Increased Plin2 Expression in Human Skeletal Muscle Is Associated with Sarcopenia and Muscle Weakness

Human aging is associated with a progressive loss of muscle mass and strength and a concomitant fat accumulation in form of inter-muscular adipose tissue, causing skeletal muscle function decline and immobilization. Fat accumulation can also occur as intra-muscular triglycerides (IMTG) deposition in lipid droplets, which are associated with perilipin proteins, such as Perilipin2 (Plin2). It is not known whether Plin2 expression changes with age and if this has consequences on muscle mass and strength. We studied the expression of Plin2 in the vastus lateralis (VL) muscle of both healthy subjects and patients affected by lower limb mobility limitation of different age. We found that Plin2 expression increases with age, this phenomenon being particularly evident in patients. Moreover, Plin2 expression is inversely correlated with quadriceps strength and VL thickness. To investigate the molecular mechanisms underpinning this phenomenon, we focused on IGF-1/p53 network/signalling pathway, involved in muscle physiology. We found that Plin2 expression strongly correlates with increased p53 activation and reduced IGF-1 expression. To confirm these observations made on humans, we studied mice overexpressing muscle-specific IGF-1, which are protected from sarcopenia. These mice resulted almost negative for the expression of Plin2 and p53 at two years of age. We conclude that fat deposition within skeletal muscle in form of Plin2-coated lipid droplets increases with age and is associated with decreased muscle strength and thickness, likely through an IGF-1- and p53-dependent mechanism. The data also suggest that excessive intramuscular fat accumulation could be the initial trigger for p53 activation and consequent loss of muscle mass and strength.     

Phylogenetic position of a copper age sheep (Ovis aries) mitochondrial DNA

Background

Sheep (Ovis aries) were domesticated in the Fertile Crescent region about 9,000-8,000 years ago. Currently, few mitochondrial (mt) DNA studies are available on archaeological sheep. In particular, no data on archaeological European sheep are available.

Methodology/Principal Findings

Here we describe the first portion of mtDNA sequence of a Copper Age European sheep. DNA was extracted from hair shafts which were part of the clothes of the so-called Tyrolean Iceman or Ötzi (5,350 - 5,100 years before present). Mitochondrial DNA (a total of 2,429 base pairs, encompassing a portion of the control region, tRNA^Phe, a portion of the 12S rRNA gene, and the whole cytochrome B gene) was sequenced using a mixed sequencing procedure based on PCR amplification and 454 sequencing of pooled amplification products. We have compared the sequence with the corresponding sequence of 334 extant lineages.

Conclusions/Significance

A phylogenetic network based on a new cladistic notation for the mitochondrial diversity of domestic sheep shows that the Ötzi''s sheep falls within haplogroup B, thus demonstrating that sheep belonging to this haplogroup were already present in the Alps more than 5,000 years ago. On the other hand, the lineage of the Ötzi''s sheep is defined by two transitions (16147, and 16440) which, assembled together, define a motif that has not yet been identified in modern sheep populations.     

5-(2-Pyrrolidinyl)oxazolidinones and 2-(2-pyrrolidinyl)benzodioxanes: Synthesis of all the stereoisomers and α4β2 nicotinic affinity

The four stereoisomers of 2-oxazolidinone 5-substituted with 1-methyl-2-pyrrolidinyl (1), of 1,4-benzodioxane 2-substituted with the same residue (2) and of the nor-methyl analogue of this latter (2a) were synthesized as candidate nicotinoids. Of the 12 compounds, two N-methylated pyrrolidinyl-benzodioxane stereoisomers, namely those with the same relative configuration at the pyrrolidine stereocentre as (S)-nicotine, bind at α4β2 nicotinic acetylcholine receptor with submicromolar affinity. Consistently with the biological data, docking analysis enlightens significant differences in binding site interactions not only between 1 and 2, but also between 2 and 2a and between the stereoisomers of 2 accounting for the critical role played, in the case of the pyrrolidinyl-benzodioxanes, by the chirality of both the stereolabile and stereostable stereogenic atoms, namely the protonated tertiary nitrogen and the two asymmetric carbons.     

New Ras CAAX mimetics: Design, synthesis, antiproliferative activity, and RAS prenylation inhibition

Mimetics of the C-terminal CAAX tetrapeptide of Ras protein were designed replacing cysteine (C) by 2-hydroxymethylbenzodioxane or 2-aminomethylbenzodioxane, respectively etherified and amidified with 2′-methyl or 2′-methoxy substituted 2-carboxy-4-hydroxybiphenyl and 2,4-dicarboxybiphenyl. These pluri-substituted biphenyl systems, used as internal spacer and AA dipeptide bioisoster, were linked to the methyl ester of l-methionine, glycine or l-leucine by an amide bond. The resultant twelve pairs of stereoisomers at the dioxane C-2 were tested for antiproliferative effect finding the maximum activity for derivatives with methyleneoxy linker between benzodioxane and 2′-methylbiphenyl. Of these compounds, the one with terminal methionine and S configuration proved a good Ras prenylation inhibitor in a cell-based assay.     

Soil properties under Norway spruce differ in spruce dominated and mixed broadleaf forests of the Southern Taiga

In natural forest, disturbance changes tree species composition which in turn affects soil properties. Two areas in the Central Forest State Biosphere Reserve, in the Russian Southern Taiga Zone, differed in the intensity of disturbance: Norway spruce was the dominant species at one site, while at the other spruce was mixed with broadleaves. The presence of broadleaves was due to large gaps in the canopy having been formed, which have triggered vegetation succession. At both sites, five plots were selected to evaluate how the presence of broadleaves influences the properties of the soils under spruce. Soil samples were taken close to spruce trees and the O, A and E horizons were analysed. A difference in the distribution of organic matter in the soil horizons was evident, with a higher concentration in the O and A horizons at the spruce dominated site, while a more homogeneous distribution was found under spruce at the site where broadleaves were abundant. The organic matter did not only differ in quantity, but also in quality as estimated by the C/N ratio, and therefore affected the CEC and element relative availability. No differences at the two sites were found for water-extractable and exchangeable elements, but the ratio between the exchangeable and the acid-extractable forms were different, suggesting a higher relative availability of the elements at the spruce dominated site, and thus potentially higher leaching. Both theoretical and empirical studies have suggested that podzolisation and accumulation of organic matter in the O horizon are related to stagnation of ecosystem processes and ecosystem decline. Our data suggest that the presence to windthrow sites and the inclusion of broadleaf species acts to slow or even reverse podzolisation even in spruce dominated sites.     

Dissecting the structural determinants of the interaction between the human cytomegalovirus UL18 protein and the CD85j immune receptor

UL18 is a glycoprotein encoded by the human cytomegalovirus genome and is thought to play a pivotal role during human cytomegalovirus infection, although its exact function is still a matter of debate. UL18 shares structural similarity with MHC class I and binds the receptor CD85j on immune cells. Besides UL18, CD85j binds MHC class I molecules. The binding properties of CD85j to MHC class I molecules have been thoroughly studied. Conversely, very little information is available on the CD85j/UL18 complex, namely that UL18 binds CD85j through its alpha3 domain with an affinity that is approximately 1000-fold higher than the MHC class I affinity for CD85j. Deeper knowledge of features of the UL18/CD85j complex would help to disclose the function of UL18 when it binds to CD85j. In this study we first demonstrated that the UL18alpha3 domain is not sufficient per se for binding and that beta2-microglobulin is necessary for UL18-CD85j interaction. We then dissected structural determinants of binding UL18 to CD85j. To this end, we constructed a three-dimensional model of the complex. The model was used to design mutants in selected regions of the putative interaction interface, the effects of which were measured on binding. Six regions in both the alpha2 and alpha3 domains and specific amino acids within them were identified that are potentially involved in the UL18-CD85j interaction. The higher affinity of UL18 to CD85j, compared with MHC class I, seems to be due not to additional interaction regions but to an overall better fit of the two molecules.     

Specific recognition of the viral protein UL18 by CD85j/LIR-1/ILT2 on CD8+ T cells mediates the non-MHC-restricted lysis of human cytomegalovirus-infected cells

Immune evasion mechanisms of human CMV are known; however, the immune control of infection remains poorly elucidated. We show that interaction between the viral protein UL18 on infected cells and the invariant receptor CD85j/LIR-1/ILT2 expressed on CTL is relevant for the control of infection. Resting and activated CD8(+) T cells lysed UL18 expressing cells, whereas cells infected with CMV defective for UL18 were not killed. Lysis was not dependent on CD8(+) T cell Ag specificity, MHC-unrestricted and specifically blocked by anti-CD85j and anti-UL18 mAb. Moreover, soluble recombinant UL18Fc immunoprecipitated CD85j from T cells. Activation is mediated by CD85j and its pathway is unrelated to CD3/TCR engagement. UL18 is detected in immunocompromised patients with productive infection and the mechanism used in vivo by human CMV to ensure survival of the immunocompetent host may be mediated by activation signals delivered by infected cells to T lymphocytes via UL18/CD85j interactions.     

The sema domain

The sema domain was first defined from sequence by Kolodkin and colleagues in the early 1990s, and constitutes the distinctive structural and functional element of semaphorins, their plexin receptors and the receptor tyrosine kinases MET and RON, three protein families with major roles in development, tissue regeneration and cancer. Recently determined crystal structures of two semaphorins (SEMA3A and SEMA4D) and the MET receptor have shown that the sema domain consists of a highly conserved variant form of the seven-blade beta-propeller fold. The structures, however, also suggest differences between these families with respect to the mode of dimerisation and the regions of the domain involved in ligand-receptor interactions. This reflects the considerable plasticity and adaptation of the sema domain in order to meet different binding requirements, properties that may underlie the vast array of ligand-receptor specificities and functions of the semaphorin superfamily.     

CD85j (leukocyte Ig-like receptor-1/Ig-like transcript 2) inhibits human osteoclast-associated receptor-mediated activation of human dendritic cells

Immature dendritic cells (DCs) derived from freshly isolated human monocytes were used to evaluate the effect of the inhibiting receptor CD85j (leukocyte Ig-like receptor-1/ILT2) on activation induced by cross-linking of the human osteoclast-associated receptor (hOSCAR). CD85j and hOSCAR were expressed consistently at the same density on monocytes and on monocyte-derived DCs (both immature and mature). Cross-linking of hOSCAR, which activates via the FcR-associated gamma-chain, induced Ca(2+) flux in DCs. Concomitant cross-linking of anti-CD85j mAb abolished this early activation event. Likewise, CD85j stimulation strongly reduced IL-8 and IL-12 production by hOSCAR-activated DCs. Inhibition of DCs via CD85j also impaired their ability to enhance Ag-specific T cell proliferation induced by hOSCAR. Finally, because hOSCAR prevents apoptosis of DCs in the absence of growth/survival factors, CD85j cross-linking was able to counteract completely this antiapoptotic effect and to reduce Bcl-2 expression enhanced by hOSCAR stimulation. Thus, CD85j is an inhibiting receptor that is functional in human DCs.