RNA N6-methyladenosine modification promotes auxin biosynthesis required for male meiosis in rice.

N6-methyladenosine (m6A) RNA modification confers an essential layer of gene regulation in living organisms, including plants; yet, the underlying mechanisms of its deposition on specific target mRNAs involved in key plant developmental processes are so far unknown. Here, we show that a core component of the rice m6A methyltransferase complex, OsFIP37, is recruited by an RNA-binding protein, OsFIP37-associated protein 1 (OsFAP1), to mediate m6A RNA modification on an auxin biosynthesis gene, OsYUCCA3, during microsporogenesis. This stabilizes OsYUCCA3 mRNA and promotes local auxin biosynthesis in anthers during male meiosis, which is essential for meiotic division and subsequent pollen development in rice. Loss of function of OsFAP1 causes dissociation of OsFIP37 with OsYUCCA3 and the resulting abolished m6A deposition on OsYUCCA3. Our findings reveal that OsFAP1-dependent m6A deposition on OsYUCCA3 by OsFIP37 constitutes a hitherto unknown link between RNA modification and hormonal control of male meiosis in plant reproductive development.

Comparative proteomics analysis reveals the mechanism of fertility alternation of thermosensitive genic male sterile rice lines under low temperature inducement.

Thermosensitive genic male sterile (TGMS) rice line has made great economical contributions in rice production. However, the fertility of TGMS rice line during hybrid seed production is frequently influenced by low temperature, thus leading to its fertility/sterility alteration and hybrid seed production failure. To understand the mechanism of fertility alternation under low temperature inducement, the extracted proteins from young panicles of two TGMS rice lines at the fertility alternation sensitivity stage were analyzed by 2DE. Eighty-three protein spots were found to be significantly changed in abundance, and identified by MALDI-TOF-TOF MS. The identified proteins were involved in 16 metabolic pathways and cellular processes. The young panicles of TGMS rice line Zhu 1S possessed the lower ROS-scavenging, indole-3-acetic acid level, soluble protein, and sugar contents as well as the faster anther wall disintegration than those of TGMS rice line Zhun S. All these major differences might result in that the former is more stable in fertility than the latter. Based on the majority of the 83 identified proteins, together with microstructural, physiological, and biochemical results, a possible fertile alteration mechanism in the young panicles of TGMS rice line under low temperature inducement was proposed. Such a result will help us in breeding TGMS rice lines and production of hybrid seed.

Electrochemical microsensor based on gold nanoparticles modified electrode for total phosphorus determinations in water.

This work mainly describes an electrochemical microsensor based on the reduction of molybdophosphate complex for total phosphorus (TP) determinations in water. The microelectrode was fabricated using microelectromechanical systems (MEMS) techniques and porous, branching gold nanoparticles (AuNPs) were electrodeposited on the microelectrode to improve its sensitivity. Calibration of the microsensor was performed with standard phosphate solutions prepared with KH2PO4 with pH adjusted to 1.0. The experimental results showed that both sensitivity and current response are improved effectively using this modified microelectrodes: The limit of detection of the microsensor is 1.2 x 10(-7) mol/l and linear range is 3 x 10(-7) to 3 x 10(-4) mol/l. The sensitivity of unmodified electrode is -0.27nA/micromol x 1(-1) (R2 = 0.994), whereas the sensitivity of AuNPs modified electrode is -0.89 nA/micromol 1(-1) (R2 = 0.8). The current response of modified electrode is 6 times larger than that of unmodified electrode in average. Detection of TP was also carried out with digested TP standard solutions for both modified and unmodified electrodes, and results were consistent with the nominal value of phosphorus concentration. This microsensor provides the probability of combining TP detection device with micro-digesting device to form a TP detection system, which can realise the automotive and on-line monitoring of TP in surface water.

Arsenic trioxide controls the fate of the PML-RARalpha oncoprotein by directly binding PML.

Arsenic, an ancient drug used in traditional Chinese medicine, has attracted worldwide interest because it shows substantial anticancer activity in patients with acute promyelocytic leukemia (APL). Arsenic trioxide (As2O3) exerts its therapeutic effect by promoting degradation of an oncogenic protein that drives the growth of APL cells, PML-RARalpha (a fusion protein containing sequences from the PML zinc finger protein and retinoic acid receptor alpha). PML and PML-RARalpha degradation is triggered by their SUMOylation, but the mechanism by which As2O3 induces this posttranslational modification is unclear. Here we show that arsenic binds directly to cysteine residues in zinc fingers located within the RBCC domain of PML-RARalpha and PML. Arsenic binding induces PML oligomerization, which increases its interaction with the small ubiquitin-like protein modifier (SUMO)-conjugating enzyme UBC9, resulting in enhanced SUMOylation and degradation. The identification of PML as a direct target of As2O3 provides new insights into the drug's mechanism of action and its specificity for APL.

Treatment of acute promyelocytic leukemia with ATRA and As2O3: a model of molecular target-based cancer therapy.

Most acute promyelocytic leukemia (APL) cases have t(15;17)(q22;q21) chromosomal translocation and PML-RARalpha chimeric gene which blocks granulocytic differentiation. The introduction of all-trans-retinoic acid (ATRA) and arsenic compounds, especially arsenic trioxide (As(2)O(3)), has provided good models to study not only differentiation and/or apoptosis therapy but also molecular target-based cancer treatment. In vivo and in vitro investigations have shown that both agents are able to induce differentiation of APL cells: ATRA tends to induce terminal differentiation, while low-dose As(2)O(3) can induce partial differentiation. Significant progress has been made in understanding the molecular mechanisms of APL pathogenesis and differentiation therapy. Pharmacological concentrations (0.1 approximately 1 microM) of ATRA derepresses transcription by releasing CoR from, and recruiting CoA to PML-RARalpha, whereas As(2)O(3) triggers a rapid degradation of PML-RARalpha. In fact, the two drugs act on the same oncoprotein through targeting different moieties and in distinct ways and thereby abrogate its dominant-negative effects on regulatory pathways necessary for granulocytic differentiation. As to apoptosis, it is clear that high-dose As(2)O(3) can induce mitochondria-mediated cell death pathway in a thiol-dependent manner, while the mechanism of ATRA-induced apoptosis needs further elucidation. Transcriptomic and proteomic analysis are also expected to find new molecular targets. It is the hope that what we have learnt from APL will benefit further developments of anti-leukemia therapy.