MKL1 potentiates lung cancer cell migration and invasion by epigenetically activating MMP9 transcription

Malignant tumors are exemplified by excessive proliferation and aggressive migration/invasion contributing to increased mortality of cancer patients. Matrix metalloproteinase 9 (MMP9) expression is positively correlated with lung cancer malignancy. The mechanism underlying an elevated MMP9 expression is not clearly defined. We demonstrate here that the transcriptional modulator megakaryocytic leukemia 1 (MKL1) was activated by hypoxia and transforming growth factor (TGF-β), two prominent pro-malignancy factors, in cultured lung cancer cells. MKL1 levels were also increased in more invasive types of lung cancer in humans. Depletion of MKL1 in lung cancer cells attenuated migration and invasion both in vitro and in vivo. Overexpression of MKL1 potentiated the induction of MMP9 transcription by hypoxia and TGF-β, whereas MKL1 silencing diminished MMP9 expression. Of interest, MKL1 knockdown eliminated histone H3K4 methylation surrounding the MMP9 promoter. Further analyses revealed that MKL1 recruited ASH2, a component of the H3K4 methyltransferase complex, to activate MMP9 transcription. Depletion of ASH2 ameliorated cancer cell migration and invasion in an MMP9-dependent manner. Together our data indicate that MKL1 potentiates lung cancer cell migration and invasion by epigenetically activating MMP9 transcription.

Augmentation of NAD(+) by NQO1 attenuates cisplatin-mediated hearing impairment

Cisplatin (cis-diaminedichloroplatinum-II) is an extensively used chemotherapeutic agent, and one of its most adverse effects is ototoxicity. A number of studies have demonstrated that these effects are related to oxidative stress and DNA damage. However, the precise mechanism underlying cisplatin-associated ototoxicity is still unclear. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as a key regulator of cellular energy metabolism and homeostasis. Here, we demonstrate for the first time that, in cisplatin-mediated ototoxicity, the levels and activities of SIRT1 are suppressed by the reduction of intracellular NAD(+) levels. We provide evidence that the decrease in SIRT1 activity and expression facilitated by increasing poly(ADP-ribose) transferase (PARP)-1 activation and microRNA-34a through p53 activation aggravates cisplatin-mediated ototoxicity. Moreover, we show that the induction of cellular NAD(+) levels using β-lapachone (β-Lap), whose intracellular target is NQO1, prevents the toxic effects of cisplatin through the regulation of PARP-1 and SIRT1 activity. These results suggest that direct modulation of cellular NAD(+) levels by pharmacological agents could be a promising therapeutic approach for protection from cisplatin-induced ototoxicity.

Altered microglial response to Aβ plaques in APPPS1-21 mice heterozygous for TREM2

BACKGROUND

Recent genome-wide association studies linked variants in TREM2 to a strong increase in the odds of developing Alzheimer's disease. The mechanism by which TREM2 influences the susceptibility to Alzheimer's disease is currently unknown. TREM2 is expressed by microglia and is thought to regulate phagocytic and inflammatory microglial responses to brain pathology. Given that a single allele of variant TREM2, likely resulting in a loss of function, conferred an increased risk of developing Alzheimer's disease, we tested whether loss of one functional trem2 allele would affect Aβ plaque deposition or the microglial response to Aβ pathology in APPPS1-21 mice.

RESULTS

There was no significant difference in Aβ deposition in 3-month old or 7-month old APPPS1-21 mice expressing one or two copies of trem2. However, 3-month old mice with one copy of trem2 exhibited a marked decrease in the number and size of plaque-associated microglia. While there were no statistically significant differences in cytokine levels or markers of microglial activation in 3- or 7-month old animals, there were trends towards decreased expression of NOS2, C1qa, and IL1a in 3-month old TREM2+/- vs. TREM2+/+ mice.

CONCLUSIONS

Loss of a single copy of trem2 had no effect on Aβ pathology, but altered the morphological phenotype of plaque-associated microglia. These data suggest that TREM2 is important for the microglial response to Aβ deposition but that a 50% decrease inTREM2 expression does not affect Aβ plaque burden.

A spiking neuron circuit based on a carbon nanotube transistor

A spiking neuron circuit based on a carbon nanotube (CNT) transistor is presented in this paper. The spiking neuron circuit has a crossbar architecture in which the transistor gates are connected to its row electrodes and the transistor sources are connected to its column electrodes. An electrochemical cell is incorporated in the gate of the transistor by sandwiching a hydrogen-doped poly(ethylene glycol)methyl ether (PEG) electrolyte between the CNT channel and the top gate electrode. An input spike applied to the gate triggers a dynamic drift of the hydrogen ions in the PEG electrolyte, resulting in a post-synaptic current (PSC) through the CNT channel. Spikes input into the rows trigger PSCs through multiple CNT transistors, and PSCs cumulate in the columns and integrate into a 'soma' circuit to trigger output spikes based on an integrate-and-fire mechanism. The spiking neuron circuit can potentially emulate biological neuron networks and their intelligent functions.

CCL2−2518 (A/G) polymorphisms and tuberculosis susceptibility: a meta-analysis

BACKGROUND

It has been found that the -2518 C-C motif ligand (CCL)-2 promoter variant increases the risk of developing active tuberculosis (TB).

OBJECTIVE

To study the association between -2518 variants and susceptibility to TB.

DESIGN

We searched Medline, PubMed and the Wan Fang databases for human genetic studies on whether the -2518 CCL2 polymorphism influences the expression of active TB. Articles published from January 1998 to November 2010 were included. A random effects model was conducted in the meta-analysis.

RESULTS

The CCL2-2518G allele (OR 1.51, 95%CI 1.11-2.04, P = 0.008) showed significant association with susceptibility to TB. In genotype analysis, the recessive model (CCL2 genotype GG, OR 1.66, 95%CI 1.19-2.33, P = 0.003) was slightly superior to the dominant model (G carrier genotypes OR 1.53, 95%CI 1.07-2.17, P = 0.018). These observations were prominent among Asians and Latin-Americans of Hispanic ancestry, but not in Africans from Ghana and South Africa. The presence of epistatic genes in one population but not in the other, environmental differences and pathogen virulence may account for this.

CONCLUSION

The CCL2-2518G allele increases the risk of developing TB in Asians and Hispanics.

Comparative safety of antiepileptic drugs during pregnancy

OBJECTIVE

To assess the safety of the newer antiepileptic drugs (AEDs) during pregnancy.

METHODS

The study population was pregnant women who enrolled in the North American AED Pregnancy Registry between 1997 and 2011. Data on AED use and maternal characteristics were collected through phone interviews at enrollment, at 7 months' gestation, and postpartum. Malformations were confirmed by medical records. The risk of major malformations was calculated among infants exposed to specific AEDs in monotherapy during the first trimester of pregnancy and among an unexposed group. Risk ratios (RRs) and 95% confidence intervals (CIs) were estimated with logistic regression.

RESULTS

The risk of major malformations was 9.3% (30 of 323) for valproate, 5.5% (11 of 199) for phenobarbital, 4.2% (15 of 359) for topiramate, 3.0% (31 of 1.033) for carbamazepine, 2.9% (12 of 416) for phenytoin, 2.4% (11 of 450) for levetiracetam, and 2.0% (31 of 1,562) for lamotrigine. Compared with lamotrigine, the RR was 5.1 (95% CI 3.0-8.5) for valproate, 2.9 (1.4-5.8) for phenobarbital, and 2.2 (1.2-4.0) for topiramate. The proportion of women with epilepsy who had seizures during pregnancy ranged from 23% for valproate to 31% for lamotrigine. Valproate was associated with a higher risk of neural tube defects, hypospadias, cardiac defects, and oral clefts and phenobarbital with a higher risk of cardiac defects and oral clefts; 5 infants exposed to topiramate (1.4%) had a cleft lip.

CONCLUSIONS

AEDs such as valproate and phenobarbital were associated with a higher risk of major malformations than newer AEDs such as lamotrigine and levetiracetam. Topiramate was associated with an increased risk of cleft lip compared with that of a reference population.

Effects of various salinities on Na(+)-K(+)-ATPase, Hsp70 and Hsp90 expression profiles in juvenile mitten crabs, Eriocheir sinensis

Eriocheir sinensis is a euryhaline crab migrating from sea to freshwater habitats during the juvenile stage. We used quantitative real-time polymerase chain reaction (qRT-PCR) to investigate the gene expression profile of Na(+)-K(+)-ATPase, Hsp70 (heat shock protein 70) and Hsp90 in megalopa exposed to salinities of 0, 2, 5, 10, and 15 parts per thousand. Both low and high salinities markedly stimulated expression of Na(+)-K(+)-ATPase, Hsp70 and Hsp90 genes of Chinese mitten crab megalopa; salinity had different effects on Na(+)-K(+)-ATPase, Hsp70 and Hsp90 levels depending on the duration of salinity stress, implying that Na(+)-K(+)-ATPase, Hsp70 and Hsp90 may play an important role in salinity tolerance in this crab species.

Parkinson's disease-associated kinase PINK1 regulates Miro protein level and axonal transport of mitochondria

Mutations in Pten-induced kinase 1 (PINK1) are linked to early-onset familial Parkinson's disease (FPD). PINK1 has previously been implicated in mitochondrial fission/fusion dynamics, quality control, and electron transport chain function. However, it is not clear how these processes are interconnected and whether they are sufficient to explain all aspects of PINK1 pathogenesis. Here we show that PINK1 also controls mitochondrial motility. In Drosophila, downregulation of dMiro or other components of the mitochondrial transport machinery rescued dPINK1 mutant phenotypes in the muscle and dopaminergic (DA) neurons, whereas dMiro overexpression alone caused DA neuron loss. dMiro protein level was increased in dPINK1 mutant but decreased in dPINK1 or dParkin overexpression conditions. In Drosophila larval motor neurons, overexpression of dPINK1 inhibited axonal mitochondria transport in both anterograde and retrograde directions, whereas dPINK1 knockdown promoted anterograde transport. In HeLa cells, overexpressed hPINK1 worked together with hParkin, another FPD gene, to regulate the ubiquitination and degradation of hMiro1 and hMiro2, apparently in a Ser-156 phosphorylation-independent manner. Also in HeLa cells, loss of hMiro promoted the perinuclear clustering of mitochondria and facilitated autophagy of damaged mitochondria, effects previously associated with activation of the PINK1/Parkin pathway. These newly identified functions of PINK1/Parkin and Miro in mitochondrial transport and mitophagy contribute to our understanding of the complex interplays in mitochondrial quality control that are critically involved in PD pathogenesis, and they may explain the peripheral neuropathy symptoms seen in some PD patients carrying particular PINK1 or Parkin mutations. Moreover, the different effects of loss of PINK1 function on Miro protein level in Drosophila and mouse cells may offer one explanation of the distinct phenotypic manifestations of PINK1 mutants in these two species.

Parkinson's disease (PD) is the second most common neurodegenerative disease. It mainly affects movement in elderly people and was traditionally considered a sporadic disease with no known cause. Discoveries of genes associated with familial PD (FPD) have demonstrated that PD pathogenesis can be significantly influenced by an individual's genetic makeup. Understanding the functions of these FPD genes will allow better understanding of the sporadic PD cases. PINK1 and Parkin are genes associated with FPD that affect patients at an early age. Mutations in PINK1 and Parkin lead to the accumulation of damaged mitochondria, the powerhouse of the cell, as a result of impairments of the mitochondrial quality control system. However, the mechanism of PINK1/Parkin action remains poorly understood. Here we show that PINK1 and Parkin act together to regulate Miro, a key component of the mitochondrial transport machinery, and that altered activities of PINK1 cause aberrant mitochondrial transport. Regulation of mitochondrial transport may be a critical aspect of the mechanisms by which the PINK1/Parkin pathway governs mitochondrial quality control. Dysfunction of this process could contribute to the loss of DA neurons, the cardinal feature of PD, as well as the peripheral neuropathy symptom associated with particular PINK1 or Parkin mutations.

Treatment limitations imposed by antiretroviral drug resistance mutations: implication for choices of first line regimens in resource-limited settings

BACKGROUND

Recent studies have suggested that failing nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens may have greater potential to induce the development of resistance mutations, which may limit options for second-line therapy.

METHODS

Antiretroviral therapy (ART)-naïve individuals aged ≥18 years who initiated triple combination ART between January 2000 and June 2006 in British Columbia, Canada were enrolled in the study. We compared genotypic sensitivity scores (GSSs) derived from the development of resistance mutations between participants who initiated ART with ritonavir-boosted protease inhibitors (PIs) with those who initiated ART with NNRTIs, and determined the effects of these mutations on remaining active drugs.

RESULTS

A total of 1666 participants initiated ART, 818 (49.1%) with NNRTI-based regimens and 848 (50.9%) with boosted PI-based regimens. Among participants who developed resistance mutations, those who initiated NNRTI-based regimens had a lower median GSS than those on boosted PI-based regimens (9.8 vs. 11.0, respectively; P<0.001). Participants on boosted PI-based regimens [adjusted odds ratio (AOR) 3.68; 95% confidence interval (CI) 2.25, 6.01], those with ≥95% adherence to highly active antiretroviral therapy (HAART) (AOR 1.84; 95% CI 1.16, 2.92) and those with baseline CD4 count >200 cells/μL (AOR 3.44; 95% CI 1.73, 6.84) were more likely to have the maximum number of drug options.

CONCLUSION

The use of NNRTI-based first-line ART regimens may limit the options for second-line treatment when the number of available drugs is limited.

Single step measurement of optical transmitters Henry factor using sinusoidal optical phase modulations

Measurement of the Henry factor over large optical bandwidth is carried out in a single step without any filtering, using a technique based on the sinusoidal phase modulation method. This fast technique was successfully applied to a directly modulated Fabry Perot laser to obtain simultaneously the linewidth enhancement factor (LEF) of 14 longitudinal modes. It is also well suited for electro-absorption modulators (EAM) for which the α-factor is determined over 15 nm optical bandwidth. A very good agreement is found with the well established fiber transfer function method.

The role of p27(Kip1) phosphorylation at serine 10 in the migration of malignant glioma cells in vitro

Until recently, Cip/Kip members were almost solely viewed as nuclear proteins with a principal function of inhibiting cyclin/cyclin dependent kinase (CDK) activity and hence, inhibiting cell cycle progression. P27(Kip1) (hereafter p27) belongs to the Cip/Kip family that binds and inhibits all the cyclin/CDK complexes, thus often referred as a universal CDK inhibitor. However, emerging studies now suggest that Cip/Kip proteins play additional roles outside of the nucleus. Indeed, previous reports have linked p27 to the regulation of actin dynamics and cell migration. In this study, we constructed a model of migration-activated glioma cells by using the migration-stimulating substrate, a kind of ECM, laminin in vitro. Our results present evidence that laminin drives glioma cell migration without altering cell proliferation. Further, actively migrating cells which expressioned high phosphorylation of p27 at Ser10, and induced its cytoplasmic localization. In this process, Jab1 and CRM1 were also involved. Thus phosphorylation of p27 at Ser10 is necessary for both cytoplasmic localization and induction of cell migration. These observations solidified a genetic role of p27 in cell migration and this was independent of cyclin/CDK inhibition. Eventually, we transiently transfected p27S10A into T98G glioma cells, found that overexpression of p27S10A inhibited cell migration but not cell proliferation. These data linked phosphorylation of p27 at Ser10 and cell motility. Therefore, the major phosphorylation site at Ser10 of p27 played a pivotal role in the migration of malignant glioma cells.

A phase I study of XL281, a selective oral RAF kinase inhibitor, in patients (Pts) with advanced solid tumors

3513

Background: XL281 is a potent and selective inhibitor of wild type and mutant RAF kinases showing anti-tumor activity in multiple xenograft models. Mutations in KRAS or BRAF can activate the RAF/MEK/ERK pathway in human tumors and may promote sensitivity to RAF kinase inhibitors. Methods: Pts were enrolled in successive cohorts of XL281 orally once daily on a 28-day cycle. Tumor response was assessed per RECIST every 8 wks. Plasma pharmacokinetic and pharmacodynamic samples were collected. The maximum tolerated dose (MTD) was expanded to 10 pts each with colorectal (CRC), melanoma, papillary thyroid (PTC) and NSCLC. Pre- and post-dose tumor and surrogate tissues were obtained. Biomarker and genotype analyses of pathway genes were performed. Results: The dose escalation phase is complete; 30 pts were treated with XL281. DLTs of fatigue, nausea, vomiting, and diarrhea were observed at the MAD (225 mg). The MTD is 150 mg. The most common related AEs included Grade 1/2, fatigue (48%), diarrhea (35%), nausea (35%), vomiting (35%) and anorexia (30%). Three pts had related AEs ≥G3: hypokalemia, nausea, and vomiting. One pt with an ocular melanoma demonstrated a cPR of 4 mos duration. Twelve pts had SD (3 -17+ mos), including 2 with I131-refractory PTC harboring BRAF V600E mutations (15+ and 17+ mos). Nine of these pts had decreases in target lesions (5–29%), including a pt with KRAS mutant CRC on study for 20 wks with marked symptomatic improvement. At the MTD, paired biopsies from 4 pts (3 melanoma, 1 NSCLC) show an average 72 % decrease in pMEK, 68 % decrease in pERK, 24 % decrease in Ki67 (proliferation) and 64 % increase in TUNEL (apoptosis). Three of 6 evaluable pts in the MTD cohort show SD at first assessment, including 1 melanoma pt with a NRAS Q61R mutation who showed a 20% decrease in target lesions. Conclusions: XL281 was generally well tolerated and the MTD was established at 150 mg. One cPR occurred in an ocular melanoma subject, and clinical benefit (PR or SD) occurred in 43% (13/30) of pts in the dose-escalation phase. XL281 demonstrates biological activity by modulation of the RAF pathway in tumor and surrogate tissue, with decreases in cell proliferation and increases in apoptosis.

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Experimental investigation of the timing jitter in self-pulsating quantum-dash lasers operating at 1.55 microm

We report for the first time on the systematic measurement of timing jitter of 40-GHz self-pulsating Fabry-Perot laser based on InAs/InP quantum dashes emitting at 1.55 microm. Two different methods, one based on optical cross-correlation and one on electrical spectrum sideband integration are used and show a good agreement, yielding a jitter of 0.86 ps in the 1 MHz---20 MHz frequency range with a potential of 280 fs for optimized driving conditions. Amplitude noise and high-frequency timing jitter contributions are also discussed.

Spatiotemporal patterns of postsynaptic density (PSD)-95 expression after rat spinal cord injury

AIMS

Postsynaptic density (PSD)-95 is a scaffolding protein linking the N-methyl-D-aspartate receptor with neuronal nitric oxide synthase (nNOS), which contributes to many physiological and pathological actions. We here investigated whether PSD-95 was involved in the secondary response following spinal cord injury (SCI).

METHODS

Spinal cord contusion (SCC) and spinal cord transection (SCT) models at thoracic (T) segment 9 (T(9)) were established in adults rats. Real-time polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence were used to detect the temporal profile and spatial distribution of PSD-95 after SCI. The association between PSD-95 and nNOS in the injured cords was also assessed by coimmmunoprecipation and double immunofluorescent staining.

RESULTS

The mRNA and protein for PSD-95 expression were significantly increased at 2 h or 8 h, and then gradually declined to the baseline level, ultimately up-regulated again from 5 days to 7 days for its mRNA level and at 7 days or 14 days for its protein level after either SCC or SCT. PSD-95 immunoreactivity was found in neurones, oligodendrocytes and synaptic puncta of spinal cord tissues within 5 mm from the lesion site. Importantly, injury-induced expression of PSD-95 was colabelled by active caspase-3 (apoptotic marker), Tau-1 (the marker for pathological oligodendrocytes) and nNOS.

CONCLUSIONS

Accompanied by the spatio-temporal changes for PSD-95 expression, the association between PSD-95 and nNOS undergoes substantial alteration after SCI. These two molecules are likely to form a complex on apoptotic neurones and pathological oligodendrocytes, which may in turn be involved in the secondary response after SCI.

Screening and characterization of yeasts for xylitol production

AIMS

To discover novel naturally occurring xylitol producing yeast species with potential for industrial applications.

METHODS AND RESULTS

Exactly 274 strains were cultivated on both solid and liquid screening medium with xylose as the sole carbon resource. Five strains were selected on the basis of significant growth and high degree of xylose assimilation. Their phylogenetic position was confirmed by the PCR-RFLP and sequence analysis of the D1/D2 domain of the 5' end of the large subunit rDNA gene (5'-LSU rDNA). Enzymatic analysis was conducted to compare xylose metabolism in each strain. Candida guilliermondii Xu280 and Candida maltosa Xu316 were found to have high xylose consumption rates and xylitol yields in the batch fermentation under micro-aerobic condition. The effect of the different media with high initial xylose concentration on biosynthesis of xylitol by both strains was investigated.

CONCLUSIONS

We have identified Candida spp. strains, which exhibit high levels of xylitol production from xylose suggesting that these may have potential for industrial applications.

SIGNIFICANCE AND IMPACTS OF THE STUDY

Microbial species are of importance for xylitol production. Xylitol production involves complicated metabolic regulation including xylose transport, production of key enzymes and cofactor regeneration. Thus, screening of naturally occurring xylose-utilizing micro-organisms is a viable and effective mean to obtain xylitol producing organisms with industrial application. Moreover, the research on selected strains will contribute to a better understanding of regulatory properties of xylose metabolism in different yeasts.

Cloning and molecular characterization of a gene coding D-xylulokinase (CmXYL3) from Candida maltosa

AIMS

To clone and identify a gene (CmXYL3) coding D-xylulokinase from Candida maltosa Xu316 and understand its physiological function.

METHODS AND RESULTS

Based on the conserved regions of the known D-xylulokinase-encoding genes, a pair of degenerate primers was designed to clone the CmXYL3 gene from C. maltosa Xu316. The coding region and sequences flanking the CmXYL3 gene were obtained by PCR-based DNA walking method. Southern blotting analysis suggested that there is a single copy of the CmXYL3 gene in the genome. The open reading frame starting from ATG and ending with TAG stop codon encoded 616 amino acids with a calculated molecular mass of 68889.743 Da. The CmXYL3 gene under the control of the GPD1 promoter was heterologously expressed in Saccharomyces cerevisiae deficient in D-xylulokinase (deltaScXKS1::LEU2) activity, and restored growth on D-xylulose. The specific activity of D-xylulokinase varied during xylose fermentation and was correlated with aeration level. After growth on different pentoses and pentitols as sole carbon sources, the highest specific activity of D-xylulokinase was observed on D-xylose.

CONCLUSIONS

The CmXYL3 gene isolated from C. maltosa Xu316 encodes a novel D-xylulokinase that plays a pivotal role in xylulose metabolism.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report that describes the isolation and cloning of D-xylulokinase gene (CmXYL3) from C. maltosa Xu316. D-xylulokinase is pivotal for growth and product formation during xylose metabolism. Better understanding of the biochemical properties and the physiological function of D-xylulokinase will contribute to optimizing fermentation conditions and determining the strategies for metabolic engineering of C. maltosa Xu316 for further improvement of xylitol yield and productivity.

Cre/lox-mediated marker gene excision in transgenic maize (Zea mays L.) plants

After the initial transformation and tissue culture process is complete, selectable marker genes, which are used in virtually all transformation approaches, are not required for the expression of the gene of interest in the transgenic plants. There are several advantages to removing the selectable marker gene after it is no longer needed, such as enabling the reuse of selectable markers and simplifying transgene arrays. We have tested the Cre/ lox system from bacteriophage P1 for its ability to precisely excise stably integrated marker genes from chromosomes in transgenic maize plants. Two strategies, crossing and autoexcision, have been tested and demonstrated. In the crossing strategy, plants expressing the Cre recombinase are crossed with plants bearing a transgene construct in which the selectable marker gene is flanked by directly repeated lox sites. Unlike previous reports in which incomplete somatic and germline excision were common, in our experiments complete somatic and germline marker gene excision occurred in the F(1) plants from most crosses with multiple independent Cre and lox lines. In the autoexcision strategy, the cre gene, under the control of a heat shock-inducible promoter, is excised along with the nptII marker gene. Our results show that a transient heat shock treatment of primary transgenic callus is sufficient for inducing cre and excising the cre and nptII genes. Genetic segregation and molecular analysis confirmed that marker gene removal is precise, complete and stable. The autoexcision strategy provides a way of removing the selectable marker gene from callus or other tissues such as embryos and kernels.