MetAP2 inhibitor treatment of high-fat and -fructose-fed dogs: impact on the response to oral glucose ingestion and a hyperinsulinemic hyperglycemic clamp.

We examined the methionine aminopeptidase 2 inhibitor fumagillin in dogs consuming a high-fat and -fructose diet (HFFD). In pilot studies (3 dogs that had consumed HFFD for 3 yr), 8 wk of daily treatment with fumagillin reduced food intake 29%, weight 6%, and the glycemic excursion during an oral glucose tolerance test (OGTT) 44%. A second group of dogs consumed the HFFD for 17 wk: pretreatment (weeks 0-4), treatment with fumagillin (FUM; n = 6), or no drug (Control, n = 8) (weeks 4-12), washout period (weeks 12-16), and fumagillin or no drug for 1 wk (week 17). OGTTs were performed at 0, 4, 11, and 16 wk. A hyperinsulinemic hyperglycemic clamp was performed in week 12; 4 chow-fed dogs underwent identical clamps. Kilocalories per day intake during the treatment period was 2,067 ± 50 (Control) versus 1,824 ± 202 (FUM). Body weights (kg) increased 1.9 ± 0.3 vs. 2.7 ± 0.8 (0-4 wk) and 1.2 ± 0.2 vs. -0.02 ± 0.9 (4-12 wk) in Control versus fumagillin. The OGTT glycemic response was 30% greater in Control versus fumagillin at 11 wk. Net hepatic glucose uptake (NHGU; mg·kg-1·min-1) in the Chow, Control, and fumagillin dogs was ~1.5 ± 0.6, -0.1 ± 0.1, and 0.3 ± 0.4 (with no portal glucose infusion) and 3.1 ± 0.6, 0.5 ± 0.3, and 1.5 ± 0.5 (portal glucose infusion at 4 mg·kg-1·min-1), respectively. Fumagillin improved glucose tolerance and NHGU in HFFD dogs, suggesting methionine aminopeptidase 2 (MetAP2) inhibitors have the potential for improving glycemic control in prediabetes and diabetes.

Effects of MetAP2 inhibition on hyperphagia and body weight in Prader-Willi syndrome: A randomized, double-blind, placebo-controlled trial.

AIMS: There are no treatments for the extreme hyperphagia and obesity in Prader-Willi syndrome (PWS). The bestPWS clinical trial assessed the efficacy, safety and tolerability of the methionine aminopeptidase 2 (MetAP2) inhibitor, beloranib. MATERIALS AND METHODS: Participants with PWS (12-65 years old) were randomly assigned (1:1:1) to biweekly placebo, 1.8 mg beloranib or 2.4 mg beloranib injection for 26 weeks at 15 US sites. Co-primary endpoints were the changes in hyperphagia [measured by Hyperphagia Questionnaire for Clinical Trials (HQ-CT); possible score 0-36] and weight by intention-to-treat. ClinicalTrials.gov registration: NCT02179151. RESULTS: One-hundred and seven participants were included in the intention-to-treat analysis: placebo (n = 34); 1.8 mg beloranib (n = 36); or 2.4 mg beloranib (n = 37). Improvement (reduction) in HQ-CT total score was greater in the 1.8 mg (mean difference -6.3, 95% CI -9.6 to -3.0; P = .0003) and 2.4 mg beloranib groups (-7.0, 95% CI -10.5 to -3.6; P = .0001) vs placebo. Compared with placebo, weight change was greater with 1.8 mg (mean difference - 8.2%, 95% CI -10.8 to -5.6; P < .0001) and 2.4 mg beloranib (-9.5%, 95% CI -12.1 to -6.8; P < .0001). Injection site bruising was the most frequent adverse event with beloranib. Dosing was stopped early due to an imbalance in venous thrombotic events in beloranib-treated participants (2 fatal events of pulmonary embolism and 2 events of deep vein thrombosis) compared with placebo. CONCLUSIONS: MetAP2 inhibition with beloranib produced statistically significant and clinically meaningful improvements in hyperphagia-related behaviours and weight loss in participants with PWS. Although investigation of beloranib has ceased, inhibition of MetAP2 is a novel mechanism for treating hyperphagia and obesity.

The expression of dominant-negative subunits selectively suppresses neuronal AMPA and kainate receptors.

Glutamate-gated ion channels are widely expressed in neurons where they serve a host of cellular functions. An appealing, but yet unexplored, way to delineate the functions of particular glutamate receptor subtypes is to direct the expression of dominant-negative and gain-of-function mutant subunits. We tested the ability of two dominant-negative subunits, an alpha-amino-3-hydroxy-5-methyl-isoxazolproprionic acid receptor subunit and a kainate receptor subunit, to silence recombinant and neuronal glutamate receptors. Co-expression studies in non-neuronal cells indicated that the inclusion of a single mutant subunit was sufficient to silence the receptor. When expressed in cerebellar granule cells, the dominant-negative subunits silenced native channels in a subtype-specific fashion. Immunocytochemical staining of control and transfected neurons, as well as studies with a gain-of-function glutamate receptor-1 mutant, indicated that the mutant subunits were expressed at levels roughly equal to the total abundance of related native subunits, and both dominant-negatives suppressed native channel expression 60-65% when tested 24 h post-transfection. If co-assembly of the mutant subunits with related native subunits is combinatorial, this level of suppression gives receptor half-lives of approximately 20 h.