Fmoc-Cl cpg was isolated in a screen
cpg2 was isolated in a screen for seizure-induced genes and is regulated by physiological activity Nedivi et al. 1993, Nedivi et al. 1996. In general, screens for activity-regulated genes have isolated a number of synaptic proteins that are the components of the basic transmission machinery, indicating that the synaptic rearrangements that occur during plasticity likely involve an augmentation of normal synaptic processes (Nedivi, 1999). Since CPG2 is important for normal synaptic function and for the activity-induced internalization of glutamate receptors that may underlie LTD, an increase in cpg2 expression may belie an increase in synapse formation during synaptic plasticity. However, following LTP, there is an increase in the number of clathrin-coated pits and vesicles in dendritic spines, which may reflect an enhancement of postsynaptic protein cycling during plasticity (Toni et al., 2001). The critical role of CPG2 in activity-dependent glutamate receptor endocytosis may explain the increased need for cpg2 expression during periods of synaptic plasticity. As the product of an activity-regulated transcript that is expressed solely in brain regions with significant synaptic plasticity mechanisms, CPG2 may underlie an Fmoc-Cl of the clathrin-mediated endocytosis pathway that enables the capacity for postsynaptic plasticity in excitatory synapses.
Acknowledgements We thank Dr. Carlos Lois for the lentivirus vectors, advice on lentivirus design, and use of his equipment; Dr. Michael Ehlers for the clathrin-GFP construct; Dr. Joshua Sanes for the anti-Syne-1 antibody; Dr. Gabor Nyiri for lowicryl-embedded hippocampal sections; Dr. Ulrich Putz for the cpg15-shRNA lentivirus; Wei-Chung Lee and Elizabeth Lester for assistance with the in situ hybridizations; and Shifali Arora for spine size quantifications and subcloning assistance. We would also like to thank Dr. Troy Littleton, Dr. Michele Jacobs, Dr. Tadahiro Fujino, and Wei-Chung Lee for critical comments on the manuscript. This work was supported by NEI (E.N.), NCRR (T.L.H.), and NIDDK (T.L.H.).
Introduction Methotrexate (MTX), as an antagonist of folate, blocks the synthesis of DNA and results in the cell cycle arrest in G1 and/or S phases (Mazur et al., 2009; Nihal et al., 2014). MTX is widely administrated as an anticancer agent as well as the treatment of several autoimmune disorders (Huang et al., 2011; Abdel-Raheem and Khedr, 2014; Favalli et al., 2014; Kivity et al., 2014; Hafez et al., 2015). Over the long term, the administration of MTX results in various organ toxicities (Abo-Haded et al., 2017; Asci et al., 2017). Hepatotoxicity is one of the most frequently reported side effects of MTX (Ali et al., 2014). Low to high doses of MTX may lead to disorders such as liver cirrhosis or fibrosis (Mhatre and Marar, 2016; Mukherjee et al., 2013). Two major mechanisms including apoptosis and oxidative stress have been suggested for MTX-induced cytotoxicity (Hafez et al., 2015; Neuman et al., 1999; El-Sheikh et al., 2015). It has been reported that MTX promotes cell death via apoptosis in both cancerous and non-transformed cells (Mazur et al., 2009). However, the most common reported mechanism for MTX induced toxicity is the oxidative stress (Ali et al., 2014; Şener et al., 2006a; Uraz et al., 2008). MTX decreases the NADPH content of cells, which in turn sensitizes hepatocytes to the oxidative stress. On the other hand, prolonged use of MTX leads to the accumulation of MTX polyglutamate derivatives in hepatocytes that result in the generation of reactive oxygen species (ROS). The elevated ROS levels and decreased antioxidant defense of cells results in the oxidative stress. This in turn stimulates the development of hepatotoxicity (Yin et al., 2009; Armagan et al., 2015). Although, it has been assumed that antioxidant compounds are able to decrease the corresponding toxicity (Şener et al., 2006b; Vardi et al., 2010; Vardi et al., 2013; De et al., 2015; Abdel-Daim et al., 2017), there is an urgent need to investigate novel therapies preventing the accumulation of MTX in non-target cells.