CGK733-induced LC3 II formation is positively associated with the expression of cyclin-dependent kinase inhibitor p21Waf1/Cip1 through modulation of the AMPK and PERK/CHOP signaling pathways

Transcriptomic Changes Associated with Loss of Cell Viability Induced by Oxysterol Treatment of a Retinal Photoreceptor-Derived Cell Line: An In Vitro Model of Smith-Lemli-Opitz Syndrome

Smith–Lemli–Opitz Syndrome (SLOS) results from mutations in the gene encoding the enzyme DHCR7, which catalyzes conversion of 7-dehydrocholesterol (7DHC) to cholesterol (CHOL). Rats treated with a DHCR7 inhibitor serve as a SLOS animal model, and exhibit progressive photoreceptor-specific cell death, with accumulation of 7DHC and oxidized sterols. To understand the basis of this cell type specificity, we performed transcriptomic analyses on a photoreceptor-derived cell line (661W), treating cells with two 7DHC-derived oxysterols, which accumulate in tissues and bodily fluids of SLOS patients and in the rat SLOS model, as well as with CHOL (negative control), and evaluated differentially expressed genes (DEGs) for each treatment. Gene enrichment analysis and compilation of DEG sets indicated that endoplasmic reticulum stress, oxidative stress, DNA damage and repair, and autophagy were all highly up-regulated pathways in oxysterol-treated cells. Detailed analysis indicated that the two oxysterols exert their effects via different molecular mechanisms. Changes in expression of key genes in highlighted pathways (Hmox1, Ddit3, Trib3, and Herpud1) were validated by immunofluorescence confocal microscopy. The results extend our understanding of the pathobiology of retinal degeneration and SLOS, identifying potential new druggable targets for therapeutic intervention into these and other related orphan diseases.

Dimethylfumarate Inhibits Colorectal Carcinoma Cell Proliferation: Evidence for Cell Cycle Arrest, Apoptosis and Autophagy

Recent studies have proven that Dimethylfumarate (DMF) has a marked anti-proliferative impact on diverse cancer entities e.g., on malignant melanoma. To explore its anti-tumorigenic potential, we examined the effects of DMF on human colon carcinoma cell lines and the underlying mechanisms of action. Human colon cancer cell line HT-29 and human colorectal carcinoma cell line T84 were treated with or without DMF. Effects of DMF on proliferation, cell cycle progression, and apoptosis were analyzed mainly by Bromodeoxyuridine (BrdU)- and Lactatdehydrogenase (LDH)assays, caspase activation, flowcytometry, immunofluorescence, and immunoblotting. In addition, combinational treatments with radiation and chemotherapy were performed. DMF inhibits cell proliferation in both cell lines. It was shown that DMF induces a cell cycle arrest in G0/G1 phase, which is accompanied by upregulation of p21 and downregulation of cyclin D1 and Cyclin dependent kinase (CDK)4. Furthermore, upregulation of autophagy associated proteins suggests that autophagy is involved. In addition, the activation of apoptotic markers provides evidence that apoptosis is involved. Our results show that DMF supports the action of oxaliplatin in a synergetic manner and failed synergy with radiation. We demonstrated that DMF has distinct antitumorigenic, cell dependent effects on colon cancer cells by arresting cell cycle in G0/G1 phase as well as activating both the autophagic and apoptotic pathways and synergizes with chemotherapy.

The IL-15-AKT-XBP1s signaling pathway contributes to effector functions and survival in human NK cells

Interleukin 15 (IL-15) is one of the most important cytokines that regulate the biology of natural killer (NK) cells1. Here we identified a signaling pathway-involving the serine-threonine kinase AKT and the transcription factor XBP1s, which regulates unfolded protein response genes2,3-that was activated in response to IL-15 in human NK cells. IL-15 induced the phosphorylation of AKT, which led to the deubiquitination, increased stability and nuclear accumulation of XBP1s protein. XBP1s bound to and recruited the transcription factor T-BET to the gene encoding granzyme B, leading to increased transcription. XBP1s positively regulated the cytolytic activity of NK cells against leukemia cells and was also required for IL-15-mediated NK cell survival through an anti-apoptotic mechanism. Thus, the newly identified IL-15-AKT-XBP1s signaling pathway contributes to enhanced effector functions and survival of human NK cells.

Hesperidin inhibits ovarian cancer cell viability through endoplasmic reticulum stress signaling pathways

Hesperidin is a vitamin P flavonoid compound primarily present in citrus fruits. The aim of the present study was to investigate whether hesperidin inhibits ovarian cancer cell viability via endoplasmic reticulum stress signaling pathways. A2780 cells were treated with various doses of hesperidin for 6, 12 or 24 h, and the viability of A2780 cells was assessed using the MTT assay. Hesperidin decreased the viability of A2780 cells and increased cytotoxicity in a dose- and time-dependent manner. In addition, hesperidin induced apoptosis and increased cleaved caspase-3 protein expression levels in A2780 cells. Furthermore, hesperidin markedly increased the protein expression of anti-growth arrest- and DNA damage-inducible gene 153, anti-CCAAT'enhancer-binding protein homologous protein, glucose-regulated protein 78 and cytochrome c in A2780 cells. The results of the present study indicated that hesperidin inhibits cell viability and induces apoptosis in ovarian cancer cells via endoplasmic reticulum stress signaling pathways. Thus, hesperidin may offer a novel therapeutic tool for ovarian carcinoma.

MicroRNA-223 alleviates lipopolysaccharide-induced PC-12 cells apoptosis and autophagy by targeting RPH1 in spinal cord injury

Spinal cord injury (SCI) is one of the most devastating diseases. MicroRNAs (miRNAs) are recognized as key regulators in SCI; however, the role of miR-223 in SCI remains unclear. Herein, our study aimed to explore the effect of miR-223 on lipopolysaccharide (LPS)-induced injury to PC-12 cells. PC-12 cells were treated with different concentrations of LPS, and then cell viability, apoptosis, apoptosis-related factors and autophagy-related factors were analyzed by CCK-8, flow cytometry and western blot. Subsequently, miR-223 mimic, miR-223 inhibitor, pEX-RPH1, sh-RPH1 and corresponding controls were transfected into PC-12 cells followed by 5 μg/ml of LPS treatment. Cell viability, apoptosis, apoptosis-related and autophagy-related factors were analyzed again. A target gene of miR-223 was validated by dual-luciferase assay. Besides, the main factors expressions of mTOR and NF-κB signal pathways were measured by western blot. LPS reduced cell viability but increased apoptotic cells rate, up-regulated Bax, cleaved-caspase-3, cleaved-caspase-9, LC-II and Beclin-1, and down-regulated Bcl-2 and p62 expressions in a dose-dependent way. Additionally, miR-223 overexpression promoted cell viability but inhibited apoptosis, and autophagy in LPS-stimulated PC-12 cells. RPH1 was a direct target of miR-223, and RPH1 exhibited contrary impacts to miR-223 on LPS-induced cell apoptosis and autophagy. Besides, the promoting effects of miR-223 suppression on cell apoptosis and autophagy were relieved by RPH1 silence. Furthermore, miR-223 blocked LPS-induced mTOR and NF-κB pathways by down-regulation of RPH1. MiR-223 improved cell viability but declined apoptosis and autophagy by targeting RPH1 and blocked mTOR and NF-κB pathways in LPS challenged PC-12 cells.

An evolutionary perspective of AMPK-TOR signaling in the three domains of life

AMPK and TOR protein kinases are the major control points of energy signaling in eukaryotic cells and organisms. They form the core of a complex regulatory network to co-ordinate metabolic activities in the cytosol with those in the mitochondria and plastids. Despite its relevance, it is still unclear when and how this regulatory pathway was formed during evolution, and to what extent its representations in the major eukaryotic lineages resemble each other. Here we have traced 153 essential proteins forming the human AMPK-TOR pathways across 412 species representing all three domains of life-prokaryotes (bacteria, archaea) and eukaryotes-and reconstructed their evolutionary history. The resulting phylogenetic profiles indicate the presence of primordial core pathways including seven proto-kinases in the last eukaryotic common ancestor. The evolutionary origins of the oldest components of the AMPK pathway, however, extend into the pre-eukaryotic era, and descendants of these ancient proteins can still be found in contemporary prokaryotes. The TOR complex in turn appears as a eukaryotic invention, possibly to aid in retrograde signaling between the mitochondria and the remainder of the cell. Within the eukaryotes, AMPK/TOR showed both a highly conserved core structure and a considerable plasticity. Most notably, KING1, a protein originally assigned as the γ subunit of AMPK in plants, is more closely related to the yeast SDS23 gene family than to the γ subunits in animals or fungi. This suggests its functional difference from a canonical AMPK γ subunit.