CSF T-Tau/Aβ42 predicts white matter microstructure in healthy adults at risk for Alzheimer's disease

Cerebrospinal fluid (CSF) biomarkers T-Tau and Aβ(42) are linked with Alzheimer's disease (AD), yet little is known about the relationship between CSF biomarkers and structural brain alteration in healthy adults. In this study we examined the extent to which AD biomarkers measured in CSF predict brain microstructure indexed by diffusion tensor imaging (DTI) and volume indexed by T1-weighted imaging. Forty-three middle-aged adults with parental family history of AD received baseline lumbar puncture and MRI approximately 3.5 years later. Voxel-wise image analysis methods were used to test whether baseline CSF Aβ(42), total tau (T-Tau), phosphorylated tau (P-Tau) and neurofilament light protein predicted brain microstructure as indexed by DTI and gray matter volume indexed by T1-weighted imaging. T-Tau and T-Tau/Aβ(42) were widely correlated with indices of brain microstructure (mean, axial, and radial diffusivity), notably in white matter regions adjacent to gray matter structures affected in the earliest stages of AD. None of the CSF biomarkers were related to gray matter volume. Elevated P-Tau and P-Tau/Aβ(42) levels were associated with lower recognition performance on the Rey Auditory Verbal Learning Test. Overall, the results suggest that CSF biomarkers are related to brain microstructure in healthy adults with elevated risk of developing AD. Furthermore, the results clearly suggest that early pathological changes in AD can be detected with DTI and occur not only in cortex, but also in white matter.     

Shotgun proteomic monitoring of Clostridium acetobutylicum during stationary phase of butanol fermentation using xylose and comparison with the exponential phase

Economically viable production of solvents through acetone-butanol-ethanol (ABE) fermentation requires a detailed understanding of Clostridium acetobutylicum. This study focuses on the proteomic profiling of C. acetobutylicum ATCC 824 from the stationary phase of ABE fermentation using xylose and compares with the exponential growth by shotgun proteomics approach. Comparative proteomic analysis revealed 22.9% of the C. acetobutylicum genome and 18.6% was found to be common in both exponential and stationary phases. The proteomic profile of C. acetobutylicum changed during the ABE fermentation such that 17 proteins were significantly differentially expressed between the two phases. Specifically, the expression of five proteins namely, CAC2873, CAP0164, CAP0165, CAC3298, and CAC1742 involved in the solvent production pathway were found to be significantly lower in the stationary phase compared to the exponential growth. Similarly, the expression of fucose isomerase (CAC2610), xylulose kinase (CAC2612), and a putative uncharacterized protein (CAC2611) involved in the xylose utilization pathway were also significantly lower in the stationary phase. These findings provide an insight into the metabolic behavior of C. acetobutylicum between different phases of ABE fermentation using xylose.     

Water saving traits co-map with a major terminal drought tolerance quantitative trait locus in pearl millet [Pennisetum glaucum (L.) R. Br.]

Low transpiration rates in pearl millet under fully irrigated conditions decrease plant water use at vegetative stage and then increase the water availability during grain filling and finally the terminal drought tolerance. Hundred and thirteen recombinant inbred lines developed from a cross between H77/833-2 and PRLT2/89-33 (terminal drought-sensitive?×?tolerant genotype) were evaluated to map transpiration rate (Tr, a proxy for canopy conductance), organ weights, leaf area and thickness and to study their interactions. Transpiration rate was increased by two H77/833-2 and two PRLT2/89-33 alleles on linkage group (LG) 2, whose importance depended on the vapor pressure deficit. The two H77/833-2 and one PRLT2/89-33 alleles co-mapped to a previously identified major terminal drought tolerance quantitative trait locus (QTL), although in a much smaller genetic interval. The other Tr allele from H77/833-2 also enhanced biomass dry weight and co-located with a formerly identified stover and tillering QTL. Leaf characteristics were linked to two loci on LG7. Plant water use was increased and decreased by different loci combinations for Tr, tillering and leaf characteristics, whose respective importance depended on the environmental conditions. Therefore, different alleles influence plant water use and have close interactions with one another and with the environment, so that different ideotypes for plant water use exist or could be designed from specific allele combinations conferring particular physiological characteristics for specific adaptation to a range of terminal drought conditions.     

Interaction with a kinesin-2 tail propels choline acetyltransferase flow towards synapse

Bulk flow constitutes a substantial part of the slow transport of soluble proteins in axons. Though the underlying mechanism is unclear, evidences indicate that intermittent, kinesin-based movement of large protein-aggregates aids this process. Choline acetyltransferase (ChAT), a soluble enzyme catalyzing acetylcholine synthesis, propagates toward the synapse at an intermediate, slow rate. The presynaptic enrichment of ChAT requires heterotrimeric kinesin-2, comprising KLP64D, KLP68D and DmKAP, in Drosophila. Here, we show that the bulk flow of a recombinant Green Fluorescent Protein-tagged ChAT (GFP::ChAT), in Drosophila axons, lacks particulate features. It occurs for a brief period during the larval stages. In addition, both the endogenous ChAT and GFP::ChAT directly bind to the KLP64D tail, which is essential for the GFP::ChAT entry and anterograde flow in axon. These evidences suggest that a direct interaction with motor proteins could regulate the bulk flow of soluble proteins, and thus establish their asymmetric distribution.     

The function of p120 catenin in filopodial growth and synaptic vesicle clustering in neurons

At the developing neuromuscular junction (NMJ), physical contact between motor axons and muscle cells initiates presynaptic and postsynaptic differentiation. Using Xenopus nerve-muscle cocultures, we previously showed that innervating axons induced muscle filopodia (myopodia), which facilitated interactions between the synaptic partners and promoted NMJ formation. The myopodia were generated by nerve-released signals through muscle p120 catenin (p120ctn), a protein of the cadherin complex that modulates the activity of Rho GTPases. Because axons also extend filopodia that mediate early nerve-muscle interactions, here we test p120ctn's function in the assembly of these presynaptic processes. Overexpression of wild-type p120ctn in Xenopus spinal neurons leads to an increase in filopodial growth and synaptic vesicle (SV) clustering along axons, whereas the development of these specializations is inhibited following the expression of a p120ctn mutant lacking sequences important for regulating Rho GTPases. The p120ctn mutant also inhibits the induction of axonal filopodia and SV clusters by basic fibroblast growth factor, a muscle-derived molecule that triggers presynaptic differentiation. Of importance, introduction of the p120ctn mutant into neurons hinders NMJ formation, which is observed as a reduction in the accumulation of acetylcholine receptors at innervation sites in muscle. Our results suggest that p120ctn signaling in motor neurons promotes nerve-muscle interaction and NMJ assembly.     

Novel levamisole derivative induces extrinsic pathway of apoptosis in cancer cells and inhibits tumor progression in mice

Background

Levamisole, an imidazo(2,1-b)thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4′-fluorophenyl)-5-thiocyanato-imidazo[2,1-b][1], [3], [4]thiadiazole).

Materials and Methods

ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo.

Results

We have determined the IC₅₀ value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC₅₀ 5 µM). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models.

Conclusion

Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.     

Role of MicroRNA Processing in Adipose Tissue in Stress Defense and Longevity

The terminal enzyme of the mitochondrial respiratory chain, cytochrome oxidase, transfers electrons to molecular oxygen, generating water. Within the inner?mitochondrial membrane, cytochrome oxidase assembles into supercomplexes, together with other respiratory chain complexes, forming so-called respirasomes. Little is known about how these higher oligomeric structures are attained. Here we report on Rcf1 and Rcf2 as cytochrome oxidase subunits in S.?cerevisiae. While Rcf2 is specific to yeast, Rcf1 is a conserved subunit with two human orthologs, RCF1a and RCF1b. Rcf1 is required for growth in hypoxia and complex assembly of subunits Cox13 and Rcf2, as well as for the oligomerization of?a subclass of cytochrome oxidase complexes into respirasomes. Our analyses reveal that the cytochrome oxidase of mitochondria displays intrinsic heterogeneity with regard to its subunit composition and that distinct forms of respirasomes can be formed by complex variants.     

Synthesis and biological evaluation of a fluorescent analog of phenytoin as a potential inhibitor of neuropathic pain and imaging agent

Here we report on a novel fluorescent analog of phenytoin as a potential inhibitor of neuropathic pain with potential use as an imaging agent. Compound 2 incorporated a heptyl side chain and dansyl moiety onto the parent compound phenytoin and produced greater displacement of BTX from sodium channels and greater functional blockade with greatly reduced toxicity. Compound 2 reduced mechano-allodynia in a rat model of neuropathic pain and was visualized ex vivo in sensory neuron axons with two-photon microscopy. These results suggest a promising strategy for developing novel sodium channel inhibitors with imaging capabilities.     

Exogenous fluorescent tracer agents based on pegylated pyrazine dyes for real-time point-of-care measurement of glomerular filtration rate

Novel pyrazine carboxamides bearing hydrophilic poly(ethylene glycol) (PEG) moieties were designed, synthesized, and evaluated for use as fluorescent glomerular filtration rate (GFR) tracer agents. Among these, compounds 4d and 5c that contain about 48 ethylene oxide units in the PEG chain exhibited the most favorable physicochemical and renal clearance properties. In vitro studies show that these two compounds have low plasma protein binding, a necessary condition for renal excretion. In vivo animal model results show that 4d and 5c have a higher urine recovery of the injected dose than iothalamate (a commonly considered gold standard GFR agent). Pharmacokinetic studies show that these two compounds exhibit a plasma clearance equivalent to iothalamate, but with a faster (i.e. lower) terminal half-life than iothalamate (possibly from restricted distribution into the extracellular space due to large molecular size and hydrodynamic volume). Furthermore, the plasma clearance of 4d and 5c remained unchanged upon blockage of the tubular secretion pathway with probenecid, a necessary condition for establishment of clearance via glomerular filtration exclusively. Finally, noninvasive real-time monitoring of this class of compounds was demonstrated by pharmacokinetic clearance of 5c by optical measurements in rat model, which correlates strongly with plasma concentration of the tracer. Hence, 4d and 5c are promising candidates for translation to the clinic as exogenous fluorescent tracer agents in real-time point-of-care monitoring of GFR.     

Protein model discrimination using mutational sensitivity derived from deep sequencing

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Highlights? Individual mutant phenotypes in a saturation library derived via deep sequencing ? Residue depth and active-site residue derivation from mutant phenotypes ? Mutant-phenotype-derived parameters used for protein model discrimination ? Derivation of sequence-structure-function relationships without protein isolation