Project description:Drug addiction represents a pathological form of learning and memory with profound implications for individuals and society. The serotonin receptor 5-HT6R, uniquely expressed on primary cilia, is associated with neurological development, cognitive impairments, emotional disorders, and reward memory for cocaine and nicotine. However, its role in morphine-related reward memory remains unclear. This study demonstrated that 5-HT6R expression was downregulated during the early stage of morphine-induced conditioned place preference (CPP) extinction but returned to baseline levels later, with no significant changes observed during CPP establishment or reinstatement. Knocking down 5-HT6R accelerated CPP extinction, while overexpression prolonged the process. Furthermore, primary cilia defects within the mPFC were noted during the early stage of CPP extinction, and the removal of primary cilia expedited this process. Finally, ATR was identified as a novel target molecule of 5-HT6R, and the 5-HT6R-ATR-primary cilia network was found to regulate morphine-induced CPP extinction, offering new insights for opioid addiction therapy.
Project description:The ATR kinase, which coordinates cellular responses to DNA replication stress, is also essential for the proliferation of normal unstressed cells. Although its role in the replication stress response is well defined, the mechanisms by which ATR supports normal cell proliferation remain elusive. Here, we show that Atr is dispensable for the viability of G0-arrested naïve B cells. However, upon cytokine-induced proliferation, Atr-deficient B cells initiate DNA replication efficiently in early S phase, but by mid-S phase they display dNTP depletion, fork stalling, and replication failure. Nonetheless, productive DNA replication can be restored in Atr-deficient cells by pathways that suppress origin firing, such as downregulation of CDC7 and CDK1 kinase activities. Together, these findings indicate that ATR supports the proliferation of normal unstressed cells by tempering the pace of origin firing during the early S phase to avoid exhaustion of dNTPs and other replication factors.
Project description:The ATR kinase, which coordinates cellular responses to DNA replication stress, is also essential for the proliferation of normal unstressed cells. Although its role in the replication stress response is well defined, the mechanisms by which ATR supports normal cell proliferation remain elusive. Here, we show that Atr is dispensable for the viability of G0-arrested naïve B cells. However, upon cytokine-induced proliferation, Atr-deficient B cells initiate DNA replication efficiently in early S phase, but by mid-S phase they display dNTP depletion, fork stalling, and replication failure. Nonetheless, productive DNA replication can be restored in Atr-deficient cells by pathways that suppress origin firing, such as downregulation of CDC7 and CDK1 kinase activities. Together, these findings indicate that ATR supports the proliferation of normal unstressed cells by tempering the pace of origin firing during the early S phase to avoid exhaustion of dNTPs and other replication factors.
Project description:The ATR kinase, which coordinates cellular responses to DNA replication stress, is also essential for the proliferation of normal unstressed cells. Although its role in the replication stress response is well defined, the mechanisms by which ATR supports normal cell proliferation remain elusive. Here, we show that Atr is dispensable for the viability of G0-arrested naïve B cells. However, upon cytokine-induced proliferation, Atr-deficient B cells initiate DNA replication efficiently in early S phase, but by mid-S phase they display dNTP depletion, fork stalling, and replication failure. Nonetheless, productive DNA replication can be restored in Atr-deficient cells by pathways that suppress origin firing, such as downregulation of CDC7 and CDK1 kinase activities. Together, these findings indicate that ATR supports the proliferation of normal unstressed cells by tempering the pace of origin firing during the early S phase to avoid exhaustion of dNTPs and other replication factors.
Project description:Stress exposure can disrupt fear extinction, which is a hallmark of some stress-related disorders. The underlying molecular mechanisms of impaired extinction, especially in females, remain poorly understood. In this study, we investigated proteomics changes in the infralimbic cortex, a region critical for fear suppression, in female rats exposed to single prolonged stress (SPS). One week after SPS exposure, adult female rats underwent auditory fear conditioning and extinction training and were classified as susceptible or resilient based on their extinction performance. Quantitative proteomics analysis using tandem mass tag labeling and bioinformatics revealed distinct proteins and pathways between groups. Susceptible rats exhibited distinct proteomic profiles in the infralimbic cortex. Several of the 53 differentially expressed proteins are associated with synaptic plasticity and memory, including neurogranin and microtubule-associated protein tau (MAPT). Pathway enrichment analysis identified alterations in synaptogenesis, clathrin-mediated endocytosis, calcium signaling, and chaperone-mediated autophagy. Functional validation using AAV-shRNA knockdown of neurogranin or MAPT in glutamatergic neurons of the infralimbic cortex improved extinction memory in SPS-exposed animals. Our findings suggest that dysregulated protein expression in the infralimbic cortex contributes to impaired extinction memory and traumatic stress susceptibility in female rats, offering insight into the neurobiological mechanisms underlying vulnerability to stress-related disorders.
Project description:Extinction learning refers to the phenomenon that a previously learned response to an environmental stimulus, for example the expression of an aversive behavior upon exposure to a specific context, is reduced when the stimulus is repeatedly presented in the absence of a previously paired aversive event. Extinction of fear memories has been implicated with the treatment of anxiety disease but the molecular processes that underlie fear extinctionare only beginning to emerge. Here we show that fear extinction initiates up-regulation of hippocampal insulin-growth factor 2 (Igf2) and down-regulation of insulin-growth factor binding protein 7 (Igfbp7). In line with this observation we demonstrate that IGF2 facilitates fear extinction, while IGFBP7 impairs fear extinction in an IGF2-dependent manner. Furthermore, we identify one cellular substrate of altered IGF2-signaling during fear extinction. To this end we show that fear extinction-induced IGF2/IGFBP7-signaling promotes the survival of 17-19 day-old newborn hippocampal neurons. In conclusion, our data suggests that therapeutic strategies that enhance IGF2-signaling and adult neurogenesis might be suitable to treat disease linked to excessive fear memory. We employed mice to investigate fear extinction in the hippocampus-dependent contextual fear conditioning paradigm. To this end, male C57BL/6J mice were exposed to the fear conditioning box (context) followed by an electric foot-shock which elicits the acquisition of conditioned contextual fear. For extinction training animals were repeatedly reexposed to the conditioned context on consecutive days (24h interval) without receiving the footshockagain (extinction trial, E). This procedure eventually results in the decline of the aversive freezing behavior. Mice that were exposed to the conditioning context without receiving fear conditioning training served as control groups. To gain a better understanding of the molecular processes underlying fear extinction we performed a genome-wide analysis of the hippocampal transcriptome during fear extinction. In the employed paradigm fear extinction is a gradual process. To capture the longitudinal course of fear extinction we decided to perform hippocampal microarray analysis at two time points: (1) After the first extinction trial (E1) when animals display high levels of aversive freezing behavior and (2) at the extinction trial on which the freezing behavior was significantly reduced when compared to E1. This extinction trial, in the case of this experiment E5, we termed “extinction trial low freezing” (ELF). Mice that were exposed to the conditioning context without receiving fear conditioning training served as control groups (3). For all three groups we hybridized 5 samples (biological replicates).
Project description:Extinction learning refers to the phenomenon that a previously learned response to an environmental stimulus, for example the expression of an aversive behavior upon exposure to a specific context, is reduced when the stimulus is repeatedly presented in the absence of a previously paired aversive event. Extinction of fear memories has been implicated with the treatment of anxiety disease but the molecular processes that underlie fear extinctionare only beginning to emerge. Here we show that fear extinction initiates up-regulation of hippocampal insulin-growth factor 2 (Igf2) and down-regulation of insulin-growth factor binding protein 7 (Igfbp7). In line with this observation we demonstrate that IGF2 facilitates fear extinction, while IGFBP7 impairs fear extinction in an IGF2-dependent manner. Furthermore, we identify one cellular substrate of altered IGF2-signaling during fear extinction. To this end we show that fear extinction-induced IGF2/IGFBP7-signaling promotes the survival of 17-19 day-old newborn hippocampal neurons. In conclusion, our data suggests that therapeutic strategies that enhance IGF2-signaling and adult neurogenesis might be suitable to treat disease linked to excessive fear memory.
Project description:Background: Whereas cilia damage and reduced cilia beat frequency have been implicated as causative of reduced mucociliary clearance in smokers, theoretically mucociliary clearance could also be affected by cilia length. Based on models of mucociliary clearance predicting cilia length must exceed the 6 -7 μm airway surface fluid depth to generate force in the mucus layer, we hypothesized cilia height may be decreased in airway epithelium of normal smokers compared to nonsmokers. Methodology/Principal Findings: Cilia length in normal nonsmokers and smokers was evaluated in aldehyde-fixed, paraffin-embedded endobronchial biopsies, and air-dried and hydrated samples brushed from human airway epithelium via fiberoptic bronchoscopy. In 28 endobronchial biopsies, healthy smoker cilia length was reduced 15% compared to nonsmokers (p<0.05). In 47 air-dried samples of airway epithelial cells, smoker cilia length was reduced 13% compared to nonsmokers (p<0.0001). Analysis of the length of individual, detached cilia in 17 samples, smoker cilia length was reduced 9% compared to nonsmokers (p<0.05). Finally, in 16 fully hydrated, unfixed samples, smoker cilia length was reduced 7% compared to nonsmokers (p<0.05). Conclusions/significance: Models predict that a reduction in cilia length would reduce mucociliary clearance, suggesting that smoking-associated shorter airway epithelial cilia plays a significant role in the pathogenesis of smoking-induced lung disease.
Project description:BACKGROUND: Extinction, the capacity for an individual to inhibit or diminish maladaptive fear memories, is a critical aspect of fear processing. In humans, weak extinction learning is often observed in anxiety and fear-related disorders, such as PTSD. However, the mechanisms behind regulating extinction and determining individual variability in extinction learning remain poorly understood. METHODS: To investigate the molecular basis of inter-individual and sex-related differences in the ability to extinguish fear, extinction learning was analyzed in inbred wild-type male and female mice. Extinction tests were combined with in vivo profiling of the differential hippocampal transcriptomes associated with weak and strong extinction learning and genetic manipulations to extend our transcriptomic findings. RESULTS: We identified significant sex-dependent and -independent differences in hippocampal gene expression between weak and strong extinction learner animals. Especially surprising was a very high transcriptomic overlap between weak learner males and females, showing upregulation of multiple genes associated with neurotoxic insult and cellular stress, including a major stress regulator, a prion-like Tia1. Viral overexpression of Tia1 in the dorsal hippocampus caused sex-independent dysregulation of microglia and diminished fear extinction learning in animals of both sexes. CONCLUSIONS: Altogether, we demonstrated the brain-based transcriptomic architecture associated with weak versus strong fear extinction learning in male and female mammalian subjects and identified the sex-independent extinction-suppressive role of hippocampal Tia1 upregulation. Our results should help better understand the mechanisms underlying individual, and sex-dependent differences in extinction and inform novel therapeutic targets for pharmacological extinction augmentation strategies in fear-related disorders.