TOC1 clock protein phosphorylation controls complex formation with NF-YB/C to repress hypocotyl growth.

Plant photoperiodic growth is coordinated by interactions between circadian clock and light signaling networks. How post-translational modifications of clock proteins affect these interactions to mediate rhythmic growth remains unclear. Here, we identify five phosphorylation sites in the Arabidopsis core clock protein TIMING OF CAB EXPRESSION 1 (TOC1) which when mutated to alanine eliminate detectable phosphorylation. The TOC1 phospho-mutant fails to fully rescue the clock, growth, and flowering phenotypes of the toc1 mutant. Further, the TOC1 phospho-mutant shows advanced phase, a faster degradation rate, reduced interactions with PHYTOCHROME-INTERACTING FACTOR 3 (PIF3) and HISTONE DEACETYLASE 15 (HDA15), and poor binding at pre-dawn hypocotyl growth-related genes (PHGs), leading to a net de-repression of hypocotyl growth. NUCLEAR FACTOR Y subunits B and C (NF-YB/C) stabilize TOC1 at target promoters, and this novel trimeric complex (NF-TOC1) acts as a transcriptional co-repressor with HDA15 to inhibit PIF-mediated hypocotyl elongation. Collectively, we identify a molecular mechanism suggesting how phosphorylation of TOC1 alters its phase, stability, and physical interactions with co-regulators to precisely phase PHG expression to control photoperiodic hypocotyl growth.

Establishment of a novel cell line for producing replication-competent adenovirus-free adenoviruses.

Adenoviruses are commonly utilized as viral vectors for gene therapy, genetic vaccines, and recombinant protein expression. To generate replication-defective adenoviruses, E1-complementing cell lines such as HEK293A are utilized; however, limitations remain. Repeated passage of E1-deleted virus in HEK293A cells increases the occurrence of replication-competent adenoviruses (RCAs). In the present study, we developed a novel cell line originating from human primary cells. L132 cells were transduced two times with E1-encoded retrovirus and three times with E1A-encoded retrovirus. Finally, we selected the most productive L132 cell line for generation of RCA-free adenovirus, GT541. GT541 can serve as an alternative cell line to HEK293A and other adenovirus-producing cells.

HOS15-mediated turnover of PRR7 enhances freezing tolerance.

Arabidopsis PSEUDORESPONSE REGULATOR7 (PRR7) is a core component of the circadian oscillator which also plays a crucial role in freezing tolerance. PRR7 undergoes proteasome-dependent degradation to discretely phase maximal expression in early evening. While its repressive activity on downstream genes is integral to cold regulation, the mechanism of the conditional regulation of the PRR7 abundance is unknown. We used mutant analysis, protein interaction and ubiquitylation assays to establish that the ubiquitin ligase adaptor, HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 15 (HOS15), controls the protein accumulation pattern of PRR7 through direct protein-protein interactions at low temperatures. Freezing tolerance and electrolyte leakage assays show that PRR7 enhances cold temperature sensitivity, supported by ChIP-qPCR at C-REPEAT BINDING FACTOR1 (CBF1) and COLD-REGULATED 15A (COR15A) promoters where PRR7 levels were higher in hos15 mutants. HOS15 mediates PRR7 turnover through enhanced ubiquitylation at low temperature in the dark. Under the same conditions, increased PRR7 association with the promoters of CBFs and COR15A in hos15 correlates with decreased CBF1 and COR15A transcription and enhanced freezing sensitivity. We propose a novel mechanism whereby HOS15-mediated degradation of PRR7 provides an intersection between the circadian system and other cold acclimation pathways that lead to increased freezing tolerance.

Association of Physical Activity With Risk of Liver Fibrosis, Sarcopenia, and Cardiovascular Disease in Nonalcoholic Fatty Liver Disease.

BACKGROUND & AIMS: International guidelines recommend physical activity for subjects with nonalcoholic fatty liver disease (NAFLD). This study investigated the association of physical activity with risk of liver fibrosis, sarcopenia, and cardiovascular disease (CVD) in NAFLD. METHODS: In this multicenter, retrospective study, 11,690 NAFLD subjects who underwent a health screening program and were assessed for physical activity (metabolic equivalent task [MET]-min/week) between 2014 and 2020 were recruited. Liver fibrosis was assessed by using the fibrosis-4 index, NAFLD fibrosis score, and FibroScan-AST score, sarcopenia by using multi-frequency bioelectric impedance analysis, and CVD risk by using atherosclerotic CVD (ASCVD) risk score, and coronary artery calcium (CAC) score were calculated. RESULTS: The prevalence of fibrosis, sarcopenia, high probability of ASCVD, and high CAC score significantly decreased with increasing quartiles of physical activity (all P for trend <.001). In a fully adjusted model, physical activity above 600 MET-min/week (≥third quartile) was independently associated with a reduced risk of fibrosis (adjusted odds ratio [aOR] = 0.59; 95% confidence interval [CI], 0.40-0.86), sarcopenia (aOR = 0.72; 95% CI, 0.58-0.88), high probability of ASCVD (aOR = 0.58; 95% CI, 0.46-0.73), and high CAC score (aOR = 0.32; 95% CI, 0.13-0.83; all P <.05). In addition, increasing amounts of physical activity were significantly associated with risk reduction between fibrosis, sarcopenia, and high probability of ASCVD (all P for trend <.001). In subjects with sarcopenic obesity or lean NAFLD, physical activity was also independently associated with reduced risk of fibrosis and high probability of ASCVD (all P <.05). CONCLUSIONS: Physical activity showed a protective effect against fibrosis, sarcopenia, and CVD in NAFLD.

Transcriptomes of the tumor-adjacent normal tissues are more informative than tumors in predicting recurrence in colorectal cancer patients.

BACKGROUND: Previous investigations of transcriptomic signatures of cancer patient survival and post-therapy relapse have focused on tumor tissue. In contrast, here we show that in colorectal cancer (CRC) transcriptomes derived from normal tissues adjacent to tumors (NATs) are better predictors of relapse. RESULTS: Using the transcriptomes of paired tumor and NAT specimens from 80 Korean CRC patients retrospectively determined to be in recurrence or nonrecurrence states, we found that, when comparing recurrent with nonrecurrent samples, NATs exhibit a greater number of differentially expressed genes (DEGs) than tumors. Training two prognostic elastic net-based machine learning models-NAT-based and tumor-based in our Samsung Medical Center (SMC) cohort, we found that NAT-based model performed better in predicting the survival when the model was applied to the tumor-derived transcriptomes of an independent cohort of 450 COAD patients in TCGA. Furthermore, compositions of tumor-infiltrating immune cells in NATs were found to have better prognostic capability than in tumors. We also confirmed through Cox regression analysis that in both SMC-CRC as well as in TCGA-COAD cohorts, a greater proportion of genes exhibited significant hazard ratio when NAT-derived transcriptome was used compared to when tumor-derived transcriptome was used. CONCLUSIONS: Taken together, our results strongly suggest that NAT-derived transcriptomes and immune cell composition of CRC are better predictors of patient survival and tumor recurrence than the primary tumor.

Ubap1 knock-in mice reproduced the phenotype of SPG80.

SPG80 is a neurodegenerative disorder characterized by a pure type of juvenile-onset hereditary spastic paraplegia and is caused by a heterozygous mutation of the UBAP1 (ubiquitin-associated protein 1) gene. UBAP1 is one of the subunits of the endosomal sorting complex required for transport I and plays a role in endosome sorting by binding to ubiquitin-tagged proteins. In this study, we generated novel Ubap1+/E176Efx23 knock-in mice, in which the SOUBA domain of Ubap1 was completely deleted with the UMA domain being intact, as an animal model of SPG80. The knock-in mice with this heterozygous Ubap1 truncated mutation appeared normal at birth, but they developed progressive hind limb dysfunction several months later. Molecular pathologically, loss of neurons in the spinal cord and accumulation of ubiquitinated proteins were observed in Ubap1+/E176Efx23 knock-in mice. In addition, changes in the distributions of Rab5 and Rab7 in the spinal cord suggest that this mutation in Ubap1 disturbs endosome-mediated vesicular trafficking. This is the first report of a mouse model that reproduces the phenotype of SPG80. Our knock-in mice may provide a clue for understanding the molecular pathogenesis underlying UBAP1-related HSP and screening of therapeutic agents.

Role of Circulating Tumor DNA Profiling in Patients with Non-Small Cell Lung Cancer Treated with EGFR Inhibitor.

OBJECTIVES: During targeted therapy, tumor heterogeneity can drive the evolution of multiple tumor subclones harboring unique resistance mechanisms. Sequential profiling of plasma cell-free DNA (cfDNA) provides a noninvasive method for early detection of patient progression. We investigated whether the genetic dynamics detected in cfDNA during treatment can act as a predictive or prognostic marker of outcome. METHODS: Patients with advanced EGFR-mutated non-small cell lung cancer (NSCLC) were included for consecutive blood sampling during EGFR-tyrosine kinase inhibitor (TKI) treatment. Blood samples were serially collected from patients at baseline, first follow-up, and progression. Extracted cfDNA was analyzed with next-generation sequencing. RESULTS: Serial plasma samples (n = 187) from 63 patients were analyzed, and 44 patients showed circulating tumor DNA (ctDNA). EGFR mutations were detected in 36 of the 44 patients at baseline (81.8%). EGFR mutations were no longer detected in 19 of 36 shedders (52.8%) at 2 months after EGFR-TKI treatment and rebounded with resistant EGFR mutations (T790M or C797S) at progression. Other driver mutations such as KRAS G12D and BRAF V600E were found at baseline regardless of tissue EGFR status, suggesting tumor heterogeneity. Detection of ctDNA (shedder) at baseline associated with poor overall survival (p = 0.04) compared to nonshedder. Furthermore, in patients showing EGFR mutations in plasma at baseline, the clearing rate of those during the first 8 weeks of treatment served as a positive predictor for clinical outcome. CONCLUSION: Longitudinal liquid biopsies capture spatial and temporal heterogeneity underlining resistance to EGFR-TKIs in NSCLC. Thus, ctDNA monitoring during EGFR-TKI treatment is useful for detecting resistance mutations or predicting response. Dense serial monitoring using blood enables early prediction of treatment failure and provides a window of opportunity for well-timed intervention.

Immunomodulation of HDAC Inhibitor Entinostat Potentiates the Anticancer Effects of Radiation and PD-1 Blockade in the Murine Lewis Lung Carcinoma Model.

Although the combination of radiotherapy and immunotherapy has proven to be effective in lung cancer treatment, it may not be sufficient to fully activate the antitumor immune response. Here, we investigated whether entinostat, a histone deacetylase inhibitor, could improve the efficacy of radiotherapy and anti-PD-1 in a murine syngeneic LL/2 tumor model. A total of 12 Gy of X-rays administered in two fractions significantly delayed tumor growth in mice, which was further enhanced by oral entinostat administration. Flow cytometry-aided immune cell profiling revealed that entinostat increased radiation-induced infiltration of myeloid-derived suppressor cells and CD8+ T cells with decreased regulatory T-cells (Tregs). Transcriptomics-based immune phenotype prediction showed that entinostat potentiated radiation-activated pathways, such as JAK/STAT3/interferon-gamma (IFN-γ) and PD-1/PD-L1 signaling. Entinostat augmented the antitumor efficacy of radiation and anti-PD-1, which may be related to an increase in IFN-γ-producing CD8+ T-cells with a decrease in Treg cells. Comparative transcriptomic profiling predicted that entinostat increased the number of dendritic cells, B cells, and T cells in tumors treated with radiation and anti-PD-1 by inducing MHC-II genes. In conclusion, our findings provided insights into how entinostat improves the efficacy of ionizing radiation plus anti-PD-1 therapy and offered clues for developing new strategies for clinical trials.

SIDR: simultaneous isolation and parallel sequencing of genomic DNA and total RNA from single cells.

Simultaneous sequencing of the genome and transcriptome at the single-cell level is a powerful tool for characterizing genomic and transcriptomic variation and revealing correlative relationships. However, it remains technically challenging to analyze both the genome and transcriptome in the same cell. Here, we report a novel method for simultaneous isolation of genomic DNA and total RNA (SIDR) from single cells, achieving high recovery rates with minimal cross-contamination, as is crucial for accurate description and integration of the single-cell genome and transcriptome. For reliable and efficient separation of genomic DNA and total RNA from single cells, the method uses hypotonic lysis to preserve nuclear lamina integrity and subsequently captures the cell lysate using antibody-conjugated magnetic microbeads. Evaluating the performance of this method using real-time PCR demonstrated that it efficiently recovered genomic DNA and total RNA. Thorough data quality assessments showed that DNA and RNA simultaneously fractionated by the SIDR method were suitable for genome and transcriptome sequencing analysis at the single-cell level. The integration of single-cell genome and transcriptome sequencing by SIDR (SIDR-seq) showed that genetic alterations, such as copy-number and single-nucleotide variations, were more accurately captured by single-cell SIDR-seq compared with conventional single-cell RNA-seq, although copy-number variations positively correlated with the corresponding gene expression levels. These results suggest that SIDR-seq is potentially a powerful tool to reveal genetic heterogeneity and phenotypic information inferred from gene expression patterns at the single-cell level.

Dynamics of circulating tumor DNA during postoperative radiotherapy in patients with residual triple-negative breast cancer following neoadjuvant chemotherapy: a prospective observational study.

BACKGROUND: This study was performed to evaluate circulating tumor DNA (ctDNA) kinetics during postoperative radiotherapy (PORT) in patients with residual triple-negative breast cancer (TNBC) at surgery following neoadjuvant chemotherapy (NAC). METHODS: Stage II/III patients with post-NAC residual TNBC who required PORT were prospectively included in this study between March 2019 and July 2020. For 11 TNBC patients, next-generation sequencing targeting 38 genes was conducted in 55 samples, including tumor tissue, three plasma samples, and leukocytes from each patient. The plasma samples were collected at three-time points; pre-PORT (T0), after 3 weeks of PORT (T1), and 1 month after PORT (T2). Serial changes in ctDNA variant allele frequency (VAF) were analyzed. RESULTS: Somatic variants were found in the tumor specimens in 9 out of 11 (81.8%) patients. Mutated genes included TP53 (n = 7); PIK3CA (n = 2); and AKT1, APC, CSMD3, MYC, PTEN, and RB1 (n = 1). These tumor mutations were not found in plasma samples. Plasma ctDNA variants were detected in three (27.3%) patients at T0. Mutations in EGFR (n = 1), CTNNB1 (n = 1), and MAP2K (n = 1) was identified with ctDNA analysis. In two (18.2%) patients, the ctDNA VAF decreased through T1 and T2 while increasing at T2 in one (9.1%) patient. After a median follow-up of 22 months, no patient showed cancer recurrence. CONCLUSION: Among patients with post-NAC residual TNBC, more than a quarter exhibited a detectable amount of ctDNA after curative surgery. The ctDNA VAF changed variably during the course of PORT. Therefore, ctDNA kinetics can serve as a biomarker for optimizing adjuvant treatment.

Compensatory Mutations in GI and ZTL May Modulate Temperature Compensation in the Circadian Clock.

Circadian systems share the three properties of entrainment, free-running period, and temperature compensation (TC). TC ensures nearly the same period over a broad range of physiologically relevant temperatures; however, the mechanisms behind TC remain poorly understood. Here, we identify single point mutations in two key elements of the Arabidopsis circadian clock, GIGANTEA (GI) and ZEITLUPE (ZTL), which likely act as compensatory substitutions to establish a remarkably constant free-running period over a wide range of temperatures. Using near-isogenic lines generated from the introgression of the Cape Verde Islands (Cvi) alleles of GI and ZTL into the Landsberg erecta (Ler) background, we show how longer periods in the Cvi background at higher temperatures correlate with a difference in strength of the GI/ZTL interaction. Pairwise interaction testing of all GI/ZTL allelic combinations shows similar affinities for isogenic alleles at 22°C, but very poor interaction between GI (Cvi) and ZTL (Cvi) at higher temperature. In vivo, this would result in lower ZTL levels at high temperatures leading to longer periods in the Cvi background. Mismatched allelic combinations result in extremely strong or weak GI/ZTL interactions, indicating how the corresponding natural variants likely became fixed through epistatic selection. Additionally, molecular characterization of GI (Cvi) reveals a novel functional motif that can modulate the GI/ZTL interaction as well as nucleocytoplasmic partitioning. Taken together, these results identify a plausible temperature-dependent molecular mechanism, which contributes to the robustness of TC through natural variation in GI and ZTL alleles found on the Cape Verde Islands.

RFC1 repeat expansion in Japanese patients with late-onset cerebellar ataxia.

Recently, the expansion of an intronic AAGGG repeat in the replication factor C subunit 1 (RFC1) gene was reported to cause cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS). In Europeans, the expansion accounted for 22% of sporadic patients with late-onset ataxia. We genotyped 37 Japanese patients comprising 25 familial (autosomal recessive or undecided transmission) and 12 sporadic ones with late-onset ataxia. We found intronic repeat expansions in RFC1 in three (12%) of the familial patients and one (8.5%) of the sporadic ones. Although our cohort study was small, the disease frequency in Japanese patients with CANVAS might be lower than that in European ones. In addition, we found biallelic ACAGG repeat expansion in one patient, indicating ACAGG repeat expansion might cause CANVAS. Clinically, we found one patient with sleep apnea syndrome, which has not been reported previously. Thus, this study might expand the clinical and genetic spectrum of CANVAS.

Plasma cell-free DNA is a prognostic biomarker for survival in patients with aggressive non-Hodgkin lymphomas.

Cell-free DNA (cfDNA) can be released from tumor cells during proliferation and apoptosis; thus, a fraction of the cfDNA in patients with cancer is tumor-derived. However, the prognostic value of cfDNA in aggressive non-Hodgkin lymphoma (NHL) has not been determined. Between March 2017 and April 2019, plasma cfDNA was obtained from 158 patients with aggressive NHL who were registered in a prospective Samsung Medical Center lymphoma cohort (diffuse large B cell lymphoma (DLBCL), n = 51; T cell lymphoma (TCL), n = 51; NK/T cell lymphoma (NKTCL), n = 56). The concentration of cfDNA was estimated in longitudinal samples collected from patients with NHL before and during various chemotherapy regimens. In pretreatment samples, the median cfDNA concentration of all patients with aggressive lymphoma was 13.7 ng/dl (range 1.7-1792), which was significantly higher than that of healthy volunteers (median 7.4 ng, range 3.7-14.4, p < 0.001), and advanced stages showed a higher cfDNA level than earlier stages. Multivariate analysis identified high cfDNA as an independent factor for event-free survival that predicted poor prognosis in DLBCL (hazard ratio [HR] = 5.33, 95% confidence interval [CI] = 1.72-16.52, p = 0.003) and TCL (HR = 2.82, 95% CI = 1.10-7.20, p = 0.030). NKTCL patients with a high level of cfDNA had worse overall survival (HR = 4.71, 95% CI = 1.09-20.35, p = 0.037) compared with those with a low level of cfDNA. In this study, our results suggest the usefulness of pretreatment cfDNA as a prognostic marker for patients with DLBCL, TCL, and NKTCL.

Analyzing Somatic Genome Rearrangements in Human Cancers by Using Whole-Exome Sequencing.

Although exome sequencing data are generated primarily to detect single-nucleotide variants and indels, they can also be used to identify a subset of genomic rearrangements whose breakpoints are located in or near exons. Using >4,600 tumor and normal pairs across 15 cancer types, we identified over 9,000 high confidence somatic rearrangements, including a large number of gene fusions. We find that the 5' fusion partners of functional fusions are often housekeeping genes, whereas the 3' fusion partners are enriched in tyrosine kinases. We establish the oncogenic potential of ROR1-DNAJC6 and CEP85L-ROS1 fusions by showing that they can promote cell proliferation in vitro and tumor formation in vivo. Furthermore, we found that ∼4% of the samples have massively rearranged chromosomes, many of which are associated with upregulation of oncogenes such as ERBB2 and TERT. Although the sensitivity of detecting structural alterations from exomes is considerably lower than that from whole genomes, this approach will be fruitful for the multitude of exomes that have been and will be generated, both in cancer and in other diseases.

V-set and Ig domain-containing 4 (VSIG4)-expressing hepatic F4/80+ cells regulate oral antigen-specific responses in mouse.

Oral tolerance can prevent unnecessary immune responses against dietary antigens. Members of the B7 protein family play critical roles in the positive and/or negative regulation of T cell responses to interactions between APCs and T cells. V-set and Ig domain-containing 4 (VSIG4), a B7-related co-signaling molecule, has been known to act as a co-inhibitory ligand and may be critical in establishing immune tolerance. Therefore, we investigated the regulation of VSIG4 signaling in a food allergy and experimental oral tolerance murine models. We analyzed the contributions of the two main sites involved in oral tolerance, the mesenteric lymph node (MLN) and the liver, in VSIG4-mediated oral tolerance induction. Through the comparative analysis of major APCs, dendritic cells (DCs) and macrophages, we found that Kupffer cells play a critical role in inducing regulatory T cells (Tregs) and establishing immune tolerance against oral antigens via VSIG4 signaling. Taken together, these results suggest the possibility of VSIG4 signaling-based regulation of orally administered antigens.

Cancer upregulated gene 2 (CUG2), a novel oncogene, promotes stemness-like properties via the NPM1-TGF-ß signaling axis.

Our previous study reported that cancer upregulated gene (CUG)2, a novel oncogene, induces both faster cell migration and anti-cancer drug resistance. We thus wonder whether CUG2 also induces stemness, a characteristic of cancer stem cells (CSCs) and further examine the molecular mechanism of this phenotype. To test that CUG2 induces stemness, we examined expression of stemness-related factors. Overexpression of CUG2 enhanced expression levels of stemness-related factors in human lung carcinoma A549 and immortalized bronchial BEAS-2B cells. Consequently, CUG2 increased cellular spherical cluster forming ability. Overexpression of CUG2 also induced tumor formation in xenotransplanted nude mice whereas transplantation of control cells failed to, implying that CUG2 possesses malignant tumorigenic potential. We paid attention to nucleophosmin (NPM1) for its known interaction with CUG2. Suppression of NPM1 hindered the CUG2-mediated stemness-like phenotypes and diminished TGF-ß transcriptional activity and signaling. TGF-ß increased stemness-like phenotypes in the control cells whereas TGF-ß inhibitor blocked induction of the phenotypes, indicating that NPM1 is required for CUG2-mediated stemness-like phenotypes through TGF-ß signaling. Furthermore, the suppression of Smad- and non-Smad-dependent TGF-ß signaling pathways also prevented CUG2 from inducing stemness-like phenotypes. Altogether, we suggest that the novel CUG2 oncogene promotes cellular transformation and stemness, mediated by nuclear NPM1 protein and TGF-ß signaling.

Caveolin-1 prevents palmitate-induced NF-κB signaling by inhibiting GPRC5B-phosphorylation.

Tyrosine phosphorylation of GPRC5B and phosphorylation-dependent recruitment of Fyn through the SH2 domain have been implicated in NF-κB activation and obesity-linked adipose inflammation. GPRC5B tightly associates with caveolin-1 (Cav1); however, the role of this interaction remains elusive. Here, we report that Cav1 reduces GPRC5B-mediated NF-κB signaling by blocking GPRC5B-phosphorylation. We demonstrate highly abundant tyrosine phosphorylation of GPRC5B is observed in Neuro2a cells lacking endogenous Cav1 expression. Reversely, exogenous expression of Cav1 in these cells inhibits GPRC5B-phosphorylation. Although GPRC5B lacks conventional caveolin-binding motif, cytoplasmic tail of GPRC5B directly interacts with the C-terminal domain of Cav1. The vacant scaffolding domain of Cav1 in the protein complex suggests a potential mechanism for blocking GPRC5B-phosphorylation by Cav1, because Fyn loses the activity by binding with Cav1-scaffolding domain. Enhanced GPRC5B-mediated NF-κB signaling in Cav1-deficient cells were observed under palmitate-induced metabolic stress. These results support Cav1 functions as a negative modulator for GPRC5B action.

The tyrosinase inhibitory effects of isoxazolone derivatives with a (Z)-ß-phenyl-α, ß-unsaturated carbonyl scaffold.

Thirteen (Z)-4-(substituted benzylidene)-3-phenylisoxazol-5(4H)-ones were designed to confirm the geometric effect of the double bond of the ß-phenyl-α, ß-unsaturated carbonyl scaffold on tyrosinase inhibitory activity. Compounds 1a-1m, which all possessed the (Z)-ß-phenyl-α, ß-unsaturated carbonyl scaffold, were synthesized using a tandem reaction consisting of an isoxazolone ring formation and a Knoevenagel condensation, and three starting materials, ethyl benzoylacetate, hydroxylamine and benzaldehydes. Some of the compounds showed inhibitory activity against mushroom tyrosinase as potent as compounds containing the "(E)"-ß-phenyl-α, ß-unsaturated carbonyl scaffold. Compounds 1c and 1m showed greater inhibitory activity than kojic acid: IC50 = 32.08 ±â€¯2.25 µM for 1c; IC50 = 14.62 ±â€¯1.38 µM for 1m; and IC50 = 37.86 ±â€¯2.21 µM for kojic acid. A kinetic study indicated that 1m inhibited tyrosinase in a competitive manner and that it probably binds to the enzyme's active site. In silico docking simulation supported binding of 1m (-7.6 kcal/mol) to the active site of tyrosinase with stronger affinity than kojic acid (-5.7 kcal/mol). Similar results were obtained using cell-based assays, and in B16F10 cells, compound 1m dose-dependently inhibited tyrosinase activity and melanogenesis. These results indicate the anti-melanogenic effect of compound 1m is due to the inhibition of tyrosinase and (Z)-isomer of the ß-phenyl-α, ß-unsaturated carbonyl scaffold can, like its congener the (E)-isomer, act as an excellent scaffold for tyrosinase inhibition.

GW2 Functions as an E3 Ubiquitin Ligase for Rice Expansin-Like 1.

Seed size is one of the most important traits determining the yield of cereal crops. Many studies have been performed to uncover the mechanism of seed development. However, much remains to be understood, especially at the molecular level, although several genes involved in seed size have been identified. Here, we show that rice Grain Width 2 (GW2), a RING-type E3 ubiquitin ligase, can control seed development by catalyzing the ubiquitination of expansin-like 1 (EXPLA1), a cell wall-loosening protein that increases cell growth. Microscopic examination revealed that a GW2 mutant had a chalky endosperm due to the presence of loosely packed, spherical starch granules, although the grain shape was normal. Yeast two-hybrid and in vitro pull-down assays showed a strong interaction between GW2 and EXPLA1. In vitro ubiquitination analysis demonstrated that EXPLA1 was ubiquitinated by GW2 at lysine 279 (K279). GW2 and EXPLA1 colocalized to the nucleus when expressed simultaneously. These results suggest that GW2 negatively regulates seed size by targeting EXPLA1 for degradation through its E3 ubiquitin ligase activity.