Project description:We demonstrate that stress differentially regulates glutamate homeostasis in the dorsal and ventral hippocampus and established a previously unknown role for the glial marker xCT in the homeostatic regulation of the ventral dentate gyrus (vDG) in stress resilience and antidepressant responses. We provide RNAseq roadmap for the stress-sensitive vDG and show that the transcription factor REST binds to xCT promoter in co-occupancy with the epigenetic marker H3K27acet, to negatively regulate xCT expression. Reduced xCT was also observed in a genetic mouse model of inherent susceptibility to depression. Pharmacologically modulating histone acetylation with next-generation therapeutics, such as acetyl-N-cysteine (NAC) or acetyl-L-carnitine (LAC), rapidly increased xCT reduction and activated a network that included mGlu2 receptors to prime an enhanced glutamate homeostasis that promoted stress resilience and antidepressant-like responses. Moreover, pharmacological xCT blockage counteracted NAC prophylactic effects. Anatomical (vDG) and cell-type specific (GFAP+) virus-overexpression mimicked the effects of pharmacological treatments in increasing stress resilience. These findings establish xCT as critical regulator of the glutamate system in a network with mGlu2 receptors. These studies also point to a role of histone acetylation as mediator of stress resilience.
Project description:The hippocampus - one of the most studied brain regions – is a key target of the stress response and vulnerable to the detrimental effects of stress. Although its intrinsic organization is highly conserved throughout its long dorsal-ventral axis, the dorsal hippocampus is linked to spatial navigation and memory formation, whereas the ventral hippocampus is linked to emotional regulation. Here, we provide the first combined transcriptomic and proteomic profiling that reveals striking differences between dorsal and ventral hippocampus. Using various acute stress challenges we demonstrate that both regions display very distinct molecular responses, and that the ventral hippocampus is particularly responsive to the effects of stress. We demonstrate that separately analyzing dorsal and ventral hippocampus greatly increases the ability to detect region-specific stress effects, and we identify an epigenetic network, which is specifically sensitive to acute stress in the ventral hippocampus.
Project description:Major depressive disorder (MDD) is a complex condition with unclear pathophysiology. Molecular disruptions within the periphery and limbic brain regions contribute to depression symptomatology. Here, we utilized a mouse chronic stress model of MDD and performed metabolomic, lipidomic, and proteomic profiling on serum plus several brain regions (ventral hippocampus, nucleus accumbens, and prefrontal cortex) of susceptible, resilient, and unstressed control mice. Proteomic analysis identified three serum proteins reduced in susceptible animals; lipidomic analysis detected differences in lipid species between resilient and susceptible animals in serum and brain; and metabolomic analysis revealed pathway dysfunctions of purine metabolism, beta oxidation, and antioxidants, which were differentially associated with stress susceptibility vs resilience by brain region. Antidepressant treatment ameliorated MDD-like behaviors and affected key metabolites within outlined networks, most dramatically in the ventral hippocampus. This work presents a resource for chronic stressinduced, tissue-specific changes in proteins, lipids, and metabolites and illuminates how molecular dysfunctions contribute to individual differences in stress sensitivity
Project description:Chronic psychosocial stress is a risk factor for psychiatric disorders, and genetic factors interact in conferring susceptibility. The chronic social defeat stress (CSDS) mouse model allows identifying factors underlying resilience and susceptibility to chronic psychosocial stress. We used RNA-sequencing to identify genes and pathways affected by CSDS in three brain regions: medial prefrontal cortex (mPFC), ventral hippocampus (vHPC), and bed nucleus of the stria terminalis (BNST), of male mice from strains C57BL/6Crl and DBA/2Crl.
Project description:Tumor cells increase glutamate release through the cystine/glutamate transporter xCT to balance oxidative homeostasis in tumor cells and promote tumor progression. Here, we demonstrated that although inhibition of xCT either by pharmacological inhibitor (sulfasalazine, SAS), approved by FDA for inflammatory diseases, or genetic knockdown induced ROS-related death in melanoma cells. Taken together, our results reveal that inhibition of xCT by SAS is a promising therapeutic strategy for melanoma.
Project description:Purpose: The goal of this study was to characterize molecular stress responses on transcriptional level in dorsal and ventral hippocampus separately. Methods: mRNA profiles of whole, dorsal and ventral hippocampus of mice 45min after first exposure to different acute stressors. The stressors were novelty (6min novel environment), restraint (30min immobilization), or cold swim (6min in 18 degree Celcius water). 5 mice were used per condition, using Illumina HiSeq4000. The sequence reads that passed quality filters were mapped with STAR, counted with RSEM and differential gene expression was calculated using the bioconducter package edgeR. Results: With our workflow, we identified 13902 genes per sample. Approximately 20% of the genes were differentially expressed between dorsal and ventral hippocampus at baseline, with a log2 fold change >±0.3 and p value <0.005. Approximately 100 genes are differentially expressed upon stress treatment in the whole hippocampus. If ventral and dorsal hippocampus were analyzed separately, numbers increased to 150 and 250 respectively. Stress-responsive genes vary between dorsal and ventral hippocampus, and also vary between different stressors. Further analysis identified a functional epigenetic gene cluster specific for the stress response in the ventral hippocampus. Conclusions: Our study represents the first RNA-seq analysis of dorsal and ventral hippocampus after different acute stress exposures.
Project description:Kaposiâs sarcoma-associated herpesvirus (KSHV) is the etiological agent of primary effusion lymphoma (PEL), a rapidly progressing malignancy mostly arising in HIV-infected patients. Even under conventional chemotherapy, PEL continues to portend nearly 100% mortality within several months, which urgently requires novel therapeutic strategies. We have previously demonstrated that targeting xCT, an amino acid transporter for cystine/glutamate exchange, induces significant PEL cell apoptosis through regulation of multiple host and viral factors. More importantly, one of xCT selective inhibitors, Sulfasalazine (SASP), effectively prevents PEL tumor progression in an immune-deficient xenograft model. In the current study, we use Illumina microarray to explore the genomic gene profile altered by SASP treatment within 3 KSHV+ PEL cell-lines, and discover that many genes involved in oxidative stress/antioxidant defense system, apoptosis/anti-apoptosis/cell death, and cellular response to unfolded proteins/topologically incorrect proteins are potentially regulated by xCT. We further functionally validate 2 downstream candidates, OSGIN1 (Oxidative stress-induced growth inhibitor 1) and XRCC5 (X-ray repair cross-complementing protein 5), their relationship with PEL cell survival/proliferation and chemoresistance, respectively. Together, our data indicate that targeting these xCT-regulated novel downstream genes may help devise promising therapeutic strategies against PEL and/or other AIDS-related lymphoma. 3 KSHV PEL cell lines were treated with xCT selective inhibitor Sulfasalazine (SASP) and the gene expression signature was compared to that of untreated cells
Project description:Acinar cell dedifferentiation is one of the most notable features of acute and chronic pancreatitis. It can also be the initial step that facilitates pancreatic cancer development. In the present study, we further decipher the precise mechanism and regulation using murine experimental models. Our RNAseq analysis indicates that, early acinar cell dedifferentiation is accompanied by multiple pathways related to cell survival that are highly enriched, and where SLC7A11 (xCT) is transiently upregulated. xCT is the specific subunit of the cystine/glutamate antiporter system xC-. Acinar cells with depleted or reduced xCT function show an increase in ferroptosis relating to lipid peroxidation. Lower glutathione levels and more lipid ROS accumulation could be rescued by the antioxidant N-acetylcysteine or the ferroptosis inhibitor Ferrostatin-1. In caerulein-induced acute pancreatitis in mice, xCT also prevents lipid peroxidation in acinar cells. In conclusion, during stress, acinar cell fate seems to be poised for avoiding several forms of cell death. xCT specifically prevents acinar cell ferroptosis by fueling the glutathione pool and maintaining ROS balance. The data suggest that xCT offers a druggable tipping point to steer the acinar cell fate in stress conditions.
Project description:Using NGS, we report the impact of chronic stress on the transcriptome of the dorsal and ventral hippocampus in the ewe. This study identifies specific transcriptional signatures of the dorsal VS ventral hippocampus (>220 DEG) and demonstrates a very limited transcriptional impact of stress, exclusively restricted to the dorsal hippocampus (<10 DEG).