Effects of Neonatal Treatment With 6-Hydroxydopamine and Endocrine Disruptors on Motor Activity and Gene Expression in Rats

To investigate the mechanisms underlying motor hyperactivity, we performed intracisternal injection of 6-hydroxydopamine or endocrine disruptors in rats on postnatal day 5. 6-Hydroxydopamine (100 μg, 488 nmol) caused a significant increase in spontaneous motor activities at 4 weeks of age. Gene-expression profiling using a cDNA membrane array revealed alterations in several classes of gene at 8 weeks of age. In the midbrain, gene expression was enhanced in dopamine transporter 1; a platelet-derived growth factor receptor; dopamine receptor D4; galanin receptor 2; arginine vasopressin receptor 2; neuropeptide Y; tachykinin 2; and fibroblast growth factor 10. Expression was also enhanced in the glutamate/aspartate transporter gene in the striatum. Rats received an endocrine disruptor (87 nmol), such as bisphenol A, nonylphenol, p-octylphenol, or diethylhexylphthalate, which also caused motor hyperactivity at 4 weeks. The effects of bisphenol A on motor activity were dose-dependent from 0.87 to 87 nmol. The phenols caused a deficit in dopamine neurons, similarly to the deficit caused by 6-hydroxydopamine. Gene-expression profiles after treatment with endocrine disruptors showed variation and differed from those of 6- hydroxydopamine. The results suggest that neonatal treatment with environmental chemicals can generate an animal model of attention-deficit hyperactivity disorder, in which clinical symptoms are pervasive

An Excellent Monitoring System for Surface Ubiquitination-Induced Internalization in Mammals

Background. At present, it is difficult to visualize the internalization of surface receptors induced by ubiquitination that is taken place at the plasma membrane in mammals. This problem makes it difficult to reveal molecular basis for ubiquitinationmediated internalization in mammals. Methodology/Principle Findings. In order to overcome it, we have generated T-REx-c-MIR, a novel mammalian Tet-on B cell line using a constitutively active E3 ubiquitin ligase, c-MIR, and its artificial target molecule. By applying the surface biotinylation method to T-REx-c-MIR, we succeeded to monitor the fate of surface target molecules after initiation of ubiquitination process by doxycycline (Dox)-induced c-MIR expression. Target molecules that preexisted at the plasma membrane before induction of c-MIR expression were oligo-ubiquitinated and degraded by Dox-induced c-MIR expression. Dox-induced c-MIR expression initiated rapid internalization of surface target molecules, and blockage of the internalization induced the accumulation of the surface target molecules that were newly ubiquitinated by c-MIR. Inhibition of the surface ubiquitination by down-regulating ubiquitin conjugating enzyme E2 impaired the internalization of target molecules. Finally, a complex of c-MIR and target molecule was detected at the plasma membrane. Conclusions/ Significances. These results demonstrate that in T-REx-c-MIR, surface target molecule is ubiquitinated at the plasma membrane and followed by being internalized from the plasma membrane. Thus, T-REx-c-MIR is a useful experimental tool t

Analysis of gene expression in human umbilical vein endothelial cells exposed to a 50-Hz magnetic field

Human umbilical vein endothelial cells (HUVECs) were exposed to 100-μT, 50-Hz sinusoidal intermittent (5 min off, 10 min on) magnetic fields for 24 h. Total RNA was extracted from exposed and sham-exposed cells and was then analyzed via a DNA microarray technique. Interestingly, the expression of a subunit of the L-type Ca channel was 2.3-fold higher in exposed cells; this finding may be relevant to similar previously published results (an increase of α1C and α1D subunits of L-type Ca channel in neuronal stem cells as preveiously demonstrated by Piacentini and colleagues in 2008. However, analysis of the false discovery rate precluded us from drawing firm conclusions about the effects of magnetic fields on gene expression in HUVECs. Nevertheless, non-coding RNAs were more common than coding RNAs among the genes that were differentially expressed with a > 2-fold or < 0.5-fold difference between exposed and sham-exposed cells. A similar result was obtained when the expression data from exposed cells or those from sham-exposed cells were analyzed separately. Thus, the higher frequency of non-coding RNAs than that of coding RNAs among the differentially expressed genes was attributed to the higher degree of fluctuation in the expression of non-coding RNA. Interestingly, this fluctuation seems to be a characteristic intrinsic to non-coding RNAs themselves