Mutations in the U5 snRNA result in altered splicing of subsets of pre-mRNAs and reduced stability of Prp8

The U5 snRNA loop 1 aligns the 5′ and 3′ exons for ligation during the second step of pre-mRNA splicing. U5 is intimately associated with Prp8, which mediates pre-mRNA repositioning within the catalytic core of the spliceosome and interacts directly with U5 loop 1. The genome-wide effect of three U5 loop 1 mutants has been assessed by microarray analysis. These mutants exhibited impaired and improved splicing of subsets of pre-mRNAs compared to wild-type U5. Analysis of pre-mRNAs that accumulate revealed a change in base prevalence at specific positions near the splice sites. Analysis of processed pre-mRNAs exhibiting mRNA accumulation revealed a bias in base prevalence at one position within the 5′ exon. While U5 loop 1 can interact with some of these positions the base bias is not directly related to sequence changes in loop 1. All positions that display a bias in base prevalence are at or next to positions known to interact with Prp8. Analysis of Prp8 in the presence of the three U5 loop 1 mutants revealed that the most severe mutant displayed reduced Prp8 stability. Depletion of U5 snRNA in vivo also resulted in reduced Prp8 stability. Our data suggest that certain mutations in U5 loop 1 perturb the stability of Prp8 and may affect interactions of Prp8 with a subset of pre-mRNAs influencing their splicing. Therefore, the integrity of U5 is important for the stability of Prp8 during splicing and provides one possible explanation for why U5 loop 1 and Prp8 are so highly conserved.     

Bronchiectasis in acute leukaemia.

Five children in remission from acute lymphoblastic leukaemia developed bronchiectasis when on chemotherapy. Persistent collapse or consolidation on chest radiographs was helpful in suggesting the diagnosis. Necropsy established the diagnosis in one child who died of massive haemoptysis when in complete remission, and bronchography confirmed the diagnosis in three. In a further child the diagnosis was based on clinical and chest X-ray findings alone. The surviving children were treated with prophylactic rotating antibiotics. Routine chest radiographs are recommended in children with acute lymphoblastic leukaemia, as bronchiectasis may otherwise be underdiagnosed.     

1-Benzylbenzimidazoles: the discovery of a novel series of bradykinin B(1) receptor antagonists

The design, synthesis, and structure-activity studies of a novel series of BK B(1) receptor antagonists based on a 1-benzylbenzimidazole chemotype are described. A number of compounds, for example, 38g, with excellent affinity for the cynomolgus macaque and rat bradykinin B(1) receptor were discovered.     

Aminoquinazolines as TRPV1 antagonists: modulation of drug-like properties through the exploration of 2-position substitution

A focused SAR exploration of the lead 4-aminoquinazoline TRPV1 antagonist 2 led to the discovery of compound 18. In rats, compound 18 is readily absorbed following oral dosing and demonstrates excellent in vivo potency and efficacy in an acute inflammatory pain model.     

Regulation of Insulin and Leptin Signaling by Muscle Suppressor of Cytokine Signaling 3 (SOCS3)

Skeletal muscle resistance to the key metabolic hormones, leptin and insulin, is an early defect in obesity. Suppressor of cytokine signaling 3 (SOCS3) is a major negative regulator of both leptin and insulin signaling, thereby implicating SOCS3 in the pathogenesis of obesity and associated metabolic abnormalities. Here, we demonstrate that SOCS3 mRNA expression is increased in murine skeletal muscle in the setting of diet-induced and genetic obesity, inflammation, and hyperlipidemia. To further evaluate the contribution of muscle SOCS3 to leptin and insulin resistance in obesity, we generated transgenic mice with muscle-specific overexpression of SOCS3 (MCK/SOCS3 mice). Despite similar body weight, MCK/SOCS3 mice develop impaired systemic and muscle-specific glucose homeostasis and insulin action based on glucose and insulin tolerance tests, hyperinsulinemic-euglycemic clamps, and insulin signaling studies. With regards to leptin action, MCK/SOCS3 mice exhibit suppressed basal and leptin-stimulated activity and phosphorylation of alpha2 AMP-activated protein kinase (α2AMPK) and its downstream target, acetyl-CoA carboxylase (ACC). Muscle SOCS3 overexpression also suppresses leptin-regulated genes involved in fatty acid oxidation and mitochondrial function. These studies demonstrate that SOC3 within skeletal muscle is a critical regulator of leptin and insulin action and that increased SOCS may mediate insulin and leptin resistance in obesity.     

Hypothalamic-pituitary-adrenal function

Basal hypothalamic-pituitary-adrenal (HPA) function is characterised by pulses of corticosterone secretion followed by a transient refractory period when the axis appears to be inhibited. In females pulses of corticosterone secretion occur approximately once per hour with variation in pulse amplitude underlying a diurnal rhythm. Males show smaller pulses of secretion which become widely spaced during the early light phase nadir. Pulsatility is altered by genetic programming, early life experiences and reproductive status. Activation of the HPA axis during adjuvant induced arthritis results in an increase in the pulse frequency. This is associated with a marked change in hypothalamic gene expression with a diminution of CRH mRNA and a marked increase of AVP mRNA which becomes the predominant HPA secretagogue.