Role of internalization of M2 muscarinic receptor via clathrin-coated vesicles in desensitization of the muscarinic K+ current in heart

In the heart, ACh activates the ACh-activated K(+) current (I(K,ACh)) via the M(2) muscarinic receptor. The relationship between desensitization of I(K,ACh) and internalization of the M(2) receptor has been studied in rat atrial cells. On application of the stable muscarinic agonist carbachol for 2 h, I(K,ACh) declined by approximately 62% with time constants of 1.5 and 26.9 min, whereas approximately 83% of the M(2) receptor was internalized from the cell membrane with time constants of 2.9 and 51.6 min. Transfection of the cells with beta-adrenergic receptor kinase 1 (G protein-receptor kinase 2) and beta-arrestin 2 significantly increased I(K,ACh) desensitization and M(2) receptor internalization during a 3-min application of agonist. Internalized M(2) receptor in cells exposed to carbachol for 2 h was colocalized with clathrin and not caveolin. It is concluded that a G protein-receptor kinase 2- and beta-arrestin 2-dependent internalization of the M(2) receptor into clathrin-coated vesicles could play a major role in I(K,ACh) desensitization.     

A distal methyl substituent attenuates mitochondrial protein synthesis inhibition in oxazolidinone antibacterials

Oxazolidinone analogs bearing substituted piperidine or azetidine C-rings are described. Analogs with a methyl group at the 3-position of the azetidine ring or the 4-position of the piperidine ring exhibited reduced mitochondrial protein synthesis inhibition while retaining good antibacterial potency.     

Wnt/β-catenin signaling is required for development of the exocrine pancreas

Background  

β-catenin is an essential mediator of canonical Wnt signaling and a central component of the cadherin-catenin epithelial adhesion complex. Dysregulation of β-catenin expression has been described in pancreatic neoplasia. Newly published studies have suggested that β-catenin is critical for normal pancreatic development although these reports reached somewhat different conclusions. In addition, the molecular mechanisms by which loss of β-catenin affects pancreas development are not well understood. The goals of this study then were; 1] to further investigate the role of β-catenin in pancreatic development using a conditional knockout approach and 2] to identify possible mechanisms by which loss of β-catenin disrupts pancreatic development. A Pdx1-cre mouse line was used to delete a floxed β-catenin allele specifically in the developing pancreas, and embryonic pancreata were studied by immunohistochemistry and microarray analysis.     

The death of a drum: objects,persons, and changing social form on the Rai Coast of Papua New Guinea

Slit‐gong drums, made and used as part of affinal exchange relations on the Rai Coast of Papua New Guinea, are considered to be a kind of person. They cannot be extracted from the kin formations in which they came into being because they are part of the transformed relations that their manufacture effects. In an unprecedented event in 2010, a large slit‐gong used by a local community school was attacked during a dispute. In light of this, I examine irreplaceability and substitutability in relation to persons on the Rai Coast and explore what the attack implies about the changing status of objects and things under new economic and social conditions.     

Rice 14-3-3 protein (GF14e) negatively affects cell death and disease resistance

Plant 14-3-3 proteins regulate important cellular processes, including plant immune responses, through protein-protein interactions with a wide range of target proteins. In rice (Oryza sativa), the GF14e gene, which encodes a 14-3-3 protein, is induced during effector-triggered immunity (ETI) associated with pathogens such as Xanthomonas oryzae pv. oryzae (Xoo). To determine whether the GF14e gene plays a direct role in resistance to disease in rice, we suppressed its expression by RNAi silencing. GF14e suppression was correlated with the appearance of a lesion-mimic (LM) phenotype in the transgenic plants at 3 weeks after sowing. This indicates inappropriate regulation of cell death, a phenotype that is frequently associated with enhanced resistance to pathogens. GF14e-silenced rice plants showed high levels of resistance to a virulent strain of Xoo compared with plants that were not silenced. Enhanced resistance was correlated with GF14e silencing prior to and after development of the LM phenotype, higher basal expression of a defense response peroxidase gene (POX22.3), and accumulation of reactive oxygen species (ROS). In addition, GF14e-silenced plants also exhibit enhanced resistance to the necrotrophic fungal pathogen Rhizoctonia solani. Together, our findings suggest that GF14e negatively affects the induction of plant defense response genes, cell death and broad-spectrum resistance in rice.     

The discovery of benzanilides as c-Met receptor tyrosine kinase inhibitors by a directed screening approach

A directed screen of a relatively small number of compounds, selected for kinase ATP pocket binding potential, yielded a novel series of hit compounds (1). Hit explosion on two binding residues identified compounds 27 and 43 as the best leads for an optimization program having reduced secondary metabolism, as measured by in vitro rat hepatocytes incubation, leading to oral bio-availability. Structure-activity relationships and molecular modeling have suggested a binding mode for the most potent inhibitor 12.     

Targeting the Ubiquitin E3 Ligase MuRF1 to Inhibit Muscle Atrophy

Progressive muscle wasting, also known as myopathy or muscle atrophy is a debilitating and life-threatening disorder. Myopathy is a pathological condition of many diseases including cancer, diabetes, COPD, and AIDS and is a natural consequence of inactivity and aging (sarcopenia). Muscle atrophy occurs when there is a net loss of muscle mass resulting in a change in the balance between protein synthesis and protein degradation. The ubiquitin pathway and specific ubiquitin pathway enzymes have been directly implicated in the progression of atrophy. The ubiquitin E3 ligase Muscle-specific RING Finger E3 ligase (MuRF1) is upregulated and increases protein degradation and muscle wasting in numerous muscle atrophy models. The inhibition of MuRF1 could be a novel mechanism to prevent or reverse muscle wasting associated with various pathologies. We screened a small molecule library for inhibitors to MuRF1 activity and identified P013222, an inhibitor of MuRF1 autoubiquitylation. Further, P013222 was shown to inhibit MuRF1-dependent substrate ubiquitylation, and was active in inhibiting MuRF1 in a cellular atrophy model. Thus MuRF1 can be targeted in a specific manner and produce positive results in cellular atrophy models.