The transmembrane domain of the rice small protein OsS1Fa1 is responsible for subcellular localization and drought tolerance

OsS1Fa1, a homologue of spinach S1Fa, is a small protein in rice that contains four distinct conserved motifs and participates in drought tolerance. However, the biological functions of these conserved motifs have not been characterized to date. Therefore, we investigated the roles of these conserved domains in the localization and cellular function of OsS1Fa1. We analysed the subcellular localization of OsS1Fa1 using confocal laser scanning microscopy (CLSM), following particle bombardment and bacterial infiltration. An E. coli in vivo reconstituted sumoylation assay was conducted to investigate sumoylation of OsS1Fa1. We characterized the function of the transmembrane domain of OsS1Fa1 in drought tolerance using transgenic Arabidopsis plants. Fluorescence analysis showed that OsS1Fa1 localized to the nuclear and cytoplasmic membranes. Mutation and cell fractionation analyses revealed that the membrane localization domain determined the subcellular localization of OsS1Fa1. The rice homologue OsS1Fa2 and Arabidopsis orthologs AtS1Fa1, AtS1Fa2, and AtS1Fa3 also exhibited similar localization patterns as OsS1Fa1. Sumoylation analysis demonstrated that OsS1Fa1 was conjugated with the small ubiquitin-related modifier (SUMO). Transgenic analysis showed that overexpression of OsS1Fa1(TMm1), a mutant form of the transmembrane domain of OsS1Fa1, in Arabidopsis did not enhance drought stress tolerance, whereas OsS1Fa1 overexpression improved the drought tolerance of transgenic Arabidopsis. Our data indicate that rice and Arabidopsis S1Fa1 proteins localize in the nuclear and cytoplasmic membranes, and that transmembrane domain determines subcellular localization and plays an important role in drought stress tolerance.

Genetic Control of Tolerance to Drought Stress in Wild Soybean (Glycine soja) at the Vegetative and the Germination Stages

Drought stress, which is becoming more prevalent due to climate change, is a significant abiotic factor that adversely impacts crop production and yield stability. Cultivated soybean (Glycine max), a versatile crop for humans and animals, exhibits sensitivity to drought, resulting in reduced growth and development under drought conditions. However, few genetic studies have assessed wild soybean's (Glycine soja) response to drought stress. In this work, we conducted a genome-wide association study (GWAS) and analysis of wild soybean accessions to identify loci responsible for drought tolerance at the vegetative (n = 187) and the germination stages (n = 135) using the available resequencing data. The GWAS analysis of the leaf wilting score (LWS) identified eight single-nucleotide polymorphisms (SNPs) on chromosomes 10, 11, and 19. Of these, wild soybeans with both SNPs on chromosomes 10 (adenine) and 11 (thymine) produced lower LWS, indicating that these SNPs have an important role in the genetic effect on LWS for drought tolerance at the vegetative stage. At the germination stage, nine SNPs associated with five phenotypic measurements were identified on chromosomes 6, 9, 10, 13, 16, and 17, and the genomic regions identified at the germination stage were different from those identified for the LWS, supporting our previous finding that there may not be a robust correlation between the genes influencing phenotypes at the germination and vegetative stages. This research will benefit marker-assisted breeding programs aimed at enhancing drought tolerance in soybeans.

E3 SUMO ligase SIZ1 splicing variants localize and function according to external conditions

SIZ1 (SAP and MIZ1) is a member of the Siz/PIAS-type RING family of E3 SUMO (small ubiquitin-related modifier) ligases that play key roles in growth, development, and stress responses in plant and animal systems. Nevertheless, splicing variants of SIZ1 have not yet been characterized. Here, we identified four splicing variants of Arabidopsis (Arabidopsis thaliana) SIZ1, which encode three different protein isoforms. The SIZ1 gene encodes an 873-amino acid (aa) protein. Among the four SIZ1 splicing variants (SSVs), SSV1 and SSV4 encode identical 885 aa proteins; SSV2 encodes an 832 aa protein; and SSV3 encodes an 884 aa protein. SSV2 mainly localized to the plasma membrane, whereas SIZ1, SSV1/SSV4, and SSV3 localized to the nucleus. Interestingly, SIZ1 and all SSVs exhibited similar E3 SUMO ligase activities and preferred SUMO1 and SUMO2 for their E3 ligase activity. Transcript levels of SSV2 were substantially increased by heat treatment, while those of SSV1, SSV3, and SSV4 transcripts were unaffected by various abiotic stresses. SSV2 directly interacted with and sumoylated cyclic nucleotide-gated ion channel 6 (CNGC6), a positive thermotolerance regulator, enhancing the stability of CNGC6. Notably, transgenic siz1-2 mutants expressing SSV2 exhibited greater heat stress tolerance than wild-type plants, whereas those expressing SIZ1 were sensitive to heat stress. Furthermore, transgenic cngc6 plants overaccumulating a mutated mCNGC6 protein (K347R, a mutation at the sumoylation site) were sensitive to heat stress, similar to the cngc6 mutants, while transgenic cngc6 plants overaccumulating CNGC6 exhibited restored heat tolerance. Together, we propose that alternative splicing is an important mechanism that regulates the function of SSVs during development or under adverse conditions, including heat stress.

Arabidopsis COP1 guides stomatal response in guard cells through pH regulation

Plants rely on precise regulation of their stomatal pores to effectively carry out photosynthesis while managing water status. The Arabidopsis CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), a critical light signaling repressor, is known to repress stomatal opening, but the exact cellular mechanisms remain unknown. Here, we show that COP1 regulates stomatal movement by controlling the pH levels in guard cells. cop1-4 mutants have larger stomatal apertures and disrupted pH dynamics within guard cells, characterized by increased vacuolar and cytosolic pH and reduced apoplastic pH, leading to abnormal stomatal responses. The altered pH profiles are attributed to the increased plasma membrane (PM) H+-ATPase activity of cop1-4 mutants. Moreover, cop1-4 mutants resist to growth defect caused by alkali stress posed on roots. Overall, our study highlights the crucial role of COP1 in maintaining pH homeostasis of guard cells by regulating PM H+-ATPase activity, and demonstrates how proton movement affects stomatal movement and plant growth.

Arabidopsis retromer subunit AtVPS29 is involved in SLY1-mediated gibberellin signaling

KEY MESSAGE

Retromer protein AtVPS29 upregulates the SLY1 protein and downregulates the RGA protein, positively stimulating the development of the root meristematic zone, which indicates an important role of AtVPS29 in gibberellin signaling. In plants, the large retromer complex is known to play roles in multiple development processes, including cell polarity, programmed cell death, and root hair growth in Arabidopsis. However, many of its roles in plant development remain unknown. Here, we show that Arabidopsis trimeric retromer protein AtVPS29 (vacuolar protein sorting 29) modulates gibberellin signaling. The SLEEPY1 (SLY1) protein, known as a positive regulator of gibberellic acid (GA) signaling, exhibited lower abundance in vps29-3 mutants compared to wild-type (WT) plants. Conversely, the DELLA repressor protein, targeted by the E3 ubiquitin ligase SCF (Skp, Cullin, F-box) complex and acting as a negative regulator of GA signaling, showed increased abundance in vps29-3 mutants compared to WT. The vps29-3 mutants exhibited decreased sensitivity to exogenous GA supply in contrast to WT, despite an upregulation in the expression of GA receptor genes within the vps29-3 mutants. In addition, the expression of the GA synthesis genes was downregulated in vps29-3 mutants, implying that the loss of AtVPS29 causes the downregulation of GA synthesis and signaling. Furthermore, vps29-3 mutants exhibited a reduced meristematic zone accompanied by a decreased cell number. Together, these data indicate that AtVPS29 positively regulates SLY1-mediated GA signaling and plant growth.

COP1 controls salt stress tolerance by modulating sucrose content

The E3 ubiquitin ligase Constitutive Photomorphogenic 1 (COP1) plays evolutionarily conserved and divergent roles. In plants, COP1 regulates a large number of developmental processes including photomorphogenesis, seedling emergence, and gravitropism. Nevertheless, its function in abiotic stress tolerance remains largely unknown. Here, we demonstrate the role of COP1 in salt stress tolerance in Arabidopsis thaliana. In soil, cop1-4 and cop1-6 mutants were more tolerant to high salinity than wild-type (WT) plants during vegetative growth. However, in high salt-containing Murashige and Skoog (MS) medium, cop1-4 and cop1-6 seedlings exhibited significantly impaired growth compared with WT plants. Notably, cop1-4 and cop1-6 seedlings recovered their growth to the WT level upon exogenous sucrose treatment even under high salinity conditions. Compared with WT plants, the sucrose content of cop1-4 mutants was much higher at the vegetative growth stage but similar at the seedling stage. Upon exogenous sucrose supply, root elongation was significantly stimulated in cop1-4 seedlings but only slightly stimulated in WT plants. Thus, no significant difference was observed in root length between the two genotypes. Altogether, our data indicate that cop1 mutants are more tolerant to salt stress than WT plants, and the salt tolerance of cop1 mutants is correlated with their sucrose content.

COP1 mutation causes low leaf temperature under various abiotic stresses in Arabidopsis thaliana

Stomata are microscopic pores on epidermal cells of leaves and stems that regulate water loss and gas exchange between the plant and its environment. Constitutive photomorphogenic 1 (COP1) is an E3 ubiquitin ligase that is involved in plant growth and development and multiple abiotic stress responses by regulating the stability of various target proteins. However, little is known about how COP1 controls stomatal aperture and leaf temperature under various environmental conditions. Here, we show that COP1 participates in leaf temperature and stomatal closure regulation under normal and stress conditions in Arabidopsis. Leaf temperature of cop1 mutants was relatively lower than that of wild type (WT) under drought, salt, and heat stress and after abscisic acid (ABA), CaCl2, and H2O2 treatments. However, leaf temperature was generally higher in both WT and cop1 mutants after abiotic stress and chemical treatment than that of untreated WT and cop1 mutants. Stomatal aperture was wider in cop1 mutants than that in WT under all conditions tested, although the extent of stomatal closure varied between WT and cop1 mutants. Under dark conditions, leaf temperature was also lower in cop1 mutants than that in WT. Expression of the genes encoding ABA receptors, ABA biosynthesis proteins, positive regulators of stomatal closure and heat tolerance, and ABA-responsive proteins was lower in cop1 mutants that that in WT. In addition, expression of respiration-related genes was lower in cop1 mutants that that in WT. Taken together, the data provide evidence that mutations in COP1 lead to wider stomatal aperture and higher leaf temperature under normal and stress conditions, indicating that leaf temperature is highly correlated with stomatal aperture.

Intronic long noncoding RNA, RICE FLOWERING ASSOCIATED (RIFLA), regulates OsMADS56-mediated flowering in rice

Long noncoding RNAs (lncRNAs) are known to play important roles in several plant processes such as flowering, organ development and stress response. However, studies exploring the diversity and complexity of lncRNAs and their mechanism of action in plants are far fewer that those in animals. Here, we show that an intronic lncRNA in rice (Oryza sativa L.), RICE FLOWERING ASSOCIATED (RIFLA), is required for the inhibition of OsMADS56 expression. RIFLA is produced from the first intron of the OsMADS56 gene. Overexpression of RIFLA in rice repressed OsMADS56 expression but activated the expression of flowering inducers Hd3a and RFT1. Additionally, RIFLA-overexpressing transgenic rice plants flowered earlier than the wild type. Under normal conditions, the transcript level of the rice enhancer of zeste gene OsiEZ1, a homolog of Arabidopsis histone H3K27-specific methyltransferase genes SWINGER (SWN) and CURLY LEAF (CLF), was as low as that of RIFLA, whereas the transcript level of OsMADS56 was relatively high. In the osiez1 mutant, OsMADS56 expression was upregulated, whereas RIFLA expression was downregulated. Additionally, RIFLA formed a complex with OsiEZ1. Together, these results suggest that the floral repressor activity of OsMADS56 is epigenetically regulated by RIFLA and OsiEZ1.

A mutation in the pPLA-IIα gene encoding PATATIN-RELATED PHOSPHOLIPASE a causes late flowering in Arabidopsis

Arabidopsis PATATIN-RELATED PHOSPHOLIPASE 2A (pPLA-IIα) participates in the responses to various growth conditions. The factors affecting pPLA-IIα gene expression and pPLA-IIα protein activity for gycerolipids have been studied thoroughly, but the role of pPLA-IIα during the reproductive phase remains unclear. The effect of pPLA-IIα on flowering time was therefore investigated. ppla-iiα mutants flowered later than wild-type plants under long day conditions. Expression of the floral stimulators FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) was downregulated in ppla-iiα mutants compared with their expression in wild-type plants, but expression of the floral repressor FLOWERING LOCUS C (FLC) was upregulated. In addition, expression levels of COLDAIR, a long intronic noncoding RNA, decreased in ppla-iiα mutants. Taken together, these data indicate that pPLA-IIα acts as a positive regulator of flowering time through repression of FLC expression.

Overexpression of Rice OsS1Fa1 Gene Confers Drought Tolerance in Arabidopsis

Small peptides and proteins play critical regulatory roles in plant development and environmental stress responses; however, only a few of these molecules have been identified and characterized to date because of their poor annotation and other experimental challenges. Here, we present that rice (Oryza sativa L.) OsS1Fa1, a small 76-amino acid protein, confers drought stress tolerance in Arabidopsis thaliana. OsS1Fa1 was highly expressed in leaf, culm, and root tissues of rice seedlings during vegetative growth and was significantly induced under drought stress. OsS1Fa1 overexpression in Arabidopsis induced the expression of selected drought-responsive genes and enhanced the survival rate of transgenic lines under drought. The proteasome inhibitor MG132 protected the OsS1Fa1 protein from degradation. Together, our data indicate that the small protein OsS1Fa1 is induced by drought and is post-translationally regulated, and the ectopic expression of OsS1Fa1 protects plants from drought stress.

Ammonium-mediated reduction in salicylic acid content and recovery of plant growth in Arabidopsis siz1 mutants is modulated by NDR1 and NPR1

The siz1 mutants exhibit high SA accumulation and consequently severe dwarfism. Although siz1 mutants exhibit growth recovery upon exogenous ammonium supply, the underlying mechanism remains unknown. Here, we investigated the effect of ammonium on SA level and plant growth in SA-accumulating mutants. The growth of siz1-2 and siz1-3 mutants was recovered to wild-type (WT) levels upon exogenous ammonium supply, but that of siz1-3 ndr1 (non-race-specific disease resistance 1) and siz1-3 npr1 (non-expressor of pathogenesis related gene 1) double mutants was unaffected. The SA level was decreased by exogenous ammonium application in siz1-3 ndr1, siz1-3 npr1, and siz1-3 mutants. The level of nitrate reductase (NR) was almost the same in all genotypes (WT, siz1-3, ndr1, npr1, siz1-3 ndr1, and siz1-3 npr1), regardless of the ammonium treatment, suggesting that exogenous ammonium supply to ndr1 siz1-3 and npr1 siz1-3 double mutants does not have any effect on their growth and NR levels, but decreases the SA level. Taken together, these results indicate that ammonium acts as a signaling molecule to regulate the SA amount, and NDR1 and NPR1 play a positive role in the ammonium-mediated growth recovery of siz1 mutants.

Mutation of the OsGlyRS3 gene affects heading date in rice

Aminoacyl-tRNA synthetases play a critical role in protein synthesis by catalyzing the covalent attachment of amino acids to their cognate tRNAs. However, the role of aminoacyl-tRNA synthetases in the transition from vegetative to reproductive growth in plants remains poorly understood. In this study, a rice (Oryza sativa) glycyl-tRNA synthetase 3, OsGlyRS3, was found to impact heading date in rice. Flowering in osglyrs3, a mutant line containing a T-DNA insertion in OsGlyRS3, was advanced by approximately 2 weeks compared to wild type. Expression analysis of flowering regulator genes showed that transcript levels of Heading date 1 (Hd1), Heading date 3a (Hd3a), and OsMADS51 were elevated in osglyrs3. These data indicate that the loss of OsGlyRS3 activity induces the expression of flowering-activating genes, resulting in early flowering.

Changes of Neurotransmitters in Youth with Internet and Smartphone Addiction: A Comparison with Healthy Controls and Changes after Cognitive Behavioral Therapy

BACKGROUND AND PURPOSE

Neurotransmitter changes in youth addicted to the Internet and smartphone were compared with normal controls and in subjects after cognitive behavioral therapy. In addition, the correlations between neurotransmitters and affective factors were investigated.

MATERIALS AND METHODS

Nineteen young people with Internet and smartphone addiction and 19 sex- and age-matched healthy controls (male/female ratio, 9:10; mean age, 15.47 ± 3.06 years) were included. Twelve teenagers with Internet and smartphone addiction (male/female ratio, 8:4; mean age, 14.99 ± 1.95 years) participated in 9 weeks of cognitive behavioral therapy. Meshcher-Garwood point-resolved spectroscopy was used to measure γ-aminobutyric acid and Glx levels in the anterior cingulate cortex. The γ-aminobutyric acid and Glx levels in the addicted group were compared with those in controls and after cognitive behavioral therapy. The γ-aminobutyric acid and Glx levels correlated with clinical scales of Internet and smartphone addiction, impulsiveness, depression, anxiety, insomnia, and sleep quality.

RESULTS

Brain parenchymal and gray matter volume-adjusted γ-aminobutyric acid-to-creatine ratios were higher in subjects with Internet and smartphone addiction (P = .028 and .016). After therapy, brain parenchymal- and gray matter volume-adjusted γ-aminobutyric acid-to-creatine ratios were decreased (P = .034 and .026). The Glx level was not statistically significant in subjects with Internet and smartphone addiction compared with controls and posttherapy status. Brain parenchymal- and gray matter volume-adjusted γ-aminobutyric acid-to-creatine ratios correlated with clinical scales of Internet and smartphone addictions, depression, and anxiety. Glx/Cr was negatively correlated with insomnia and sleep quality scales.

CONCLUSIONS

The high γ-aminobutyric acid levels and disrupted balance of γ-aminobutyric acid-to-Glx including glutamate in the anterior cingulate cortex may contribute to understanding the pathophysiology and treatment of Internet and smartphone addiction and associated comorbidities.

A P3A-Type ATPase and an R2R3-MYB Transcription Factor Are Involved in Vacuolar Acidification and Flower Coloration in Soybean

The determination of flower color mainly depends on the anthocyanin biosynthesis pathway and vacuolar pH; however, unlike the former, the mechanism of vacuolar acidification in soybean remains uncharacterized at the molecular level. To investigate this mechanism, we isolated four recessive purple-blue EMS-induced flower mutants from the purple flower soybean cultivar, Pungsannamul. The petals of all the mutants had increased pH compared with those of wild Pungsannamul. One of the mutants had a single nucleotide substitution in GmPH4, a regulator gene encoding an MYB transcription factor, and the substitution resulted in a premature stop codon in its first exon. The other three mutants had nucleotide substitutions in GmPH5, a single new gene that we identified by physical mapping. It corresponds to Glyma.03G262600 in chromosome 3 and encodes a proton pump that belongs to the P_3A-ATPase family. The substitutions resulted in a premature stop codon, which may be a defect in the ATP-binding capacity of GmPH5 and possibly a catalytic inefficiency of GmPH5. The result is consistent with their genetic recessiveness as well as the high pH of mutant petals, suggesting that GmPH5 is directly involved in vacuolar acidification. We also found that the expression of GmPH5 and several putative "acidifying" genes in the gmph4 mutant was remarkably reduced, indicating that GmPH4 may regulate the genes involved in determining the vacuolar pH of soybean petals.

P2497Exercise training could reduce inflammatory activity of visceral adipose tissue in overweight women

Objectives

Visceral adipose tissue (VAT) plays pivotal roles for an increased risk of cardiometabolic disease through triggering inflammatory process. This prospective study aimed to evaluate whether the exercise training could reduce inflammatory activity of VAT assessed by 18F-fluorodeoxyglucoase (FDG) positron emission tomography-computerized tomography (PET/CT).

Methods

Twenty-three overweight women who participated in exercise training program were included. Exercise training program was composed of aerobic exercise (45 min/session, 300 Kcal/day) and muscle strength training (20 min/session, 100 Kcal/day) 5 times per week for 3 months. They underwent F-18 FDG PET/CT before starting exercise program (baseline) and after completion of 3 months exercise program. Anthropometric data, clinical laboratory data, VAT area, and maximum standardized uptake value (SUVmax) of VAT were compared between baseline and after completion of the total exercise program.

Results

Baseline VAT SUVmax showed significant correlation with body weight, body mass index (BMI), waist circumference, and hip circumference. VAT SUVmax was significantly reduced by exercise training program. Exercise training program also reduced body weight, BMI, waist circumference, hip circumference, VAT area, subcutaneous adipose tissue area and blood pressure. The change of VAT SUVmax was significantly higher than the change of VAT area.

Conclusions

Exercise training could reduce the inflammatory activity of VAT assessed by F-18 FDG PET/CT. Thus, exercise would be a promising non-pharmacological strategy to reduce inflammatory activity of VAT. Furthermore, F-18 FDG PET/CT could be useful to evaluate the effect of therapeutic intervention targeted to inflammatory VAT activity.

P1249Prognostic impact of sarcopenia on major adverse cardiovascular outcomes in coronary artery disease patients undergoing successful percutaneous coronary intervention

Background

Sarcopenia is an emerging marker of frailty. Its prognostic impact on atherosclerotic cardiovascular disease (ASCVD) requires further investigation.

Purpose

We investigated the long-term prognostic impact of computed tomography (CT)-determined sarcopenia in patients with coronary artery disease (CAD).

Methods

Total 475 CAD patients those who underwent successful percutaneous coronary intervention (PCI) and performed CT scan within 30 days of PCI were enrolled. The cross-sectional area of skeletal muscle at the first lumbar vertebra (L1) level was measured. Sarcopenia was defined as L1 skeletal muscle index of less than 34.60 cm2/m2 for men and of less than 25.90 cm2/m2 for women. Primary outcome was 3-year all-cause mortality and secondary outcome was 3-year major adverse cardiovascular event (MACE), a composite of all-cause mortality, any myocardial infarction, and repeat revascularization.

Results

Sarcopenia was present in 214 (45.1%) of 475 patients. The incidence of 3-year all-cause mortality and MACE was significantly higher in patients with sarcopenia than in those without sarcopenia (17.7% vs. 5.7%, p<0.001; and 35.0% vs. 11.2%, p<0.001, respectively). In the fully adjusted multivariable analysis, sarcopenia was an independent predictor of higher risk of 3-year all-cause mortality (odds ratio [OR]: 2.98; 95% confidence interval [CI]: 1.35 to 6.58, p=0.007) and MACE (OR: 4.39; 95% CI: 2.49 to 7.73, p<0.001). The results were consistent after propensity-score matched analysis with 100 pairs of study population (C-statistics = 0.868).

Kaplan–Meier analysis of 3-year outcomes Overall population PSM population Sarcopenia (n=214) No sarcopenia (n=261) Log-rank p-value Sarcopenia (n=100) No sarcopenia (n=100) Log-rank p-value All-cause mortality 36 (17.7) 14 (5.7) <0.001 19 (20.0) 7 (7.7) 0.013 Non-fatal MI 12 (6.6) 5 (2.0) 0.021 6 (7.0) 2 (2.3) 0.134 Repeat revascularization 32 (20.3) 14 (6.2) <0.001 17 (23.3) 8 (8.0) 0.027 Total MACEs 68 (35.0) 27 (11.2) <0.001 36 (39.3) 14 (15.4) 0.001 Data are expressed as n (%). MACE = major adverse cardiovascular event; MI = myocardial infarction; PSM = propensity-score matched.

Clinical impact of sarcopenia on CAD

Conclusion

Sarcopenia is a useful predictor of adverse clinical outcomes in patients with CAD undergoing PCI. CT-determined sarcopenia may further aid in risk stratification and decision-making for patients with established ASCVD.

Acknowledgement/Funding

National Research Foundation of Korea (NRF-2016R1A2B3013825), Ministry of Future Creation and Science of Korea (2018K000255)

P4339Reference values for cardiorespiratory fitness in healthy Koreans: compared to western nations and nomogram

Introduction

Cardiorespiratory Fitness (CRF), defined as the integrated ability to properly oxygenate skeletal muscles during physical activity, is associated with a high risk of cardiovascular disease and all-cause mortality. The reference range for CRF may differ among nations, with Asians under-represented in previous data.

Purpose

In this study, we sought to establish reference values of CRF for Asians using a recent Korean cohort.

Methods

We analyzed 2646 healthy Korean adults recently enrolled in the Korea Institute of Sports Science Fitness Standards (KISS FitS) project with estimated maximal oxygen uptake (VO2max) values during treadmill test. Patients with cardiovascular or renal disease, systemic infection, pregnant women and those with orthopedic injuries unable to measure physical fitness were excluded. Age-specific mean VO2max values were compared with those from recent American, Norwegian, Danish cohorts and old Korean data.

Results

Age-specific reference values for healthy Korean adults in this cohort were as shown (Table). We were able to draw a nomogram to predict exercise capacity for a given age and MET value (Figure). When compared to other countries, less CRF reduction by aging was seen in Asians than in other Westerners. When compared to old Korean data from the 1980s, values were similar after adjustment for difference in methods, except for those under 30 years old which were decreased.

Exercise capacity of healthy Korean Men Women Age VO2max (ml/kg/min) N P-value for trend Age VO2max (ml/kg/min) N P-value for trend 19–29 42.3±6.3± 209 <0.01 19–29 34.3±4.3± 110 <0.01 30–39 42.0±5.0± 170 39–39 32.2±4.5± 211 40–49 41.4±5.6± 238 40–49 30.8±4.6± 284 50–59 38.0±5.7± 274 50–59 28.3±4.6± 367 60–69 32.4±6.2± 134 60–69 26.0±5.7± 336 70–79 27.2±5.6± 83 70–79 23.9±4.4± 195 >80 24.1±4.0± 11 >80 21.0±3.7± 24 Total 38.6±7.4± 1119 Total 28.5±5.8 1527 Data are presented as mean ± standard deviation. VO2max, maximal oxygen uptake; N, number.

Nomogram of exercise capacity in Koreans

Conclusions

While there was no significant change in CRF over time in the same ethnic group, there was a clear inter-ethnic difference. CRF should be assessed according to ethnic or national standards, and it is necessary to establish a reference for each nation or ethnicity with periodic updates.

Acknowledgement/Funding

National Sports Promotion Fund of the Korea Sports Promotion Foundation in 2015

P2501Validation of FRIEND and ACSM equations for cardiorespiratory fitness: comparison to direct measurement in male CAD patients

Introduction

Cardiorespiratory fitness (CRF) is associated with a high risk of cardiovascular disease and all-cause mortality. The regression equation of American College of Sports Medicine (ACSM) was a preferred method for estimating maximal oxygen consumption (VO2max). It is well-known that CRF is overestimated in ACSM equation. Recently, Kokkinos reported more precise equation from the Fitness Registry and the Importance of Exercise National Database (FRIEND). Both equations were made from western healthy people.

Purpose

In this study, we compared VO2max estimated by ACSM and FRIEND equations to VO2max directly measured in male coronary artery disease (CAD) patients.

Methods

We analyzed 103 male CAD patients who underwent percutaneous coronary intervention and who participated in cardiac rehabilitation between June 2015 and December 2018. VO2max was directly measured by the gas exchange analysis during treadmill test with modified Bruce protocol. Exclusive criteria were pulmonary disease, chronic kidney disease on hemodialysis, malignancy, peripheral artery disease, insufficient cardiopulmonary exercise test and orthopedic injuries. Directly measured VO2max were compared to ACSM and FRIEND equations.

Results

Age-specific VO2max values, which were directly measured from male CAD patients, were shown in Table. Smaller CRF difference was shown in FRIEND equation than ACSM equation. Compared to the measured value, CRF estimated by ACSM equation was overestimated by 22%, but the one estimated by FRIEND equation had only 2% gap. Figure presents Bland-Altman plots. ACSM equation had the higher bias (5.52ml/kg/min) compared with FRIEND equation (0.200ml/kg/min).

Comparison table of VO2max estimated by ACSM and FRIEND equations with directly measured VO2max in male CAD patients Age Number VO2max (ml/kg/min) Measured ACSM % predicted FRIEND % predicted 30–39 4 29.5 ± (6.6) 35.7 ± (6.1) 122.3 ± (8.5) 29.1 ± (4.3) 100.1 ± (8.7) 40–49 20 29.1 ± (5.1) 35.7 ± (5.4) 123.6 ± (11.1) 29.1 ± (3.8) 101.2 ± (9.5) 50–59 32 25.6 ± (4.3) 31.5 ± (5.1) 123.8 ± (10.1) 26.2 ± (3.6) 103.2 ± (8.5) 60–69 27 26.0 ± (5.1) 31.1 ± (2.6) 120.5 ± (12.6) 25.9 ± (4.0) 100.8 ± (10.5) 70–79 18 21.2 ± (6.0) 26.8 ± (5.4) 123.2 ± (14.8) 22.8 ± (3.9) 105.2 ± (12.0) >80 2 25.0 ± (10.1) 22.8 ± (2.6) 97 ± (28.9) 19.9 ± (1.9) 85.1 ± (27.0) Total 103 25.7 ± (5.6) 31.4 ± (6.0) 122.2 ± (12.4) 26.1 ± (4.3) 102.1 ± (10.4) Data are presented as mean ± (standard deviation).

Bland-Altman plots

Conclusions

FRIEND equation can estimate CRF more accurately than ACSM equation, even in Asian patients with CAD.

4098Reduced skeletal muscle mass is associated to worsened long-term clinical outcomes in patients with coronary artery disease: a quantitative analysis by computed tomography

Background

Sarcopenia is closely associated to poor clinical outcomes in patients with atherosclerotic cardiovascular disease (ASCVD). However, it is unclear whether the skeletal muscle mass at baseline has quantitative effect on future cardiovascular outcomes.

Purpose

We investigated the quantitative effect of skeletal muscle mass on future cardiovascular outcomes in patients with coronary artery disease (CAD).

Methods

Total 475 patients those who underwent successful percutaneous coronary intervention (PCI) for CAD and performed computed tomography (CT) scan within 30 days of PCI were enrolled. The cross-sectional area of skeletal muscle at the first lumbar vertebra (L1) level was measured. Whole study population was divided into 4 groups according to the sex-specific quartiles of skeletal muscle index (SMI). Primary outcome was all-cause mortality and secondary outcome was major adverse cardiovascular event (MACE) within 3 years of follow-up.

Results

Mean follow-up duration was 4.11±3.02 years and average time period from the date of PCI to CT scan was −3.33±11.72 days. The incidence of 3-year all-cause mortality (23.2% vs. 9.9% vs. 6.6% vs. 4.4%, p<0.001) and MACE (42.9% vs. 24.0% vs. 14.3% vs. 6.2%, p<0.001) was significantly higher in the group of lower quartiles of L1-SMI. In the fully adjusted multivariable analysis, lower quartiles of L1-SMI was an independent predictor of higher risk of all-cause mortality and MACE (lowest vs. highest quartile; OR: 4.90, 95% CI: 1.54 to 15.5, p=0.007; and OR: 12.3, 95% CI: 4.99 to 30.4, p<0.001, respectively).

Results of 3-year clinical outcomes SMI Q1 (n=124) SMI Q2 (n=116) SMI Q3 (n=112) SMI Q4 (n=123) Log-rank p-value All-cause mortality 27 (23.2) 11 (9.9) 7 (6.6) 5 (4.4) <0.001 Non-fatal MI 9 (8.7) 3 (3.0) 2 (2.0) 3 (2.6) 0.038 Repeat revascularization 20 (24.9) 15 (15.2) 7 (7.1) 4 (3.8) <0.001 Total MACEs 47 (42.9) 26 (24.0) 15 (14.3) 7 (6.2) <0.001 Data are expressed as n (%). MACE = major adverse cardiovascular event; MI = myocardial infarction; SMI = skeletal muscle index; Q = quartile.

Impact of reduced skeletal muscle on CAD

Conclusion

Skeletal muscle mass at baseline is a powerful predictor of future adverse clinical outcomes in patients with CAD undergoing successful PCI. Quantitative assessment of skeletal muscle mass at L1 level by CT scan provides prognostic implication for future cardiovascular risk stratification.

Acknowledgement/Funding

National Research Foundation of Korea (NRF-2016R1A2B3013825), Ministry of Future Creation and Science of Korea (2018K000255)

P2523Hand grip strength as a predictor of exercise capacity in coronary heart disease

A recent study has shown that quadriceps strength can be used to predict the level of exercise capacity in patients with coronary heart disease (CHD). We investigated whether the relationship between muscular strength and exercise capacity is also observed with hand grip strength (HGS). We studied 443 participants (age, 61.8±11.2 y; 77.7% male) who underwent coronary intervention and participated in cardiac rehabilitation between 2015 and 2018. Participants were assessed for grip strength, measured using a Jamar dynamometer. Logistic regression was used to assess the relationship between various clinical measures (HGS, age, sex, etc) with the distance walked on a 6-minute walk test (6MWT) and maximal oxygen uptake (VO2max). HGS was significantly related to distance walked on the 6MWT (r=0.435, p<0.001). It was the only predictor of all exercise capacity categories, and one of the strongest predictors of each exercise capacity category. A HGS of 25.5% of body weight predicted an achievement of a 200 m walk on the 6MWT (positive predictive value = 0.95). However, HGS less than 35.5% of body weight predicted that 500m could not be done in 6 minutes (negative predictive value = 0.97). This trend was also observed in the subgroups in which VO2max was measured. This study demonstrates that HGS is associated with exercise capacity in CHD and can be used to predict the level of exercise capacity. These findings may contribute to setting the recommended level of daily activity as well as the level of cardiac rehabilitation in CHD.

Logistic regression models for different levels of exercise capacity Level of exercise capacity B±S.E p-value Odd ratio 95% CI Distance of 6MWT   200 m Grip strength 0.054±0.014 <0.001 1.056 1.027–1.086   300 m Grip strength 0.042±0.009 <0.001 1.042 1.024–1.062   400 m Grip strength 0.047±0.011 <0.001 1.048 1.026–1.070   500 m Grip strength 0.051±0.016 0.001 1.053 1.021–1.086 VO2max level   4 METs Grip strength 0.054±0.010 <0.001 1.056 1.036–1.076   6 METs Grip strength 0.059±0.011 <0.001 1.061 1.039–1.083   8 METs Grip strength 0.081±0.015 <0.001 1.085 1.053–1.117   10 METs Grip strength 0.113±0.049 0.019 1.12 1.019–3.232 Data are presented as mean ± standard deviation (SD). 6MWT, 6-minute walk test; STEMI, ST-Elevation Myocardial Infarction; SE, standard error; CI, confidence interval; VO2max, Maximal Oxygen uptake; METs, Metabolic equivalents.

P6445Stress hyperglycemia and in-hospital mortality in patients with ST-segment elevation myocardial infarction

Introduction

Stress hyperglycemia is common in acute ill patients and associated with poor clinical outcomes. Some studies demonstrated the association of stress hyperglycemia and poor outcomes in acute MI. However, current results for the impact of stress hyperglycemia on mortality in acute MI who underwent PCI are insufficient.

Purpose

We aimed to evaluate the impact of stress hyperglycemia on clinical outcomes of patients with STEMI underwent primary PCI in large scale multi-center registry.

Methods

From 2007 to 2014, in 1,538 patients of the INTERSTELLAR (Incheon-Bucheon Cohort of Patients Undergoing Primary PCI for Acute ST-Elevation Myocardial Infarction) cohort, 997 patients without diabetes who underwent primary PCI for STEMI were retrospectively analyzed. We defined random glucose more than 200mg/dl at admission without diabetic history or results of HbA1C more than 6.5% as stress hyperglycemia. The primary endpoint was in-hospital all-cause death and the secondary endpoint was all-cause death within 1 year after index PCI.

Results

From 997 nondiabetic cohort population, 117 patients with stress hyperglycemia and 880 patients without stress hyperglycemia were enrolled. Baseline characteristics including age, sex, hypertension, hyperlipidemia, atrial fibrillation, left main disease, and multivessel disease were not significantly different between two groups. However, systolic blood pressure was lower (111.2±39.2 vs. 125.5±28.1, p<0.001) and hypoxic liver injury was frequent (31.0% vs. 20.1%, p=0.007) in stress hyperglycemia. In-hospital and 1-year all-cause mortality were higher in stress hyperglycemia (13.7% vs. 2.7%, p<0.001; 15.4% vs. 3.8%, p<0.001, respectively). However, there is no significant difference in post-discharge mortality rate. Stress hyperglycemia was a significant independent predictor of in-hospital death (adjusted OR: 5.67, 95% CI: 2.40–13.39; p<0.001). Hypotension (defined less than 90mmHg) and left ventricular dysfunction (defined less than 40% of LVEF on echocardiography) were significantly associated with stress hyperglycemia (adjusted OR: 5.72, 95% CI: 3.33–9.82; p<0.001; adjusted OR: 2.38, 95% CI: 1.49–3.82; p<0.001, respectively).

Landmark analysis of all-cause death

Conclusions

In nondiabetic patients who underwent primary PCI for STEMI, stress hyperglycemia is significantly associated with an increased in-hospital all-cause mortality but did not increase post-discharge mortality within 1 year.

The rice SUMO conjugating enzymes OsSCE1 and OsSCE3 have opposing effects on drought stress

Posttranslational modification of proteins by the small ubiquitin-related modifier (SUMO) protein is involved in diverse cellular processes. In sumoylation, SUMO-conjugating enzyme (SCE) conjugates SUMO to substrate proteins. Similarly to yeast and animals, Arabidopsis encodes a single SCE gene, but other plants encode at least two SCE genes. In this study, we report the molecular characterization of three Oryza sativa SCE genes. Their levels of expression are commonly upregulated by drought stress but are differentially regulated by hormones and sugars. Only the OsSCE1 gene showed photoperiod- and light-dependent diurnal oscillations in the leaves. Yeast two-hybrid assays showed that OsSCEs do not show SUMO isoform specificity. Three rice OsSCE proteins localize primarily to the nucleus. Interestingly, OsSCE1 is distributed in specific parts of the nucleus and shows sumoylation activities in the absence of a SUMO ligase in E. coli. In addition, overexpression of the OsSCE1 gene alters the biomass and grain yield parameters in transgenic rice plants. Overexpression of the OsSCE3 gene in transgenic rice plants enhances drought stress tolerance. In contrast, OsSCE1-OX transgenic rice plants are hypersensitive to drought stress. Our results suggest that these genes may be involved in different cellular processes.

Biosynthesis of DDMP saponins in soybean is regulated by a distinct UDP-glycosyltransferase

2,3-Dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) saponins are one of the major saponin groups that are widely distributed in legumes such as pea, barrel medic, chickpea, and soybean. The steps involved in DDMP saponin biosynthesis remain uncharacterized at the molecular level. We isolated two recessive mutants that lack DDMP saponins from an ethyl methanesulfonate-induced mutant population of soybean cultivar Pungsannamul. Segregation analysis showed that the production of DDMP saponins is controlled by a single locus, named Sg-9. The locus was physically mapped to a 130-kb region on chromosome 16. Nucleotide sequence analysis of candidate genes in the region revealed that each mutant has a single-nucleotide polymorphism in the Glyma.16G033700 encoding a UDP-glycosyltransferase UGT73B4. Enzyme assays and mass spectrum-coupled chromatographic analysis reveal that the Sg-9 protein has glycosyltransferase activity, converting sapogenins and group B saponins to glycosylated products, and that mutant proteins had only partial activities. The tissue-specific expression profile of Sg-9 matches the accumulation pattern of DDMP saponins. This is the first report on a new gene and its function in the biosynthesis of DDMP saponins. Our findings indicate that Sg-9 encodes a putative DDMP transferase that plays a critical role in the biosynthesis of DDMP saponins.

Grain width 2 (GW2) and its interacting proteins regulate seed development in rice (Oryza sativa L.)

BACKGROUND

Seed size has been extensively studied in crop plants, as it determines crop yield. However, the mechanism of seed development remains elusive. In this study, we explored the mechanism of seed development in rice (Oryza sativa L.), and identified proteins affecting seed size.

RESULTS

Proteomic analysis showed that glyceraldehyde 3-phosphate dehydrogenase, chitinase 14 (CHT14), and phosphoglycerate kinase (PGK) accumulated to high levels in the seeds of the natural japonica rice mutant Oochikara, which carries a loss-of-function mutation in the grain width 2 (GW2) gene; GW2 encodes a RING-type E3 ubiquitin ligase. In vitro pull-down and ubiquitination assays showed that CHT14 and PGK directly interacted with GW2 but were not ubiquitinated by GW2. Immunoblot analysis revealed that protein disulfide isomerase-like 1-1 accumulated to high levels in young developing seeds of the gw2 mutant compared with the wild type. Histochemical β-glucuronidase staining showed strong expression of GW2 in leaf and root tissues but weak expression in leaf sheaths and internodes. In addition, transformation of the green fluorescent protein (GFP) gene under the control of the GW2 promoter in rice revealed GFP expression in the aleurone layer of seeds.

CONCLUSIONS

Collectively, these results suggest that GW2 regulates seed size through direct interactions with proteins involved in carbohydrate metabolism by modulating their activity or stability and controlling disulfide bond formation in various proteins during seed development. Additionally, GW2 participates in vegetative as well as reproductive growth, and protects the seed from pathogen attack.