Working channel endoscope in lumbar spine surgery

Percutaneous endoscopic lumbar discectomy (PELD) is a well established modality in the treatment of patients with herniated lumbar discs. Since the time of its inception towards the end of 20th century, this technique has undergone significant modifications. With better understanding of the patho-anatomy and development of instrumentation the indications for PELD are on the rise. In the modern era of knowledge exchange there have been considerable variations among different endoscopic surgeons about classical indications and the implications of a particular technique pertaining to those indications. During last 15 years of experience in practicing endoscopic surgery, Choi has published many articles, regarding the techniques of PELD, across many scientific journals. In our practice there has been considerable shift from central debulking to discectomy to selective fragmentectomy. With further advancements the span of this technique is definitely on the rise. Here, we wish to share all the published data along with my current practice trends in more precise manner to help newer endoscopic spine surgeons understand the implications and limitations of a working channel endoscope in lumbar spine pathologies.

A histone methyltransferase inhibits seed germination by increasing PIF1 mRNA expression in imbibed seeds

Phytochrome-interacting factor 1 (PIF1) inhibits light-dependent seed germination. The specific function of PIF1 in seed germination is partly due to its high level of expression in imbibed seeds, but the associated regulatory factors have not been identified. Here we show that mutation of the early flowering in short days (EFS) gene, encoding an H3K4 and H3K36 methyltransferase, decreases the level of H3K36me2 and H3K36me3 but not H3K4me3 at the PIF1 locus, reduces the targeting of RNA polymerase II to the PIF1 locus, and reduces mRNA expression of PIF1 in imbibed seeds. Consistently, the efs mutant geminated even under the phyBoff condition, and had an expression profile of PIF1 target genes similar to that of the pif1 mutant. Introduction of an EFS transgene into the efs mutant restored the level of H3K36me2 and H3K36me3 at the PIF1 locus, the high-level expression of PIF1 mRNA, the expression pattern of PIF1 target genes, and the light-dependent germination of these seeds. Introduction of a PIF1 transgene into the efs mutant also restored the expression pattern of PIF1 target genes and light-dependent germination in imbibed seeds, but did not restore the flowering phenotype. Taken together, our results indicate that EFS is necessary for high-level expression of PIF1 mRNA in imbibed seeds.

ABA-insensitive3, ABA-insensitive5, and DELLAs Interact to activate the expression of SOMNUS and other high-temperature-inducible genes in imbibed seeds in Arabidopsis

Seeds monitor the environment to germinate at the proper time, but different species respond differently to environmental conditions, particularly light and temperature. In Arabidopsis thaliana, light promotes germination but high temperature suppresses germination. We previously reported that light promotes germination by repressing SOMNUS (SOM). Here, we examined whether high temperature also regulates germination through SOM and found that high temperature activates SOM expression. Consistent with this, som mutants germinated more frequently than the wild type at high temperature. The induction of SOM mRNA at high temperature required abscisic acid (ABA) and gibberellic acid biosynthesis, and ABA-insensitive3 (ABI3), ABI5, and DELLAs positively regulated SOM expression. Chromatin immunoprecipitation assays indicated that ABI3, ABI5, and DELLAs all target the SOM promoter. At the protein level, ABI3, ABI5, and DELLAs all interact with each other, suggesting that they form a complex on the SOM promoter to activate SOM expression at high temperature. We found that high-temperature-inducible genes frequently have RY motifs and ABA-responsive elements in their promoters, some of which are targeted by ABI3, ABI5, and DELLAs in vivo. Taken together, our data indicate that ABI3, ABI5, and DELLAs mediate high-temperature signaling to activate the expression of SOM and other high-temperature-inducible genes, thereby inhibiting seed germination.

ABA-insensitive3, ABA-insensitive5, and DELLAs Interact to activate the expression of SOMNUS and other high-temperature-inducible genes in imbibed seeds in Arabidopsis

Seeds monitor the environment to germinate at the proper time, but different species respond differently to environmental conditions, particularly light and temperature. In Arabidopsis thaliana, light promotes germination but high temperature suppresses germination. We previously reported that light promotes germination by repressing SOMNUS (SOM). Here, we examined whether high temperature also regulates germination through SOM and found that high temperature activates SOM expression. Consistent with this, som mutants germinated more frequently than the wild type at high temperature. The induction of SOM mRNA at high temperature required abscisic acid (ABA) and gibberellic acid biosynthesis, and ABA-insensitive3 (ABI3), ABI5, and DELLAs positively regulated SOM expression. Chromatin immunoprecipitation assays indicated that ABI3, ABI5, and DELLAs all target the SOM promoter. At the protein level, ABI3, ABI5, and DELLAs all interact with each other, suggesting that they form a complex on the SOM promoter to activate SOM expression at high temperature. We found that high-temperature-inducible genes frequently have RY motifs and ABA-responsive elements in their promoters, some of which are targeted by ABI3, ABI5, and DELLAs in vivo. Taken together, our data indicate that ABI3, ABI5, and DELLAs mediate high-temperature signaling to activate the expression of SOM and other high-temperature-inducible genes, thereby inhibiting seed germination.

Phytochrome-interacting factors have both shared and distinct biological roles

Phytochromes are plant photoreceptors that perceive red and far-red light. Upon the perception of light in Arabidopsis, light-activated phytochromes enter the nucleus and act on a set of interacting proteins, modulating their activities and thereby altering the expression levels of ∼10% of the organism's entire gene complement. Phytochromeinteracting factors (PIFs) belonging to Arabidopsis basic helix-loop-helix (bHLH) subgroup 15 are key interacting proteins that play negative roles in light responses. Their activities are post-translationally countered by light-activated phytochromes, which promote the degradation of PIFs and directly or indirectly inhibit their binding to DNA. The PIFs share a high degree of similarity, but examinations of pif single and multiple mutants have indicated that they have shared and distinct functions in various developmental and physiological processes. These are believed to stem from differences in both intrinsic protein properties and their gene expression patterns. In an effort to clarify the basis of these shared and distinct functions, we compared recently published genome-wide ChIP data, developmental gene expression maps, and responses to various stimuli for the various PIFs. Based on our observations, we propose that the biological roles of PIFs stem from their shared and distinct DNA binding targets and specific gene expression patterns.

DELLA proteins and their interacting RING Finger proteins repress gibberellin responses by binding to the promoters of a subset of gibberellin-responsive genes in Arabidopsis

DELLA proteins, consisting of GA INSENSITIVE, REPRESSOR OF GA1-3, RGA-LIKE1 (RGL1), RGL2, and RGL3, are central repressors of gibberellin (GA) responses, but their molecular functions are not fully understood. We isolated four DELLA-interacting RING domain proteins, previously designated as BOTRYTIS SUSCEPTIBLE1 INTERACTOR (BOI), BOI-RELATED GENE1 (BRG1), BRG2, and BRG3 (collectively referred to as BOIs). Single mutants of each BOI gene failed to significantly alter GA responses, but the boi quadruple mutant (boiQ) showed a higher seed germination frequency in the presence of paclobutrazol, precocious juvenile-to-adult phase transition, and early flowering, all of which are consistent with enhanced GA signaling. By contrast, BOI overexpression lines displayed phenotypes consistent with reduced GA signaling. Analysis of a gai-1 boiQ pentuple mutant further indicated that the GAI protein requires BOIs to inhibit a subset of GA responses. At the molecular level, BOIs did not significantly alter the stability of a DELLA protein. Instead, BOI and DELLA proteins are targeted to the promoters of a subset of GA-responsive genes and repress their expression. Taken together, our results indicate that the DELLA and BOI proteins inhibit GA responses by interacting with each other, binding to the same promoters of GA-responsive genes, and repressing these genes.

Calcium dependent sucrose uptake links sugar signaling to anthocyanin biosynthesis in Arabidopsis

Sugars enhance light signaling-induced anthocyanin accumulation in Arabidopsis seedlings via differential regulation of several positive and negative transcription factors. Ca(2+) plays a role as a second messenger in sugar signaling in grape and wheat. However, whether anthocyanin pigmentation is modulated by changes in intracellular Ca(2+) level in Arabidopsis is not known. Here, we used a pharmaceutical approach that Ca(2+) antagonists strongly interfered with sucrose uptake and anthocyanin accumulation by downregulating the expression of sucrose transporter 1 (SUC1) and transcriptional regulatory factors, such as PAP1. Time course analysis of the effect of Ca(2+) antagonists showed the early inhibition of sucrose-induced sugar uptake leading to decreased anthocyanin accumulation, indicating that Ca(2+) signals play a role in sugar uptake rather than in anthocyanin biosynthesis. An early increase in cytosolic Ca(2+) level in Arabidopsis roots in response to sucrose feeding was significantly inhibited by Ca(2+) antagonists. Taken together, these results indicate that sucrose-induced sugar uptake in Arabidopsis is modulated by changes in endogenous Ca(2+) levels, which in turn regulate anthocyanin accumulation.

Asian venous thromboembolism guidelines: prevention of venous thromboembolism

Venous thromboembolism (VTE) prophylaxis is under-utilized in Asia because of the misconception that its incidence is lower in Asians as compared to the Caucasians. The available data on VTE in Asia is limited due to the lack of well-designed multicenter randomized controlled trials as well as non-standardized research designs, making data comparison difficult. Emerging data indicates that the VTE incidence is not low in Asia, and is comparable to that reported in the Western literature in some instances. There is also a trend towards increasing incidence of VTE, as demonstrated by a number of hospital-based studies in Asia. This could be attributed to lifestyle changes, ageing population, increasing awareness of VTE and wider availability of Duplex ultrasound. The risk of VTE in hospitalized patients remain the same in Asians and Caucasians, even though there may be factors that are inherent to patients in Asia that influence the slight variation in incidence. The utilization rate of VTE prophylaxis remains suboptimal in Asia. The Asian Venous Thrombosis Forum (AVTF) comprises participants from various countries such as China, Hong Kong, India, Indonesia, Korea, Malaysia, Philippines, Singapore, Taiwan, Thailand and experts from Australia and Europe. The forum evaluated the available data on VTE from the Asian region and formulated guidelines tailored to meet the needs of the region. We recommend that serious considerations are given to VTE prophylaxis especially in the at-risk group and a formal hospital policy be established to facilitate the implementation. On admission to the hospital, we recommend assessing the patients for both VTE and bleeding risk. We recommend mechanical prophylaxis for patients at increased risk of bleeding and utilizing it as an adjunctive measure in combination with pharmacological prophylaxis in patients with high risk of VTE. For patients undergoing general or gynecological surgery and with moderate risk for VTE, we recommend prophylaxis with one of the following: low dose unfractionated heparin (LDUH), low molecular weight heparin (LMWH), fondaparinux or intermittent pneumatic compression (IPC). For the same group of patients at high risk of VTE, we recommend pharmacological or combination of pharmacological and mechanical prophylaxis. For patients undergoing major orthopedic surgeries like total hip replacement, total knee replacement and proximal hip fracture surgery, we recommend using one of the following: LMWH, fondaparinux, rivaroxaban, apixaban, edoxaban, dabigatran, warfarin or aspirin with IPC. For patients admitted to the hospital with acute medical illness and has moderate risk of VTE, we recommend prophylaxis with LDUH, LMWH or Fondaparinux. For the same group at high risk of VTE, we recommend combination of pharmacological and mechanical prophylaxis.

Phytochrome B inhibits binding of phytochrome-interacting factors to their target promoters

Phytochromes are red and far-red light receptors in plants that mediate critical responses to light throughout the lifecycle. They achieve this in part by targeting negatively acting bHLH transcription factors called phytochrome-interacting factors (PIFs) for degradation within the nucleus. However, it is not known whether protein degradation is the primary mechanism by which phytochromes inhibit these repressors of photomorphogenesis. Here, we use chromatin immunoprecipitation to show that phyB inhibits the regulatory activity of PIF1 and PIF3 by releasing them from their DNA targets. The N-terminal fragment of phyB (NG-GUS-NLS; NGB) also inhibits binding of PIF3 to its target promoters. However, unlike full-length phyB, NGB does not promote PIF3 degradation, establishing the activity of NGB reflects its ability to inhibit PIF binding to DNA. We further show that Pfr forms of both full-length phyB and NGB inhibit DNA binding of PIF1 and PIF3 in vitro. Taken together, our results indicate that phyB inhibition of PIF function involves two separate processes: sequestration and protein degradation.

Cytokinins enhance sugar-induced anthocyanin biosynthesis in Arabidopsis

In higher plants, the regulation of anthocyanin synthesis by various factors including light, sugars and hormones is mediated by numerous regulatory factors acting at the transcriptional level. Here, the association between sucrose and the plant hormone, cytokinin, in the presence of light was investigated to elucidate cytokinin signaling cascades leading to the transcriptional activation of anthocyanin biosynthesis genes in Arabidopsis seedlings. We showed that cytokinin enhances anthocyanin content and transcript levels of sugar inducible structural gene UDPglucose: flavonoid 3-O-glucosyl transferase (UF3GT) and regulatory gene PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1). Genetic analysis showed that cytokinin signaling modulates sugar-induced anthocyanin biosynthesis through a two-component signaling cascade involving the type-B response regulators ARR1, ARR10 and ARR12 in a redundant manner. Genetic, physiological and molecular biological approaches demonstrated that cytokinin enhancement is partially dependent on phytochrome and cryptochrome downstream component HY5, but mainly on photosynthetic electron transport. Taken together, we suggest that cytokinin acts down-stream of the photosynthetic electron transport chain in which the plastoquinone redox poise is modulated by sugars in a photoreceptor independent manner.

Interactions between HLH and bHLH factors modulate light-regulated plant development

Phytochromes (Phy) and phytochrome-interacting factor (PIF) transcription factors constitute a major signaling module that controls plant development in response to red and far-red light. A low red:far-red ratio is interpreted as shading by neighbor plants and induces cell elongation-a phenomenon called shade-avoidance syndrome (SAS). PAR1 and its closest homolog PAR2 are negative regulators of SAS; they belong to the HLH transcription factor family that lacks a typical basic domain required for DNA binding, and they are believed to regulate gene expressions through DNA binding transcription factors that are yet to be identified. Here, we show that light signal stabilizes PAR1 protein and PAR1 interacts with PIF4 and inhibits PIF4-mediated gene activation. DNA pull-down and chromatin immunoprecipitation (ChIP) assays showed that PAR1 inhibits PIF4 DNA binding in vitro and in vivo. Transgenic plants overexpressing PAR1 (PAR1OX) are insensitive to gibberellin (GA) or high temperature in hypocotyl elongation, similarly to the pifq mutant. In addition to PIF4, PAR1 also interacts with PRE1, a HLH transcription factor activated by brassinosteroid (BR) and GA. Overexpression of PRE1 largely suppressed the dwarf phenotype of PAR1OX. These results indicate that PAR1-PRE1 and PAR1-PIF4 heterodimers form a complex HLH/bHLH network regulating cell elongation and plant development in response to light and hormones.

ABI3 and PIL5 collaboratively activate the expression of SOMNUS by directly binding to its promoter in imbibed Arabidopsis seeds

A previous study showed that SOMNUS (SOM), which encodes a C3H-type zinc finger protein, is a key negative regulator of seed germination that acts downstream of PHYTOCHROME INTERACTING FACTOR3-LIKE5 (PIL5). However, it was not determined if PIL5 is the sole regulator of SOM expression. Public microarray data suggest that the expression of SOM mRNA is regulated also by ABSCISIC ACID INSENSITIVE3 (ABI3), another key regulator of seed germination. By analyzing abi3 mutants and ABI3 overexpression lines, we show here that ABI3 activates the expression of SOM mRNA collaboratively with PIL5 in imbibed seeds. Chromatin immunoprecipitation analysis coupled with electrophoretic mobility shift assay indicate that ABI3 activates the expression of SOM mRNA by directly binding to two RY motifs present in the SOM promoter in vivo, which is further supported by the greatly decreased expression of a reporter gene driven by a SOM promoter bearing mutated RY motifs. At the protein level, the ABI3 protein interacts with the PIL5 protein. The ABI3-PIL5 interaction, however, does not affect targeting of ABI3 and PIL5 to SOM promoters. Taken together, our results indicate that ABI3 and PIL5 collaboratively activate the expression of SOM mRNA by directly binding to and interacting with each other at the SOM promoter.

Genome-wide DNA-binding specificity of PIL5, an Arabidopsis basic Helix-Loop-Helix (bHLH) transcription factor

PIL5 is a member of the basic Helix-Loop-Helix (bHLH) transcription factor superfamily. We previously showed that PIL5 binds to the G-box (CACGTG) motif with high affinity. However, since there are many randomly matched G-box motifs throughout the genome, other factors must account for the in-vivo PIL5 binding specificity. In this study, we investigated if in-vivo PIL5 binding sites can be explained by any other attributes extracted from various sources. Our results showed that PIL5 binding sites can be explained by attributes such as neighbouring motif composition, nucleosome density, DNA methylation and distance from transcription start site in addition to G-box.

Ethylene suppression of sugar-induced anthocyanin pigmentation in Arabidopsis

Anthocyanin accumulation is regulated negatively by ethylene signaling and positively by sugar and light signaling. However, the antagonistic interactions underlying these signalings remain to be elucidated fully. We show that ethylene inhibits anthocyanin accumulation induced by sucrose (Suc) and light by suppressing the expression of transcription factors that positively regulate anthocyanin biosynthesis, including GLABRA3, TRANSPARENT TESTA8, and PRODUCTION OF ANTHOCYANIN PIGMENT1, while stimulating the concomitant expression of the negative R3-MYB regulator MYBL2. Genetic analyses show that the ethylene-mediated suppression of anthocyanin accumulation is dependent upon ethylene signaling components responsible for the triple response. Furthermore, these positive and negative signaling pathways appear to be under photosynthetic control. Suc and light induction of anthocyanin accumulation was almost fully inhibited in wild-type Arabidopsis (Arabidopsis thaliana) ecotype Columbia and ethylene (ethylene response1 [etr1-1]) and light (long hypocotyl1 [hy1], cryptochrome1/2, and hy5) signaling mutants treated with the photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The transcript level of the sugar transporter gene SUC1 was enhanced in ecotype Columbia treated with the ethylene-binding inhibitor silver and in etr1-1, ethylene insensitive2 (ein2-1), and ein3 ein3-like1 mutants. In contrast, 3-(3,4-dichlorophenyl)-1,1-dimethylurea treatment reduced SUC1 expression, which indicates strongly that SUC1 represents an integrator for signals provided by sugar, light, and ethylene. SUC1 mutations lowered accumulations of anthocyanin pigment, soluble sugar content, and ethylene production in response to Suc and light signals. These data demonstrate that the suppression of SUC1 expression by ethylene inhibits Suc-induced anthocyanin accumulation in the presence of light and, hence, fine-tunes anthocyanin homeostasis.

Histone occupancy-dependent and -independent removal of H3K27 trimethylation at cold-responsive genes in Arabidopsis

Trimethylation of histone H3 at lysine 27 (H3K27me3) is a histone marker that is present in inactive gene loci in both plants and animals. Transcription of some of the genes with H3K27me3 should be induced by internal or external cues, yet the dynamic fate of H3K27me3 in these genes during transcriptional regulation is poorly understood in plants. Here we show that H3K27me3 in two cold-responsive genes, COR15A and ATGOLS3, decreases gradually in Arabidopsis during exposure to cold temperatures. We found that removal of H3K27me3 can occur by both histone occupancy-dependent and -independent mechanisms. Upon cold exposure, histone H3 levels decreased in the promoter regions of COR15A and ATGOLS3 but not in their transcribed regions. When we returned cold-exposed plants to normal growth conditions, transcription of COR15A and ATGOLS3 was completely repressed to the initial level before cold exposure in 1 day. In contrast, plants still maintained the cold-triggered decrease in H3K27me3 at COR15A and ATGOLS3, but this decrease did not enhance transcriptional induction of the two genes upon re-exposure to cold. Taken together, these results indicate that gene activation is not inhibited by H3K27me3 itself but rather leads to removal of H3K27me3, and that H3K27me3 can be inherited at a quantitative level, thereby serving as a memory marker for recent transcriptional activity in Arabidopsis.

-93G>A polymorphism of hMLH1 associated with prognosis for patients with colorectal cancer

4039

Background: Polymorphisms in the DNA repair genes may contribute to variation in DNA repair capacity, thereby affecting the risk of carcinogenesis and prognosis of colorectal cancer. Accordingly, the present study analyzed polymorphisms of DNA repair genes and their impact on the prognosis for patients with colorectal cancer. Methods: Three hundred and ninety- seven consecutive patients with curatively resected colorectal adenocarcinoma were enrolled in the present study. The genomic DNA was extracted from fresh colorectal tissue and 14 polymorphisms of DNA repair genes (XRCC1, hMLH1, ERCC2, ERCC4, VARS2[rs2074511, rs2249459], XPA, XPC, POLR2A, POLR2B, RFC1, RFC4, XAB2, DNMT3B) determined using a PCR-RFLP assay. Results: The median age of the patients was 63 years (range, 21–85), and 218 (54.9%) patients had colon cancer and 179 (45.1%) patients rectal cancer. Pathologic stages after surgery were as follows: stage 0/I (n=86, 21.7%), stage II (n=146, 36.8%), stage III (n=145, 36.5%), and stage IV (n=20, 5.0%). Multivariate survival analysis including stage, differentiation, age, and CEA level showed that the survival for the patients with the -93AA genotype of hMLH1 was worse than for the patients with the combined -93GG and GA genotype (overall survival: hazard ratio [HR]=2.953, 95% Confidential Interval [CI], 1.273–6.850, P=0.012; disease-free survival: HR=2.299, 95% CI, 1.417–3.730, P=0.001), whereas the other polymorphisms were not associated with survival. Conclusions: The -93G>A polymorphism of hMLH1 was found to be an independent prognostic marker for patients with colorectal cancer. Accordingly, in addition to the pathologic stage, the analysis of -93G>A polymorphism of hMLH1 can help identify patient subgroups at high risk of a poor disease outcome.

No significant financial relationships to disclose.

RIPK1 gene polymorphism as a prognostic marker for survival in patients with colorectal cancer

e15078

Background: Since apoptosis plays a key role in cancer progression, we hypothesized that single nucleotide polymorphisms (SNPs) of apoptosis-related gene can affect survival after curative resection in patients with colorectal cancer. Patients and Methods: Three hundred and ninety seven patients with colorectal cancer who underwent surgery with curative intent were enrolled in the present study. The genomic DNA was extracted from fresh colorectal mucosal tissue, and the 19 SNPs of 15 apoptosis-related genes (CASP3, CASP6–10, FAS, FAS ligand [FASLG], TNSFR1A, TNSFR10B, RIPK1, BCL2, BCL2 ligand [BCL2L], TP53, and PTGS2) were determined using a PCR-RFLP assay. Results: The median age of the patients was 63 years (range, 21–85), and 218 (54.9%) patients had colon cancer and 179 (45.1%) patients rectal cancer. Pathologic stages after surgery were as follows: stage 0/I (n=86, 21.7%), stage II (n=146, 36.8%), stage III (n=145, 36.5%), and stage IV (n=20, 5.0%). Multivariate survival analysis including pathologic stage, differentiation, age, and CEA level showed that relapse-free survival for the patients with the GA+AA genotype of RIPK1 (Receptor interacting serine/threonine kinase 1) +83G>A (rs2272990) was worse than for the patients with the GG genotype (hazard ratio [HR]=1.66, 95% confidence interval [CI]=1.03–2.68, p=0.038). However, no associations were observed between the polymorphisms and overall survival (OS) in a multivariate analysis. Conclusions: RIPK1 gene polymorphism can be considered as a possible prognostic marker for survival after curative resection in patient with colorectal cancer.

No significant financial relationships to disclose.

Interaction of light and hormone signals in germinating seeds

Seed germination is regulated by several environmental factors, such as moisture, oxygen, temperature, light, and nutrients. Light is a critical regulator of seed germination in small-seeded plants, including Arabidopsis and lettuce. Phytochromes, a class of photoreceptors, play a major role in perceiving light to induce seed germination. Classical physiological studies have long suggested the involvement of gibberellin (GA) and abscisic acid (ABA) in the phytochrome-mediated germination response. Recent studies have demonstrated that phytochromes modulate endogenous levels of GA and ABA, as well as GA responsiveness. Several key components that link the perception of light and the modulation of hormone levels and responsiveness have been identified. Complex regulatory loops between light, GA and ABA signaling pathways have been uncovered.

Genome-wide analysis of genes targeted by PHYTOCHROME INTERACTING FACTOR 3-LIKE5 during seed germination in Arabidopsis

PHYTOCHROME INTERACTING FACTOR 3-LIKE5 (PIL5) is a basic helix-loop-helix transcription factor that inhibits seed germination by regulating the expression of gibberellin (GA)- and abscisic acid (ABA)-related genes either directly or indirectly. It is not yet known, however, whether PIL5 regulates seed germination solely through GA and ABA. Here, we used Chromatin immunoprecipitation-chip (ChIP-chip) analysis to identify 748 novel PIL5 binding sites in the Arabidopsis thaliana genome. Consistent with the molecular function of PIL5 as a transcription regulator, most of the identified binding sites are located in gene promoter regions. Binding site analysis shows that PIL5 binds to its target sites mainly through the G-box motif in vivo. Microarray analysis reveals that phytochromes regulate a large number of genes mainly through PIL5 during seed germination. Comparison between the ChIP-chip and microarray data indicates that PIL5 regulates 166 genes by directly binding to their promoters. Many of the identified genes encode transcription regulators involved in hormone signaling, while some encode enzymes involved in cell wall modification. Interestingly, PIL5 directly regulates many transcription regulators of hormone signaling and indirectly regulates many genes involved in hormone metabolism. Taken together, our data indicate that PIL5 inhibits seed germination not just through GA and ABA, but also by coordinating hormone signals and modulating cell wall properties in imbibed seeds.

CRY1 inhibits COP1-mediated degradation of BIT1, a MYB transcription factor, to activate blue light-dependent gene expression in Arabidopsis

Cryptochromes (CRY) are one of the two major classes of photoreceptors that perceive light stimuli in the UV-A to blue light region and they are involved in multiple aspects of plant growth and development. However, knowledge regarding their signaling transduction components and mechanisms remains limited. Here, we report that a MYB transcription factor Blue Insensitive Trait 1 (BIT1), plays an important role in controlling blue light responses. Hypocotyl growth responses indicate that BIT1 functions as a positive element in blue light signaling, since BIT1 antisense and knock-out lines show a reduced light response in blue light. BIT1 controls blue light-dependent expression of various genes such as PsbS, a member of the light-harvesting complex gene family. A transactivation assay showed that BIT1 regulates promoter activity of PsbS in a blue light-dependent manner and that it requires CRY1 for activation of the PsbS promoter. BIT1 undergoes degradation in darkness and CRY1 functions to stabilize BIT1 in a blue light-dependent manner. In contrast, COP1 binds to BIT1 and mediates its degradation. We propose that the PsbS promoter is activated in blue light via the blue light-dependent stabilization of BIT1 by CRY1, while in darkness BIT1 is degraded by COP1-mediated proteolysis.

SOMNUS, a CCCH-type zinc finger protein in Arabidopsis, negatively regulates light-dependent seed germination downstream of PIL5

Light absorbed by seed phytochromes of Arabidopsis thaliana modulates abscisic acid (ABA) and gibberellic acid (GA) signaling pathways at least partly via PHYTOCHROME-INTERACTING FACTOR3-LIKE5 (PIL5), a phytochrome-interacting basic helix-loop-helix transcription factor. Here, we report a new mutant, somnus (som), that germinates in darkness, independently of various light regimens. SOM encodes a nucleus-localized CCCH-type zinc finger protein. The som mutant has lower levels of ABA and elevated levels of GA due to expressional changes in ABA and GA metabolic genes. Unlike PIL5, however, SOM does not regulate the expression of GA-INSENSITIVE and REPRESSOR OF GA1 (RGA/RGA1), two DELLA genes encoding GA negative signaling components. Our in vivo analysis shows that PIL5 activates the expression of SOM by binding directly to its promoter, suggesting that PIL5 regulates ABA and GA metabolic genes partly through SOM. In agreement with these results, we also observed that the reduced germination frequency of a PIL5 overexpression line is rescued by the som mutation and that this rescue is accompanied by expressional changes in ABA and GA metabolic genes. Taken together, our results indicate that SOM is a component in the phytochrome signal transduction pathway that regulates hormone metabolic genes downstream of PIL5 during seed germination.

LZF1, a HY5-regulated transcriptional factor, functions in Arabidopsis de-etiolation

We surveyed differential gene expression patterns during early photomorphogenesis in both wild-type and mutant Arabidopsis defective in HY5, an influential positive regulator of the responses of gene expression to a light stimulus, to identify light-responsive genes whose expression was HY5 dependent. These gene-expression data identified light-regulated zinc finger protein 1 (LZF1), a gene encoding a previously uncharacterized C2C2-CO B-box transcriptional regulator. HY5 has positive trans-activating activity toward LZF1 and binding affinity to LZF1 promoter in vivo. HY5 is needed but not sufficient for the induction of LZF1 expression. Anthocyanin content is significantly diminished in lzf1 under far red, which is the most efficient light for the induction of LZF1. The expression of PAP1/MYB75 is elevated in plants overexpressing LZF1, which leads to the hyperaccumulation of anthocyanin in transgenic Arabidopsis. The transition from etioplast to chloroplast and the accumulation of chlorophyll were notably compromised in the lzf1 mutant. We provide molecular evidence that LZF1 influences chloroplast biogenesis and function via regulating genes encoding chloroplast proteins. In the absence of HY5, mutation of LZF1 leads to further reduced light sensitivity for light-regulated inhibition of hypocotyl elongation and anthocyanin and chlorophyll accumulation. Our data indicate that LZF1 is a positive regulator functioning in Arabidopsis de-etiolation.

Decoding of light signals by plant phytochromes and their interacting proteins

Phytochromes are red/far-red light photoreceptors that convert the information contained in external light into biological signals. The decoding process starts with the perception of red light, which occurs through photoisomerization of a chromophore located within the phytochrome, leading to structural changes that include the disruption of intramolecular interactions between the N- and C-terminal domains of the phytochrome. This disruption exposes surfaces required for interactions with other proteins. In contrast, the perception of far-red light reverses the photoisomerization, restores the intramolecular interaction, and closes the interacting surfaces. Light information represented by the concentration of opened interacting surfaces is converted into biological signals through the modulating activity of interacting proteins. This review summarizes plant phytochromes, phytochrome-interacting proteins, and signal transmission from phytochromes to their interacting proteins.

Vascular endothelial growth factor gene polymorphisms and risk of colorectal cancer

4123

Background: Angiogenesis is closely related to the development, growth, and metastasis of solid tumors, including colorectal cancer (CRC), and the vascular endothelial growth factor (VEGF) is known to be a potent pro-angiogenic factor. Accordingly, the present study was conducted to evaluate the potential association between two VEGF polymorphisms (+405G > C, and 936C > T) and the risk of CRC. Methods: The VEGF genotypes were determined using fresh colorectal tumor tissue from 477 patients with CRC who underwent surgical resection and peripheral blood lymphocytes from 413 healthy controls based on a polymerase chain reaction/denaturing high-performance liquid chromatography (PCR/DHPLC) assay. The incidence of genotypes and haplotypes of two VEGF polymorphisms was compared between the patients with CRC and the controls. Results: The distribution of genotypes and allele frequencies of the 936C > T polymorphism in the CRC group did not differ from those in the control group. However, compared with the combined GC and CC genotype, the GG genotype of +405G > C polymorphism was significantly associated with an increased risk of CRC [odds ratio (OR), 1.575; 95% confidence interval (CI), 1.178–2.104; P = 0.002]. In the haplotype analyses, haplotype +405G / 936C was also associated with a significantly increased risk of CRC (OR, 1.264; 95% CI, 1.043–1.531; P = 0.017), whereas haplotype +405C / 936C was associated with a decreased risk of CRC (OR, 0.818; 95% CI, 0.677–0.989; P = 0.038). None of the VEGF polymorphisms studied significantly influenced the clinical or pathologic features of CRC. Conclusions: These findings suggest that the VEGF +405G > C polymorphism may be associated with the risk of CRC in the Korean population.

No significant financial relationships to disclose.

Cyberknife stereotactic radiosurgery in patients with primary hepatocellular carcinoma

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Background: Conventional radiotherapy has historically played a limited role in the primary treatment of hepatocellular carcinoma (HCC). This study evaluated the effect of Cyberknife stereotactic radiosurgery (SRS) with for both for small primary non-resectable HCC, and for advanced HCC with portal vein tumor thrombosis (PVTT). Methods: From March 2004 to March 2005, thirty one patients with HCC were treated Cyberknife SRS was used for 32 lesions in patients with SRS for primary HCC. There was performed in 22 patients (23 lesions) with targeting to the primary HCC was treated (Group A), and in 9 patients with targeting to the PVTT was treated (Group B). The total SRS doses treated were 30–39 Gy (median, 36 Gy) to the 70–85%, 3 fractions and the target volume was of 3.6–57.3 cc (median, 25.2 cc). Results: The median follow up was 10.5 months. A complete response (CR) was achieved in 10 lesions, a partial response (PR) in 13 lesions, stable disease was noted in 6 lesions, and disease progression in 3 lesions. The response rate (CR+PR) was 71.9% (group A: 82.6%, group B: 44.4%). The level of serum alpha-fetoprotein after the treatment was decreased significantly in 17 patients (54.8%) (group A: 54.5%, group B: 55.5%). Complications were observed in 15 patients, among them, greater than grade 3 complication was observed in two patients of group A (gastric ulcer bleeding (1), liver necrosis (1)). Conclusions: These results suggest that Cyberknife SRS could be considered as an effective and safe treatment for primary HCC. For PVTT, Cyberknife SRS as the only curative tool, and produced acceptable local control in this study.

No significant financial relationships to disclose.

Vascular endothelial growth factor (VEGF) gene polymorphisms associated with prognosis for patients with colorectal cancer

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Background: Vascular endothelial growth factor (VEGF) or its family may be considered to play an important role in lymphangiogenesis and lymphatic tumor spread, thereby affecting prognosis of colorectal cancer. Accordingly, the present study analyzed VEGF gene polymorphisms and their impact on the prognosis for patients with colorectal cancer. Patients and Methods: Four hundred and sixty-five consecutive patients with surgically treated colorectal adenocarcinoma were enrolled in the present study. The genomic DNA was extracted from fresh colorectal tumor tissue and 3 VEGF (-2578C > A, -634G > C, and +936C > T) gene polymorphisms determined using a PCR/DHPLC (Polymerase chain reaction/Denaturing high-performance liquid chromatography) assay. Results: The median age of the patients was 64 years (range, 21–89), and 264 (56.7%) patients had colon cancer and 201 (48.2%) patients rectal cancer. Pathologic stages evaluable (n=464) after surgery were as follows: stage I (n=79, 17.0%), stage II (n=157, 33.8%), stage III (n=157, 33.8%), and stage IV (n=71, 15.3%). Multivariate survival analysis including stage, differentiation, and CEA level showed that survival for patients with the -634CC (overall survival [OS]: hazard ratio [HR]=0.175, P<0.001; progression-free survival [PFS]: HR=0.554, P=0.040) or GC genotype (OS: HR=0.158, P<0.001; PFS: HR=0.630, P=0.044) were better than for patients with the -634GG genotype, whereas the +936TT (OS: HR=65.959, P<0.001; PFS: HR=2.823, P=0.016) or CT genotype (OS: HR=16.116, P<0.001; PFS: HR=3.507, P<0.001) were associated with a worse survival compared to the CC genotype. In haplotype analysis, the -2578A/-634G/+936T haplotype exhibited a significantly worse survival when compared to the wild -2578C/-634G/+936C haplotype (OS: HR=4.670, P<0.001; PFS: HR=3.624, P<0.001). Conclusions: VEGF gene polymorphisms were found to be an independent prognostic marker for patients with colorectal cancer. Accordingly, the analysis of VEGF gene polymorphisms can help identify patient subgroups at high risk of a poor disease outcome.

No significant financial relationships to disclose.

Natural anticoagulants limit lipopolysaccharide-induced pulmonary coagulation but not inflammation

Pulmonary coagulopathy and hyperinflammation may contribute to an adverse outcome in sepsis. The present study determines the effects of natural inhibitors of coagulation on bronchoalveolar haemostasis and inflammation in a rat model of endotoxaemia. Male Sprague-Dawley rats were randomised to treatment with normal saline, recombinant human activated protein C (APC), plasma-derived antithrombin (AT), recombinant human tissue factor pathway inhibitor (TFPI), heparin or recombinant tissue plasminogen activator (tPA). Rats were intravenously injected with lipopolysaccharide (LPS), which induced a systemic inflammatory response and pulmonary inflammation. Blood and bronchoalveolar lavage were obtained at 4 and 16 h after LPS injection, and markers of coagulation and inflammation were measured. LPS injection caused an increase in the levels of thrombin-AT complexes, whereas plasminogen activator activity was attenuated, both systemically and within the bronchoalveolar compartment. Administration of APC, AT and TFPI significantly limited LPS-induced generation of thrombin-AT complexes in the lungs, and tPA stimulated pulmonary fibrinolytic activity. However, none of the agents had significant effects on the production of pulmonary cytokines, chemokines, neutrophil influx and myeloperoxidase activity. Natural inhibitors of coagulation prevent bronchoalveolar activation of coagulation, but do not induce major alterations of the pulmonary inflammatory response in rat endotoxaemia.