Genetic characterization of mutants resistant to the antiauxin p-chlorophenoxyisobutyric acid reveals that AAR3, a gene encoding a DCN1-like protein, regulates responses to the synthetic auxin 2,4-dichlorophenoxyacetic acid in Arabidopsis roots

To isolate novel auxin-responsive mutants in Arabidopsis (Arabidopsis thaliana), we screened mutants for root growth resistance to a putative antiauxin, p-chlorophenoxyisobutyric acid (PCIB), which inhibits auxin action by interfering the upstream auxin-signaling events. Eleven PCIB-resistant mutants were obtained. Genetic mapping indicates that the mutations are located in at least five independent loci, including two known auxin-related loci, TRANSPORT INHIBITOR RESPONSE1 and Arabidopsis CULLIN1. antiauxin-resistant mutants (aars) aar3-1, aar4, and aar5 were also resistant to 2,4-dichlorophenoxyacetic acid as shown by a root growth assay. Positional cloning of aar3-1 revealed that the AAR3 gene encodes a protein with a domain of unknown function (DUF298), which has not previously been implicated in auxin signaling. The protein has a putative nuclear localization signal and shares homology with the DEFECTIVE IN CULLIN NEDDYLATION-1 protein through the DUF298 domain. The results also indicate that PCIB can facilitate the identification of factors involved in auxin or auxin-related signaling.     

Differential role of two VDR coactivators, DRIP205 and SRC-3, in keratinocyte proliferation and differentiation

Cell programs such as proliferation and differentiation involve the selective activation and repression of gene expression. The vitamin D receptor (VDR), through 1,25(OH)(2)D(3), controls the proliferation and differentiation of keratinocytes. Previously, we have identified two VDR binding coactivator complexes. In proliferating keratinocytes VDR bound preferentially to the DRIP complex, whereas in differentiated keratinocytes the SRC complex was preferred. We proposed that different coactivators are required for sequential gene regulation in the transition from proliferation to differentiation. Here we examined the roles of DRIP205 and SRC-3 in this transition. Silencing of DRIP205 and VDR caused hyperproliferation of keratinocytes, demonstrated by increased XTT and BrdU incorporation. SRC-3 silencing, on the other hand, did not have an effect on proliferation. In contrast, SRC-3 as well as DRIP205 and VDR silencing blocked keratinocyte differentiation as shown by decreased expression of keratin 1 and filaggrin. These results are consistent with the differential localization of DRIP205 and SRC-3 in skin. These results indicate that DRIP205 is required for keratinocyte proliferation. Both DRIP205 and SRC-3 are required for the keratinocyte differentiation. These results support the concept that the selective use of coactivators by VDR underlies the selective regulation of gene expression in keratinocyte proliferation and differentiation.     

Selective photo-cross-linking of 2'-O-psoralen-conjugated oligonucleotide with RNAs having point mutations

It has been reported that point mutations in genes are responsible for various cancers and the selective regulation of the gene expression is an important issue to develop a new type of anticancer drugs. In this report, we present a new type of antisense molecule that photo-cross-links to an oligoribonucleotide having a point mutation site in a sequence specific manner. 2'-O-psoralen-conjugated adenosine was synthesized in four steps from adenosine and introduced in the middle of an oligodeoxyribonucleotide (2'-Ps-oligo). Compared with 5'-O-psoralen-conjugated oligodeoxyribonucleotide (5'-Ps-oligo), which has a psoralen at the 5'-end, 2'-Ps-oligo more selectively photo-cross-linked to a pyrimidine base of the site of alteration from purine to pyrimidine in the oligoribonucleotide.     

Wheat bran protects Fischer-344 rats from diquat-induced oxidative stress by activating antioxidant system: selenium as an antioxidant

Wheat bran had a protective effect against diquat toxicity in rats fed a purified diet (PD). We studied the effects of wheat bran on the antioxidant system in the liver of rats treated with saline and diquat. Although feeding wheat bran did not affect the concentration of hepatic non-protein sulfhydryl or the activity of glucose 6-phosphate dehydrogenase in the saline-injected rats, these values were significantly higher in the rats fed PD containing wheat bran (W-PD) than in rats fed only PD after administering diquat. The glutathione peroxidase and reductase activities were significantly elevated by wheat bran in the saline-injected rats. Although the glutathione peroxidase activity was unchanged in both the PD-fed rats and W-PD-fed rats after the diquat treatment, the glutathione reductase activity was significantly decreased in both the PD-fed and W-PD-fed rats. Feeding the rats with PD containing 0.15 ppm selenium as well as with W-PD elevated the activity of hepatic glutathione peroxidase and attenuated the diquat toxicity. These results indicate that wheat bran protected against diquat toxicity by activating the hepatic antioxidant system, and that selenium was the key antioxidant in wheat bran.     

Methotrexate chronotherapy is effective against rheumatoid arthritis

Methotrexate (MTX) is the most important drug for treating rheumatoid arthritis (RA). It has been stated that cytokines play an important role in the pathogenesis of RA, and that cytokine levels increase and show 24-h rhythms in RA patients. Previously, we found that arthritis was relieved after the administration of MTX at specific times in synchronization with the 24-h rhythm of tumor necrosis factor (TNF)-α in collagen-induced arthritis (CIA) animals. Based on our findings in an earlier study of the dosing time-dependent effects of MTX in MRL/lpr mice, which develop autoimmune disorders that share similarities with human RA, we examined here the utility of MTX chronotherapy in Japanese RA patients. In an initial animal modeling study, we collected blood from MRL/lpr mice at different times (2, 6, 10, 14, 18, or 22 hours after the light was turned on [HALO]), and we measured TNF-α mRNA expression in leukocytes. MTX was administered to the mice at two different dosing times (6 or 18 HALO), and various blood parameters were measured to estimate arthritis activity. TNF-α mRNA levels showed a clear 24-h rhythm with a peak at 22 HALO and a trough at 18 HALO after RA had developed. In these MRL/lpr mice, inflammation and TNF-α were markedly reduced when the MTX dosing time was matched to the time (18 HALO) when the TNF-α level began to increase. We then applied these findings to Japanese RA patients by switching them from the standard MTX three times/wk (day 1: after breakfast and supper; day 2: after breakfast schedule), to chronotherapy, in which the dose and number of doses/wk were not changed but MTX was administered once-a-day at bedtime. Disease Activity Score (DAS)28, modified health assessment questionnaire (MHAQ), and adverse effects were assessed. With MTX chronotherapy, DAS28, which is commonly used to quantitatively assess RA symptoms, was significantly improved at all follow-up clinical visit times compared with the baseline (vs. 1 mo: p?=?.0197, 2 mos: p?=?.0107, 3 mos: p?=?.0087). Significant symptom recovery was observed in 41.2% of patients, and 23.5% of patients achieved clinical remission during the 3 mos of follow-up. Functional capacity of RA patients, as indicated by the MHAQ, was markedly improved by chronotherapy. There were no severe adverse effects. Thus, we demonstrated (i) inflammation and plasma TNF-α concentrations were significantly reduced in MRL/lpr mice treated with MTX at 18 HALO, the time when TNF-α mRNA level began to increase; and (ii) MTX bedtime chronotherapy was safe, markedly reduced disease activity, and improved the functional capacity of RA patients. The findings on RA patients show that bedtime MTX chronotherapy can improve RA symptoms compared to the current standard dosing methods.     

Discovery of orally available tetrahydroquinoline-based glucocorticoid receptor agonists

A series of tetrahydroquinoline derivatives were synthesized and profiled for their ability to act as glucocorticoid receptor selective modulators. Structure-activity relationships of the tetrahydroquinoline B-ring lead to the discovery of orally available GR-selective agonists with high in vivo activity.     

Nonsteroidal 2,3-dihydroquinoline glucocorticoid receptor agonists with reduced PEPCK activation

Continuing studies based on dihydroquinoline glucocorticoid receptor agonists lead to the discovery of a series of C4-oxime analogs. Representative compounds exhibited potent transrepression activity with minimal transactivation of phosphoenolpyruvate caboxykinase (PEPCK), a key protein in the gluconeogenesis pathway. These compounds represent promising leads in identifying GR agonists with high anti-inflammatory activity and attenuated potential for glucose elevation.     

5a-Carba-β-D-glucopyranose derivatives as novel sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors for the treatment of type 2 diabetes

5a-Carba-β-D-glucopyranose derivatives were synthesized and identified as novel SGLT2-selective inhibitors. These inhibitors exhibited potent SGLT2 inhibition with high selectivity over SGLT1. Among the tested compounds, 6f indicated the most potent hSGLT2 inhibition and the highest selectivity over hSGLT1. Moreover, the pharmacokinetics data also showed that 6h, which had the same aglycon structure as sergliflozin-active (3-active), had a threefold longer half-life time (T(1/2)) than sergliflozin (3) with a high distribution volume in db/db mice. Subsequently, 6h lowered blood glucose levels as much as 3 and showed longer hypoglycemic action than 3 in db/db mice.