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Signal-dependent RNA polymerase II (RNA Pol II) productive elongation is an integral component of gene transcription, including that of immediate early genes (IEGs) induced by neuronal activity. However, it remains unclear how productively elongating RNA Pol II overcomes nucleosomal barriers. Using RNAi, three degraders, and several small-molecule inhibitors, we show that the mammalian switch/sucrose non-fermentable (SWI/SNF) complex of neurons (neuronal BRG1/BRM-associated factor or nBAF) is required for activity-induced transcription of neuronal IEGs, including Arc. The nBAF complex facilitates promoter-proximal RNA Pol II pausing and signal-dependent RNA Pol II recruitment (loading) and, importantly, mediates productive elongation in the gene body via interaction with the elongation complex and elongation-competent RNA Pol II. Mechanistically, RNA Pol II elongation is mediated by activity-induced nBAF assembly (especially ARID1A recruitment) and its ATPase activity. Together, our data demonstrate that the nBAF complex regulates several aspects of RNA Pol II transcription and reveal mechanisms underlying activity-induced RNA Pol II elongation. These findings may offer insights into human maladies etiologically associated with mutational interdiction of BAF functions. [Display omitted] • The neuronal BAF complex mediates activity-induced immediate early gene transcription • Neuronal activity induces extrabasal assembly of the nBAF complex • Neuronal BAF interacts with the RNA Pol II elongation complex and mediates productive elongation • ATPase activity is required for mediation of RNA Pol II elongation by the BAF complex Cornejo et al. demonstrate that the neuronal BAF chromatin remodeling complex is necessary for productive elongation of RNA Pol II and activity-induced gene transcription. Such regulatory role is mediated mechanistically by activity-induced nBAF assembly and its ATPase activity. [ABSTRACT FROM AUTHOR]

In 2014, we proposed that orexin signaling transformed motivationally relevant states into adaptive behavior directed toward exploiting an opportunity or managing a threat, a process we referred to as motivational activation. Advancements in animal models since then have permitted higher-resolution measurements of motivational states; in particular, the behavioral economics approach for studying drug demand characterizes conditions that lead to the enhanced motivation that underlies addiction. This motivational plasticity is paralleled by persistently increased orexin expression in a topographically specific manner—a finding confirmed across species, including in humans. Normalization of orexin levels also reduces drug motivation in addiction models. These new advancements lead us to update our proposed framework for the orexin function. We now propose that the capacity of orexin neurons to exhibit dynamic shifts in peptide production contributes to their role in adaptive motivational regulation and that this is achieved via a pool of reserve orexin neurons. This reserve is normally bidirectionally recruited to permit motivational plasticity that promotes flexible, adaptive behavior. In pathological states such as addiction, however, we propose that the orexin system loses capacity to adaptively adjust peptide production, resulting in focused hypermotivation for drug, driven by aberrantly and persistently high expression in the orexin reserve pool. This mechanistic framework has implications for the understanding and treatment of several psychiatric disorders beyond addiction, particularly those characterized by motivational dysfunction. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.12.022 Byline: Rebecca McLennan (a), Jessica M. Teddy (a), Jennifer C. Kasemeier-Kulesa (a), Morgan H. Romine (a), Paul M. Kulesa (a)(b) Keywords: VEGF; Neural crest; Cell migration; Cranial; Chick; Confocal; Time-lapse imaging; Chemoattraction Abstract: The neural crest is an excellent model to study embryonic cell migration, since cell behaviors can be studied in vivo with advanced optical imaging and molecular intervention. What is unclear is how molecular signals direct neural crest cell (NCC) migration through multiple microenvironments and into specific targets. Here, we tested the hypothesis that the invasion of cranial NCCs, specifically the rhombomere 4 (r4) migratory stream into branchial arch 2 (ba2), is due to chemoattraction through neuropilin-1-vascular endothelial growth factor (VEGF) interactions. We found that the spatio-temporal expression pattern of VEGF in the ectoderm correlated with the NCC migratory front. RT-PCR analysis of the r4 migratory stream showed that ba2 tissue expressed VEGF and r4 NCCs expressed VEGF receptor 2. When soluble VEGF receptor 1 (sVEGFR1) was injected distal to the r4 migratory front, to bind up endogenous VEGF, NCCs failed to completely invade ba2. Time-lapse imaging revealed that cranial NCCs were attracted to ba2 tissue or VEGF sources in vitro. VEGF-soaked beads or VEGF-expressing cells placed adjacent to the r4 migratory stream caused NCCs to divert from stereotypical pathways and move towards an ectopic VEGF source. Our results suggest a model in which NCC entry and invasion of ba2 is dependent on chemoattractive signaling through neuropilin-1-VEGF interactions. Author Affiliation: (a) Stowers Institute for Medical Research, 1000 E. 50th St., Kansas City, MO 64110, USA (b) Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, MO 66160, USA Article History: Received 26 August 2009; Revised 21 November 2009; Accepted 16 December 2009

The perifornical/lateral hypothalamic area (LHA) orexin (hypocretin) system is involved in drug-seeking behavior elicited by drug-associated stimuli. Cocaine exposure is associated with presynaptic plasticity at LHA orexin cells such that excitatory input to orexin cells is enhanced acutely and into withdrawal. These changes may augment orexin cell reactivity to drug-related cues during abstinence and contribute to relapse-like behavior. Studies in hypothalamic slices from drug-naïve animals indicate that agonism of group III metabotropic glutamate receptors (mGluRs) reduces presynaptic glutamate release onto orexin cells. Therefore, we examined the group III mGluR system as a potential target to reduce orexin cell excitability in-vivo, including in animals with cocaine experience. First, we verified that group III mGluRs regulate orexin cell activity in behaving animals by showing that intra-LHA infusions of the selective agonist L-(+)-2-Amino-4-phosphonobutyric acid (L-AP4) reduces c- fos expression in orexin cells following 24 h food deprivation. Next, we extended these findings to show that intra-LHA L-AP4 infusions reduced discriminative stimulus-driven cocaine-seeking following withdrawal. Importantly, L-AP4 had no effect on lever pressing for sucrose pellets or general motoric behavior. Finally, using whole-cell patch-clamp recordings from identified orexin cells in orexin-GFP transgenic mice, we show enhanced presynaptic drive to orexin cells following 14d withdrawal and that this plasticity can be normalized by L-AP4. Together, these data indicate that activation of group III mGluRs in LHA reduces orexin cell activity in vivo and may be an effective strategy to suppress cocaine-seeking behavior following withdrawal. These effects are likely mediated, at least in part, by normalization of presynaptic plasticity at orexin cells that occurs as a result of cocaine exposure. This article is part of the Special Issue entitled 'Hypothalamic Control of Homeostasis'. • Cocaine induces plasticity in the lateral hypothalamic area (LHA). • Group III mGluRs within the LHA may be a target to suppress this plasticity. • LHA L-AP4 (Group III mGluR agonist) reduced cocaine-seeking after 14d abstinence. • Locomotor behavior/responding for sucrose was unaffected by LHA L-AP4. • L-AP4 suppressed excitatory drive to orexin cells associated with cocaine in slices. [ABSTRACT FROM AUTHOR]

The orexin (hypocretin) system is important for reward-driven motivation but has not been implicated in the expression of a multiphenotype addicted state. Rats were assessed for economic demand for cocaine before and after 14 days of short access, long access, or intermittent access (IntA) to cocaine. Rats were also assessed for a number of other DSM-5–relevant addiction criteria following differential access conditions. Orexin system function was assessed by quantification of numbers and activity of orexin cells, pharmacological blockade of the orexin-1 receptor, and subregion-specific knockdown of orexin cell populations. IntA produced a cluster of addiction-like behaviors that closely recapitulate key diagnostic criteria for addiction to a greater extent than long access or short access. IntA was accompanied by an increase in number and activity of orexin-expressing neurons within the lateral hypothalamic subregion. This increase in orexin cell number and activity persisted during protracted withdrawal from cocaine for at least 150 days and was accompanied by enhanced incubation of craving in the same rats. Selective knockdown of lateral hypothalamic orexin neurons reduced motivation for cocaine, and orexin-1 receptor signaling played a larger role in drug seeking after IntA. We provide the first evidence that lateral hypothalamic orexin system function extends beyond general reward seeking to play a critical role in expression of a multiphenotype addiction-like state. Thus, the orexin system is a potential novel target for pharmacotherapies designed to treat cocaine addiction. In addition, these data point to the IntA model as a preferred approach to modeling addiction-like behavior in rats. [ABSTRACT FROM AUTHOR]