Mechanisms of Niemann-Pick type C1 Like 1 protein degradation in intestinal epithelial cells

Nedd4-1 regulates human sodium-dependent vitamin C transporter-2 functional expression in neuronal and epithelial cells

The ubiquitin-proteasomal pathway regulates the functional expression of many membrane transporters in a variety of cellular systems. Nothing is currently known about the role of ubiquitin E3 ligase, neural precursor cell-expressed developmentally down-regulated gene 4 (Nedd4-1) and the proteasomal degradation pathway in regulating human vitamin C transporter-2 (hSVCT2) in neuronal cells. hSVCT2 mediates the uptake of ascorbic acid (AA) and is the predominantly expressed vitamin C transporter isoform in neuronal systems. Therefore, we addressed this knowledge gap in our study. Analysis of mRNA revealed markedly higher expression of Nedd4-1 in neuronal samples than that of Nedd4-2. Interestingly, Nedd4-1 expression in the hippocampus was higher in patients with Alzheimer's disease (AD) and age-dependently increased in the J20 mouse model of AD. The interaction of Nedd4-1 and hSVCT2 was confirmed by coimmunoprecipitation and colocalization. While the coexpression of Nedd4-1 with hSVCT2 displayed a significant decrease in AA uptake, siRNA-mediated knockdown of Nedd4-1 expression up-regulated the AA uptake. Further, we mutated a classical Nedd4 protein interacting motif ("PPXY") within the hSVCT2 polypeptide and observed markedly decreased AA uptake due to the intracellular localization of the mutated hSVCT2. Also, we determined the role of the proteasomal degradation pathway in hSVCT2 functional expression in SH-SY5Y cells and the results indicated that the proteasomal inhibitor (MG132) significantly up-regulated the AA uptake and hSVCT2 protein expression level. Taken together, our findings show that the regulation of hSVCT2 functional expression is at least partly mediated by the Nedd4-1 dependent ubiquitination and proteasomal pathways.

Eryngium Species as a Potential Ally for Treating Metabolic Syndrome and Diabetes

Medicinal plants possess natural compounds that can be used as an alternative for synthetic medicines that may cause long-term side effects on patients such as neurocognitive effects, muscular and hepatic toxicity. Metabolic Syndrome is associated with increased risk of several diseases such as diabetes, cardiovascular disease, dyslipidemia, and hypertension thus, becoming the greatest challenge as a growing public health concern worldwide. Latin-American countries possess a wide diversity of medicinal plants that have been used to treat different health conditions since pre-Hispanic times. Eryngium spp. has been studied due to their beneficial properties mainly to treat diabetes, dyslipidemia, blood pressure, and digestive problems. This review gives an update mainly on the pharmacological activities of the Eryngium spp., summarizing the biological activities and plausible mechanism of action of their bioactive components toward metabolic syndrome. For instance, flavonoids and tannins proved to increase the levels of HDL and reduced the levels of VLDL, LDL. On the other hand, phenolic acids improved glucose metabolism through the inhibition of phosphoenolpyruvate carboxykinase and glucose 6-phosphatase (G6Pase) and reestablished the impaired activity of enzymes related to glucose oxidation and glycogen synthesis. The terpenes and sesquiterpenes like β-farnese, β-pinene, and calamenene exhibited a protective effect by reducing the oxidizing damage by the regulation of the Reactive Oxygen Species (ROS). Saponins controlled the dyslipidemia by reducing the serum concentrations of lipids, triglycerides and total cholesterol. Finally, the aerial parts of Eryngium had the capacity of inhibiting dietary carbohydrate digestive enzymes, thus controlling glucose levels. The Eryngium plant is normally consumed as an infusion to obtain the benefits of the plants, however novel technologies such as cavitation, ultrasound assisted, microwave assisted, and supercritical fluid have been applied to improve the extraction yields and selectivity of bioactive compounds. The common treatment to control diabetic dyslipidemia are synthetic medicines such as metformin and ezetimibe, which allows the regulation of glucose, cholesterol and insulin resistance. However, patients that take these medications may present side effects such as muscular toxicity, hepatic toxicity, neurocognitive effects, just to name a few. More studies regarding the efficacy and safety of the use of traditional medicinal herbs are required. However, these materials may be used in the treatment of diabetes related conditions to ensure life quality and reduce side effects among the diabetic population.

Role of Cholesterol and Lipid Rafts in Cancer Signaling: A Promising Therapeutic Opportunity?

Cholesterol is a lipid molecule that plays an essential role in a number of biological processes, both physiological and pathological. It is an essential structural constituent of cell membranes, and it is fundamental for biosynthesis, integrity, and functions of biological membranes, including membrane trafficking and signaling. Moreover, cholesterol is the major lipid component of lipid rafts, a sort of lipid-based structures that regulate the assembly and functioning of numerous cell signaling pathways, including those related to cancer, such as tumor cell growth, adhesion, migration, invasion, and apoptosis. Considering the importance of cholesterol metabolism, its homeostasis is strictly regulated at every stage: import, synthesis, export, metabolism, and storage. The alterations of this homeostatic balance are known to be associated with cardiovascular diseases and atherosclerosis, but mounting evidence also connects these behaviors to increased cancer risks. Although there is conflicting evidence on the role of cholesterol in cancer development, most of the studies consistently suggest that a dysregulation of cholesterol homeostasis could lead to cancer development. This review aims to discuss the current understanding of cholesterol homeostasis in normal and cancerous cells, summarizing key findings from recent preclinical and clinical studies that have investigated the role of major players in cholesterol regulation and the organization of lipid rafts, which could represent promising therapeutic targets.