CFTR mediates bicarbonate-dependent activation of miR-125b in preimplantation embryo development

Although HCO₃⁻ is known to be required for early embryo development, its exact role remains elusive. Here we report that HCO₃⁻ acts as an environmental cue in regulating miR-125b expression through CFTR-mediated influx during preimplantation embryo development. The results show that the effect of HCO₃⁻ on preimplantation embryo development can be suppressed by interfering the function of a HCO₃⁻-conducting channel, CFTR, by a specific inhibitor or gene knockout. Removal of extracellular HCO₃⁻ or inhibition of CFTR reduces miR-125b expression in 2 cell-stage mouse embryos. Knockdown of miR-125b mimics the effect of HCO₃⁻ removal and CFTR inhibition, while injection of miR-125b precursor reverses it. Downregulation of miR-125b upregulates p53 cascade in both human and mouse embryos. The activation of miR-125b is shown to be mediated by sAC/PKA-dependent nuclear shuttling of NF-κB. These results have revealed a critical role of CFTR in signal transduction linking the environmental HCO₃⁻ to activation of miR-125b during preimplantation embryo development and indicated the importance of ion channels in regulation of miRNAs.     

Involvement of the acid sphingomyelinase pathway in uva-induced apoptosis

The sphingomyelin-ceramide pathway is an evolutionarily conserved ubiquitous signal transduction system that regulates many cell functions including apoptosis. Sphingomyelin (SM) is hydrolyzed to ceramide by different sphingomyelinases. Ceramide serves as a second messenger in mediating cellular effects of cytokines and stress. In this study, we find that acid sphingomyelinase (SMase) activity was induced by UVA in normal JY lymphoblasts but was not detectable in MS1418 lymphoblasts from Niemann-Pick type D patients who have an inherited deficiency of acid SMase. We also provide evidence that UVA can induce apoptosis by activating acid SMase in normal JY cells. In contrast, UVA-induced apoptosis was inhibited in MS1418 cells. Exogenous SMase and its product, ceramide (10-40 micrometer), induced apoptosis in JY and MS1418 cells, but the substrate of SMase, SM (20-80 micrometer), induced apoptosis only in JY cells. These results suggest that UVA-induced apoptosis by SM is dependent on acid SMase activity. We also provide evidence that induction of apoptosis by UVA may occur through activation of JNKs via the acid SMase pathway.     

Regulation of Xenopus oocyte meiosis arrest by G protein betagamma subunits

BACKGROUND: Progesterone induces the resumption of meiosis (maturation) in Xenopus oocytes through a nongenomic mechanism involving inhibition of an oocyte adenylyl cyclase and reduction of intracellular cAMP. However, progesterone action in Xenopus oocytes is not blocked by pertussis toxin, and this finding indicates that the inhibition of the oocyte adenylyl cyclase is not mediated by the alpha subunits of classical G(i)-type G proteins. RESULTS: To investigate the possibility that G protein betagamma subunits, rather than alpha subunits, play a key role in regulating oocyte maturation, we have employed two structurally distinct G protein betagamma scavengers (G(t)alpha and betaARK-C(CAAX)) to sequester free Gbetagamma dimers. We demonstrated that the injection of mRNA encoding either of these Gbetagamma scavengers induced oocyte maturation. The Gbetagamma scavengers bound an endogenous, membrane-associated Gbeta subunit, indistinguishable from Xenopus Gbeta1 derived from mRNA injection. The injection of Xenopus Gbeta1 mRNA, together with bovine Ggamma2 mRNA, elevated oocyte cAMP levels and inhibited progesterone-induced oocyte maturation. CONCLUSION: An endogenous G protein betagamma dimer, likely including Xenopus Gbeta1, is responsible for maintaining oocyte meiosis arrest. Resumption of meiosis is induced by Gbetagamma scavengers in vitro or, naturally, by progesterone via a mechanism that suppresses the release of Gbetagamma.     

药用植物浸提液抑制蛋白核小球藻生长的化感效应

研究了11种药用植物浸提液对水华藻种蛋白核小球藻的影响,结果显示:黄连、重楼、贯众、防己4种药用植物的浸提液均有抑藻效应。当药用植物浸提液的相对浓度为1g/L处理时,其半抑制效应时间LT50的排序为:防己重楼黄连贯众。进一步研究防己的相对浓度梯度抑藻效应,结果表明:在相对浓度为2g/L时,实验3d后的藻细胞几乎全部死亡;防己的抑藻效应受贮藏时间和贮藏温度的影响不显著。在所研究的药用植物中,防己的抑藻效果最好,在抑藻方面有较大应用前景,其它3种药用植物对轻度藻类爆发的控制也有潜在应用价值。     

Construction of a Bacillus thuringiensis engineered strain with high toxicity and broad pesticidal spectrum against coleopteran insects

A newly engineered strain, denominated BIOT185, was constructed through integrating the cry8Ca2 gene into the endogenous plasmid of BT185 (contains cry8Ea1) by homologous recombination. The thermosensitive plasmid vector was eliminated by the rising temperature of recombinant cultures. No antibiotic gene or other unnecessary genes were introduced to the new strain. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis and Western blot analysis demonstrated that the cry8Ca2 gene was expressed normally and produced a 130-kDa protein in the BIOT185 strain. Bioassay results showed that the new strain had high toxicity to the pests Anomala corpulenta and Holotrichia parallela, which often damage the same fields.     

Discovery of GlyT1 inhibitors with improved pharmacokinetic properties

Glycine transporter 1 (GlyT1) represents a novel target for the treatment of schizophrenia via the potentiation of glutamatergic NMDA receptors. The discovery of 4,4-disubstituted piperidine inhibitors of GlyT1 which exhibit improved pharmacokinetic properties, including oral bioavailability, is discussed.     

Synthesis and evaluation of new endomorphin analogues modified at the Pro2 residue

Six new endomorphin analogues, incorporating constrained amino acids in place of native proline have been synthesized. Residues of (S)-azetidine-2-carboxylic acid (Aze), 3,4-dehydro-(S)-proline (Δ³Pro), azetidine-3-carboxylic acid (3Aze) and dehydro-alanine (ΔAla) have been used to prepare [Δ³Pro²]EM-2 (1), [Aze²]EM-1 (2), [Aze²]EM-2 (3), [3Aze²]EM-1 (4), [3Aze²]EM-2 (5) and [ΔAla²]EM-2 (6). Binding assays and functional bioactivities for μ- and δ-receptors are reported. The highest affinity, bioactivity and selectivity are shown by peptides 2 and 3 containing the Aze residue.     

TIN2 protein dyskeratosis congenita missense mutants are defective in association with telomerase

Dyskeratosis congenita (DC) is a progressive and heterogeneous congenital disorder that affects multiple systems and is characterized by bone marrow failure and a triad of abnormal skin pigmentation, nail dystrophy, and oral leukoplakia. One common feature for all DC patients is abnormally short telomeres and defects in telomere biology. Most of the known DC mutations have been found to affect core components of the telomerase holoenzyme. Recently, multiple mutations in the gene encoding the telomeric protein TIN2 have been identified in DC patients with intact telomerase genes, but the molecular mechanisms underlying TIN2 mutation-mediated DC remain unknown. Here, we demonstrate that ectopic expression of TIN2 with DC missense mutations in human cells led to accelerated telomere shortening, similar to the telomere phenotypes found in DC patients. However, this telomere shortening was not accompanied by changes in total telomerase activity, localization of TIN2, or telomere end protection status. Interestingly, we found TIN2 to participate in the TPP1-dependent recruitment of telomerase activity. Furthermore, DC mutations in TIN2 led to its decreased ability to associate with TERC and telomerase activity. Taken together, our data suggest that TIN2 mutations in DC may compromise the telomere recruitment of telomerase, leading to telomere shortening and the associated pathogenesis.