HISTONE DEACETYLASE 9 transduces heat signal in plant cells.

Heat stress limits plant growth, development, and crop yield, but how plant cells precisely sense and transduce heat stress signals remains elusive. Here, we identified a conserved heat stress response mechanism to elucidate how heat stress signal is transmitted from the cytoplasm into the nucleus for epigenetic modifiers. We demonstrate that HISTONE DEACETYLASE 9 (HDA9) transduces heat signals from the cytoplasm to the nucleus to play a positive regulatory role in heat responses in Arabidopsis. Heat specifically induces HDA9 accumulation in the nucleus. Under heat stress, the phosphatase PP2AB'ß directly interacts with and dephosphorylates HDA9 to protect HDA9 from 26S proteasome-mediated degradation, leading to the translocation of nonphosphorylated HDA9 to the nucleus. This heat-induced enrichment of HDA9 in the nucleus depends on the nucleoporin HOS1. In the nucleus, HDA9 binds and deacetylates the target genes related to signaling transduction and plant development to repress gene expression in a transcription factor YIN YANG 1-dependent and -independent manner, resulting in rebalance of plant development and heat response. Therefore, we uncover an HDA9-mediated positive regulatory module in the heat shock signal transduction pathway. More important, this cytoplasm-to-nucleus translocation of HDA9 in response to heat stress is conserved in wheat and rice, which confers the mechanism significant implication potential for crop breeding to cope with global climate warming.

Soluplus-Mediated Diosgenin Amorphous Solid Dispersion with High Solubility and High Stability: Development, Characterization and Oral Bioavailability.

BACKGROUND AND PURPOSE: The traditional Chinese medicine, diosgenin (Dio), has attracted increasing attention because it possesses various therapeutic effects, including anti-tumor, anti-infective and anti-allergic properties. However, the commercial application of Dio is limited by its extremely low aqueous solubility and inferior bioavailability in vivo. Soluplus, a novel excipient, has great solubilization and capacity of crystallization inhibition. The purpose of this study was to prepare Soluplus-mediated Dio amorphous solid dispersions (ASDs) to improve its solubility, bioavailability and stability. METHODS: The crystallization inhibition studies were firstly carried out to select excipients using a solvent shift method. According to solubility and dissolution results, the preparation methods and the ratios of drug to excipient were further optimized. The interaction between Dio and Soluplus was characterized by differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and molecular docking. The pharmacokinetic study was conducted to explore the potential of Dio ASDs for oral administration. Furthermore, the long-term stability of Dio ASDs was also investigated. RESULTS: Soluplus was preliminarily selected from various excipients because of its potential to improve solubility and stability. The optimized ASDs significantly improved the aqueous solubility of Dio due to its amorphization and the molecular interactions between Dio and Soluplus, as evidenced by dissolution test in vitro, DSC, FT-IR spectroscopy, SEM, PXRD and molecular docking technique. Furthermore, pharmacokinetic studies in rats revealed that the bioavailability of Dio from ASDs was improved about 5 times. In addition, Dio ASDs were stable when stored at 40°C and 75% humidity for 6 months. CONCLUSION: These results indicated that Dio ASDs, with its high solubility, high bioavailability and high stability, would open a promising way in pharmaceutical applications.

BZR1 Family Transcription Factors Function Redundantly and Indispensably in BR Signaling but Exhibit BRI1-Independent Function in Regulating Anther Development in Arabidopsis.

BRASSINAZOLE-RESISTANT 1 family proteins (BZRs) are central transcription factors that govern brassinosteroid (BR)-regulated gene expression and plant growth. However, it is unclear whether there exists a BZR-independent pathway that mediates BR signaling. In this study, we found that disruption of all BZRs in Arabidopsis generated a hextuple mutant (bzr-h) displaying vegetative growth phenotypes that were almost identical to those of the null mutant of three BR receptors, bri1brl1brl3 (bri-t). By RNA sequencing, we found that global gene expression in bzr-h was unaffected by 2 h of BR treatment. The anthers of bzr-h plants were loculeless, but a similar phenotype was not observed in bri-t, suggesting that BZRs have a BR signaling-independent regulatory role in anther development. By real-time PCR and in situ hybridization, we found that the expression of SPOROCYTELESS (SPL), which encodes a transcription factor essential for anther locule development, was barely detectable in bzr-h, suggesting that BZRs regulate locule development by affecting SPL expression. Our findings reveal that BZRs are indispensable transcription factors required for both BR signaling and anther locule development, providing new insight into the molecular mechanisms underlying the microsporogenesis in Arabidopsis.

Preparation and Evaluation of Diosgenin Nanocrystals to Improve Oral Bioavailability.

Diosgenin (DSG), a well-known steroid sapogenin derived from Dioscorea nipponica Makino and Dioscorea zingiberensis Wright, has a variety of bioactivities. However, it shows low oral bioavailability due to poor aqueous solubility and strong hydrophobicity. The present study aimed to develop DSG nanocrystals to increase the dissolution and then improve the oral bioavailability and biopharmaceutical properties of DSG. DSG nanocrystals were prepared by the media milling method using a combination of pluronic F127 and sodium dodecyl sulfate as surface stabilizers. The physicochemical properties of the optimal DSG nanocrystals were characterized using their particle size distribution, morphology, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy data, and solubility and dissolution test results. Pharmacokinetic studies of the DSG coarse suspension and its nanocrystals were performed in rats. The particle size and polydispersity index of DSG nanocrystals were 229.0 ± 3.7 nm and 0.163 ± 0.064, respectively. DSG retained its original crystalline state during the manufacturing process, and its chemical structure was not compromised by the nanonizing process. The dissolution rate of the freeze-dried DSG nanocrystals was significantly improved in comparison with the original DSG. The pharmacokinetic studies showed that the AUC0-72h and C max of DSG nanocrystals increased markedly (p < 0.01) in comparison with the DSG coarse suspension by about 2.55- and 2.01-fold, respectively. The use of optimized nanocrystals is a good and efficient strategy for oral administration of DSG due to the increased dissolution rate and oral bioavailability of DSG nanocrystals.

The pharmacokinetic study on the mechanism of toxicity attenuation of rhubarb total free anthraquinone oral colon-specific drug delivery system.

Rhubarb is commonly used as laxatives in Asian countries, of which anthraquinones are the major active ingredients, but there are an increased number of concerns regarding the nephrotoxicity of anthraquinones. In this study, we compared the pharmacokinetic characteristics of rhubarb anthraquinones in rats after orally administered with rhubarb and rhubarb total free anthraquinone oral colon-specific drug delivery granules (RTFA-OCDD-GN), and then explained why these granules could reduce the nephrotoxicity of anthraquinones when they produced purgative efficacy. A sensitive and reliable high performance liquid chromatography (HPLC) method has been fully validated for simultaneous determination of the five active components of rhubarb, and successfully applied to investigate and compare the remarkable differences in pharmacokinetic study of rhubarb anthraquinones after orally administered with rhubarb and RTFA-OCDD-GN. The results showed that, compared with rhubarb group, the AUC, Cmax, t1/2z and Vz/F of aloe-emodin, rhein, emodin and chrysophanol in rats receiving the RTFA-OCDD-GN were significantly decreased, and the Tmax of the four analytes was prolonged. Moreover, the Tmax of rhein, the Cmax of chrysophanol and emodin all have significant differences (P<0.05). Simultaneously, anthraquinone prototype excretion rates in urine and feces of aloe-emodin, rhein, emodin, chrysophanol and physcion were all increased. These findings suggested that oral colon-specific drug delivery technology made anthraquinone aglycone to colon-specific release after oral administration. This allowed anthraquinones to not only play the corresponding purgative effect but also avoid intestinal absorption and promote excretion. And thereby greatly reduced the nephrotoxicity of rhubarb. The result is a new breakthrough in rhubarb toxicity attenuated research.

Design and evaluation of San-huang dispersible tablet--an efficient delivery system for Traditional Chinese Medicine.

San-huang dispersible tablet (SHDT) was designed with a patented technology to enrich the active ingredients in rhubarb and with a wide selection of excipients in the new manufacturing procedure. The total rhubarb anthraquinones were first enriched in the extract by our patented technology. Eudragit L100, S100 and PEG-6000 were used to release a part of the total rhubarb anthraquinones at the colon to induce the cathartic effect of the anthraquinones by another patented technology. Microcrystalline Cellulose (MCC), low-substituted hydroxypropyl cellulose (L-HPC), sodium carboxymethyl starch (CMS-Na), and hydroxypropyl methylcellulose (HPMC) were used to ensure quick release of baicalin and berberine hydrochloride in the stomach. The dissolution of SHDT was evaluated by a method in 2005 Chinese Pharmacopoeia along with San-huang tablet (SHT), and the results demonstrated that the dissolution of baicalin and berberine hydrochloride more than double that of SHT and release of half of the rhubarb anthraquinones in colon.