Mutant huntingtin causes metabolic imbalance by disruption of hypothalamic neurocircuits

In Huntington's disease (HD), the mutant huntingtin protein is ubiquitously expressed. The disease was considered to be limited to the basal ganglia, but recent studies have suggested a more widespread pathology involving hypothalamic dysfunction. Here we tested the hypothesis that expression of mutant huntingtin in the hypothalamus causes metabolic abnormalities. First, we showed that bacterial artificial chromosome-mediated transgenic HD (BACHD) mice developed impaired glucose metabolism and pronounced insulin and leptin resistance. Selective hypothalamic expression of a short fragment of mutant huntingtin using adeno-associated viral vectors was sufficient to recapitulate these metabolic disturbances. Finally, selective hypothalamic inactivation of the mutant gene prevented the development of the metabolic phenotype in BACHD mice. Our findings establish a causal link between mutant huntingtin expression in the hypothalamus and metabolic dysfunction, and indicate that metabolic parameters are powerful readouts to assess therapies aimed at correcting dysfunction in HD by silencing huntingtin expression in the brain.     

PETIR-001, a dual inhibitor of dipeptidyl peptidase IV (DP IV) and aminopeptidase N (APN), ameliorates experimental autoimmune encephalomyelitis in SJL/J mice

Cellular dipeptidyl peptidase IV (DP IV, CD26) and amino-peptidase N (APN, CD13) play regulatory roles in T cell activation and represent potential targets for treatment of inflammatory disorders. We have developed a novel therapeutic strategy, 'peptidase-targeted Immunoregulation' (PETIR?), which simultaneously targets both cellular DP IV and APN via selective binding sites different from the active sites with a single inhibitor. To prove the therapeutic concept of PETIR? in autoimmunity of the central nervous system (CNS), we evaluated the effect of a single substance, PETIR-001, in an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE) in SJL/J mice. Administration of PETIR-001 significantly delayed and decreased clinical signs of active EAE, when given in a therapeutic manner intraperitoneally from day 15 to day 24 after induction of EAE. Both the acute phase and the first relapse of EAE were markedly inhibited. Importantly, a similar therapeutic benefit was obtained after oral administration of PETIR-001 from day 12 to day 21 after disease induction. Our results demonstrate that PETIR-001 exhibits a therapeutic effect on EAE in SJL/J mice. Thus, PETIR? represents a novel and efficient therapeutic approach for immunotherapy of CNS inflammation.     

Artefacts induced on <Emphasis Type="Italic">c</Emphasis>-type haem proteins by electrode surfaces

In this work it is demonstrated that the characterization of c-type haem containing proteins by electrochemical techniques needs to be cautiously performed when using pyrolytic graphite electrodes. An altered form of the cytochromes, which has a redox potential 300 mV lower than that of the native state and displays peroxidatic activity, can be induced by interaction with the pyrolytic graphite electrode. Proper control experiments need to be performed, as altered conformations of the enzymes containing c-type haems can show activity towards the enzyme substrate. The work was focused on the study of the activation mechanism and catalytic activity of cytochrome c peroxidase from Paracoccus pantotrophus. The results could only be interpreted with the assignment of the observed non-turnover and catalytic signals to a non-native conformation state of the electron-transferring haem. The same phenomenon was detected for Met–His monohaem cytochromes (mitochondrial cytochrome c and Desulfovibrio vulgaris cytochrome c-553), as well as for the bis-His multihaem cytochrome c ₃ from Desulfovibrio gigas, showing that this effect is independent of the axial coordination of the c-type haem protein. Thus, the interpretation of electrochemical signals of c-type (multi)haem proteins at pyrolytic graphite electrodes must be carefully performed, to avoid misassignment of the signals and incorrect interpretation of catalytic intermediates.     

Atrophic cardiac remodeling induced by taurine deficiency in wistar rats

Introduction

Micronutrient deficiency is observed in heart failure patients. Taurine, for example, represents 50% of total free amino acids in the heart, and in vivo studies have linked taurine deficiency with cardiomyopathy.

Methods

Thirty-four male Wistar rats (body weight = 100 g) were weighed and randomly assigned to one of two groups: Control (C) or taurine-deficient (T (-)). Beta-alanine at a concentration of 3% was added to the animals’ water to induce taurine deficiency in the T (-) group. On day 30, the rats were individually submitted to echocardiography; morphometrical and histopathological evaluation and metalloproteinase activity, oxidative stress and inflammation evaluation were performed. Tissue samples were collected to determine the taurine concentration in the heart.

Results

Taurine deficiency led to decreases in: ventricular wall thickness, left ventricle dry weight, myocyte sectional area, left ventricle posterior wall thickness and ventricular geometry. With regard to heart function, the velocity of the A wave, the ratio between the E and A wave, the ejection fraction, fractional shortening and cardiac output values were decreased in T (-) rats, suggesting abnormal diastolic and systolic function. Increased fibrosis, inflammation and increased activation of metalloproteinases were not observed. Oxidative stress was increased in deficient animals.

Conclusions

These data suggest that taurine deficiency promotes structural and functional cardiac alterations with unique characteristics.     

Effects of Zn,Fe and Mn on Leaf Litter Breakdown by Aquatic Fungi: a Microcosm Study

We investigated the effects of heavy metals on leaf litter decomposition in streams. Leaves were immersed (10 days) at a reference (R) and a metal‐impacted (I) site and exposed in microcosms with increased Zn, Mn or Fe content, and to stream water from site R or I. Fungal biomass was higher in microcosms with leaves colonized at I and water from R. Fungal sporulation was higher in microcosms with leaves and water from R. Concentrations of 4.9, 9.6 and 5 ppm of Zn, Mn and Fe decrease fungal sporulation. The number of fungal species (spore counts and DGGE fingerprints) was lower in leaves colonized at site I. Cluster analyses of DGGE showed that Fe was the metal that most altered the structure of fungal community. Our results suggest that metal pollution affect leaf‐associated fungi depending on metal identity and concentration, and effects appear to be less pronounced in metal‐adapted communities. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)