Small Molecule Probes of ABA Biosynthesis and Signaling

The phytohormone ABA mediates many physiological and developmental responses, and its key role in plant water relations has fueled efforts to improve crop water productivity by manipulating ABA responses. ABA's core signaling components are encoded by large gene families, which has hampered functional studies using classical genetic approaches due to redundancy. Chemical approaches can complement genetic approaches and have the advantage of delivering both biological probes and potential agrochemical leads; these benefits have spawned the discovery and design of new chemical modulators of ABA signaling and biosynthesis, which have contributed to the identification of ABA receptors and helped to define PYR1 and related subfamily III receptors as key cellular targets for chemically manipulating water productivity. In this review, we provide an overview of small molecules that have helped dissect both ABA signaling and metabolic pathways. We further discuss how the insights gleaned using ABA probe molecules might be translated to improvements in crop water productivity and future opportunities for development of small molecules that affect ABA metabolism and signaling.

A Highly Specific Genome-Wide Association Study Integrated with Transcriptome Data Reveals the Contribution of Copy Number Variations to Specialized Metabolites in Arabidopsis thaliana Accessions

Lineage-specific gene duplications contribute to a large variation in specialized metabolites among different plant species. There is also considerable variability in the specialized metabolites within a single plant species. However, it is unclear whether copy number variations (CNVs) derived from gene duplication events contribute to the diversity of specialized metabolites within species. We identified metabolome quantitative trait genes (mQTGs) associated with quantitative metabolite variations and examined the relationship between mQTGs and CNVs. We obtained 1,335 specialized metabolite signals from 53 worldwide A. thaliana accessions using liquid chromatography-quadrupole time-of-flight mass spectrometry. In this study, genes associated with specialized metabolites were inferred by either a generally authorized genome-wide association study (GWAS) approach or a novel analysis of the association between gene expression and metabolite accumulation. Genes qualified by both analyses are defined to be mQTGs. The integrated method enabled us to detect mQTGs with a low false positive rate (=5.71 × 10-4). We also identified 5,654 genes associated with 1,335 specialized metabolites. Of these genes, 4.4% were affected by CNVs, which was more than expected (χ2 test: P < 0.01). This result suggests that CNVs contribute to variations in specialized metabolites within a species. To assess the contribution of CNVs to adaptive evolution in A. thaliana, we examined the selective sweeps around the mQTGs. We observed that the mQTGs with CNVs tended to undergo selective sweeps. These observations imply that variations in specialized metabolites caused by CNVs contribute to the adaptive evolution of A. thaliana.

Conversion of carlactone to carlactonoic acid is a conserved function of MAX1 homologs in strigolactone biosynthesis

Strigolactones (SLs) are a class of plant hormones which regulate shoot branching and function as host recognition signals for symbionts and parasites in the rhizosphere. However, steps in SL biosynthesis after carlactone (CL) formation remain elusive. This study elucidated the common and diverse functions of MAX1 homologs which catalyze CL oxidation. We have reported previously that ArabidopsisMAX1 converts CL to carlactonoic acid (CLA), whereas a rice MAX1 homolog has been shown to catalyze the conversion of CL to 4-deoxyorobanchol (4DO). To determine which reaction is conserved in the plant kingdom, we investigated the enzymatic function of MAX1 homologs in Arabidopsis, rice, maize, tomato, poplar and Selaginella moellendorffii. The conversion of CL to CLA was found to be a common reaction catalyzed by MAX1 homologs, and MAX1s can be classified into three types: A1-type, converting CL to CLA; A2-type, converting CL to 4DO via CLA; and A3-type, converting CL to CLA and 4DO to orobanchol. CLA was detected in root exudates from poplar and Selaginella, but not ubiquitously in other plants examined in this study, suggesting its role as a species-specific signal in the rhizosphere. This study provides new insights into the roles of MAX1 in endogenous and rhizosphere signaling.

Structure-Based Chemical Design of Abscisic Acid Antagonists That Block PYL-PP2C Receptor Interactions

In Arabidopsis, signaling of the stress hormone abscisic acid (ABA) is mediated by PYR/PYL/RCAR receptors (PYLs), which bind to and inhibit group-A protein phosphatases 2C (PP2Cs), the negative regulators of ABA. X-ray structures of several PYL-ABA and PYL-ABA-PP2C complexes have revealed that a conserved tryptophan in PP2Cs is inserted into a small tunnel adjacent to the C4' of ABA in the PYL-ABA complex and plays a crucial role in the formation and stabilization of the PYL-ABA-PP2C complex. Here, 4'-modified ABA analogues were designed to prevent the insertion of the tryptophan into the tunnel adjacent to the C4' of ABA in these complexes. These analogues were predicted to block PYL-PP2C receptor interactions and thus block ABA signaling. To test this, 4'- O-phenylpropynyl ABA analogues were synthesized as novel PYL antagonists (PANs). Structural, thermodynamic, biochemical, and physiological studies demonstrated that PANs completely abolished ABA-induced PYL-PP2C interactions in vitro and suppressed stress-induced ABA responses in vivo more strongly than did 3'-hexylsulfanyl-ABA (AS6), a PYL antagonist we developed previously. The PANs and AS6 antagonized the effects of ABA to different degrees in different plants, suggesting that these PANs can function as chemical scalpels to dissect the complicated regulatory mechanism of ABA signaling in plants.

Gastric inhibitory polypeptide receptor antagonist, SKL-14959, suppressed body weight gain on diet-induced obesity mice

Objective

Gastric inhibitory polypeptide plays a role in glucose and lipid metabolism and is associated with obesity and insulin resistance. The objective of this study is to confirm the anti-obesity effects of the gastric inhibitory polypeptide receptor antagonist, SKL-14959, on diet-induced obesity mice.

Method

Diet-induced obesity mice at 20 weeks of age were administered with or without SKL-14959 for 96 d. Body weight and food intake were monitored throughout the experiment. Mice were sacrificed, and physiological and biochemical markers were measured, and then histochemical and gene expression analyses were also performed. In further studies, mice were orally gavaged with [14C]-oleic acid to investigate the excursion of digested lipids.

Results

SKL-14959 significantly suppressed weight gain without affecting food intake, decreased triacylglycerol contents in the liver and the muscle and the intensity stained with oil-red in the liver. It also improved plasma glutamic pyruvic transaminase and 3-hydroxybutyrate levels in addition to notably down-regulated relative gene expression of srebf1 and dgat1 in the liver despite not altering in the adipose tissue. Furthermore, SKL-14959 showed remarkable inhibition of lipid uptake in the adipose tissue after the oil challenge.

Conclusion

SKL-14959 inhibited lipids uptake and improved lipids metabolism, results in suppression of body-weight gain.

Efficient anchoring of alien chromosome segments introgressed into bread wheat by new Leymus racemosus genome-based markers

BACKGROUND

The tertiary gene pool of bread wheat, to which Leymus racemosus belongs, has remained underutilized due to the current limited genomic resources of the species that constitute it. Continuous enrichment of public databases with useful information regarding these species is, therefore, needed to provide insights on their genome structures and aid successful utilization of their genes to develop improved wheat cultivars for effective management of environmental stresses.

RESULTS

We generated de novo DNA and mRNA sequence information of L. racemosus and developed 110 polymorphic PCR-based markers from the data, and to complement the PCR markers, DArT-seq genotyping was applied to develop additional 9990 SNP markers. Approximately 52% of all the markers enabled us to clearly genotype 22 wheat-L. racemosus chromosome introgression lines, and L. racemosus chromosome-specific markers were highly efficient in detailed characterization of the translocation and recombination lines analyzed. A further analysis revealed remarkable transferability of the PCR markers to three other important Triticeae perennial species: L. mollis, Psathyrostachys huashanica and Elymus ciliaris, indicating their suitability for characterizing wheat-alien chromosome introgressions carrying chromosomes of these genomes.

CONCLUSION

The efficiency of the markers in characterizing wheat-L. racemosus chromosome introgression lines proves their reliability, and their high transferability further broadens their scope of application. This is the first report on sequencing and development of markers from L. racemosus genome and the application of DArT-seq to develop markers from a perennial wild relative of wheat, marking a paradigm shift from the seeming concentration of the technology on cultivated species. Integration of these markers with appropriate cytogenetic methods would accelerate development and characterization of wheat-alien chromosome introgression lines.

Evaluation of the Function of Primary Human Hepatocytes Co-Cultured with the Human Hepatic Stellate Cell (HSC) Line LI90

Most bioartificial liver devices utilise primary hepatocytes alone although some have considered the use of non parenchymal cells in addition. However the effects of co-culture of human hepatocytes with different sinusoidal cell types has not been fully investigated. In this study we have examined the influence of co-culturing primary human hepatocytes with the human hepatic stellate cell (HSC) line, LI90. Cultures were monitored by light microscopy and on days 4, 8 and 14 urea synthesis and cytochrome P450 activity were measured. Morphologically LI90 cells proliferated to fill spaces between and into adjacent islands of hepatocytes. On day 14 cytochrome P450 activity in co-culture was significantly improved compared to hepatocytes cultured alone. By contrast, urea synthesis in hepatocytes was unaffected by single or co-culture. Therefore it can be concluded that a combination of primary human hepatocytes with LI90 cells is beneficial for growth and some stability of hepatocytes and may therefore be appropriate for seeding bioartificial liver devices.

High IL-1α Production Was Induced in the WBN/Kob-Leprfa Type 2 Diabetes Mellitus Rat Model and Inhibited by Syphacia Muris Infection

The novel WBN/Kob-Lepr^fa (fa/fa) congenic rat strain is considered a useful rat model of type 2 diabetes mellitus (T2DM). Accumulating findings suggest that low-grade inflammation is a causative factor in T2DM and that circulating levels of inflammatory cytokines are associated with insulin resistance. However, inflammatory cytokine profiles and their correlations with T2DM development/ progression in fa/fa rats have not been studied. In this study, we found that the fa/fa rats had considerably high plasma levels of interleukin (IL)-1α. Abundant cecal IL-1α mRNA expression and cecal inflammation with infiltrating IL-1α-producing macrophages was observed in fa/fa rats. Bone marrow derived macrophages from fa/fa rats expressed high levels of IL-1α upon lipopolysaccharide stimulation. Furthermore, Syphacia muris infection, which delays the onset of T2DM, reduced both plasma and cecal IL-1α levels in fa/fa rats. These results suggest that macrophage infiltration and IL-1α secretion comprise an important part of T2DM development and that S. muris infection inhibits pro-inflammatory cytokine expression in fa/fa rats.

Titanium Fiber Plates for Bone Tissue Repair

Titanium plates are widely used in clinical settings because of their high bone affinity. However, owing to their high elastic modulus, these plates are not suitable for bone repair since their proximity to the bone surface for prolonged periods can cause stress shielding, leading to bone embrittlement. In contrast, titanium fiber plates prepared by molding titanium fibers into plates by simultaneously applying compression and shear stress at normal room temperature can have an elastic modulus similar to that of bone cortex, and stress shielding will not occur even when the plate lies flush against the bone's surface. Titanium fibers can form a porous structure suitable for cell adhesion and as a bone repair scaffold. A titanium fiber plate is combined with osteoblasts and shown that the titanium fiber plate is better able to facilitate bone tissue repair than the conventional titanium plate when implanted in rat bone defects. Capable of being used in close contact with bone for a long time, and even capable of promoting bone repair, titanium fiber plates have a wide range of applications, and are expected to make great contributions to clinical management of increasing bone diseases, including bone fracture repair and bone regenerative medicine.

Chemical Control of ABA Receptors to Enable Plant Protection Against Water Stress

This chapter describes procedures to find small molecules that bind to abscisic acid (ABA) receptors and improve plant tolerance to water stress. Abscisic acid promotes the interaction between ABA receptors and protein phosphatase 2Cs (PP2Cs), which are negative regulators of ABA signaling. This receptor-mediated ABA-dependent inhibition of PP2C activity is required for ABA action in vivo. ABA agonists can be identified by high-throughput screening for molecules that promote agonist-induced ABA receptor-PP2C interactions using yeast two-hybrid assays. In addition to in vitro assays, an in vivo test to evaluate ABA agonist activity has been devised in which an ABA-inducible GUS reporter strain is used to evaluate the effect of each ABA agonist. The effects of ABA agonists can also be determined using thermal imaging analyses and a water loss assay of stomata. Finally, the ability of each ABA agonist to confer drought stress tolerance upon plants grown in soil is determined. These methods can be used to identify various ABA agonists that protect plants against water stress.

Initial clinical presentation of single soft tissue metastasis of medullary thyroid carcinoma without primary tumor in the thyroid gland

Background

Single soft tissue metastasis of medullary thyroid carcinoma is extremely rare. In addition, several occult medullary thyroid carcinomas with distant metastasis were reported, but undetectable primary lesion at diagnosis was also extremely rare.

Case presentation

A 74-year-old man was admitted to our hospital because of a painful nodule in his left buttock for over 1 year. Needle biopsy was performed, and the histological findings revealed adenocarcinoma positive for thyroid transcription factor-1. No evidence of a primary tumor, including the lung and thyroid gland, could be found elsewhere despite detailed examinations, including thyroid echography, chest computed tomography, and fluorodeoxyglucose-positron emission tomography. The soft tissue tumor was resected with a wide margin. Immunohistochemical analysis showed the tumor cells to be positive for cytokeratin-AE1/3, cytokeratin 7, synaptophysin, chromogranin A, calcitonin, and carcinoembryonic antigen, but negative for cytokeratin 20, Napsin A, Pax8, and p40, resulting in a diagnosis of metastasis of medullary thyroid carcinoma.

Conclusion

Initial presentation with a single metastasis to soft tissue and undetectable primary tumor in the thyroid gland is an extremely rare clinical manifestation in patients with medullary thyroid carcinoma.

Massive trapezial metastasis from gastric adenocarcinoma resected and reconstructed with a vascularized scapular bone graft: A case report

RATIONALE

Isolated metastasis to the hand bones is very rare. Only seven cases of metastasis to the trapezium have been reported. To the best of our knowledge, this is the first report of a single metastasis to the trapezium from a gastric adenocarcinoma.

PATIENT CONCERNS

A 62-year-old man presented with pain and massive swelling in the right carpometacarpal joint of the thumb.

DIAGNOSES

The patient was diagnosed with trapezial metastasis of advanced gastric adenocarcinoma.

INTERVENTIONS

The patient underwent systemic chemotherapy with cisplatin and S-1, radiotherapy to the metastatic bone, and treatment with denosumab. One year later, the huge metastatic tumor was resected, and the hand was reconstructed using vascularized scapular bone.

OUTCOMES

Eighteen months postoperatively, the patient was satisfied with the appearance of the reconstructed hand and was able to use his right thumb in activities of daily living.

LESSONS

Although rare, metastasis to the trapezium should be considered in patients with persistent and progressive thumb CMC joint pain.

Prediction of muscle strength and postoperative function after knee flexor muscle resection for soft tissue sarcoma of the lower limbs

INTRODUCTION

Oncological margins and prognosis are the most important factors for operative planning of soft tissue sarcomas, but prediction of postoperative function is also necessary. The purpose of this study was to predict the knee flexion strength and postoperative function after knee flexor muscle resection for soft tissue sarcoma of the lower limbs.

MATERIALS AND METHODS

Seventeen patients underwent knee flexor muscle resection for soft tissue sarcoma of the lower limbs between 1991 and 2015. The type of resected muscles was surveyed, knee flexion strength (ratio of affected to unaffected side) was evaluated using the Biodex System isokinetic dynamometer, and differences between the type of resected muscles were examined. The Musculoskeletal Tumor Society (MSTS) score, Toronto Extremity Salvage Score (TESS), European Quality of Life-5 Dimensions (EQ-5D), and Short Form 8 (SF-8) were used to assess postoperative function and examine correlations with flexion strength. The cutoff value for flexion strength to predict good postoperative results was calculated by a receiver operating characteristic (ROC) curve and Fisher's exact test.

RESULTS

Median flexion strength decreased in the resection of sartorius (97.8%), gracilis (95.4%), gastrocnemius (85.2%; interquartile range (IQR): 85.0-86.2), medial hamstrings (semimembranosus and semitendinosus, 76.2%; IQR: 73.3-78.0), lateral hamstrings (long and short head of biceps femoris, 66.1%; IQR: 65.9-70.4), and bilateral hamstrings (27.3%; IQR: 26.6-31.5). A significant difference was observed between lateral and bilateral hamstrings resection (P=0.049). Flexion strength was associated with lower functional scales (MSTS score, P=0.021; TESS, P=0.008; EQ-5D, P=0.034). Satisfactory function was obtained at a flexion strength cutoff value of 65.7%, and strength remained above the cutoff value up to unilateral hamstrings resection.

DISCUSSION

Greater knee flexor muscles resection can result in functional deficits that are associated with decreased flexion strength. If continuity of unilateral hamstrings is maintained, good postoperative results can be expected.

LEVEL OF EVIDENCE

IV, retrospective study.

Gene Expression Profiling of Peripheral Blood From Kidney Transplant Recipients for the Early Detection of Digestive System Cancer

BACKGROUND

Kidney transplant recipients are at increased risk of developing cancer in comparison with the general population. To effectively manage post-transplantation malignancies, it is essential to proactively monitor patients. A long-term intensive screening program was associated with a reduced incidence of cancer after transplantation. This study evaluated the usefulness of the gene expression profiling of peripheral blood samples obtained from kidney transplant patients and adopted a screening test for detecting cancer of the digestive system (gastric, colon, pancreas, and biliary tract).

STUDY DESIGN AND METHOD

Nineteen patients were included in this study and a total of 53 gene expression screening tests were performed. The gene expression profiles of blood-delivered total RNA and whole genome human gene expression profiles were obtained. We investigated the expression levels of 2665 genes associated with digestive cancers and counted the number of genes in which expression was altered. A hierarchical clustering analysis was also performed. The final prediction of the cancer possibility was determined according to an algorithm.

RESULTS

The number of genes in which expression was altered was significantly increased in the kidney transplant recipients in comparison with the general population (1091 ± 63 vs 823 ± 94; P = .0024). The number of genes with altered expression decreased after the induction of mechanistic target of rapamycin (mTOR) inhibitor (1484 ± 227 vs 883 ± 154; P = .0439). No cases of possible digestive cancer were detected in this study period.

CONCLUSION

The gene expression profiling of peripheral blood samples may be a useful and noninvasive diagnostic tool that allows for the early detection of cancer of the digestive system.