GITR signaling potentiates airway hyperresponsiveness by enhancing Th2 cell activity in a mouse model of asthma

Background

Anxiety and depression are common and treatable risk factors for re-hospitalisation and death in patients with COPD. The degree of lung function impairment does not sufficiently explain anxiety and depression. The BODE index allows a functional classification of COPD beyond FEV₁. The aim of this cross-sectional study was (1) to test whether the BODE index is superior to the GOLD classification for explaining anxious and depressive symptoms; and (2) to assess which components of the BODE index are associated with these psychological aspects of COPD.

Methods

COPD was classified according to the GOLD stages based on FEV_1%predicted in 122 stable patients with COPD. An additional four stage classification was constructed based on the quartiles of the BODE index. The hospital anxiety and depression scale was used to assess anxious and depressive symptoms.

Results

The overall prevalence of anxious and depressive symptoms was 49% and 52%, respectively. The prevalence of anxious symptoms increased with increasing BODE stages but not with increasing GOLD stages. The prevalence of depressive symptoms increased with both increasing GOLD and BODE stages. The BODE index was superior to FEV_1%predicted for explaining anxious and depressive symptoms. Anxious symptoms were explained by dyspnoea. Depressive symptoms were explained by both dyspnoea and reduced exercise capacity.

Conclusion

The BODE index is superior to the GOLD classification for explaining anxious and depressive symptoms in COPD patients. These psychological consequences of the disease may play a role in future classification systems of COPD.     

Contractile behavior of the forelimb digital flexors during steady-state locomotion in horses (Equus caballus): an initial test of muscle architectural hypotheses about in vivo function

The forelimb digital flexors of the horse display remarkable diversity in muscle architecture despite each muscle-tendon unit having a similar mechanical advantage across the fetlock joint. We focus on two distinct muscles of the digital flexor system: short compartment deep digital flexor (DDF(sc)) and the superficial digital flexor (SDF). The objectives were to investigate force-length behavior and work performance of these two muscles in vivo during locomotion, and to determine how muscle architecture contributes to in vivo function in this system. We directly recorded muscle force (via tendon strain gauges) and muscle fascicle length (via sonomicrometry crystals) as horses walked (1.7 m s(-1)), trotted (4.1 m s(-1)) and cantered (7.0 m s(-1)) on a motorized treadmill. Over the range of gaits and speeds, DDF(sc) fascicles shortened while producing relatively low force, generating modest positive net work. In contrast, SDF fascicles initially shortened, then lengthened while producing high force, resulting in substantial negative net work. These findings suggest the long fibered, unipennate DDF(sc) supplements mechanical work during running, whereas the short fibered, multipennate SDF is specialized for economical high force and enhanced elastic energy storage. Apparent in vivo functions match well with the distinct architectural features of each muscle.     

Tau induces ring and microtubule formation from alphabeta-tubulin dimers under nonassembly conditions

Tau is a neuronal microtubule-associated protein that plays a central role in many cellular processes, both physiological and pathological, such as axons stabilization and Alzheimer's disease. Despite extensive studies, very little is known about the detailed molecular basis of tau binding to microtubules. We used the four-repeat recombinant htau40 and tubulin dimers to show for the first time that tau is able to induce both microtubule and ring formation from 6S alphabeta tubulin in phosphate buffer without added magnesium (nonassembly conditions). The amount of microtubules or rings formed was protein concentration-, temperature-, and nucleotide-dependent. By means of biophysical approaches, we showed that tau binds to tubulin without global-folding change, detectable by circular dichroism. We also demonstrated that the tau-tubulin interaction follows a ligand-mediated elongation process, with two tau-binding site per tubulin dimer. Moreover, using a tubulin recombinant alpha-tubulin C-terminal fragment (404-451) and a beta-tubulin C-terminal fragment (394-445), we demonstrated the involvement of both of these tubulin regions in tau binding. From this model system, we gain new insight into the mechanisms by which tau binds to tubulin and induces microtubule formation.     

Calorimetry and mass spectrometry study of oxidized calmodulin interaction with target and differential repair by methionine sulfoxide reductases

Calmodulin is known to be a target for oxidation, which leads to conversion of methionine residues to methionine sulfoxides. Previously, we reported that both methionine sulfoxide reductases MsrA and MsrB were able to reduce methionine sulfoxide residues in oxidized calmodulin. In the present study, we have made use of the interaction between calmodulin and RS20, a peptide model for calmodulin targets, to probe the structural consequences of oxidation and mode of repair both by MsrA and MsrB. Isothermal titration calorimetry and differential scanning calorimetry showed that oxidized calmodulin interacts with RS20 via its C-terminal domain only, resulting in a non-productive complex. As shown by spectrofluorometry, oxidized calmodulin treated with MsrA exhibited native binding affinity for RS20. In contrast, MsrB-treatment of oxidized calmodulin resulted in 10-fold reduced affinity. Mass spectrometry revealed that the sulfoxide derivative of methionine residue 124 was differentially repaired by MsrA and MsrB. This provided a basis for rationalizing the difference in binding affinities of oxidized calmodulin reported above, since Met124 residue had been shown to be critical for interaction with some targets. This study provides the first evidence that in an oxidized polypeptide chain MetSO residues might be differentially repaired by the two Msr enzymes.     

First tau repeat domain binding to growing and taxol-stabilized microtubules,and serine 262 residue phosphorylation

Tau phosphorylation plays a crucial role in microtubule stabilization and in Alzheimer's disease. To characterize the molecular mechanisms of tau binding on microtubules, we synthesized the peptide R1 (QTAPVPMPDLKNVKSKIGSTENLKHQPGGGKVQI), reproducing the first tau microtubule binding motif. We thermodynamically characterized the molecular mechanism of tubulin assembly with R1 in vitro, and measured, for the first time, the binding parameters of R1 on both growing and taxol-stabilized microtubules. In addition, we obtained similar binding parameters with R1 phosphorylated on Ser262. These data suggest that the consequences of Ser262 phosphorylation on tau binding to microtubules and on tubulin assembly are due to large intramolecular rearrangements of the tau protein.     

Hybrid origin of Japanese mice "Mus musculus molossinus": evidence from restriction analysis of mitochondrial DNA

The Japanese mouse, Mus musculus molossinus, has long been considered an independent subspecies of the house mouse. A survey of restriction- site haplotypes of mitochondrial DNA (mtDNA) showed that Japanese mice have two main maternal lineages. The most common haplotype is closely related to the mtDNA of the European subspecies M. m. musculus. The other common haplotype and two minor ones are closely related to each other and to the mtDNA of an Asiatic subspecies, M. m. castaneus. Two other rare variants are probably the result of recent contamination by European M. m. domesticus. The musculus type of mtDNA is found in the southern two-thirds of Japan, whereas the common castaneus type is found in the northern third and the minor variants are found sporadically throughout Japan. The castaneus mtDNA lineage had a few minor variants, whereas the musculus lineage was completely monomorphic. By contrast, the native population of M. m. castaneus and the Chinese and Korean musculus populations were highly polymorphic. These results suggest that M. m. molossinus is a hybrid between ancestral colonies, possibly very small, of M. m. musculus and M. m. castaneus, rather than an independent subspecies.      

Selenium: inhibition of microtubule formation and interaction with tubulin.

We have studied the interaction of Na2SeO3 with microtubule proteins and tubulin. This selenium compound inhibits the polymerization of MTP (half-inhibition occurred for Na2SeO3 10 microM), and to a lesser that of tubulin. This effect of selenite is related to the formation of disulfide bridges between tubulin sulfhydryl groups, inducing a conformational change of the protein. This is corroborated by the modified binding of colchicine and vinblastine in presence of selenium. The selenite inhibitory concentrations are similar to the toxic blood levels of selenium (40 microM).     

Interferon effects on microfilament organization cellular fibronectin distribution, and cell motility in human fibroblasts

We have shown previously (Pfeffer et al., 1979, Exp. Cell Res. 121:111-120) that treatment of human fibroblasts, planted at a density of 2x10(3) cells/cm(2), with purified human fibroblasts interferon (640 U/ml) for 3 d at 37 degrees C decreases the overall rate of cell proliferation to 35-40 percent of the control value. In the present experiments we have characterized the phenotype of interferon-inhibited fibroblasts. The mean volume of trypsinized, interferon-treated cells was increased 31 percent abover that of control cells. The interferon-treated population was much more heterogeneous than the control population with respect to volume, and there was a considerable overlap in the volume distributions of the two populations. The cell surface area was, on the average, increased 65 percent after interferon treatment. More than 80 percent of the treated cells had enlarged nuclei, many of which were lobed, and the fraction of binucleated cells was increased fivefold. After interferon treatment, over 40 percent of the cells showed large actin-containing fibers in the form of multiple parallel arrays. Fewer than 5 percent of the control cells contained such large actin fibers. The number of actin fibers of all sizes was tripled in the treated fibroblasts on a per cell basis and, calculated per unit surface area of the cells, the number was increased 82 percent. In contrast, 10-nm filaments and microtubules did not appear to be increased in number per unit surface area of the cells. The increases per cell in the abundance of these structures were directly related to increased cell size. After interferon treatment, fibronection was distributed in arrays of long filaments covering most portions of the cell surface. Interferon treatment markedly decreased the rate of cell locomotion as well as membrane ruffling and saltatory movements of intracellular granules.