ALBERT

Description: Soils are among the important sources of atmospheric nitric oxide (NO) and nitrous oxide (N 2 O), acting as a critical role in atmospheric chemistry. Updated data derived from 114 peer-reviewed publications with 520 field measurements were synthesized using meta-analysis procedure to examine the N fertilizer-induced soil NO and the combined with N 2 O (NO+N 2 O) emissions across global soils. Besides factors identified in earlier reviews, additional factors responsible for NO fluxes were fertilizer type, soil C/N ratio, crop residue incorporation, tillage, atmospheric carbon dioxide concentration, drought and biomass burning. When averaged across all measurements, soil NO-N fluxes were estimated to be 4.06 kg ha -1 yr -1 , with the greatest (9.75 kg ha -1 yr -1 ) in vegetable croplands and the lowest (0.11 kg ha -1 yr -1 ) in rice paddies. Soil NO emissions were more enhanced by synthetic N fertilizer (+38%), relative to organic (+20%) or mixed N (+18%) sources. Compared with synthetic N fertilizer alone, synthetic N fertilizer combined with nitrification inhibitors substantially reduced soil NO emissions by 81%. The global mean direct emission factors of N fertilizer for NO (EF NO ) and combined NO+N 2 O (EF c ) were estimated to be 1.16% and 2.58%, with 95% confidence intervals of 0.71–1.61% and 1.81–3.35%, respectively. Forests had the greatest EF NO (2.39%). Within the croplands, the EF NO (1.71%) and EF c (4.13%) were the greatest in vegetable cropping fields. Among different chemical N fertilizer varieties, ammonium nitrate had the greatest EF NO (2.93%) and EF c (5.97%). Some options such as organic instead of synthetic N fertilizer, decreasing N fertilizer input rate, nitrification inhibitor, and low irrigation frequency could be adopted to mitigate soil NO emissions. More field measurements over multi-years are highly needed to minimize the estimate uncertainties and mitigate soil NO emissions, particularly in forests and vegetable croplands. This article is protected by copyright. All rights reserved.

Description: Evapotranspiration (ET) and canopy wetness were measured over a two-year intensive field campaign at the Chi-Lan Mountain cloud forest site in Taiwan. Eddy-covariance and sap flow methods were applied to measure ET and tree sap flow of the endemic yellow cypress ( Chamaecyparis obtusa var. formosana ). ET was 553 mm yr -1 over the study period with an annual rainfall and fog deposition of 4893 and 288 mm yr -1 , respectively. The duration of canopy wetness exceeded actual fog or rain events (mostly in the afternoon) and the intercepted water was evaporated later in the following dry morning. The cumulative wet duration accounted for 52% of time over the study period, which was longer than the duration of rainfall and fog altogether (41%). As it adapted to the extremely moist environment, the yellow cypress behaved in a wet-enhanced/dry-reduced water use strategy and was sensitive to short periods of dry atmosphere with high evaporation potential. During dry days, the sap flow rate rose quickly after dawn and led to conservative water use through midday and the afternoon. During periodically wet days, the canopy was mostly wetted in the morning and the interception evaporation contributed largely to the morning ET. The initiation of morning sap flow was postponed 1-3 hours and the sap flow rate tended to peak later at midday. The midday canopy conductance was higher in the periodically wet days (10.6 mm s -1 ) as compared to 7.6 mm s -1 in the dry days. Consequently, the dry-reduced water use strategy led to much lower annual ET with respect to the available energy (~46%) and high precipitation input (~11%). The moist-adapted ecohydrology we report reveals the vulnerability of montane cloud forests to prolonged fog-free periods. More research is urgently needed to better understand the resilience of these ecosystems and formulate adaptive management plans. Copyright © 2012 John Wiley & Sons, Ltd.

Description: Three new metal-organic coordination polymers, namely, [Zn(μ 2 -BiImQuin)(OAc) 2 ] · H 2 O ( 1 ), [Zn(μ 2 -BiImQuin) 2 (H 2 O) 2 ] 2 · 4Cl · H 2 O ( 2 ), and [Mn(μ 2 -BiImQuin) 2 (N 3 ) 2 ] · 4H 2 O ( 3 ) were prepared by reaction of the corresponding transition metal salt with new rigid ligand 2,3-bisimidazol-1-ylquinoxaline ( L ) with diffusion or solution methods (BiImQuin = 2,3-bisimidazol-1-ylquinoxaline). All the complexes were characterized by elemental analysis, IR, TGA, PXRD, and single crystal X-ray diffraction determination. A one-dimensional single chain was observed in complex 1 , however one-dimensional bead-like double chains were observed in complexes 2 and 3 . In the three complexes, the rigid didentate ligands bridged the metal ions into similar “zigzag” chain, and two “zigzag” chains are arranged into bead-like double chain in complexes 2 and 3 , where each metal ion is coordinated with four different didentate BiImQuin rather than two. On the other hand, the anions do great influence on the final supramolecular structure through coordination behavior and hydrogen-bonding interactions. The complexes 1 and 2 display strong room temperature photoluminescence in visible region, which may be assigned to ligand-to-metal charge-transfer.

Description: Clinical studies have shown that the tyrosine kinase inhibitor STI571 effectively controls BCR-ABL–positive chronic myelogenous leukemia (CML). However, disease progression while on STI571 therapy has been reported, suggesting de novo or intrinsic resistance to BCR-ABL–targeted therapy. To investigate possible mediators of acquired STI571 resistance, K562 cells resistant to 5 μM STI571 (K562-R) were cloned and compared to the parental cell population. K562-R cells had reduced BCR-ABL expression and limited activation of BCR-ABL signaling cascades (Stat 5, CrkL, MAPK). STI571 failed to activate caspase cascades or to suppress expression of survival genes (bcl-xL) in resistant cells. Gene sequencing and tyrosine kinase activity measurements demonstrated that K562-R cells retained wild-type and active BCR-ABL tyrosine kinase that was inhibitable by in vitro incubation with STI571, suggesting that BCR-ABL was not coupled to proliferation or survival of K562-R cells. The src-related kinase LYN was highly overexpressed and activated in K562-R cells, and its inhibition reduced proliferation and survival of K562-R cells while having limited effects of K562 cells. Specimens taken from patients with advanced CML that progressed on STI571 therapy also were analyzed for LYN kinase expression, and they were found to be elevated to a level similar to that of K562-R cells. Comparison of samples from patients taken prior to and following STI571 failure suggested that expression and/or activation of LYN/HCK occurs during disease progression. Together, these results suggest that acquired STI571 resistance may be associated with BCR-ABL independence and mediated in part through overexpression of other tyrosine kinases.

Description: The tyrosine kinase inhibitor imatinib mesylate (Gleevec) is effective in controlling BCR-ABL expressing leukemias but resistance occurs in some early phase patients while it is more common in advanced disease. Resistance has been generally associated with mutations in the BCR-ABL kinase that effect drug affinity. However patients are also increasingly reported to fail imatinib therapy while retaining wild-type BCR-ABL expression. Our previous studies suggested a role for Lyn, a Src-related kinase, in imatinib resistance. K562 cells selected for imatinib resistance (K562R) overexpress Lyn kinase and its targeted silencing overcomes imatinib resistance and engages apoptosis. Overexpression of Lyn in K562 cells reduces imatinib sensitivity (3-fold) and patients that fail imatinib therapy in the absence of BCR-ABL mutations express a highly activated Lyn kinase that is not suppressed by imatinib. Silencing Lyn expression in patient specimens induces changes in cell survival that are proportional to the level of Lyn protein reduction. To understand the role of Lyn kinase in imatinib resistance and apoptosis we examined proteins associated with this kinase in imatinib resistant cell lines, leukemic cells overexpressing Lyn and specimens derived from imatinib resistant patients. Lyn overexpression blocked complete suppression of BCR-ABL tyrosine phosphorylation by imatinib and affected BCR-ABL signaling adaptors. Although BCR-ABL forms a stable complex with the leukemogenic-critical adaptor protein Gab2 in imatinib sensitive cells, Lyn overexpression resulted in the formation of Lyn:Gab2 complexed in resistant cells. BCR-ABL kinase inhibition failed to reduce tyrosine phosphorylation of Gab2 in these cells while Lyn silencing or kinase inhibition (with dasatinib) completely suppressed Gab2 tyrosine phosphorylation and correlated with the induction of apoptosis. Lyn silencing in K562R cells also lead to a reciprocal increase in the tyrosine phosphorylation and association with a protein of ~120kDa, identified as the E3 ligase, c-Cbl. Lyn overexpression in K562 cells reduced their imatinib sensitivity and reduced c-Cbl protein levels. Kinase inhibitor and co-transfection studies demonstrated that tyrosine phosphorylation of c-Cbl at a critical signaling site (Y774) is primarily controlled by BCR-ABL and deletion or mutation of the c-Cbl RING domain altered its BCR-ABL phosphorylation. These results suggest that c-Cbl complexes are regulated at both the protein and phosphorylation level by Lyn and BCR-ABL kinase activities, respectively. Overexpression and/or activation of Lyn may disrupt the balance and regulation of critical regulators of leukemogenic signaling (Gab2) or protein trafficking and stability (c-Cbl), resulting in increased cell survival and reduced responsiveness to BCR-ABL kinase inhibition. We conclude that Lyn alters the level and function of critical signaling adaptor proteins in CML cells.

Description: Imatinib mesylate (Gleevec) is effective therapy against Philadelphia chromosome–positive leukemia, but resistance develops in all phases of the disease. Bcr/Abl point mutations and other alterations reduce the kinase inhibitory activity of imatinib mesylate; thus, agents that target Bcr/Abl through unique mechanisms may be needed. Here we describe the activity of WP1130, a small molecule that specifically and rapidly down-regulates both wild-type and mutant Bcr/Abl protein without affecting bcr/abl gene expression in chronic myelogenous leukemia (CML) cells. Loss of Bcr/Abl protein correlated with the onset of apoptosis and reduced phosphorylation of Bcr/Abl substrates. WP1130 did not affect Hsp90/Hsp70 ratios within the cells and did not require the participation of the proteasomal pathway for loss of Bcr/Abl protein. WP1130 was more effective in reducing leukemic versus normal hematopoietic colony formation and strongly inhibited colony formation of cells derived from patients with T315I mutant Bcr/Abl–expressing CML in blast crisis. WP1130 suppressed the growth of K562 heterotransplanted tumors as well as both wild-type Bcr/Abl and T315I mutant Bcr/Abl–expressing BaF/3 cells transplanted into nude mice. Collectively, our results demonstrate that WP1130 reduces wild-type and T315I mutant Bcr/Abl protein levels in CML cells through a unique mechanism and may be useful in treating CML.

Description: SETD2, the histone H3 lysine 36 methyltransferase, previously identified by us, plays an important role in the pathogenesis of hematologic malignancies, but its role in myelodysplastic syndromes (MDSs) has been unclear. In this study, low expression of SETD2 correlated with shortened survival in patients with MDS, and the SETD2 levels in CD34+ bone marrow cells of those patients were increased by decitabine. We knocked out Setd2 in NUP98-HOXD13 (NHD13) transgenic mice, which phenocopies human MDS, and found that loss of Setd2 accelerated the transformation of MDS into acute myeloid leukemia (AML). Loss of Setd2 enhanced the ability of NHD13+ hematopoietic stem and progenitor cells (HSPCs) to self-renew, with increased symmetric self-renewal division and decreased differentiation and cell death. The growth of MDS-associated leukemia cells was inhibited though increasing the H3K36me3 level by using epigenetic modifying drugs. Furthermore, Setd2 deficiency upregulated hematopoietic stem cell signaling and downregulated myeloid differentiation pathways in the NHD13+ HSPCs. Our RNA-seq and chromatin immunoprecipitation–seq analysis indicated that S100a9, the S100 calcium-binding protein, is a target gene of Setd2 and that the addition of recombinant S100a9 weakens the effect of Setd2 deficiency in the NHD13+ HSPCs. In contrast, downregulation of S100a9 leads to decreases of its downstream targets, including Ikba and Jnk, which influence the self-renewal and differentiation of HSPCs. Therefore, our results demonstrated that SETD2 deficiency predicts poor prognosis in MDS and promotes the transformation of MDS into AML, which provides a potential therapeutic target for MDS-associated acute leukemia.

Description: BCR-ABL is an unregulated tyrosine kinase expressed as a consequence of chromosomal translocation in chronic myelogenous leukemia (CML). The tyrosine kinase activity of BCR-ABL activates signaling cascades that induce cytokine independence and transformation of myeloid progenitor cells. Targeted inhibition of this kinase with specific inhibitors (imatinib or BMS-354825) is a very effective therapy for some CML patients but resistance to these agents (through point mutations and other mechanisms) leads to advanced disease with very few therapeutic options. An alternate therapeutic strategy is to reduce BCR-ABL expression or its critical downstream signaling elements important for transformation. We examined BCR-ABL signaling elements and gene expression changes that occur in CML cells following kinase inhibition by imatinib in newly established imatinib sensitive and resistant cells to identify critical signaling elements involved in CML cell death. Imatinib rapidly and progressively suppressed c-myc expression in imatinib sensitive but not resistant cells prior to the onset of apoptosis. These results suggested that c-myc expression was regulated by BCR-ABL signaling and may play a role in CML tumorigenicity. To confirm a role for c-myc in CML cell growth and/or survival, c-myc expression was specifically down-regulated by siRNA using a novel electroporation instrument (AMAXA) that permits high level gene transfer with limited toxicity in CML cell lines. Jak2 siRNA was used as a control. c-myc, but not Jak2 siRNA, suppressed c-myc expression and cell growth and survival in both imatinib sensitive and resistant CML cells, suggesting that targeted suppression of c-myc may have therapeutic activity against both kinase inhibitor sensitive and resistant CML cells. Since the tyrphostin AG490 was previously shown to inhibit c-myc expression in CML cells through its inhibitory effects on Jak2, we screened a series of 〉 200 AG490 derivatives for their ability to rapidly reduce c-myc expression in hematological malignancies. After several rounds of testing we synthesized an agent (WP-1066) capable of rapid c-myc downregulation (beginning 1–5 min after treatment with 1–2 microM) but poor Jak2 kinase inhibitory activity (IC50 〉 100 microM). These results suggested a more direct effect of WP-1066 on c-myc protein expression than AG490 and mechanistic studies suggest that WP-1066 reduces c-myc protein stability but does not affect c-myc gene expression. In BCR-ABL expressing cells WP-1066 rapidly reduced c-myc protein levels in CML cells and inhibited the growth and survival of cell lines or patient specimens expressing wild-type or mutant forms of BCR-ABL that effect tyrosine kinase inhibitory activity (T315I in BV-173R cells). Equal concentrations of imatinib or WP-1066 reduced BCR-ABL activation and downstream signaling (Stat5 phosphorylation) in CML cells. However, WP-1066 differed from imatinib in its ability to downregulate BCR-ABL protein expression without affects on c-abl or Stat5 expression. Similar results were obtained in clinical specimens taken from patients with BCR-ABL point mutations that mediate imatinib (or BMS-354825) resistance. Nude mouse studies demonstrated that WP-1066 reduced the growth of K562 tumors to an extent similar to that of imatinib. Together these results suggest that WP-1066 downregulates BCR-ABL and c-myc expression, induces apoptosis in CML cells expressing wild-type or mutant BCR-ABL and may have therapeutic activity in imatinib (or BMS-354825) resistant CML tumors.