A suite of haploid genetic screens identifies SPRING as a novel determinant of SREBP signaling and cholesterol metabolism
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PROVIDER: PRJNA600886 | ENA |
REPOSITORIES: ENA
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Project description:The sterol-regulatory element binding protein (SREBP) transcription factors are central transcriptional regulators of sterol- and fatty acid metabolism. Using a suite of human haploid genetic screens, we identify the SREBP Regulating Gene (SPRING; C12ORF49) as a novel regulator of this pathway. SPRING is a glycosylated Golgi-resident membrane protein. Genetic ablation of SPRING in human Hap1 cells, murine Hepa1-6 hepatoma cells, and in primary murine hepatocytes leads to a marked reduction in SREBP signaling. In mice, deletion of Spring results in embryonic lethality. However, we show that adenoviral-mediated silencing of hepatic Spring expression also attenuates the SREBP response. Mechanistically, we demonstrate that attenuated SREBP signaling in SPRINGKO cells is a result of reduced SREBP cleavage-activating protein (SCAP) and its mislocalization. Whereas in control cells SCAP cycles between the ER and the Golgi in a sterol-dependent manner, in SPRINGKO cells SCAP is trapped in the Golgi irrespective of the cellular sterol status. Consistent with limited functional SCAP in SPRINGKO cells, reintroducing SCAP restores SREBP-dependent signaling, cholesterol biosynthesis, and lipoprotein uptake. Consistent with SREBP signaling being required for cell growth and proliferation, a wide range of human tumor cell lines display dependency on SPRING expression. In conclusion, we identify SPRING as a previously unrecognized determinant of the SREBP pathway that is essential for proper SCAP function.
2020-01-23 | GSE143530 | GEO
Project description:The sterol-regulatory element binding proteins (SREBP) are central transcriptional regulators of lipid metabolism. Using haploid genetic screens we identify the SREBP Regulating Gene (SPRING/C12ORF49) as a determinant of the SREBP pathway. SPRING is a glycosylated Golgi-resident membrane protein and its ablation in Hap1 cells, Hepa1-6 hepatoma cells, and primary murine hepatocytes reduces SREBP signaling. In mice, Spring deletion is embryonic lethal yet silencing of hepatic Spring expression also attenuates the SREBP response. Mechanistically, attenuated SREBP signaling in SPRINGKO cells results from reduced SREBP cleavage-activating protein (SCAP) and its mislocalization to the Golgi irrespective of the cellular sterol status. Consistent with limited functional SCAP in SPRINGKO cells, reintroducing SCAP restores SREBP-dependent signaling and function. Moreover, in line with the role of SREBP in tumor growth, a wide range of tumor cell lines display dependency on SPRING expression. In conclusion, we identify SPRING as a previously unrecognized modulator of SREBP signaling.
| S-EPMC7048761 | biostudies-literature
Project description:We undertook a unbiased genome-wide haploid genetic screen to identify new components in interferon lambda signaling. In addition, we performed a genome-wide screen to identify genes that repress spontaneous activation of interferon stimulated genes in the absence of interferon. Both of these screens were performed using a HAP1 cell line containing GFP reporter under the transcriptional regulation of the Interferon-Stimulated Response Element from IFIT2. We also overexpressed IL28RA (IFNLR1) in this cell line, in order to sensitize the cells to type III interferon
2017-07-25 | E-MTAB-5866 | biostudies-arrayexpress
Project description:Comparative haploid genetic screens to annotate common and specialized genes required for the biogenesis of individual GPI anchored proteins. SEC62 and SEC63 were required for proper PrP targeting, and were dispensable for CD59. CD59 however, required a GPI side chain modification for maturation, in addition to the aspartyl intramembrane cleaving protease: SPPL3.
2015-05-13 | GSE68796 | GEO
Project description:Mammalian haploid embryonic stem cells (haESCs) provide new possibilities for large-scale genetic screens because they bear only one copy of each chromosome. However, haESCs are prone to spontaneous diploidization through unknown mechanisms. Here, we report that a small molecule combination could restrain mouse haESCs from diploidization by impeding exit from naïve pluripotency and by shortening the S-G2/M phases. Combined with 2i and PD166285, our chemical cocktail could maintain haESCs in the haploid state for at least five weeks without fluorescence-activated cell sorting (FACS) enrichment of haploid cells. Taken together, we established an effective chemical approach for long-term maintenance of haESCs, and highlighted that proper cell cycle progression was critical for the maintenance of haploid state.
2017-10-31 | GSE104519 | GEO
Project description:The sterol regulatory element binding proteins (SREBPs) are transcription factors that govern cholesterol and fatty acid metabolism. Owing to their central role in controlling hepatic lipid and lipoprotein metabolism their activity is tightly coordinated, and accordingly dysregulation of the SREBP pathway is associated with development of dyslipidemia and non-alcoholic fatty liver disease. Using a suite of genome-wide genetic screens we have recently identified SPRING (C12ORF49) as a novel post-transcriptional regulator of SREBP activation in vitro. Our previous work demonstrated that constitutive ablation of Spring in mice is embryonically lethal. Here we show that inducible global deletion of Spring is also untolerated, and therefore to interrogate the physiological role of SPRING in controlling hepatic lipid metabolism we developed liver-specific Spring knockout mice (LKO). Liver transcriptomics and proteomics analysis revealed severely attenuated SREBP signaling in livers and in hepatocytes of LKO mice, which was associated with marked effects on both plasma and hepatic lipid levels. In plasma, total cholesterol levels were dramatically reduced in both male and female LKO mice, apparent in both the LDL and HDL fractions, while triglyceride levels remained largely unaffected. In liver, loss of Spring diminished cholesterol and triglyceride biosynthesis resulting in decreased hepatic cholesterol and triglyceride content. This coincided with reduced secretion of VLDL into the circulation. Consistent with diminished hepatic de novo lipogenesis, LKO mice were protected from developing hepatosteatosis when challenged with a fructose-rich diet. Supporting the significance of our findings in mice, we identified common and rare SPRING genetic variants that are strongly associated with circulating HDL-c and ApoA1 levels in humans. Collectively, our study positions SPRING as a core component of hepatic SREBP signaling, and consequently of systemic lipid metabolism in mice and humans.
2023-08-01 | GSE236045 | GEO
Project description:Sterol regulatory element binding proteins (SREBPs) are key transcriptional regulators of lipid metabolism. To define functional differences between the three mammalian SREBPs we are using genome-wide ChIP-seq with isoform-specific antibodies and chromatin from select tissues of mice challenged with different dietary conditions that enrich for specific SREBPs. We show hepatic SREBP-2 binds preferentially to two different gene-proximal motifs. Gene ontology analyses suggests SREBP-2 targets lipid metabolic processes as expected but apoptosis and autophagy gene categories were also enriched. We show SREBP-2 directly activates autophagy genes during cell sterol depletion, conditions known to induce both autophagy and nuclear SREBP-2 levels. Additionally, SREBP-2 knockdown during nutrient depletion decreased autophagosome formation and lipid droplet association of the autophagosome targeting protein LC3. Thus, the lipid droplet could be viewed as a third source of cellular cholesterol, which along with sterol synthesis and uptake, is also regulated by SREBP-2. Examination of hepatic SREBP-2 binding using ChIP-Seq. One ChIP-Seq dataset and one IgG control.
2011-03-22 | E-GEOD-28082 | biostudies-arrayexpress
Project description:Fine-tuning of lipogenic gene expression is important for the maintenance of long-term homeostasis of intracellular lipids. The SREBP family of transcription factors are master regulators that control the transcription of lipogenic and cholesterogenic genes, but the mechanisms modulating SREBP-dependent transcription are still not fully understood. We previously reported that CDK8, a subunit of the transcription co-factor Mediator complex, phosphorylates SREBP at a conserved threonine residue. Here, using Drosophila as a model system, we observed that the phosphodeficient SREBP proteins (SREBP-Thr390Ala) were more stable and more potent in stimulating the expression of lipogenic genes and promoting lipogenesis in vivo than wild-type SREBP. In addition, starvation blocked the effects of wild-type SREBP-induced lipogenic gene transcription, whereas phosphodeficient SREBP was resistant to this effect. Furthermore, our biochemical analyses identified six highly conserved amino acid residues in the N-terminus disordered region of SREBP that are required for its interactions with both Cdk8 and the MED15 subunit of the small Mediator complex. These results support that the concerted actions of Cdk8 and MED15 are essential for the tight regulation of SREBP-dependent transcription.
2022-11-09 | GSE217104 | GEO
Project description:Phenotypes of haploid embryonic stem cells (haESCs) are dominant for recessive traits in mice. However, one major obstacle to their use is self-diploidization in daily culture. Although haESCs maintain haploidy well by deleting p53, whether they can sustain haploidy in differentiated status and the mechanism behind remain unknown. To address that, we induced p53-deficient haESCs into multiple differentiated lineages keeping a haploid status in vitro. Besides, haploid cells also remained in chimeric embryos and teratomas arising from p53-null haESCs. Transcriptome analysis revealed that apoptosis genes were down-regulated in p53-null haESCs, comparing to that in wild-type haESCs. Finally, we knocked-out p73, another apoptosis gene, and observed stabilization of haploidy in haESCs, either. These results indicated that the main mechanism of diploidization was apoptosis-related genes triggered cell death in haploid cell cultures. Thus, we can derive haploid somatic cells by manipulating apoptosis gene, facilitating genetic screens of lineage-specific development.
2020-04-07 | GSE148118 | GEO