The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base edit...The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.展开更多
Myelination is an essential feature of the vertebrate nervous system that provides electrical insulation to axons,thereby facilitating the transmission of nerve impulses.Deficiencies in myelination in diseases such as...Myelination is an essential feature of the vertebrate nervous system that provides electrical insulation to axons,thereby facilitating the transmission of nerve impulses.Deficiencies in myelination in diseases such as multiple sclerosis（MS）lead to serious neurological disorders.展开更多
This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type ...This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type microchannel from two inlets.The transfer function for the Y-type microchannel is given by solving the governing equation for the Taylor-Aris dispersion in the microchannel. The amplitude-frequency and phase-frequency relations are provided which show that a shallow Y-type microchannel acts as a low-pass filter. The transports of different dynamic biochemical signals are investigated. In comparison with a fully mixing microfluidic channel, the magnitudes of the dynamic signals at the outlets in a Y-type microchannel are much smaller than those in a fully mixing microchannel, which demonstrates that the amplitude attenuation in a Y-type microchannel is larger than that of a fully mixing microchannel due to the transverse molecular diffusion. In order to control the desired signal in a microchannel, the solution of the inverse problem for the channel is also presented.展开更多
The effects of Sonic hedgehog(Shh) signaling pathway activation on S-type neuroblastoma(NB) cell lines and its role in NB tumorigenesis were investigated.Immunohistochemistry was used to detect the expression of Shh p...The effects of Sonic hedgehog(Shh) signaling pathway activation on S-type neuroblastoma(NB) cell lines and its role in NB tumorigenesis were investigated.Immunohistochemistry was used to detect the expression of Shh pathway components— Patched1(PTCH1) and Gli1 in 40 human primary NB samples.Western blotting and RT-PCR were used to examine the protein expression and mRNA levels of PTCH1 and Gli1 in three kinds of S-type NB cell lines(SK-N-AS,SK-N-SH and SHEP1),respectively.Exogenous Shh was administrated to activate Shh signaling pathway while cyclopamine was used as a selective antagonist of Shh pathway.S-type NB cell lines were treated with different concentrations of Shh or/and cyclopamine for different durations.Cell viability was measured by using MTT method.Apoptosis rate and cell cycle were assayed by flow cytometry.The xenograft experiments were used to evaluate the role of Shh pathway in tumor growth in immunodeficient mice.High-level expression of PTCH1 and Gli1 was detected in both NB samples and S-type NB cell lines.Cyclopamine decreased the survival rate of the three cell lines while Shh increased it,and the inhibition effects of cyclopamine could be partially reversed by shh pre-treatment.Cyclopamine induced the cell apoptosis and the cell cycle arrest in G0/G1 phase,while Shh induced the reverse effects and could partially prevent effects of cyclopamine.Cyclopamine could also inhibit the growth of NB in vivo.Our studies revealed that activation of the Shh pathway is important for survival and proliferation of S-type NB cells in vivo and in vitro through affecting cell apoptosis and cell cycle,suggesting a new therapeutic approach to NB.展开更多
Ⅰ型神经纤维瘤病(neurofibromatosis type 1,NF1)是一种由NF1基因突变导致的常染色体显性遗传病,以多发皮肤咖啡斑和神经纤维瘤为主要特征,国际上针对NF1尚无规范治疗策略。NF 1基因庞大,其编码的神经纤维蛋白(neurofibromin,NF)参与...Ⅰ型神经纤维瘤病(neurofibromatosis type 1,NF1)是一种由NF1基因突变导致的常染色体显性遗传病,以多发皮肤咖啡斑和神经纤维瘤为主要特征,国际上针对NF1尚无规范治疗策略。NF 1基因庞大,其编码的神经纤维蛋白(neurofibromin,NF)参与细胞增殖调控,该病发病机制复杂,为药物研发带来较大挑战。在NF1信号通路方面,丝裂原活化蛋白激酶的激酶的激酶/丝裂原活化蛋白激酶的激酶/丝裂原活化蛋白激酶通路(RAF/MEK/ERK)、磷脂酰肌醇3激酶/蛋白激酶B/哺乳动物雷帕霉素靶蛋白通路(PI3K/AKT/mTOR)、无翅蛋白/β联蛋白通路(WNT/β-catenin)、河马蛋白/转录共激活子/YES相关蛋白通路(HIPPO/TAZ/YAP)等均有研究,其中针对RAF/MEK/ERK通路的MEK1/2抑制剂药物已上市,即司美替尼(selumetinib),用于治疗NF1和不能手术的丛状神经纤维瘤(plexiform neurofibroma,PNF)患者。近年研究发现,NF1肿瘤微环境包括施万细胞(Schwann cells,SCs)及其前体、肥大细胞、巨噬细胞、T细胞、树突状细胞、细胞外基质和周围血管等,对NF1的发生发展发挥不可忽视的作用。现今NF1的治疗方法包括手术切除肿瘤、放射治疗和药物治疗,这些方法均有缺陷,迫切需要从NF1信号通路及肿瘤微环境等方面继续深入探索新的治疗药物。本文主要综述了NF1相关信号通路及肿瘤微环境的研究现状,重点讨论了NF1基因突变引起的信号通路改变以及肿瘤微环境的组分异常,并剖析了NF1疾病可能的发病机制,以期为临床NF1早期诊断、治疗、预防和药物研发提供新的思路。展开更多
基金supported by the Beijing Scholars Program[BSP041]。
文摘The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.
文摘Myelination is an essential feature of the vertebrate nervous system that provides electrical insulation to axons,thereby facilitating the transmission of nerve impulses.Deficiencies in myelination in diseases such as multiple sclerosis（MS）lead to serious neurological disorders.
基金National Natural Science Foundation of Chinagrant number:11172060the Fundamental Research Funds for the Central Universities in China
文摘This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type microchannel from two inlets.The transfer function for the Y-type microchannel is given by solving the governing equation for the Taylor-Aris dispersion in the microchannel. The amplitude-frequency and phase-frequency relations are provided which show that a shallow Y-type microchannel acts as a low-pass filter. The transports of different dynamic biochemical signals are investigated. In comparison with a fully mixing microfluidic channel, the magnitudes of the dynamic signals at the outlets in a Y-type microchannel are much smaller than those in a fully mixing microchannel, which demonstrates that the amplitude attenuation in a Y-type microchannel is larger than that of a fully mixing microchannel due to the transverse molecular diffusion. In order to control the desired signal in a microchannel, the solution of the inverse problem for the channel is also presented.
基金supported by a grant from the National Natural Sciences Foundation of China (No.30600189)
文摘The effects of Sonic hedgehog(Shh) signaling pathway activation on S-type neuroblastoma(NB) cell lines and its role in NB tumorigenesis were investigated.Immunohistochemistry was used to detect the expression of Shh pathway components— Patched1(PTCH1) and Gli1 in 40 human primary NB samples.Western blotting and RT-PCR were used to examine the protein expression and mRNA levels of PTCH1 and Gli1 in three kinds of S-type NB cell lines(SK-N-AS,SK-N-SH and SHEP1),respectively.Exogenous Shh was administrated to activate Shh signaling pathway while cyclopamine was used as a selective antagonist of Shh pathway.S-type NB cell lines were treated with different concentrations of Shh or/and cyclopamine for different durations.Cell viability was measured by using MTT method.Apoptosis rate and cell cycle were assayed by flow cytometry.The xenograft experiments were used to evaluate the role of Shh pathway in tumor growth in immunodeficient mice.High-level expression of PTCH1 and Gli1 was detected in both NB samples and S-type NB cell lines.Cyclopamine decreased the survival rate of the three cell lines while Shh increased it,and the inhibition effects of cyclopamine could be partially reversed by shh pre-treatment.Cyclopamine induced the cell apoptosis and the cell cycle arrest in G0/G1 phase,while Shh induced the reverse effects and could partially prevent effects of cyclopamine.Cyclopamine could also inhibit the growth of NB in vivo.Our studies revealed that activation of the Shh pathway is important for survival and proliferation of S-type NB cells in vivo and in vitro through affecting cell apoptosis and cell cycle,suggesting a new therapeutic approach to NB.
