Project description:Brain metastasis represents a substantial source of morbidity and mortality in various cancers, and is characterized by high resistance to chemotherapy. Here we define the role of the most abundant cell type in the brain, the astrocyte, in brain metastasis. Cancer cells assemble of carcinoma-astrocyte gap junctions composed of connexin 43 (Cx43). Cx43 in cancer cells support brain metastatic colonization. We employ translating ribosome affinity purification (TRAP) to isolate translating mRNA from cancer cells in mixed asrtocyte co-cultures to determine the mechanism behind this Cx43-mediated brain metastatic growth. Once engaged with the astrocyte gap-junctional network, brain metastatic cancer cells employ these channels to transfer the cytosolic dsDNA response messenger cGAMP to astrocytes, activating the cGAS-STING pathway and production of inflammatory cytokines IFNα and TNFα. As paracrine signals, these factors activate the STAT1 and NF-κB pathways in brain metastatic cells, which support tumour growth and chemoresistance.
Project description:Analysis of dsDNA-induced innate immune response at gene expression level. The hypothesis tested in this study was that K224R mutation significantly inhibits hSTING activity. Results provide important information of the response of hSTING and its variants to cytosolic dsDNA, such as induction of type I IFN genes and proinflammatory cytokine genes.
Project description:It was previously reported that inhibition of autophagosome formation by MRT68921 induced accumulation of cytosolic dsDNA, which can activate cytosolic DNA-sensor signaling pathway, thereby reducing cell viability through reactive oxygen species generation in leukemia cells. Thus, we examined the effect of combination treatment of MRT68921 and a leukemia differentiation therapeutic drug, all-trans retinoic acid.
Project description:<p>Osteocytes could release some small molecules (≤ 1 kDa) through gap junctions and hemichannels to extracellular environment, such as prostaglandin E2 (PGE2), nitric oxide (NO) and adenosine triphosphate (ATP), which play key roles in transferring signals between bone cells and other tissue cells. Connexin (Cx) 43 is the most abundant connexin in osteocytes. To further discover molecules released by osteocytes through Cx43 channels and better understand the regulatory function of Cx43 channels in osteocytes, we performed non-targeted global metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on conditioned medium collected from osteocytes isolated from two transgenic mouse models with Cx43 dominant negative mutants driven by a 10 kb-DMP1 promoter: R76W (gap junctions are blocked, whereas hemichannels are promoted) and Δ130-136 (both gap junctions and hemichannels are blocked). The results revealed that several new categories of molecules, such as “fatty acyls” and “carboxylic acids and derivatives”, could be released through osteocytic Cx43 channels. In addition, alteration of Cx43 channel function affected the release of metabolites related to inflammatory reaction and oxidative stress. Pathway analysis further showed that citric acid cycle was the most differential metabolic pathway regulated by Cx43 channels. In sum, these results isolated new potential metabolites released by osteocytes through Cx43 channels, and offered a novel perspective to understand the regulatory mechanisms of osteocytes on themselves and other cells as well.</p>
Project description:Extensive literature documented that astrocytes release neurotransmitters, cytokines and other signaling molecules that modulate migration, maturation and myelin synthesis of oligodendrocytes through mechanisms primarily converging on cytosolic [Ca2+] transients. Considering the long term effects, it is expected that astrocyte conditioned medium is a major regulator of gene expression in oligodendrocytes even in the absence of cytosol-to-cytosol communication via astrocyte-oligodendrocyte gap junction channels. Indeed, by comparing the transcriptomes of immortalized precursor oligodendrocyte (Oli-neu) cells when cultured alone and cocultured with non-touching astrocytes we found profound changes in gene expression level, control and networking. Remarkably, the astrocyte proximity was more effective in remodeling the myelination (MYE) gene fabric and its control by cytokine receptor (CYR) modulated intercellular Ca2+-signaling (ICS) transcriptomic network than the db-cAMP treatment induced transformation into myelin-associated glycoprotein-positive oligodendrocyte-like cells. Moreover, astrocyte proximity up-regulated 37 MYE genes and switched on another 14 MYE, 23 ICS and 4 CYR genes, enhancing the roles of the leukemia inhibitory factor receptor and connexins Cx29 and Cx47. The novel Prominent Gene Analysis identified enhancer of zeste homolog 2 as the most relevant MYE gene in the astrocyte proximity, notch gene homolog1 in control and B-cell leukemia/lymphoma 2 in differentiated Oli-neu cells.
Project description:MartínJiménez2017 - Genome-scale reconstruction of the human astrocyte metabolic network
This model is described in the article:
Genome-Scale Reconstruction
of the Human Astrocyte Metabolic Network.
Martín-Jiménez CA,
Salazar-Barreto D, Barreto GE, González J.
Front Aging Neurosci 2017; 9: 23
Abstract:
Astrocytes are the most abundant cells of the central
nervous system; they have a predominant role in maintaining
brain metabolism. In this sense, abnormal metabolic states have
been found in different neuropathological diseases.
Determination of metabolic states of astrocytes is difficult to
model using current experimental approaches given the high
number of reactions and metabolites present. Thus, genome-scale
metabolic networks derived from transcriptomic data can be used
as a framework to elucidate how astrocytes modulate human brain
metabolic states during normal conditions and in
neurodegenerative diseases. We performed a Genome-Scale
Reconstruction of the Human Astrocyte Metabolic Network with
the purpose of elucidating a significant portion of the
metabolic map of the astrocyte. This is the first global
high-quality, manually curated metabolic reconstruction network
of a human astrocyte. It includes 5,007 metabolites and 5,659
reactions distributed among 8 cell compartments,
(extracellular, cytoplasm, mitochondria, endoplasmic reticle,
Golgi apparatus, lysosome, peroxisome and nucleus). Using the
reconstructed network, the metabolic capabilities of human
astrocytes were calculated and compared both in normal and
ischemic conditions. We identified reactions activated in these
two states, which can be useful for understanding the
astrocytic pathways that are affected during brain disease.
Additionally, we also showed that the obtained flux
distributions in the model, are in accordance with
literature-based findings. Up to date, this is the most
complete representation of the human astrocyte in terms of
inclusion of genes, proteins, reactions and metabolic pathways,
being a useful guide for in-silico analysis of several
metabolic behaviors of the astrocyte during normal and
pathologic states.
This model is hosted on
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and identified by:
MODEL1608180000.
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To the extent possible under law, all copyright and related or
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Project description:How a tissue returns to homeostasis following injury remains enigmatic. Here, we show that elevated Ca2+ dynamics among enterocytes (ECs) mediated by nAchRs (nicotinic Acetylcholine (Ach) Receptor) in the adult Drosophila midgut, are essential for the epithelium to return to homeostasis after injury. This bioelectric signal is controlled by 1) changes in EC-responsiveness to Ach; 2) enteric neuro-EC interactions; and 3) epithelial gap junctions. Our findings demonstrate how a bioelectric signal during regeneration, initiated by local neuro-epithelial communication and propagated by gap junctions, is coupling the epithelium into a unified response that promotes return to homeostasis.
Project description:Development of effective therapies against brain metastasis is currently hindered by limitations in our understanding of the molecular mechanisms driving it. Here we define the contributions of tumour-secreted exosomes to brain metastatic colonization and demonstrate that pre-conditioning the brain microenvironment with exosomes from brain metastatic cells enhances cancer cell outgrowth. Proteomic analysis identified cell migration-inducing and hyaluronan-binding protein (CEMIP) as elevated in exosomes from brain metastatic, but not lung or bone metastatic cells. CEMIP depletion in tumour cells impaired brain metastasis, disrupting invasion and tumour cell association with the brain vasculature, phenotypes rescued by pre-conditioning the brain microenvironment with CEMIP+ exosomes. Moreover, uptake of CEMIP+ exosomes by brain endothelial and microglial cells induced endothelial cell branching and inflammation in the perivascular niche by upregulating Ptgs2, Tnf, and Ccl/Cxcl 86 cytokines, known to promote brain vascular remodeling and metastasis. CEMIP was elevated in tumour tissues and exosomes from patients with brain metastasis and predicted brain metastasis progression and patient survival. Collectively, our findings suggest that targeting of exosomal CEMIP could constitute a future avenue for the prevention and treatment of brain metastasis.
Project description:Genome wide DNA methylation profiling of brain metastasis from colorectal and lung cancer. The Illumina Infinium MethylationEPIC was used to obtain DNA methylation profiles across approximately 850,000 CpGs in brain metastasis samples. Samples included 1 breast ductal invasive carcinoma, 4 colon adenocarcinoma, 1 melanoma, 1 multiple mieloma, 7 non small cell lung cancer adenocarcinoma, 3 non small cell lung cancer G3, 4 non small cell lung cancer SCC, 1 prostate cancer adenocarcinoma and 1 serous carcinoma.