Radiosynthesis and in vivo evaluation of [11C]MC80 for P-glycoprotein imaging

P-glycoprotein (P-gp) is an ATP-dependent efflux pump protecting the body against xenobiotics. The in vitro characterized modulator 6,7-dimethoxy-2-(6-methoxy-naphthalen-2-ylmethyl)-1,2,3,4-tetrahydroisoquinoline (MC80) of the P-gp pump was labelled with ¹¹C and evaluated in vivo for its potential to image P-gp function and expression. Radiochemical pure (>98%) [¹¹C]MC80 was obtained within 25 min starting from [¹¹C]methyl iodide with radiochemical yield of 26%. Biodistribution studies in FVB mice demonstrated a high baseline brain uptake (7.66 ± 1.38%ID/g at 1 min pi). Cerebral uptake was increased in mdr1a knock-out mice as well as after CsA pretreatment. Pre-administration of an excess of non-radioactive MC80 caused a reduced uptake in several target organs including brain, pancreas and intestines. The results indicate that [¹¹C]MC80 kinetics are modulated by P-gp. Reversed phase-HPLC analysis of brain revealed an excellent metabolic profile (>90% intact [¹¹C]MC80).     

Whole Grain Rye Intake,Reflected by a Biomarker,Is Associated with Favorable Blood Lipid Outcomes in Subjects with the Metabolic Syndrome – A Randomized Study

Background and Aim

Few studies have explored the possible plasma cholesterol lowering effects of rye consumption. The aim of this secondary analysis in the SYSDIET study was to investigate the association between plasma alkylresorcinols (AR), a biomarker for whole grain wheat and rye intake, and blood lipid concentrations in a population with metabolic syndrome. Furthermore, we analyzed the associations between the AR C17∶0/C21∶0 ratio, a suggested marker of the relative intake of whole grain/bran rye, and blood lipid concentrations.

Methods

Participants were 30–65 years of age, with body mass index (BMI) 27–40 kg/m² and had metabolic syndrome. Individuals were recruited through six centers in the Nordic countries and randomized either to a healthy Nordic diet (ND, n = 93), rich in whole grain rye and wheat, as well as berries, fruits and vegetables, rapeseed oil, three fish meals per week and low-fat dairy products, or a control diet (n = 65) for 18/24 weeks. Associations between total plasma AR concentration and C17∶0/C21∶0 homologue ratio and blood lipids were investigated in pooled (ND + control group) regression analyses at 18/24 weeks adjusted for baseline value for the dependent variable, age, BMI and statin use.

Results

When adjusted for confounders, total plasma AR at 18/24 weeks was not significantly associated with blood lipids but the AR ratio C17∶0/C21∶0 was inversely associated with LDL cholesterol concentrations (B (95% CI): −0.41 (−0.80 to −0.02)), log LDL/HDL cholesterol ratio (−0.20 (−0.37 to −0.03)), log non-HDL cholesterol (−0.20 (−0.37 to −0.03)), log apolipoprotein B (−0.12 (−0.24 to 0.00)) and log triglyceride concentrations (−0.35 (−0.59 to −0.12)).

Discussion

Increased proportion of whole grain rye, reflected by a biomarker, in the diet is associated with favorable blood lipid outcomes, a relationship that should be further investigated.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00992641","term_id":"NCT00992641"}}NCT00992641     

The emergence of protein complexes: quaternary structure, dynamics and allostery. Colworth Medal Lecture

All proteins require physical interactions with other proteins in order to perform their functions. Most of them oligomerize into homomers, and a vast majority of these homomers interact with other proteins, at least part of the time, forming transient or obligate heteromers. In the present paper, we review the structural, biophysical and evolutionary aspects of these protein interactions. We discuss how protein function and stability benefit from oligomerization, as well as evolutionary pathways by which oligomers emerge, mostly from the perspective of homomers. Finally, we emphasize the specificities of heteromeric complexes and their structure and evolution. We also discuss two analytical approaches increasingly being used to study protein structures as well as their interactions. First, we review the use of the biological networks and graph theory for analysis of protein interactions and structure. Secondly, we discuss recent advances in techniques for detecting correlated mutations, with the emphasis on their role in identifying pathways of allosteric communication.     

NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula

1. Download : Download high-res image (121KB)
2. Download : Download full-size image

     

Comparative chemical screening and genetic analysis reveal tentoxin as a new virulence factor in Cochliobolus miyabeanus,the causal agent of brown spot disease on rice

Brown spot disease, caused by Cochliobolus miyabeanus, is currently considered to be one of the most important yield reducers of rice (Oryza sativa L.). Despite its agricultural importance, little is known about the virulence mechanisms deployed by the fungus. Therefore, we set out to identify novel virulence factors with a role in disease development. This article reports, for the first time, the production of tentoxin by C. miyabeanus as a virulence factor during brown spot disease and the identification of the non‐ribosomal protein synthetase (NRPS) CmNps3, responsible for tentoxin biosynthesis. We compared the chemical compounds produced by C. miyabeanus strains differing in virulence ability using ultra‐high‐performance liquid chromatography (UHPLC) coupled to high‐resolution Orbitrap mass spectrometry (HRMS). The production of tentoxin by a highly virulent strain was revealed by principal component analysis of the detected ions and confirmed by UHPLC coupled to tandem‐quadrupole mass spectrometry (MS/MS). The corresponding NRPS was identified by in silico genome analysis and confirmed by gene deletion. Infection tests with wild‐type and Cmnps3 mutants showed that tentoxin acts as a virulence factor and is correlated with chlorosis development during the second phase of infection. Although rice has previously been classified as a tentoxin‐insensitive plant species, our data demonstrate that tentoxin production by C. miyabeanus affects symptom development.     

The α‐subunit of the trimeric GTPase Go2 regulates axonal growth

The Goα splice variants Go1α and Go2α are subunits of the most abundant G‐proteins in brain, Go1 and Go2. Only a few interacting partners binding to Go1α have been described so far and splice variant‐specific differences are not known. Using a yeast two‐hybrid screen with constitutively active Go2α as bait, we identified Rap1GTPase activating protein (Rap1GAP) and Girdin as interacting partners of Go2α, which was confirmed by co‐immunoprecipitation. Comparison of subcellular fractions from brains of wild type and Go2α?/? mice revealed no differences in the overall expression level of Girdin or Rap1GAP. However, we found higher amounts of active Rap1‐GTP in brains of Go2α deficient mutants, indicating that Go2α may increase Rap1GAP activity, thereby effecting the Rap1 activation/deactivation cycle. Rap1 has been shown to be involved in neurite outgrowth and given a Rap1GAP‐Go2α interaction, we found that the loss of Go2α affected axonal outgrowth. Axons of cultured cortical and hippocampal neurons prepared from embryonic Go2α?/? mice grew longer and developed more branches than those from wild‐type mice. Taken together, we provide evidence that Go2α regulates axonal outgrowth and branching.