Publications by authors named "Shijun Ma"

9 Publications

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The potential roles of different metacaspases in maize defense response.

Plant Signal Behav 2021 Jun 12;16(6):1906574. Epub 2021 Apr 12.

The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, PR China.

Metacaspases (MCs), a class of cysteine-dependent proteases, act as important regulators in plant defense response. In maize genome, there are 11 which have been categorized into two types (type I and II) based on their structural differences. In this study, we investigated the different transcript patterns of 11 in maize defense response mediated by the nucleotide-binding, leucine-rich-repeat protein Rp1-D21. We further predicted that many -elements responsive to salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA) and auxin were identified in the promoter regions of , and several different transcription factors were predicted to bind to their promoters. We analyzed the localization of with previously identified quantitative trait loci (QTLs) in maize disease resistance, and found that all other , except for , are co-located with at least one QTL associated with disease resistance to southern leaf blight, northern leaf blight, gray leaf spot or ear rot. Based on previous RNA-seq analysis, different display different transcript levels in response to and . All the results imply that the members of might have differential functions to different maize diseases. This study lays the basis for further investigating the roles of in maize disease resistance.
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http://dx.doi.org/10.1080/15592324.2021.1906574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143262PMC
June 2021

Maize metacaspases modulate the defense response mediated by the NLR protein Rp1-D21 likely by affecting its subcellular localization.

Plant J 2021 01 20;105(1):151-166. Epub 2020 Nov 20.

The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, 266237, PR China.

Plants usually employ resistance (R) genes to defend against the infection of pathogens, and most R genes encode intracellular nucleotide-binding, leucine-rich repeat (NLR) proteins. The recognition between R proteins and their cognate pathogens often triggers a rapid localized cell death at the pathogen infection sites, termed the hypersensitive response (HR). Metacaspases (MCs) belong to a cysteine protease family, structurally related to metazoan caspases. MCs play crucial roles in plant immunity. However, the underlying molecular mechanism and the link between MCs and NLR-mediated HR are not clear. In this study, we systematically investigated the MC gene family in maize and identified 11 ZmMCs belonging to two types. Further functional analysis showed that the type I ZmMC1 and ZmMC2, but not the type II ZmMC9, suppress the HR-inducing activity of the autoactive NLR protein Rp1-D21 and of its N-terminal coiled-coil (CC ) signaling domain when transiently expressed in Nicotiana benthamiana. ZmMC1 and ZmMC2 physically associate with CC in vivo. We further showed that ZmMC1 and ZmMC2, but not ZmMC9, are predominantly localized in a punctate distribution in both N. benthamiana and maize (Zea mays) protoplasts. Furthermore, the co-expression of ZmMC1 and ZmMC2 with Rp1-D21 and CC causes their re-distribution from being uniformly distributed in the nucleocytoplasm to a punctate distribution co-localizing with ZmMC1 and ZmMC2. We reveal a novel role of plant MCs in modulating the NLR-mediated defense response and derive a model to explain it.
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http://dx.doi.org/10.1111/tpj.15047DOI Listing
January 2021

Estimating Physical Composition of Municipal Solid Waste in China by Applying Artificial Neural Network Method.

Environ Sci Technol 2020 08 17;54(15):9609-9617. Epub 2020 Jul 17.

State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Physical composition of municipal solid waste (PCMSW) is the fundamental parameter in domestic waste management; however, high fidelity, wide coverage, upscaling, and year continuous data sets of PCMSW in China are insufficient. A traceable and predictable methodology for estimating PCMSW in China is established for the first time by analyzing 503 PCMSW data sets of 135 prefecture-level cities in China. A hyperspherical transformation method was used to eliminate the constant sum constraint in statistically analyzing PCMSW data. Moreover, a back-propagation (BP) neural network methodology was applied to establish quantitative models between city-level PCMSW and its socio-economic factors, including city size, per capita gross regional product, geographical location, gas coverage rate, and year. Results show that (1) national-level PCMSW in 2017 was estimated as organic fraction (53.7%), ash and stone (8.3%), paper (16.9%), plastic and rubber (13.6%), textile (2.3%), wood (2.2%), metal (0.6%), glass (1.5%), and others (1.0%); (2) organic fraction, paper, and plastics showed an increasing trend from 1990 to 2017, while ash and stone decreased significantly; (3) organic fractions in East, North, and Central-South China were higher than those in other regions. This enables us to fill the data gap in the practice of municipal solid waste management in China.
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http://dx.doi.org/10.1021/acs.est.0c01802DOI Listing
August 2020

Maize ZmFNSI Homologs Interact with an NLR Protein to Modulate Hypersensitive Response.

Int J Mol Sci 2020 Apr 5;21(7). Epub 2020 Apr 5.

The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China.

Nucleotide binding, leucine-rich-repeat (NLR) proteins are the major class of resistance (R) proteins used by plants to defend against pathogen infection. The recognition between NLRs and their cognate pathogen effectors usually triggers a rapid localized cell death, termed the hypersensitive response (HR). Flavone synthase I (FNSI) is one of the key enzymes in the flavone biosynthesis pathway. It also displays salicylic acid (SA) 5-hydroxylase (S5H) activity. A close homolog of FNSI/S5H displays SA 3-hydroxylase (S3H) activity. Both FNSI/S5H and S3H play important roles in plant innate immunity. However, the underlying molecular mechanisms and the relationship between S5H and S3H with the NLR-mediated HR are not known in any plant species. In this study, we identified three genes encoding ZmFNSI-1, ZmFNSI-2 and ZmS3H that are significantly upregulated in a maize line carrying an autoactive NLR mutant. Functional analysis showed that ZmFNSI-1 and ZmFNSI-2, but not ZmS3H, suppressed HR conferred by Rp1-D21 and its signaling domain CC when transiently expressed in . ZmFNSI-1 and ZmFNSI-2 physically interacted with CC. Furthermore, ZmFNSI-1 and ZmFNSI-2 interacted with HCT, a key enzyme in lignin biosynthesis pathway, which can also suppress Rp1-D21-mediated HR. These results lay the foundation for the further functional analysis of the roles of FNSI in plant innate immunity.
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http://dx.doi.org/10.3390/ijms21072529DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177559PMC
April 2020

Recycling sustainability of waste paper industry in Beijing City: An analysis based on value chain and GIS model.

Waste Manag 2020 Apr 18;106:62-70. Epub 2020 Mar 18.

Stake Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

China established a self-organized and market-driven recycling system, which was dominated by the informal sectors. In recent years, the amount of domestically-recycled waste paper grew slower than expectation in China, which may be resulted from a decline in economic sustainability of current recycling system. For understanding the waste paper recycling system in most cities in China, the economic mechanism remains unclear and the city-level data is extremely insufficient. In this work, an index of recycling sustainability (IRS, benefit divided by cost) is analyzed with a resolution of 1 km grid in Beijing City, by adopting value chain and GIS methodology. Five degrees of IRS are defined, from high-degree (IRS > 1.10) to low-degree (IRS < 0.95). Different stakeholders in the informal waste paper recycling system were interviewed to fill the data gap. Results show that: (1) from 2015 to 2018, the informal recycling of waste paper accounted for approximate 80% in Beijing; (2) the number of informal recyclables distribution sites decreased from 27 to 11, and their average distance to the city-center rose from 27.5 km to 40.9 km; (3) in 2015 and 2018, the grids with high-degree IRS accounted for 99.5% and 89.2%, respectively, indicating a sustainable waste paper recycling industry in Beijing; and (4) according to the scenario analysis, if the operating cost rises by 30%, the grids with low-degree IRS accounts for 98.5%, indicating a nontrivial challenges when the recycling cost keeps increasing in the future. Policy recommendations are put forward for a more sustainable paper waste recycling system in China.
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http://dx.doi.org/10.1016/j.wasman.2020.03.013DOI Listing
April 2020

MnSOD mediates shear stress-promoted tumor cell migration and adhesion.

Free Radic Biol Med 2018 12 5;129:46-58. Epub 2018 Sep 5.

Faculty of Health Sciences, University of Macau, Taipa, Macau, China. Electronic address:

Circulation of cancer cells in the bloodstream is a vital step for distant metastasis, during which cancer cells are exposed to hemodynamic shear stress (SS). The actions of SS on tumor cells are complicated and not fully understood. We previously reported that fluidic SS was able to promote migration of breast cancer cells by elevating the cellular ROS level. In this study, we further investigated the mechanisms regulating SS-promoted cell migration and identified the role of MnSOD in the related pathway. We found that SS could enhance tumor cell adhesion to extracellular matrix and endothelial monolayer, and MnSOD also regulated this process. Briefly, SS stimulates the generation of mitochondrial superoxide in tumor cells. MnSOD then converts superoxide into hydrogen peroxide, which activates ERK1/2 to promote tumor cell migration and activates FAK to promote tumor cell adhesion. Combining our previous and present studies, we present experimental evidence on the pro-metastatic effects of hemodynamic SS and reveal the underlying mechanism. Our findings provide new insights into the nature of cancer metastasis and the understanding of tumor cell responses to external stresses and have valuable implications for cancer therapy development.
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http://dx.doi.org/10.1016/j.freeradbiomed.2018.09.004DOI Listing
December 2018

Hemodynamic shear stress stimulates migration and extravasation of tumor cells by elevating cellular oxidative level.

Cancer Lett 2017 03 10;388:239-248. Epub 2016 Dec 10.

Faculty of Health Sciences, University of Macau, Taipa, Macau, China. Electronic address:

Cancer cells are shed into the blood stream and are exposed to hemodynamic shear stress during metastasis. It has been shown that shear stress can destroy circulating tumor cells (CTCs) both in vitro and in vivo. However, it remains unclear whether shear stress can modulate the properties and functions of tumor cells in a manner that might help CTCs to exit circulation. In this study, we established a microfluidic circulatory system to apply physiological fluid shear stress on breast cancer cells and demonstrated that an arterial level of shear stress significantly enhanced tumor cell migration in transwell and wound healing assays, and enhanced extravasation in a transendothelial assay. Circulatory treatment elevated the intracellular levels of reactive oxygen species (ROS), which is an early and indispensable event for activating the extracellular signal-regulated kinases (ERK1/2). Subsequently, ERK1/2 activation promoted the migration of tumor cells and enhanced their extravasation. Finally, reducing cellular ROS production suppressed tumor cell extravasation in both a transendothelial assay and a zebrafish model. This new understanding of how fluid shear stress promotes tumor cell migration has important implications in cancer treatment and can help us to identify potential therapeutic targets for inhibiting tumor progression.
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http://dx.doi.org/10.1016/j.canlet.2016.12.001DOI Listing
March 2017

High expression of MnSOD promotes survival of circulating breast cancer cells and increases their resistance to doxorubicin.

Oncotarget 2016 Aug;7(31):50239-50257

Faculty of Health Sciences, University of Macau, Taipa, Macau, China.

Understanding the survival mechanism of metastatic cancer cells in circulation will provide new perspectives on metastasis prevention and also shed new light on metastasis-derived drug resistance. In this study, we made it feasible to detect apoptosis of circulating tumor cells (CTCs) in real-time by integrating a fluorescence resonance energy transfer (FRET)-based caspase sensor into one in vitro microfluidic circulatory system, and two in vivo models: zebrafish circulation and mouse lung metastatic model. Our study demonstrated that fluid shear stresses triggered apoptosis of breast cancer cells in circulation by elevating the mitochondrial production of the primary free radical, superoxide anion. Cancer cells with high levels of manganese superoxide dismutase (MnSOD) exhibited stronger resistance to shear force-induced apoptosis and formed more lung metastases in mice. These metastasized cells further displayed higher resistance to chemotherapeutic agent doxorubicin, which also generates superoxide in mitochondria. Specific siRNA-mediated MnSOD knockdown reversed all three phenotypes. Our findings therefore suggest that MnSOD plays an important integrative role in supporting cancer cell survival in circulation, metastasis, and doxorubicin resistance. MnSOD can serve as a new biomarker for identifying metastatic CTCs and a novel therapeutic target for inhibiting metastasis and destroying doxorubicin-resistant breast cancer cells.
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http://dx.doi.org/10.18632/oncotarget.10360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5226580PMC
August 2016

C2-symmetric proline-derived tetraamine as highly effective catalyst for direct asymmetric Michael addition of ketones to chalcones.

Org Biomol Chem 2012 May 26;10(18):3721-9. Epub 2012 Mar 26.

Department of Chemistry, The Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, China.

A C(2)-symmetric tetraamine catalyst was developed for the asymmetric Michael addition of ketones to chalcones. The corresponding adducts 1,5-dicarbonyl compounds were obtained in good chemical yields with high levels of diastereo- and enantioselectivities (up to >99 : 1 dr and 93% ee) under mild conditions. By studying the ESI-MS of the intermediates, a proposed mechanism was disclosed.
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http://dx.doi.org/10.1039/c2ob06897dDOI Listing
May 2012