In the adult hypothalamus, the neuronal precursor role is attributed to the radial glia‐like cells that line the third‐ventricle (3V) wall called tanycytes. Under nutritional cues, including ...hypercaloric diets, tanycytes proliferate and differentiate into mature neurons that moderate body weight, suggesting that hypothalamic neurogenesis is an adaptive mechanism in response to metabolic changes. Previous studies have shown that the tanycyte glucosensing mechanism depends on connexin‐43 hemichannels (Cx43 HCs), purine release, and increased intracellular free calcium ion concentration (Ca2+)i mediated by purinergic P2Y receptors. Since, Fibroblast Growth Factor 2 (FGF2) causes similar purinergic events in other cell types, we hypothesize that this pathway can be also activated by FGF2 in tanycytes to promote their proliferation. Here, we used bromodeoxyuridine (BrdU) incorporation to evaluate if FGF2‐induced tanycyte cell division is sensitive to Cx43 HC inhibition in vitro and in vivo. Immunocytochemical analyses showed that cultured tanycytes maintain the expression of in situ markers. After FGF2 exposure, tanycytic Cx43 HCs opened, enabling release of ATP to the extracellular milieu. Moreover, application of external ATP was enough to induce their cell division, which could be suppressed by Cx43 HC or P2Y1‐receptor inhibitors. Similarly, in vivo experiments performed on rats by continuous infusion of FGF2 and a Cx43 HC inhibitor into the 3V, demonstrated that FGF2‐induced β‐tanycyte proliferation is sensitive to Cx43 HC blockade. Thus, FGF2 induced Cx43 HC opening, triggered purinergic signaling, and increased β‐tanycytes proliferation, highlighting some of the molecular mechanisms involved in the cell division response of tanycyte.
This article has an Editorial Highlight see https://doi.org/10.1111/jnc.15218.
Fibroblast growth factor 2 (FGF2) accelerates basal‐tanycyte cell division, which is sensitive to Cx43 hemichannel inhibition in vitro and in vivo. In primary cultures of tanycyte, the mitogen FGF2 acts over FGF1R inducing Cx43 hemichannel opening and ATP release. Extracellular ATP induces tanycytic division through P2Y1 receptors. In vivo infusion of FGF2 with a Cx43 hemichannel inhibitor into the 3V showed less tanycytes in mitosis. These findings contribute to elucidate the molecular mechanisms involved in tanycyte proliferation.
This article has an Editorial Highlight see https://doi.org/10.1111/jnc.15218.
SALL2, also known as Spalt-like transcription factor 2, is a member of the SALL family of transcription factors involved in development and conserved through evolution. Since its identification in ...1996, findings indicate that SALL2 plays a role in neurogenesis, neuronal differentiation and eye development. Consistently, SALL2 deficiency associates with neural tube defects and coloboma, a congenital eye disease. Relevant to cancer, clinical studies indicate that SALL2 is deregulated in various cancers and is a specific biomarker for Synovial Sarcoma. However, the significance of SALL2 deregulation in this disease is controversial. Here, we present and discuss all available information about SALL2 since its discovery, including isoforms, regulation, targets and functions. We specifically discuss the role of SALL2 in the regulation of cell proliferation and survival within the context of the identified target genes, its interaction with viral oncogenes, and its association with the TP53 tumor suppressor and MYC oncogene. Special attention is given to p53-independent SALL2 regulation of pro-apoptotic genes BAX and PMAIP1, and the implication of these findings on the apoptotic response of cancer cells to therapy. Understanding SALL2 function and the molecular mechanisms governing its expression and activity is critical to comprehend why and how SALL2 could contribute to disease. This knowledge will open new perspectives for the development of molecular targeted approaches in disease.
Variation in Disrupted-in-Schizophrenia 1 (DISC1) increases the risk for neurodegenerative diseases, schizophrenia, and other mental disorders. However, the functions of DISC1 associated with the ...development of these diseases remain unclear. DISC1 has been reported to inhibit Akt/mTORC1 signaling, a major regulator of translation, and recent studies indicate that DISC1 could exert a direct role in translational regulation. Here, we present evidence of a novel role of DISC1 in the maintenance of protein synthesis during oxidative stress. In order to investigate DISC1 function independently of Akt/mTORC1, we used Tsc2−/− cells, where mTORC1 activation is independent of Akt. DISC1 knockdown enhanced inhibition of protein synthesis in cells treated with sodium arsenite (SA), an oxidative agent used for studying stress granules (SGs) dynamics and translational control. N-acetyl-cysteine inhibited the effect of DISC1, suggesting that DISC1 affects translation in response to oxidative stress. DISC1 decreased SGs number in SA-treated cells, but resided outside SGs and maintained protein synthesis independently of a proper SG nucleation. DISC1-dependent stimulation of translation in SA-treated cells was supported by its interaction with eIF3h, a component of the canonical translation initiation machinery. Consistent with a role in the homeostatic maintenance of translation, DISC1 knockdown or overexpression decreased cell viability after SA exposure. Our data suggest that DISC1 is a relevant component of the cellular response to stress, maintaining certain levels of translation and preserving cell integrity. This novel function of DISC1 might be involved in its association with pathologies affecting tissues frequently exposed to oxidative stress.
•DISC1 supports homeostatic maintenance of translation during oxidative stress.•DISC1-eIF3h interaction occurring outside of SG could be relevant for its function.•DISC1 is required for supporting cell viability during oxidative stress.•DISC1 supports cell viability during the over-stimulation of SG response.
Abstract
The induction of genotoxic stress by chemotherapy is one of the first line treatments to eliminate neoplastic cells through apoptosis or programmed cell death. Our laboratory has ...characterized the Sall2 transcription factor, conserved among vertebrates, as a stress-response molecule, and demonstrated both in vitro and in vivo its requirement in the cell death-response caused by genotoxic stress. Few transcriptional targets of Sall2 are known, thus, additional targets most likely remain to be identified. We isolated mouse embryonic fibroblasts (MEFs) from a murine model deficient in Sall2 and from its normal counterpart, and use them to characterize the Sall2-dependent transcriptional response upon genotoxic stress using RNA-seq experiments. Under control conditions we identified ninety-six Sall2-dependent genes involved in immune system, inflammation, cell adhesion and the response to wounding. Under genotoxic stress one hundred twenty six genes were differentially expressed and dependent on Sall2, these genes are mainly involved in immunity, development and cell-cycle regulation. Finally, we performed validation of the analysis using qPCR. With this experimental outline, we are expecting to gain insights on how Sall2 contributes to the transcriptional program under normal and genotoxic stress-induced conditions.
Citation Format: Carlos A. Farkas, Francisco Fuentes, Boris Rebolledo, Kateryna Makova, Anton Nekrutenko, Ariel Castro, Roxana Pincheira. Role of Sall2 transcription factor under genotoxic stress: A transcriptomic approach. abstract. In: Proceedings of the Fourth AACR International Conference on Frontiers in Basic Cancer Research; 2015 Oct 23-26; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2016;76(3 Suppl):Abstract nr B17.
The advancement of hybrid sequencing technologies is increasingly expanding genome assemblies that are often annotated using hybrid sequencing transcriptomics, leading to improved genome ...characterization and the identification of novel genes and isoforms in a wide variety of organisms.
We developed an easy-to-use genome-guided transcriptome annotation pipeline that uses assembled transcripts from hybrid sequencing data as input and distinguishes between coding and long non-coding RNAs by integration of several bioinformatic approaches, including gene reconciliation with previous annotations in GTF format. We demonstrated the efficiency of this approach by correctly assembling and annotating all exons from the chicken SCO-spondin gene (containing more than 105 exons), including the identification of missing genes in the chicken reference annotations by homology assignments.
Our method helps to improve the current transcriptome annotation of the chicken brain. Our pipeline, implemented on Anaconda/Nextflow and Docker is an easy-to-use package that can be applied to a broad range of species, tissues, and research areas helping to improve and reconcile current annotations. The code and datasets are publicly available at https://github.com/cfarkas/annotate_my_genomes.
SALL2 is a transcription factor involved in development and disease. Deregulation of SALL2 has been associated with cancer, suggesting that it plays a role in the disease. However, how SALL2 is ...regulated and why is deregulated in cancer remain poorly understood. We previously showed that the p53 tumor suppressor represses SALL2 under acute genotoxic stress. Here, we investigated the effect of Histone Deacetylase Inhibitor (HDACi) Trichostatin A (TSA), and involvement of Sp1 on expression and function of SALL2 in Jurkat T cells. We show that SALL2 mRNA and protein levels were enhanced under TSA treatment. Both, TSA and ectopic expression of Sp1 transactivated the SALL2 P2 promoter. This transactivation effect was blocked by the Sp1-binding inhibitor mithramycin A. Sp1 bound in vitro and in vivo to the proximal region of the P2 promoter. TSA induced Sp1 binding to the P2 promoter, which correlated with dynamic changes on H4 acetylation and concomitant recruitment of p300 or HDAC1 in a mutually exclusive manner. Our results suggest that TSA-induced Sp1-Lys703 acetylation contributes to the transcriptional activation of the P2 promoter. Finally, using a CRISPR/Cas9 SALL2-KO Jurkat-T cell model and gain of function experiments, we demonstrated that SALL2 upregulation is required for TSA-mediated cell death. Thus, our study identified Sp1 as a novel transcriptional regulator of SALL2, and proposes a novel epigenetic mechanism for SALL2 regulation in Jurkat-T cells. Altogether, our data support SALL2 function as a tumor suppressor, and SALL2 involvement in cell death response to HDACi.
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•In Jurkat T cells, SALL2 gene is regulated by an epigenetic mechanism that involves p300, HDAC1 and Sp1.•Sp1 directly binds to proximal regions of SALL2-P2 promoter, and its binding increased by Trichostatin A treatment.•TSA and other FDA-approved HDACi upregulate SALL2 expression in Jurkat T cells.•SALL2 is required for the cell death response to TSA treatment in Jurkat T cells.
Abstract
SALL2- a member of the Spalt gene family- is a poorly characterized transcription factor found deregulated in various cancers, which suggest it plays a role in the disease. We previously ...identified SALL2 as a novel interacting protein of neurotrophin receptors and showed that it plays a role in neuronal function, which does not necessarily explain why or how SALL2 is deregulated in cancer. Previous evidences indicate that SALL2 gene is regulated by the WT1 and AP4 transcription factors. Here, we identified SALL2 as a novel downstream target of the P53 tumor suppressor protein. Bioinformatic analysis of the SALL2 gene revealed several putative P53 half sites along the promoter region. Either overexpression of wild-type P53 or induction of the endogenous P53 by the genotoxic agent doxorubicin repressed SALL2 promoter activity in various cell lines. However, Q143A, R175H and R248W P53 mutants, which are frequently found in the tumors of cancer patients, were unable to repress SALL2 promoter activity. Chromatin immunoprecipitation analysis using a specific P53 antibody further supported the binding to, and regulation of the SALL2 promoter by P53. Importantly, by using a p53ERTAM knockin model expressing a variant of P53 that is completely dependent on 4-hydroxy-tamoxifen for its activity, we show that P53 activation diminished SALL2 RNA and protein levels during genotoxic cellular stress in primary mouse embryo fibroblasts (MEFs) and radiosentive tissues in vivo. Thus, our finding indicates that P53 represses SALL2 expression in a context-specific manner, adding knowledge to understanding SALL2 gene regulation, and a potential mechanism for its deregulation in cancer
Citation Format: Carlos Farkas, Carla Martins, David Escobar, Ariel Castro, David Donner, Roxana Pincheira. p53 transcriptionally represses the SALL2 transcription factor under genotoxic stress. abstract. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-51. doi:10.1158/1538-7445.AM2013-LB-51
R1 was isolated from a pulp mill wastewater treatment plant because of its ability to use methoxylated aromatics as growth substrates. We report the 5.56-Mb genome sequence of strain R1, which can ...provide insights into the biodegradation of lignin-derived phenolic monomers and potentially support processes for lignocellulose conversion.
sp. strains ALS1279 and ALS1131 were isolated from wastewater treatment facilities on the basis of their ability to use furfural, a key lignocellulose-derived inhibitor, as their only carbon source. ...Here, we present the draft genome sequences of both strains, which can shed light on catabolic pathways for furan compounds in pseudomonads.
SALL2- a member of the Spalt gene family- is a poorly characterized transcription factor found deregulated in various cancers, which suggests it plays a role in the disease. We previously identified ...SALL2 as a novel interacting protein of neurotrophin receptors and showed that it plays a role in neuronal function, which does not necessarily explain why or how SALL2 is deregulated in cancer. Previous evidences indicate that SALL2 gene is regulated by the WT1 and AP4 transcription factors. Here, we identified SALL2 as a novel downstream target of the p53 tumor suppressor protein. Bioinformatic analysis of the SALL2 gene revealed several putative p53 half sites along the promoter region. Either overexpression of wild-type p53 or induction of the endogenous p53 by the genotoxic agent doxorubicin repressed SALL2 promoter activity in various cell lines. However R175H, R249S, and R248W p53 mutants, frequently found in the tumors of cancer patients, were unable to repress SALL2 promoter activity, suggesting that p53 specific binding to DNA is important for the regulation of SALL2. Electrophoretic mobility shift assay demonstrated binding of p53 to one of the identified p53 half sites in the Sall2 promoter, and chromatin immunoprecipitation analysis confirmed in vivo interaction of p53 with the promoter region of Sall2 containing this half site. Importantly, by using a p53ERTAM knockin model expressing a variant of p53 that is completely dependent on 4-hydroxy-tamoxifen for its activity, we show that p53 activation diminished SALL2 RNA and protein levels during genotoxic cellular stress in primary mouse embryo fibroblasts (MEFs) and radiosensitive tissues in vivo. Thus, our finding indicates that p53 represses SALL2 expression in a context-specific manner, adding knowledge to the understanding of SALL2 gene regulation, and to a potential mechanism for its deregulation in cancer.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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