Sensitive Imaging of Cellular RNA via Cascaded Proximity-Induced Fluorogenic Reactions.

Owing to its important biological functions, RNA has become a promising molecular biomarker of various diseases. With a dynamic change in its expression level and a relatively low amount within the complicated biological matrix, signal amplification detection based on DNA probes has been put forward, which is helpful for early diagnosis and prognostic prediction. However, conventional methods are confined to cell lysates or dead cells and are not only time-consuming in sample preparation but also inaccessible to the spatial-temporal information of target RNAs. To achieve live-cell imaging of specific RNAs, both the detection sensitivity and intracellular delivery issues should be addressed. Herein, a new cascaded fluorogenic system based on the combination of hybridization chain reactions (HCRs) and proximity-induced bioorthogonal chemistry is developed, in which a bioorthogonal reaction pair (a tetrazine-quenched dye and its complementary dienophile) is brought into spatial proximity upon target RNA triggering the HCR to turn on and amplify the fluorescence in one step, sensitively indicating the cellular distribution of RNA with minimal false positive results caused by unspecific degradation. Facilitated by a biodegradable carrier based on black phosphorus with high loading capacity and excellent biocompatibility, the resulting imaging platform allows wash-free tracking of target RNAs inside living cells.

Effects of acarbose and metformin on the inflammatory state in newly diagnosed type 2 diabetes patients: a one-year randomized clinical study.

OBJECTIVE: This study aimed to investigate the changes in inflammatory biomarkers between newly diagnosed type 2 diabetes (T2DM) patients under one-year acarbose treatments and those under metformin managements. METHODS: Seventy patients with newly diagnosed T2DM and 32 volunteers with normal glucose tolerance (normal controls, NCs) were enrolled. Seventy patients with T2DM were randomly assigned to two subgroups and treated with acarbose (n=34) or metformin (n=36) for 1 year. Blood glucose, insulin, glycosylated hemoglobin (A1C), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and inflammatory biomarker levels (interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-2 (IL-2), and ferritin) were detected at 0, 6 and 12 months. RESULTS: After adjusting for sex, the waist-to-hip ratio (WHR) and body mass index (BMI), higher fasting plasma glucose (FPG), standard meal test 1/2 hr and 2 hr glucose, TG, TC, LDL-C, IL-6, TNF-α, IL-2 and ferritin levels were observed in T2DM group than in NCs (P<0.05). After 6 months of treatment, TNF-α levels were significantly decreased in both subgroups, and IL-6 and ferritin levels were significantly decreased after 12 months (P<0.05). However, no significant differences in the IL-6, TNF-α and ferritin levels were observed between the two subgroups. Moreover, significantly higher IL-6 and TNF-α levels were detected in the T2DM group than in NCs after 12 months of treatment (P<0.05). CONCLUSION: Patients with newly diagnosed T2DM exhibited a marked chronic inflammatory state characterized by increased IL-6, TNF-α, IL-1ß, IL-2 and ferritin levels. After 1 year of treatment with acarbose or metformin, IL-6, TNF-α, IL-1ß and ferritin levels were significantly decreased compared with the baseline. The anti-inflammatory effects of acarbose and metformin were comparable and required a long-term treatment (1 year), but the characteristics were different. Further investigations are needed to determine whether this effect was independent of the hypoglycemic effects.

A nonpeptidic agonist of glucagon-like peptide 1 receptors with efficacy in diabetic db/db mice.

Peptidic mimics of the gut hormone glucagon-like peptide (GLP) 1, exemplified by the recently approved drug exenatide, show promise as therapies for type 2 diabetes. Such "incretin mimetics" regulate glucose appearance in the plasma and can restore glucose-stimulated insulin secretion without excess risk of hypoglycemia. The need for injection, which may limit the use of peptidic GLP-1 receptor (GLP-1R) agonists, has driven largely unsuccessful efforts to find smaller molecules. The failure to identify orally effective agonists has instead promoted the indirect approach of inhibiting the GLP-1-degrading enzyme dipeptidyl peptidase IV. Here we report a nonpeptidic GLP-1R agonist with sufficient activity to evoke effects in whole animals, including antidiabetic efficacy in db/db mice. Two substituted cyclobutanes (S4P and Boc5) were developed after screening a compound library against a cell line stably cotransfected with GLP-1R and a cAMP-responsive reporter. Each bound to GLP-1R and increased intracellular cAMP. Agonist effects were blocked by the GLP-1R antagonist exendin(9-39). Boc5 amplified glucose-stimulated insulin secretion in isolated rat islets. Both i.p. and oral administration of Boc5 dose-dependently inhibited food intake in mice, an effect that could be blocked by pretreatment with exendin(9-39). Daily injections of Boc5 into db/db mice reduced HbA1c to nondiabetic values, an effect not observed in ad libitum-fed or pair-fed diabetic controls. Thus, Boc5 behaved as a full GLP-1 mimetic in vitro and in vivo. The chemical genus represented by Boc5 may prompt the exploration of orally available GLP-1R agonists with potential utility in diabetes and obesity.

Development of a homogeneous calcium mobilization assay for high throughput screening of mas-related gene receptor agonists.

AIM: To develop homogeneous calcium mobilization assay for high-throughput screening (HTS) of mas-related gene (Mrg) receptor agonists. METHODS: CHO-K1 cells stably expressing the full-length MrgD receptor and a calcium-sensitive dye were used to develop an HTS assay based on intracellular calcium influx. This method was applied to large-scale screening of a library containing 8000 synthetic compounds and natural product extracts. cAMP measurements were carried out to verify the bioactivities of the hits found by the calcium mobilization assay. Similar approaches were also employed in the identification of the MrgA1 receptor agonists following HTS of 16,000 samples. RESULTS: EC(50) values of the positive control compounds (beta-alanine for MrgD receptor and dynorphin A for MrgA1 receptor) determined by the calcium mobilization assay were consistent with those reported in the literature, and the Z' factors were 0.65 and 0.50 for MrgD and MrgA1 receptor assay, respectively. About 31 compounds for the MrgD receptor and 48 compounds for the MrgA1 receptor showing > or =20% of the maximal agonist activities found in the controls were initially identified as hits. Secondary screening confirmed that 2 compounds for each receptor possessed specific agonist activities. Intracellular cAMP level measurements indicated that the 2 confirmed hits displayed the functionality of the MrgD receptor agonists. CONCLUSION: A series of validation studies demonstrated that the homogeneous calcium mobilization assay developed was highly efficient, amenable to automation and a robust tool to screen potential MrgD and MrgA1 receptor agonists. Its application may be expanded to other G-protein coupled receptors that mobilize calcium influx upon activation.