Analysis of White Matter Damage in Patients with Multiple Sclerosis via a Novel In Vivo MR Method for Measuring Myelin, Axons, and G-Ratio

BACKGROUND AND PURPOSE

Myelin and axon volume fractions can now be estimated via MR imaging in vivo, as can the g-ratio, which equals the ratio of the inner to the outer diameter of a nerve fiber. The purpose of this study was to evaluate WM damage in patients with MS via this novel MR imaging technique.

MATERIALS AND METHODS

Twenty patients with relapsing-remitting MS with a combined total of 149 chronic plaques were analyzed. Myelin volume fraction was calculated based on simultaneous tissue relaxometry. Intracellular and CSF compartment volume fractions were quantified via neurite orientation dispersion and density imaging. Axon volume fraction and g-ratio were calculated by combining these measurements. Myelin and axon volume fractions and g-ratio were measured in plaques, periplaque WM, and normal-appearing WM.

RESULTS

All metrics differed significantly across the 3 groups (P < .001, except P = .027 for g-ratio between periplaque WM and normal-appearing WM). Those in plaques differed most from those in normal-appearing WM. The percentage changes in plaque and periplaque WM metrics relative to normal-appearing WM were significantly larger in absolute value for myelin volume fraction than for axon volume fraction and g-ratio (P < .001, except P = .033 in periplaque WM relative to normal-appearing WM for comparison between myelin and axon volume fraction).

CONCLUSIONS

In this in vivo MR imaging study, the myelin of WM was more damaged than axons in plaques and periplaque WM of patients with MS. Myelin and axon volume fractions and g-ratio may potentially be useful for evaluating WM damage in patients with MS.

Fruitless Represses robo1 Transcription to Shape Male-Specific Neural Morphology and Behavior in Drosophila

The Drosophila fruitless (fru) gene is regarded as a master regulator of the formation of male courtship circuitry, yet little is known about its molecular basis of action. We show that roundabout 1 (robo1) knockdown in females promotes formation of the male-specific neurite in sexually dimorphic mAL interneurons and that overexpression of the male-specific Fru(BM) diminishes the expression of Robo1 in the fly brain. Our electrophoretic mobility shift and reporter assays identify the 42-bp segment encompassing the palindrome sequence T T C G C T G C G C C G T G A A in the 5' UTR of robo1 exon1 as the Fru(BM)-responsive element. We find that ∼10-bp deletions in the palindrome sequence induce a loss of the male-specific neurite and disrupt male courtship patterns. This study paves the way for a thorough understanding of the mechanism whereby Fru proteins orchestrate transcription for the formation of courtship circuitry.

The Transgenic RNAi Project at Harvard Medical School: Resources and Validation

To facilitate large-scale functional studies in Drosophila, the Drosophila Transgenic RNAi Project (TRiP) at Harvard Medical School (HMS) was established along with several goals: developing efficient vectors for RNAi that work in all tissues, generating a genome-scale collection of RNAi stocks with input from the community, distributing the lines as they are generated through existing stock centers, validating as many lines as possible using RT-qPCR and phenotypic analyses, and developing tools and web resources for identifying RNAi lines and retrieving existing information on their quality. With these goals in mind, here we describe in detail the various tools we developed and the status of the collection, which is currently composed of 11,491 lines and covering 71% of Drosophila genes. Data on the characterization of the lines either by RT-qPCR or phenotype is available on a dedicated website, the RNAi Stock Validation and Phenotypes Project (RSVP, http://www.flyrnai.org/RSVP.html), and stocks are available from three stock centers, the Bloomington Drosophila Stock Center (United States), National Institute of Genetics (Japan), and TsingHua Fly Center (China).

Drosophila innate immunity: regional and functional specialization of prophenoloxidases

Background

The diversification of immune systems during evolution involves the expansion of particular gene families in given phyla. A better understanding of the metazoan immune system requires an analysis of the logic underlying such immune gene amplification. This analysis is now within reach due to the ease with which we can generate multiple mutations in an organism. In this paper, we analyze the contribution of the three Drosophila prophenoloxidases (PPOs) to host defense by generating single, double and triple mutants. PPOs are enzymes that catalyze the production of melanin at the site of infection and around parasites. They are the rate-limiting enzymes that contribute to the melanization reaction, a major immune mechanism of arthropods. The number of PPO-encoding genes is variable among insects, ranging from one in the bee to ten in the mosquito.

Results

By analyzing mutations alone and in combination, we ascribe a specific function to each of the three PPOs of Drosophila. Our study confirms that two PPOs produced by crystal cells, PPO1 and PPO2, contribute to the bulk of melanization in the hemolymph, upon septic or clean injury. In contrast, PPO3, a PPO restricted to the D. melanogaster group, is expressed in lamellocytes and contributes to melanization during the encapsulation process. Interestingly, another overlapping set of PPOs, PPO2 and PPO3, achieve melanization of the capsule upon parasitoid wasp infection.

Conclusions

The use of single or combined mutations allowed us to show that each PPO mutant has a specific phenotype, and that knocking out two of three genes is required to abolish fully a particular function. Thus, Drosophila PPOs have partially overlapping functions to optimize melanization in at least two conditions: following injury or during encapsulation. Since PPO3 is restricted to the D. melanogaster group, this suggests that production of PPO by lamellocytes emerged as a recent defense mechanism against parasitoid wasps. We conclude that differences in spatial localization, immediate or late availability, and mode of activation underlie the functional diversification of the three Drosophila PPOs, with each of them having non-redundant but overlapping functions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12915-015-0193-6) contains supplementary material, which is available to authorized users.

BIOSAFETY. Safeguarding gene drive experiments in the laboratory

Multiple stringent confinement strategies should be used whenever possible

Phenotype-based clustering of glycosylation-related genes by RNAi-mediated gene silencing

Glycan structures are synthesized by a series of reactions conducted by glycosylation-related (GR) proteins such as glycosyltransferases, glycan-modifying enzymes, and nucleotide-sugar transporters. For example, the common core region of glycosaminoglycans (GAGs) is sequentially synthesized by peptide-O-xylosyltransferase, β1,4-galactosyltransferase I, β1,3-galactosyltransferase II, and β1,3-glucuronyltransferase. This raises the possibility that functional impairment of GR proteins involved in synthesis of the same glycan might result in the same phenotypic abnormality. To examine this possibility, comprehensive silencing of genes encoding GR and proteoglycan core proteins was conducted in Drosophila. Drosophila GR candidate genes (125) were classified into five functional groups for synthesis of GAGs, N-linked, O-linked, Notch-related, and unknown glycans. Spatiotemporally regulated silencing caused a range of malformed phenotypes that fell into three types: extra veins, thick veins, and depigmentation. The clustered phenotypes reflected the biosynthetic pathways of GAGs, Fringe-dependent glycan on Notch, and glycans placed at or near nonreducing ends (herein termed terminal domains of glycans). Based on the phenotypic clustering, CG33145 was predicted to be involved in formation of terminal domains. Our further analysis showed that CG33145 exhibited galactosyltransferase activity in synthesis of terminal N-linked glycans. Phenotypic clustering, therefore, has potential for the functional prediction of novel GR genes.

A genetic screen identifies Tor as an interactor of VAPB in a Drosophila model of amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disorder characterized by selective death of motor neurons. In 5–10% of the familial cases, the disease is inherited because of mutations. One such mutation, P56S, was identified in human VAPB that behaves in a dominant negative manner, sequestering wild type protein into cytoplasmic inclusions.

We have conducted a reverse genetic screen to identify interactors of Drosophila VAPB. We screened 2635 genes and identified 103 interactors, of which 45 were enhancers and 58 were suppressors of VAPB function. Interestingly, the screen identified known ALS loci – TBPH, alsin2 and SOD1. Also identified were genes involved in cellular energetics and homeostasis which were used to build a gene regulatory network of VAPB modifiers. One key modifier identified was Tor, whose knockdown reversed the large bouton phenotype associated with VAP(P58S) expression in neurons. A similar reversal was seen by over-expressing Tuberous Sclerosis Complex (Tsc1,2) that negatively regulates TOR signaling as also by reduction of S6K activity. In comparison, the small bouton phenotype associated with VAP(wt) expression was reversed with Tsc1 knock down as well as S6K-CA expression. Tor therefore interacts with both VAP(wt) and VAP(P58S), but in a contrasting manner. Reversal of VAP(P58S) bouton phenotypes in larvae fed with the TOR inhibitor Rapamycin suggests upregulation of TOR signaling in response to VAP(P58S) expression.

The VAPB network and further mechanistic understanding of interactions with key pathways, such as the TOR cassette, will pave the way for a better understanding of the mechanisms of onset and progression of motor neuron disease.

Loss- and gain-of-function analyses of vacuolar protein sorting 2 in Notch signaling of Drosophila melanogaster

Notch signaling is an evolutionarily conserved mechanism that controls many cell-fate specifications through local cell-cell interactions. The core mechanisms of Notch activation and its subsequent intracellular signaling are well understood. Various cellular functions are required for the activation and regulation of Notch signaling. Among them, the endocytosis of Notch and its ligands is important for the activation and suppression of Notch signaling. The endosomal sorting complex required for transport (ESCRT) proteins are required to sort ubiquitinated membrane proteins, such as Notch, into early endosomes. A loss-of-function allele of vacuolar protein sorting 2 (vps2), which encodes a component of ESCRT-III, has been reported. However, this vps2 mutant still produces the N-terminal half of the protein, and its phenotypes were studied in only a few organs. Here, we generated the first null mutant allele of Drosophila vps2, designated vps2², to better understand the function of this gene. In Drosophila wing imaginal discs homozygous for the vps2² allele, early endosomes and multivesicular bodies (MVBs) were enlarged, and Notch and Delta accumulated inside them. As reported for the previous vps2 mutant, the epithelium grew excessively under this condition. We further studied the roles of vps2 by RNA interference-knockdown. These experiments revealed that a partial reduction of vps2 attenuated Notch signaling; in contrast, the loss-of-function vps2 mutant is reported to up-regulate the Notch signaling in eye imaginal disc cells. These results suggest that Notch signaling can be up- or down-regulated, depending on the level of vps2 expression. Finally, we found that vps2 overexpression also resulted in early-endosome enlargement and the accumulation of Notch and Delta. In these cells, a portion of the Vps2 protein was detected in MVBs and colocalized with Notch. These data indicate that the expression of vps2 must be precisely regulated to maintain the normal structure of early endosomes.

Pulmonary AL amyloidosis in a patient with primary Sjögren syndrome

Abstract The condition of a 29-year-old woman with primary Sjögren syndrome (SS) was complicated by amyloid light chains- (AL-) type amyloidosis in the paranasal sinus. She had not complained of respiratory symptoms, but her chest computed tomography (CT) scan revealed bilateral multiple nodular shadows. Lung biopsy specimens using video-associated thoracoscopy showed amyloidoma in a subpleural nodular lesion and amyloid deposits in the interstitial parenchymal walls and pulmonary vessels. Pulmonary AL amyloidosis, presumably related to a chronic inflammatory lymphoproliferative process in SS, has rarely been reported.

Successful treatment of reactive hemophagocytic syndrome by plasmapheresis and high-dose γ-globulin in a patient with systemic lupus erythematosus

Abstract A 31-year-old woman who had been administered corticosteroid and immunosuppressive agents for systemic lupus erythematosus (SLE) without flare-up was diagnosed as having reactive hemophagocytic syndrome (HPS) with severe disseminated intravascular coagulation. The causative underlying disease was uncertain, but it was not the SLE itself. Her fulminant HPS with increased serum ferritin and inflammatory cytokines (sIL-2R, TNF-α, IL-6, and IFN-γ) was successfully treated with plasmapheresis and high-dose γ-globulin therapy.

Highly improved gene targeting by germline-specific Cas9 expression in Drosophila

We report a simple yet extremely efficient platform for systematic gene targeting by the RNA-guided endonuclease Cas9 in Drosophila. The system comprises two transgenic strains: one expressing Cas9 protein from the germline-specific nanos promoter and the other ubiquitously expressing a custom guide RNA (gRNA) that targets a unique site in the genome. The two strains are crossed to form an active Cas9-gRNA complex specifically in germ cells, which cleaves and mutates the target site. We demonstrate rapid generation of mutants in seven neuropeptide and two microRNA genes in which no mutants have been described. Founder animals stably expressing Cas9-gRNA transmitted germline mutations to an average of 60% of their progeny, a dramatic improvement in efficiency over the previous methods based on transient Cas9 expression. Simultaneous cleavage of two sites by co-expression of two gRNAs efficiently induced internal deletion with frequencies of 4.3-23%. Our method is readily scalable to high-throughput gene targeting, thereby accelerating comprehensive functional annotation of the Drosophila genome.

Drosophila apc regulates delamination of invasive epithelial clusters

Border Cells in the Drosophila ovaries are a useful genetic model for understanding the molecular events underlying epithelial cell motility. During stage 9 of egg chamber development they detach from neighboring stretched cells and migrate between the nurse cells to reach the oocyte. RNAi screening allowed us to identify the dapc1 gene as being critical in this process. Clonal and live analysis showed a requirement of dapc1 in both outer border cells and contacting stretched cells for delamination. This mutant phenotype was rescued by dapc1 or dapc2 expression. Loss of dapc1 function was associated with an abnormal lasting accumulation of β-catenin/Armadillo and E-cadherin at the boundary between migrating border and stretched cells. Moreover, β-catenin/armadillo or E-cadherin downregulation rescued the dapc1 loss of function phenotype. Altogether these results indicate that Drosophila Apc1 is required for dynamic remodeling of β-catenin/Armadillo and E-cadherin adhesive complexes between outer border cells and stretched cells regulating proper delamination and invasion of migrating epithelial clusters.

Cisterna-specific localization of glycosylation-related proteins to the Golgi apparatus

The Golgi apparatus is an intracellular organelle playing central roles in post-translational modification and in the secretion of membrane and secretory proteins. These proteins are synthesized in the endoplasmic reticulum (ER) and transported to the cis-, medial-and trans-cisternae of the Golgi. While trafficking through the Golgi, proteins are sequentially modified with glycan moieties by different glycosyltransferases. Therefore, it is important to analyze the glycosylation function of the Golgi at the level of cisternae. Markers widely used for cis-, medial- and trans-cisternae/trans Golgi network (TGN) in Drosophila are GM130, 120 kDa and Syntaxin16 (Syx16); however the anti-120 kDa antibody is no longer available. In the present study, Drosophila Golgi complex-localized glycoprotein-1 (dGLG1) was identified as an antigen recognized by the anti-120 kDa antibody. A monoclonal anti-dGLG1 antibody suitable for immunohistochemistry was raised in rat. Using these markers, the localization of glycosyltransferases and nucleotide-sugar transporters (NSTs) was studied at the cisternal level. Results showed that glycosyltransferases and NSTs involved in the same sugar modification are localized to the same cisternae. Furthermore, valuable functional information was obtained on the localization of novel NSTs with as yet incompletely characterized biochemical properties.

Identification of genes required for neural-specific glycosylation using functional genomics

Glycosylation plays crucial regulatory roles in various biological processes such as development, immunity, and neural functions. For example, α1,3-fucosylation, the addition of a fucose moiety abundant in Drosophila neural cells, is essential for neural development, function, and behavior. However, it remains largely unknown how neural-specific α1,3-fucosylation is regulated. In the present study, we searched for genes involved in the glycosylation of a neural-specific protein using a Drosophila RNAi library. We obtained 109 genes affecting glycosylation that clustered into nine functional groups. Among them, members of the RNA regulation group were enriched by a secondary screen that identified genes specifically regulating α1,3-fucosylation. Further analyses revealed that an RNA-binding protein, second mitotic wave missing (Swm), upregulates expression of the neural-specific glycosyltransferase FucTA and facilitates its mRNA export from the nucleus. This first large-scale genetic screen for glycosylation-related genes has revealed novel regulation of fucTA mRNA in neural cells.

Increased apoptosis of myoblasts in Drosophila model for the Walker-Warburg syndrome

Walker-Warburg syndrome, a progressive muscular dystrophy, is a severe disease with various kinds of symptoms such as muscle weakness and occasional seizures. The genes of protein O-mannosyltransferases 1 and 2 (POMT1 and POMT2), fukutin, and fukutin-related protein are responsible for this syndrome. In our previous study, we cloned Drosophila orthologs of human POMT1 and POMT2 and identified their activity. However, the mechanism of onset of this syndrome is not well understood. Furthermore, little is known about the behavioral properties of the Drosophila POMT1 and POMT2 mutants, which are called rotated abdomen (rt) and twisted (tw), respectively. First, we performed various kinds of behavioral tests and described in detail the muscle structures by using these mutants. The mutant flies exhibited abnormalities in heavy exercises such as climbing or flight but not in light movements such as locomotion. Defective motor function in mutants appeared immediately after eclosion and was exaggerated with aging. Along with motor function, muscle ultrastructure in the tw mutant was altered, as seen in human patients. We demonstrated that expression of RNA interference (RNAi) for the rt gene and the tw mutant was almost completely lethal and semi-lethal, respectively. Flies expressing RNAi had reduced lifespans. These findings clearly demonstrate that Drosophila POMT mutants are models for human muscular dystrophy. We then observed a high density of myoblasts with an enhanced degree of apoptosis in the tw mutant, which completely lost enzymatic activity. In this paper, we propose a novel mechanism for the development of muscular dystrophy: POMT mutation causes high myoblast density and position derangement, which result in apoptosis, muscle disorganization, and muscle cell defects.

Induction of pole cells in sterilized Drosophila embryos by injection of subcellular fraction from eggs

A subcellular fraction isolated from a homogenate of young Drosophila embryos was shown to be capable of inducing pole cells when injected into UV-sterilized Drosophila embryos. Most of the pole cell-inducing activity was recovered from the precipitate after centrifugation at 27,000 x g. The activity remained in this precipitate (called F-3 fraction hereafter) even after membranous structures were removed from it through centrifugation on a sucrose density gradient. Dialysis, lyophilization, and heating at 80 degrees C for 10 min did not inactivate the F-3 fraction. The pole cells, which were produced when the F-3 fraction was injected at the posterior pole of UV-sterilized embryos, did not develop into germ cells. Furthermore, the F-3 fraction was unable to induce pole cells when injected into the anterior region of the egg. These results can be explained by assuming that (i) pole cell formation and germ cell determination are controlled by different factors, (ii) pole cell formation requires at least two factors, which are normally localized in the posterior-pole cytoplasm, one of which is sensitive and one resistant to the UV dosage we used, and (iii) the subcellular fraction we obtained contains the UV-sensitive factor but not the UV-resistant factor.

Bortezomib-resistant myeloma cell lines: a role for mutated PSMB5 in preventing the accumulation of unfolded proteins and fatal ER stress

Bortezomib is an effective agent for treating multiple myeloma (MM). To investigate the underlying mechanisms associated with acquired resistance to this agent, we established two bortezomib-resistant MM cell lines, KMS-11/BTZ and OPM-2/BTZ, the 50% inhibitory concentration values of which were respectively 24.7- and 16.6-fold higher than their parental cell lines. No activation of caspase and BH3-only proteins such as Noxa was noted in bortezomib-resistant cells after exposure to the drug. The accumulation of polyubiquitinated proteins was reduced in bortezomib-resistant cells compared with the parental cells, associated with avoidance of catastrophic ER stress as assessed by downregulation of CHOP expression. These resistant MM cells have a unique point mutation, G322A, in the gene encoding the proteasome beta5 subunit (PSMB5), likely resulting in conformational changes to the bortezomib-binding pocket of this subunit. KMS-11 parental cells transfected to express mutated PSMB5 also showed reduced bortezomib-induced apoptosis compared with those expressing wild-type PSMB5 or the parental cells. Expression of mutated PSMB5 was associated with the prevention of the accumulation of unfolded proteins. Thus, a fraction of MM cells may acquire bortezomib resistance by suppressing apoptotic signals through the inhibition of unfolded protein accumulation and subsequent excessive ER stress by a mutation of the PSMB5 gene.

Membrane protein location-dependent regulation by PI3K (III) and rabenosyn-5 in Drosophila wing cells

The class III phosphatidylinositol-3 kinase (PI3K (III)) regulates intracellular vesicular transport at multiple steps through the production of phosphatidylinositol-3-phosphate (PI(3)P). While the localization of proteins at distinct membrane domains are likely regulated in different ways, the roles of PI3K (III) and its effectors have not been extensively investigated in a polarized cell during tissue development. In this study, we examined in vivo functions of PI3K (III) and its effector candidate Rabenosyn-5 (Rbsn-5) in Drosophila wing primordial cells, which are polarized along the apical-basal axis. Knockdown of the PI3K (III) subunit Vps15 resulted in an accumulation of the apical junctional proteins DE-cadherin and Flamingo and also the basal membrane protein beta-integrin in intracellular vesicles. By contrast, knockdown of PI3K (III) increased lateral membrane-localized Fasciclin III (Fas III). Importantly, loss-of-function mutation of Rbsn-5 recapitulated the aberrant localization phenotypes of beta-integrin and Fas III, but not those of DE-cadherin and Flamingo. These results suggest that PI3K (III) differentially regulates localization of proteins at distinct membrane domains and that Rbsn-5 mediates only a part of the PI3K (III)-dependent processes.

A blood-borne PDGF/VEGF-like ligand initiates wound-induced epidermal cell migration in Drosophila larvae

Epidermal cell migration is critical for restoration of tissue structure and function after damage. However, the mechanisms by which differentiated cells neighboring the wound sense the wound and assume a motile phenotype remain unclear. Here, we show that Pvr, a receptor tyrosine kinase (RTK) related to platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) receptors, and one of its ligands, Pvf1, are required for epidermal wound closure. Morphological comparison of wound-edge cells lacking Pvr or the Jun N-terminal kinase (JNK) signaling pathway previously implicated in larval wound closure suggests that Pvr signaling leads wound-margin epidermal cells to extend actin-based cell processes into the wound gap while JNK mediates transient dedifferentiation of cells at the wound margin. Genetic epistasis experiments reinforce the conclusion that the JNK and Pvr signaling pathways act in parallel. Tissue-specific knockdown and rescue experiments suggest that epidermally derived Pvf1 may be sequestered in the blood and that tissue damage exposes blood-borne Pvf1 to Pvr receptors on wound-edge epidermal cells and initiates the extension of cell processes into the wound gap. These results uncover a novel mechanism of sensing tissue damage and suggest that PDGF/VEGF ligands and receptors may play a conserved autocrine role in epidermal wound closure.

TARGETED EXPRESSION OF IP3SPONGE AND IP3DSRNA IMPAIRES SUGAR TASTE SENSATION INDROSOPHILA

We evaluated the role of IP(3) in sugar taste reception in Drosophila melanogaster by inactivating the IP(3) signaling using genetic tools. We used the "IP(3) sponge," composed of the modified ligand-binding domain from the mouse IP(3) receptor, which was designed to absorb IP(3) in competition with native IP(3) receptors. Another tool was a transgene that generates double-stranded RNA against IP(3) receptor mRNA. Both inhibitors diminished the sensitivity of flies to trehalose and sucrose, as estimated by behavioral assays and electrophysiological recordings from the sugar receptor cells. The result indicates that IP(3) signaling is indispensable for sugar reception in Drosophila.

Correlation of hENT1 expression with response and survival in non-small cell lung cancer patients treated with gemcitabine-containing chemotherapy

e22032

Background: The most active gemcitabine uptake has been found via the human equilibrative nucleoside transporter 1 (hENT1). This study was to explore the prognostic impact of the hENT1 on response and survival in Non-small lung cancer (NSCLC) patients treated with gemcitabine-containing chemotherapy. Methods: We developed polyclonal antibody for hENT1. Then we stained hENT1 expression by immunohistochemical analysis in 24 biopsy samples of NSCLC which was formaline-fixed, paraffin- embedded tissues. We were treated with gemcitabine alone or gemcitabine-containing chemotherapy until third-line regimen. Results: They comprised 16 males and 8 females with a median age of 63 years (range 45–82 years). Seventeen patients had adenocarcinomas, six had squamous-cell carcinomas, and one had a large-cell carcinoma. All patients were treated with gemcitabine- containing chemotherapy, with 9, 12, and 3 patients receiving this as a first-, second-, and third-line therapy, respectively. The hENT1-positive staining in NSCLC samples was significantly associated with response to gemcitabine-containing chemotherapy (Fisher's exact test, P<0.05). Responses to gemcitabine-containing chemotherapy were evident in none of the seven patients with no hENT1 expression. Further 3 years survival differed by hENT1 staining: 714 days for hENT1-positive, 316 days for hENT1-negative (HR 2.86; 95%CI 1.13–15.16, P<0.05). Conclusions: While there are some determinants for gemcitabine sensitivity, hENT1 expression may be a predictive maker for the response and survival to gemcitabine-containing chemotherapy in NSCLC.

No significant financial relationships to disclose.

Insight into the regulation of glycan synthesis in Drosophila chaoptin based on mass spectrometry

Background

A variety of N-glycans attached to protein are known to involve in many important biological functions. Endoplasmic reticulum (ER) and Golgi localized enzymes are responsible to this template-independent glycan synthesis resulting glycoforms at each asparagine residues. The regulation mechanism such glycan synthesis remains largely unknown.

Methodology/Principal Findings

In order to investigate the relationship between glycan structure and protein conformation, we analyzed a glycoprotein of Drosophila melanogaster, chaoptin (Chp), which is localized in photoreceptor cells and is bound to the cell membrane via a glycosylphosphatidylinositol anchor. Detailed analysis based on mass spectrometry revealed the presence of 13 N-glycosylation sites and the composition of the glycoform at each site. The synthetic pathway of glycans was speculated from the observed glycan structures and the composition at each N-glycosylation site, where the presence of novel routes were suggested. The distribution of glycoforms on a Chp polypeptide suggested that various processing enzymes act on the exterior of Chp in the Golgi apparatus, although virtually no enzyme can gain access to the interior of the horseshoe-shaped scaffold, hence explaining the presence of longer glycans within the interior. Furthermore, analysis of Chp from a mutant (RNAi against dolichyl-phosphate α-d-mannosyltransferase), which affects N-glycan synthesis in the ER, revealed that truncated glycan structures were processed. As a result, the distribution of glycoforms was affected for the high-mannose-type glycans only, whereas other types of glycans remained similar to those observed in the control and wild-type.

Conclusions/Significance

These results indicate that glycan processing depends largely on the backbone structure of the parent polypeptide. The information we obtained can be applied to other members of the LRR family of proteins.

RNAi-mediated knockdown showing impaired cell survival in Drosophila wing imaginal disc

The genetically amenable organism Drosophila melanogaster has been estimated to have 14,076 protein coding genes in the genome, according to the flybase release note R5.13 (http://flybase.bio.indiana.edu/static_pages/docs/release_notes.html). Recent application of RNA interference (RNAi) to the study of developmental biology in Drosophila has enabled us to carry out a systematic investigation of genes affecting various specific phenotypes. In order to search for genes supporting cell survival, we conducted an immunohistochemical examination in which the RNAi of 2,497 genes was independently induced within the dorsal compartment of the wing imaginal disc. Under these conditions, the activities of a stress-activated protein kinase JNK (c-Jun N-terminal kinase) and apoptosis-executing factor Caspase-3 were monitored. Approximately half of the genes displayed a strong JNK or Caspase-3 activation when their RNAi was induced. Most of the JNK activation accompanied Caspase-3 activation, while the opposite did not hold true. Interestingly, the area activating Caspase-3 was more broadly seen than that activating JNK, suggesting that JNK is crucial for induction of non-autonomous apoptosis in many cases. Furthermore, the RNAi of essential factors commonly regulating transcription and translation showed a severe and cell-autonomous apoptosis but also elicited another apoptosis at an adjacent area in a non-autonomous way. We also found that the frequency of apoptosis varies depending on the tissues.

Transposition of the vertebrate Tol2 transposable element in Drosophila melanogaster

The Tol2 element is a transposon found from a genome of a vertebrate, a small teleost medaka fish. Tol2 encodes a gene for a transposase which is active in vertebrate animals so far tested; for instance, in fish, frog, chicken and mammals, and transgenesis methods using Tol2 have been developed in these model vertebrates. However, it has not been known whether Tol2 can transpose in animals other than vertebrates. Here we report transposition of Tol2 in an invertebrate Drosophila melanogaster. First, we injected a transposon donor plasmid containing a Tol2 construct and mRNA encoding the Tol2 transposase into Drosophila eggs, and found that the Tol2 construct could be excised from the plasmid. Second, we crossed the injected flies, raised the offspring, and found that the Tol2 construct was integrated into the genome of germ cells and transmitted to the next generation. Finally, we constructed a Tol2 construct containing the white gene and injected the transposon donor plasmid and the transposase mRNA into fertilized eggs from the white mutant. We analyzed their offspring, and found that G1 flies with wild type red eyes could be obtained from 35% of the injected fly. We cloned and sequenced 34 integration loci from these lines and showed that these insertions were indeed created through transposition and distributed throughout the genome. Our present study demonstrates that the medaka fish Tol2 transposable element does not require vertebrate-specific host factors for its transposition, and also provides a possibility that Tol2 may be used as a new genetic tool for transgenesis and genome analysis in Drosophila.

Functional analysis of proteoglycan galactosyltransferase II RNA interference mutant flies

Heparan sulfate proteoglycan plays an important role in developmental processes by modulating the distribution and stability of the morphogens Wingless, Hedgehog, and Decapentaplegic. Heparan and chondroitin sulfates share a common linkage tetrasaccharide structure, GlcAbeta1,3Galbeta1,3Galbeta1,4Xylbeta-O-Ser. In the present study, we identified Drosophila proteoglycan galactosyltransferase II (dbeta3GalTII), determined its substrate specificity, and performed its functional analysis by using RNA interference (RNAi) mutant flies. The enzyme transferred a galactose to Galbeta1,4Xyl-pMph, confirming that it is the Drosophila ortholog of human proteoglycan galactosyltransferase II. Real-time PCR analyses revealed that dbeta3GalTII is expressed in various tissues and throughout development. The dbeta3GalTII RNAi mutant flies showed decreased amounts of heparan sulfate proteoglycans. A genetic interaction of dbeta3GalTII with Drosophila beta1,4-galactoslyltransferase 7 (dbeta4GalT7) or with six genes that encode enzymes contributing to the synthesis of glycosaminoglycans indicated that dbeta3GalTII is involved in heparan sulfate synthesis for wing and eye development. Moreover, dbeta3GalTII knock-down caused a decrease in extracellular Wingless in the wing imaginal disc of the third instar larvae. These results demonstrated that dbeta3GalTII contributes to heparan sulfate proteoglycan synthesis in vitro and in vivo and also modulates Wingless distribution.

Light activates output from evening neurons and inhibits output from morning neurons in the Drosophila circadian clock

Animal circadian clocks are based on multiple oscillators whose interactions allow the daily control of complex behaviors. The Drosophila brain contains a circadian clock that controls rest–activity rhythms and relies upon different groups of PERIOD (PER)–expressing neurons. Two distinct oscillators have been functionally characterized under light-dark cycles. Lateral neurons (LNs) that express the pigment-dispersing factor (PDF) drive morning activity, whereas PDF-negative LNs are required for the evening activity. In constant darkness, several lines of evidence indicate that the LN morning oscillator (LN-MO) drives the activity rhythms, whereas the LN evening oscillator (LN-EO) does not. Since mutants devoid of functional CRYPTOCHROME (CRY), as opposed to wild-type flies, are rhythmic in constant light, we analyzed transgenic flies expressing PER or CRY in the LN-MO or LN-EO. We show that, under constant light conditions and reduced CRY function, the LN evening oscillator drives robust activity rhythms, whereas the LN morning oscillator does not. Remarkably, light acts by inhibiting the LN-MO behavioral output and activating the LN-EO behavioral output. Finally, we show that PDF signaling is not required for robust activity rhythms in constant light as opposed to its requirement in constant darkness, further supporting the minor contribution of the morning cells to the behavior in the presence of light. We therefore propose that day–night cycles alternatively activate behavioral outputs of the Drosophila evening and morning lateral neurons.

Living organisms have evolved circadian clocks that anticipate daily changes in their environment. Their clockwork is fully endogenous, but can be reset by external cues. (Light is the most efficient cue.) The circadian neuronal network of the fruit fly (Drosophila) brain perceives light through the visual system and a dedicated photoreceptor molecule, cryptochrome. Flies exhibit a bimodal locomotor activity pattern that peaks at dawn and dusk in light–dark conditions. These morning and evening activity bouts are controlled by two distinct neuronal clocks in the fly brain. By using flies with a deficient cryptochrome pathway, we have uncovered an unexpected role for light in the circadian system. In addition to synchronizing the two oscillators to solar time, light also controls their behavioral output. The morning oscillator can periodically rouse the fly when in constant darkness, but not in constant light, whereas the evening oscillator can do the same in constant light, but not in constant darkness. This suggests the existence of a light-dependent switch between oscillators that appears to require the visual system. Such a mechanism likely contributes to better separate the active periods of the fly at dawn and dusk, and may help the animal to adapt to seasonal changes in day length.

In fruit flies, light not only resets the circadian clock to solar time, but also enables the signaling from one oscillator while disabling the signaling from the other.

Drosophila NAT1, a homolog of the vertebrate translational regulator NAT1/DAP5/p97, is required for embryonic germband extension and metamorphosis

Translational regulation has been to shown to play major roles in the patterning of the early Drosophila embryo. The eIF4G family member NAT1/p97/DAP5 has been identified as a novel translational repressor. To genetically dissect the in vivo function of this unconventional eIF4G-related translational regulator, Drosophila NAT1 (dNAT1) mutants were isolated using a reverse-genetics approach. Four transposon insertion mutants and a deletion mutant affecting the dNAT1 locus were analyzed. Genetic complementation tests and germline rescue using a 12 kb dNAT1 genomic DNA fragment revealed these to be loss-of-function mutants. One P-element insertion line, dNAT1(GS1.), shows severe embryonic lethality and abnormal germband extension. Abnormalities at metamorphosis were also found, including defective head eversion and salivary gland degeneration in the hypomorphic allele dNAT(ex1). A phenotypic analysis of dNAT1 mutants suggests that dNAT protein plays a specific rather than general role in translational regulation.

Disproportionate representation of KRAS gene mutation in atypical adenomatous hyperplasia, but even distribution of EGFR gene mutation from preinvasive to invasive adenocarcinomas

In the resected lung, additional small lesions are occasionally found incidentally, and include the full spectrum of preinvasive to invasive lesions under the current putative schema of the sequential development of lung cancer. In this study, we examined EGFR and KRAS gene mutations in 119 synchronous pulmonary lesions, including 40 precursor lesions (atypical adenomatous hyperplasia, AAH), 26 carcinomas in situ (non-mucinous bronchioloalveolar carcinoma, BAC), 14 minimally invasive adenocarcinomas, 34 overt invasive adenocarcinomas, and five of other subtypes of cancer. Although the mutually exclusive nature of KRAS and EGFR gene mutations was maintained even in preinvasive lesions, the incidences of the lesions along the putative progression schema were quite different. The KRAS gene was mutated in 33% of AAH, 12% of carcinomas in situ, 8% of minimally invasive adenocarcinomas and 0% of well-differentiated adenocarcinomas, whereas the frequencies of EGFR mutation did not fluctuate greatly, at 25%, 51%, 36%, 86% and 67%, respectively. These results are consistent with the findings of a published gene-targeted mouse model; the mice expressing oncogenic KRAS developed AAH but not invasive adenocarcinoma, whereas a spectrum of preinvasive to invasive adenocarcinomas was observed in the mice expressing mutant EGFR. Taking these factors together, it is suggested that AAH could develop by either KRAS or EGFR gene mutation, but AAH harbouring a KRAS gene mutation might not progress further to an invasive cancer.

Proteome analyses of the growth inhibitory effects of NCH-51, a novel histone deacetylase inhibitor, on lymphoid malignant cells

Recent reports showing successful inhibition of cancer and leukemia cell growth using histone deacetylase inhibitor (HDACi) compounds have highlighted the potential use of HDACi as anti-cancer agents. However, high incidence of toxicity and low stability in vivo were observed with hydroxamic acid-based HDACi such as suberoylanilide hydroxamic acid (SAHA), thus limiting its clinical applicability. In this study, we found that a novel non-hydroxamate HDACi NCH-51 could inhibit the cell growth of a variety of lymphoid malignant cells through apoptosis induction, more effectively than SAHA. Activation of caspase-3, -8 and -9, but not -7 was detected after the treatment with NCH-51. Gene expression profiles showed that NCH-51 and SAHA similarly upregulated p21 and downregulated anti-apoptotic molecules including survivin, bcl-w and c-FLIP. Proteome analysis using two-dimensional electrophoresis revealed that NCH-51 upregulated anti-oxidant molecules including peroxiredoxin 1 and 2 and glutathione S-transferase at the protein level. Interestingly, NCH-51 induced reactive oxygen species (ROS) after 8 h whereas SAHA continuously declined ROS. Pretreatment with an antioxidant, N-acetyl-L-cysteine, abolished the cytotoxicity of NCH-51. These findings suggest that NCH-51 exhibits cytotoxicity by sustaining ROS at the higher level greater than SAHA. This study indicates the therapeutic efficacy of NCH-51 and novel insights for anti-HDAC therapy.

Natural variation of ebony gene controlling thoracic pigmentation in Drosophila melanogaster

We identified the causal genetic variation for the difference in the thoracic trident pigmentation intensity between two wild-derived strains of Drosophila melanogaster. It was found to be the difference in expression level of ebony, which codes for an enzyme in the melanin-synthesis pathway and has pleiotropic effects on vision and behavior.