Downregulation Of Unfolded Protein Response Research Articles

Pharmacological inhibition of p300 ameliorates steatosis, inflammation, and fibrosis in mice with non-alcoholic steatohepatitis

The histone acetyltransferase p300 plays a pivotal role in regulating gene expression and cellular phenotype through epigenetic mechanisms. It significantly influences lipid metabolism, which is a key factor in the pathogenesis of non-alcoholic steatohepatitis (NASH), by modulating the transcription of genes involved in lipid synthesis and accumulation. This study aimed to investigate the protective potential of inhibiting p300 in NASH. Male C57BL/6J mice were subjected to a methionine- and choline-deficient (MCD) diet for 4 weeks to induce NASH, and during this period, the p300 inhibitor C646 (10 mg/kg) was administered three times a week. C646 treatment reduced the elevation of p300 expression and histone H3 acetylation, leading to a decrease in liver injury markers in the serum and an improvement in the histological abnormalities observed in MCD diet-fed mice. C646 also reduced lipid accumulation by modulating de novo lipogenesis and suppressed inflammation, including cytokine overproduction and macrophage infiltration. Furthermore, C646 mitigated liver fibrosis and myofibroblast accumulation. This protective effect was achieved through the inhibition of apoptosis by reducing p53 and Bax expression and the suppression of ferroptosis by decreasing lipid peroxidation while enhancing antioxidant defenses. Additionally, C646 alleviated endoplasmic reticulum stress, as evidenced by the downregulation of unfolded protein response signaling molecules. These results highlight the potential of p300 as a therapeutic target for NASH.

Functional characterization of a single nucleotide polymorphism associated with Alzheimer's disease in a hiPSC-based neuron model.

Neurodegenerative diseases encompass a group of debilitating conditions resulting from progressive nerve cell death. Of these, Alzheimer's disease (AD) occurs most frequently, but is currently incurable and has limited treatment success. Late onset AD, the most common form, is highly heritable but is caused by a combination of non-genetic risk factors and many low-effect genetic variants whose disease-causing mechanisms remain unclear. By mining the FinnGen study database of phenome-wide association studies, we identified a rare variant, rs148726219, enriched in the Finnish population that is associated with AD risk and dementia, and appears to have arisen on a common haplotype with older AD-associated variants such as rs429358. The rs148726219 variant lies in an overlapping intron of the FosB proto-oncogene (FOSB) and ERCC excision repair 1 (ERCC1) genes. To understand the impact of this SNP on disease phenotypes, we performed CRISPR/Cas9 editing in a human induced pluripotent stem cell (hiPSC) line to generate isogenic clones harboring heterozygous and homozygous alleles of rs148726219. hiPSC clones differentiated into induced excitatory neurons (iNs) did not exhibit detectable molecular or morphological variation in differentiation potential compared to isogenic controls. However, global transcriptome analysis showed differential regulation of nearby genes and upregulation of several biological pathways related to neuronal function, particularly synaptogenesis and calcium signaling, specifically in mature iNs harboring rs148726219 homozygous and heterozygous alleles. Functional differences in iN circuit maturation as measured by calcium imaging were observed across genotypes. Edited mature iNs also displayed downregulation of unfolded protein response and cell death pathways. This study implicates a phenotypic impact of rs148726219 in the context of mature neurons, consistent with its identification in late onset AD, and underscores a hiPSC-based experimental model to functionalize GWAS-identified variants.

Adar-Mediated Aberrant a-to-I RNA Editing Is Driven By 1q Amplification and Contributes to Proteasome Inhibitor Resistance in Multiple Myeloma

Multiple Myeloma (MM) is an incurable malignancy of plasma cells characterized by wide and remarkable genetic heterogeneity. The amplification of 1q identifies a class of patients characterized by a more aggressive disease course and poor prognosis. While previous research has identified several oncogenes with prognostic relevance located in 1q, the biological mechanisms underlying the poor clinical outcome associated with this alteration is still unclear.ADAR (Adenosine Deaminase Acting on RNA) is an enzyme responsible for A-to-I editing, a post-transcriptional process which contributes to transcriptome and proteome diversity by conversion of specific adenosines into inosines in both coding and non-coding transcripts. Such changes may affect RNA stability and regulation and introduce mutations in the corresponding proteins.Recent research has reported dysregulation of RNA editing in cancer, revealing its oncogenicity and clinical relevance. Since ADAR is located in 1q21, the critical amplified region in MM, we sought to investigate the implications of ADAR activity in MM.We have previously shown increased ADAR expression and A-to-I RNA editing in a small group of newly diagnosed patients with 1q21 amplification enrolled in the MMRF CoMMpass study (Lagana et al, ASH 2016), and that ADAR expression could differentiate prognosis. To further investigate and characterize the role of ADAR and RNA Editing in MM, we have analyzed 590 RNAseq samples from newly diagnosed patients in CoMMpass. ADAR copy number gain was observed in 111 samples (19%).ADAR expression was significantly higher in patients with 1q21 gain (p < 0.0001), supporting the role of copy number gain as a driver of ADAR expression. Moreover, patients with high expression of ADAR and no CN alterations, showed significant activation of Interferon pathways (Fig. 1A). This can be explained by the fact that one isoform of ADAR (p150) is regulated by an interferon-inducible promoter. Multivariate regression of ADAR expression against ADAR CN and STAT1 expression, as a measure of interferon signaling activation, showed that both ADAR CN and STAT1 expression were significant independent predictors of ADAR expression.To investigate the functional impact of ADAR activity, we implemented a computational pipeline to calculate sample-wise Alu Editing Index (AEI). A-to-I RNA editing targets predominantly Alu elements, repetitive sequences abundantly interspersed throughout the human genome, mostly within introns and untranslated regions (UTRs). AEI has been developed and validated as a global measure of RNA editing activity at the sample level (Bazak et al, Genome Res 2014). Our analysis in MM revealed that AEI could discriminate between good and poor prognosis in terms of both PFS and OS (p < 0.0001). Moreover, AEI could critically stratify patients with 1q21 gain in terms of PFS (p < 0.01) (Fig. 1B). This finding suggests that RNA editing can be an adverse prognostic factor independently of 1q21 gain.Patients with high AEI were characterized by down-regulation of immunoglobulin transcripts and of the Unfolded Protein Response (UPR) pathway. In particular, patients with high AEI exhibited down-regulation of key activators of UPR such as NFYC, ATF4 and XBP1, and of transcriptional targets of XBP1s, the active spliced form of XBP1. Decreased UPR and low XBP1s expression in pre-plasmablasts have been shown to induce resistance to proteasome inhibitors (PI) (e.g. Bortezomib) through de-differentiation of plasma cells (Leung-Hagesteijn et al, Cancer Cell 2013). Among patients who received Bortezomib-based first line therapy, we found that AEI was significantly higher (p<0.01) in patients whose best response was stable disease (SD) or progressive disease (PD) (23; 4.5%) compared to patients who had complete (CR) or stringent complete response (sCR) (118; 23%) (Fig. 1C). siRNA meditated knockdown of ADAR increased sensitivity to Bortezomib in MM cell lines with 1q amplification and high ADAR expression (OPM2), consistently with our in-silico findings.In conclusion, we propose a model of MM where ADAR-mediated RNA editing is driven by gain of 1q21 and interferon signaling and contributes to disease aggressiveness and resistance to PI-based therapy through down-regulation of UPR (Fig. 1D). [Display omitted] DisclosuresMadduri:Foundation Medicine, Inc.: Consultancy. Chari:Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding; Amgen: Honoraria, Research Funding; Novartis: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding; Celgene Corporation: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Cho:Agenus, Inc.: Research Funding; Genentech: Other: advisory board, Research Funding; Ludwig Institute for Cancer Research: Research Funding; Bristol Myers-Squibb: Other: advisory board, Research Funding; Multiple Myeloma Research Foundation: Research Funding. Barlogie:Millenium Pharmaceuticals: Consultancy, Research Funding; Celgene Corporation: Consultancy, Research Funding. Jagannath:Merck: Consultancy; Medicom: Speakers Bureau; Celgene: Consultancy; Bristol-Meyers Squibb: Consultancy; Novartis: Consultancy; MMRF: Speakers Bureau. Dudley:Ecoeos, Inc.: Equity Ownership; Ayasdi, Inc.: Equity Ownership; Ontomics, Inc.: Equity Ownership; Personalis: Patents & Royalties; AstraZeneca: Consultancy; NuMedii, Inc.: Equity Ownership, Patents & Royalties; Janssen Pharmaceuticals, Inc.: Consultancy; GlaxoSmithKline: Consultancy.

Shikimic acid protects skin cells from UV-induced senescence through activation of the NAD+-dependent deacetylase SIRT1.

UV radiation is one of the main contributors to skin photoaging by promoting the accumulation of cellular senescence, which in turn induces a proinflammatory and tissue-degrading state that favors skin aging. The members of the sirtuin family of NAD+-dependent enzymes play an anti-senescence role and their activation suggests a promising approach for preventing UV-induced senescence in the treatment of skin aging. A two-step screening designed to identify compounds able to protect cells from UV-induced senescence through sirtuin activation identified shikimic acid (SA), a metabolic intermediate in many organisms, as a bona-fide candidate. The protective effects of SA against senescence were dependent on specific activation of SIRT1 as the effect was abrogated by the SIRT1 inhibitor EX-527. Upon UV irradiation SA induced S-phase accumulation and a decrease in p16INK4A expression but did not protect against DNA damage or increased polyploidies. In contrast, SA reverted misfolded protein accumulation upon senescence, an effect that was abrogated by EX-527. Consistently, SA induced an increase in the levels of the chaperone BiP, resulting in a downregulation of unfolded protein response (UPR) signaling and UPR-dependent autophagy, avoiding their abnormal hyperactivation during senescence. SA did not directly activate SIRT1 in vitro, suggesting that SIRT1 is a downstream effector of SA signaling specifically in the response to cellular senescence. Our study not only uncovers a shikimic acid/SIRT1 signaling pathway that prevents cellular senescence, but also reinforces the role of sirtuins as key regulators of cell proteostasis.

Lifetime Genistein Intake Increases the Response of Mammary Tumors to Tamoxifen in Rats.

Whether it is safe for estrogen receptor-positive (ER+) patients with breast cancer to consume soy isoflavone genistein remains controversial. We compared the effects of genistein intake mimicking either Asian (lifetime) or Caucasian (adulthood) intake patterns to that of starting its intake during tamoxifen therapy using a preclinical model. Female Sprague-Dawley rats were fed an AIN93G diet supplemented with 0 (control diet) or 500 ppm genistein from postnatal day 15 onward (lifetime genistein). Mammary tumors were induced with 7,12-dimethylbenz(a)anthracene (DMBA), after which a group of control diet-fed rats were switched to genistein diet (adult genistein). When the first tumor in a rat reached 1.4 cm in diameter, tamoxifen was added to the diet and a subset of previously only control diet-fed rats also started genistein intake (post-diagnosis genistein). Lifetime genistein intake reduced de novo resistance to tamoxifen, compared with post-diagnosis genistein groups. Risk of recurrence was lower both in the lifetime and in the adult genistein groups than in the post-diagnosis genistein group. We observed downregulation of unfolded protein response (UPR) and autophagy-related genes (GRP78, IRE1α, ATF4, and Beclin-1) and genes linked to immunosuppression (TGFβ and Foxp3) and upregulation of cytotoxic T-cell marker CD8a in the tumors of the lifetime genistein group, compared with controls, post-diagnosis, and/or adult genistein groups. Genistein intake mimicking Asian consumption patterns improved response of mammary tumors to tamoxifen therapy, and this effect was linked to reduced activity of UPR and prosurvival autophagy signaling and increased antitumor immunity. Clin Cancer Res; 23(3); 814-24. ©2017 AACR.

Protective effect of total flavonoid C-glycosides from Abrus mollis extract on lipopolysaccharide-induced lipotoxicity in mice

Abrus mollis is a widely used traditional Chinese medicine for treating acute and chronic hepatitis, steatosis, and fibrosis. It was found that the total flavonoid C-glycosides from Abrus mollis extract (AME) showed potent antioxidant, anti-inflammatory, and hepatoprotective activities. To further investigate the hepatoprotective effect of AME and its possible mechanisms, lipopolysaccharide (LPS)-induced liver injury models were applied in the current study. The results indicated that AME significantly attenuated LPS-induced lipid accumulation in mouse primary hepatocytes as measured by triglyceride (TG) and total cholesterol (TC) assays and Oil Red O staining. Meanwhile, AME exerted a protective effect on LPS-induced liver injury as shown by decreased liver index, serum aminotransferase levels, and hepatic lipid accumulation. Real-time PCR and immunoblot data suggested that AME reversed the LPS-mediated lipid metabolism gene expression, such as sterol regulatory element-binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase 1 (ACC1). In addition, LPS-induced overexpression of activating transcription factor 4 (ATF4), X-box-binding protein-1 (XBP-1), and C/EBP homologous protein (CHOP) were dramatically reversed by AME. Furthermore, AME also decreased the expression of LPS-enhanced interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2). Here, it is demonstrated for the first time that AME ameliorated LPS-induced hepatic lipid accumulation and that this effect of AME can be attributed to its modulation of hepatic de novo fatty acid synthesis. This study also suggested that the hepatoprotective effect of AME may be related to its down-regulation of unfolded protein response (UPR) activation.

Inhibition of Akt Potentiates 2-DG–Induced Apoptosis via Downregulation of UPR in Acute Lymphoblastic Leukemia

The ability to pair the regulation of metabolism and cellular energetics with oncogenes and tumor suppressor genes provides cancer cells with a growth and survival advantage over normal cells. We investigated the mechanism of cell death induced by 2-deoxy-D-glucose (2-DG), a sugar analog with dual activity of inhibiting glycolysis and N-linked glycosylation, in acute lymphoblastic leukemia (ALL). We found that, unlike most other cancer phenotypes in which 2-DG only inhibits cell proliferation under normoxic conditions, ALL lymphoblasts undergo apoptosis. Bp-ALL cell lines and primary cells exhibited sensitivity to 2-DG, whereas T-ALL cells were relatively resistant, revealing phenotypic differences within ALL subtypes. Cotreatment with D-mannose, a sugar essential for N-linked glycosylation, rescues 2-DG-treated ALL cells, indicating that inhibition of N-linked glycosylation and induction of ER stress and the unfolded protein response (UPR) is the predominant mechanism of 2-DG's cytotoxicity in ALL. 2-DG-treated ALL cells exhibit upregulation of P-AMPK, P-Akt, and induction of ER stress/UPR markers (IRE1α, GRP78, P-eIF2α, and CHOP), which correlate with PARP cleavage and apoptosis. In addition, we find that pharmacologic and genetic Akt inhibition upregulates P-AMPK, downregulates UPR, and sensitizes ALL cells to remarkably low doses of 2-DG (0.5 mmol/L), inducing 85% cell death and overcoming the relative resistance of T-ALL. In contrast, AMPK knockdown rescues ALL cells by upregulating the prosurvival UPR signaling. Therefore, 2-DG induces ALL cell death under normoxia by inducing ER stress, and AKT and AMPK, traditionally thought to operate predominantly on the glycolytic pathway, differentially regulate UPR activity to determine cell death or survival.