High-fat diet feeding triggers a regenerative response in the adult zebrafish brain.

Non-alcoholic fatty liver disease (NAFLD) includes a range of liver conditions ranging from excess fat accumulation to liver failure. NAFLD is strongly associated with high-fat diet (HFD) consumption that constitutes a metabolic risk factor. While HFD has been elucidated concerning its several systemic effects, there is little information about its influence on the brain at the molecular level. Here, by using a high-fat diet (HFD)-feeding of adult zebrafish, we first reveal that excess fat uptake results in weight gain and fatty liver. Prolonged exposure to HFD induces a significant increase in the expression of pro-inflammation, apoptosis, and proliferation markers in the liver and brain tissues. Immunofluorescence analyses of the brain tissues disclose stimulation of apoptosis and widespread activation of glial cell response. Moreover, glial activation is accompanied by an initial decrease in the number of neurons and their subsequent replacement in the olfactory bulb and the telencephalon. Long-term consumption of HFD causes activation of Wnt/ß-catenin signaling in the brain tissues. Finally, fish fed an HFD induces anxiety, and aggressiveness and increases locomotor activity. Thus, HFD feeding leads to a non-traumatic brain injury and stimulates a regenerative response. The activation mechanisms of a regeneration response in the brain can be exploited to fight obesity and recover from non-traumatic injuries.

Nradd Acts as a Negative Feedback Regulator of Wnt/ß-Catenin Signaling and Promotes Apoptosis.

Wnt/ß-catenin signaling controls many biological processes for the generation and sustainability of proper tissue size, organization and function during development and homeostasis. Consequently, mutations in the Wnt pathway components and modulators cause diseases, including genetic disorders and cancers. Targeted treatment of pathway-associated diseases entails detailed understanding of the regulatory mechanisms that fine-tune Wnt signaling. Here, we identify the neurotrophin receptor-associated death domain (Nradd), a homolog of p75 neurotrophin receptor (p75NTR), as a negative regulator of Wnt/ß-catenin signaling in zebrafish embryos and in mammalian cells. Nradd significantly suppresses Wnt8-mediated patterning of the mesoderm and neuroectoderm during zebrafish gastrulation. Nradd is localized at the plasma membrane, physically interacts with the Wnt receptor complex and enhances apoptosis in cooperation with Wnt/ß-catenin signaling. Our functional analyses indicate that the N-glycosylated N-terminus and the death domain-containing C-terminus regions are necessary for both the inhibition of Wnt signaling and apoptosis. Finally, Nradd can induce apoptosis in mammalian cells. Thus, Nradd regulates cell death as a modifier of Wnt/ß-catenin signaling during development.

More Favorable Palmitic Acid Over Palmitoleic Acid Modification of Wnt3 Ensures Its Localization and Activity in Plasma Membrane Domains.

While the lateral organization of plasma membrane components has been shown to control binding of Wnt ligands to their receptors preferentially in the ordered membrane domains, the role of posttranslational lipid modification of Wnt on this selective binding is unknown. Here, we identify that the canonical Wnt is presumably acylated by palmitic acid, a saturated 16-carbon fatty acid, at a conserved serine residue. Acylation of Wnt3 is dispensable for its secretion and binding to Fz8 while it is essential for Wnt3's proper binding and domain-like diffusion in the ordered membrane domains. We further unravel that non-palmitoylated Wnt3 is unable to activate Wnt/ß-catenin signaling either in zebrafish embryos or in mammalian cells. Based on these results, we propose that the lipidation of canonical Wnt, presumably by a saturated fatty acid, determines its competence in interacting with the receptors in the appropriate domains of the plasma membrane, ultimately keeping the signaling activity under control.

Ruxolitinib induces autophagy in chronic myeloid leukemia cells.

Ruxolitinib is the first agent used in myelofibrosis treatment with its potent JAK2 inhibitory effect. In this novel study, we aimed to discover the anti-leukemic effect of ruxolitinib in K-562 human chronic myeloid leukemia cell line compared to NCI-BL 2171 human healthy B lymphocyte cell line. Cytotoxic effect of ruxolitinib was determined by using WST-1 assay. IC50 values for K-562 and NCI-BL 2171 cell lines were defined as 20 and 23.6 µM at the 48th hour, respectively. Autophagic effects of ruxolitinib were detected by measuring LC3B-II protein formation. Ruxolitinib induced autophagic cell death in K-562 and NCI-BL 2171 cell lines 2.11- and 1.79-fold compared to control groups, respectively. To determine the autophagy-related gene expression changes, total RNA was isolated from K-562 and NCI-BL 2171 cells treated with ruxolitinib and untreated cells as control group. Reverse transcription procedure was performed for cDNA synthesis, and gene expressions were shown by RT-qPCR. Ruxolitinib treatment caused a notable decrease in expression of AKT, mTOR, and STAT autophagy inhibitor genes in K-562 cells, contrariwise control cell line. Ruxolitinib is a promising agent in chronic myeloid leukemia treatment by blocking JAK/STAT pathway known as downstream of BCR-ABL and triggering autophagy. This is the first study that reveals the relationship between ruxolitinib and autophagy induction.

Zoledronic acid induces apoptosis via stimulating the expressions of ERN1, TLR2, and IRF5 genes in glioma cells.

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor that affects older people. Although the current therapeutic approaches for GBM include surgical resection, radiotherapy, and chemotherapeutic agent temozolomide, the median survival of patients is 14.6 months because of its aggressiveness. Zoledronic acid (ZA) is a nitrogen-containing bisphosphonate that exhibited anticancer activity in different cancers. The purpose of this study was to assess the potential effect of ZA in distinct signal transduction pathways in U87-MG cells. In this study, experiments performed on U87-MG cell line (Human glioblastoma-astrocytoma, epithelial-like cell line) which is an in vitro model of human glioblastoma cells to examine the cytotoxic and apoptotic effects of ZA. IC50 dose of ZA, 25 µM, applied on U87-MG cells during 72 h. ApoDIRECT In Situ DNA Fragmentation Assay was used to investigate apoptosis of U87MG cells. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) (LightCycler480 System) was carried out for 48 gene expression like NF-κB, Toll-like receptors, cytokines, and inteferons. Our results indicated that ZA (IC50 dose) increased apoptosis 1.27-fold in U87MG cells according to control cells. According to qRT-PCR data, expression levels of the endoplasmic reticulum-nuclei-1 (ERN1), Toll-like receptor 2 (TLR2), and human IFN regulatory factor 5 (IRF5) tumor suppressor genes elevated 2.05-, 2.08-, and 2.3-fold by ZA, respectively, in U87MG cells. Our recent results indicated that ZA have a key role in GBM progression and might be considered as a potential agent in glioma treatment.

New approaches for cancer immunotherapy.

Immunotherapy is a promising field that offers alternative methods for treatment of cancer. The current strategy consists of cancer vaccines, monoclonal antibodies, and cellular therapies. Cancer vaccines aim to eradicate cancer cells via immune system. Thus, they may attack these cells derived from any type of cancer, besides their role in preventing cancer. Lymphocytes and dendritic cells are often used in cellular therapy. In addition, monoclonal antibodies are designed to target specific antigens found in cancer cells. Currently, at least 12 clinically approved monoclonal antibodies are being used and many cancer vaccines are being developed with ongoing phase studies for cancer therapy. Relevant studies are focused on glioma and several other cancer types. Correspondingly, the combination of effective methods may enhance the efficacy of immunotherapy. It is thought that particularly immune checkpoint inhibitors will play a crucial role in immunotherapeutic approaches.