Neuronal differentiation induces SNORD115 expression and is accompanied by post-transcriptional changes of serotonin receptor 2c mRNA

The serotonin neurotransmitter system is widespread in the brain and implicated in modulation of neuronal responses to other neurotransmitters. Among 14 serotonin receptor subtypes, 5-HT2cR plays a pivotal role in controlling neuronal network excitability. Serotonergic activity conveyed through receptor 5-HT2cR is regulated post-transcriptionally via two mechanisms, alternative splicing and A-to-I RNA editing. Brain-specific small nucleolar RNA SNORD115 harbours a phylogenetically conserved 18-nucleotide antisense element with perfect complementarity to the region of 5ht2c primary transcript that undergoes post-transcriptional changes. Previous 5ht2c minigene studies have implicated SNORD115 in fine-tuning of both post-transcriptional events. We monitored post-transcriptional changes of endogenous 5ht2c transcripts during neuronal differentiation. Both SNORD115 and 5ht2c were upregulated upon neuronal commitment. We detected increased 5ht2c alternative exon Vb inclusion already at the stage of neuronal progenitors, and more extensive A-to-I editing of non-targeted sites A and B compared to adjacent adenosines at sites E, C and D throughout differentiation. As the extent of editing is known to positively correlate with exon Vb usage while it reduces receptor functionality, our data support the model where SNORD115 directly promotes alternative exon inclusion without the requirement for conversion of key adenosines to inosines, thereby favouring production of full-length receptor isoforms with higher potency

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This chapter describes lasers and other sources of coherent light that operate in a wide wavelength range. First, the general principles for the generation of coherent continuous-wave and pulsed radiation are treated including the interaction of radiation with matter, the properties of optical resonators and their modes as well as such processes as Q-switching and mode-locking. The general introduction is followed by sections on numerous types of lasers, the emphasis being on todayʼs most important sources of coherent light, in particular on solid-state lasers and several types of gas lasers. An important part of the chapter is devoted to the generation of coherent radiation by nonlinear processes with optical parametric oscillators, difference- and sum-frequency generation, and high-order harmonics. Radiation in the extended ultraviolet (EUV) and x-ray ranges can be generated by free electron lasers (FEL) and advanced x-ray sources. Ultrahigh light intensities up to 1021 W/cm2 open the door to studies of relativistic laser–matter interaction and laser particle acceleration. The chapter closes with a section on laser stabilization