kinase, and the cAMP response element binding protein (CREB) was significantly attenuated in KO mice. Stimulation of hippocampal slices with forskolin also caused greater stimulation of protein kinase A (PKA) in the WT as compared with those of the KO mice. Again, phosphorylation of the downstream targets of PKA was attenuated in the KO mice. These results suggest that Ng plays a pivotal role in regulating both PKC-and PKA-mediated signaling pathways, and that the deficits in learning and memory of spatial tasks detected in the KO mice may be the result of defects in the signaling pathways leading to the phosphorylation of CREB.

NeurograninyRC3 is a neural-specific Ca21-sensitive calmodulin CaM)-binding protein whose CaM-binding affinity is modulated by phosphorylation and oxidation. Here we show that deletion of the Ng gene in mice did not result in obvious developmental or neuroanatomical abnormalities but caused an impairment of spatial learning and changes in hippocampal short- and long-term plasticity (paired-pulse depression, synaptic fatigue, long-term potentiation induction). These deficits were accompanied by a decreased basal level of the activated Ca21yCaM-dependent kinase II (CaMKII) ('60% of wild type). Furthermore, hippocampal slices of the mutant mice displayed a reduced ability to generate activated CaMKII after stimulation of protein phosphorylation and oxidation by treatments with okadaic acid and sodium nitroprusside, respectively. These results indicate a central role of Ng in the regulation of CaMKII activity with decisive influences on synaptic plasticity and spatial learning.

FUSE-binding protein (FBP) binds the single-stranded far upstream element of active c-myc genes, pos- sesses potent transcription activation and repression domains, and is necessary for c-myc expression. A novel 60 kDa protein, the FBP interacting repressor (FIR), blocked activator-dependent, but not basal, transcription through TFIIH. Recruited through FBP' s nucleic acid-binding domain, FIR formed a ternary complex with FBP and FUSE. FIR repressed a c-myc reporter via the FUSE. The amino terminus of FIR con-tained an activator-selective repression domain capable of acting in cis or even in trans in vivo and in vitro. The repression domain of FIR targeted only TFIIH' s p89/XPB helicase, required at several stages in tran-scription, but not factors required for promoter selection. Thus, FIR locks TFIIH in an activation-resistant configuration that still supports basal transcription.

探讨cPKCs特定亚型在脑低氧预适应形成过程中的作用，借助已建立的小鼠整体低氧预适应模型，应用SDS-PAGE和Western bolt等生化技术，并结合Gel Doc成像系统，半定量检测脑组织内cPKCα和γ的膜转位水平和蛋白表达量。结果发现，随低氧暴露次数（低氧2-4次）增加，在小鼠海马和皮层组织内cPKCγ膜转位水平增高显著（p<0.05，n=6）；然而，cPKCα的膜转位水平和cPKCα及γ的蛋白表达量的变化均不显著。提示，cPKCγ的激活可能参与了脑低氧预适应的形成过程。